Rule2023-14486
Endangered and Threatened Wildlife and Plants; Threatened Species Status With Section 4(d) Rule for Cactus Ferruginous Pygmy-Owl
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
July 20, 2023
Effective
August 21, 2023
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (Service), determine threatened species status under the Endangered Species Act of 1973 (Act), as amended, for the cactus ferruginous pygmy-owl (Glaucidium brasilianum cactorum), a bird subspecies found in Mexico, southern Arizona, and southern Texas. This rule adds the subspecies to the List of Endangered and Threatened Wildlife. We also finalize a rule under the authority of section 4(d) of the Act that provides measures that are necessary and advisable to provide for the conservation of this subspecies. We concluded that designation of critical habitat is prudent and determinable at this time. Critical habitat will be proposed in a separate rule-making.
Full Text
<html>
<head>
<title>Federal Register, Volume 88 Issue 138 (Thursday, July 20, 2023)</title>
</head>
<body><pre>
[Federal Register Volume 88, Number 138 (Thursday, July 20, 2023)]
[Rules and Regulations]
[Pages 46910-46950]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2023-14486]
[[Page 46909]]
Vol. 88
Thursday,
No. 138
July 20, 2023
Part IV
Department of the Interior
-----------------------------------------------------------------------
Fish and Wildlife Service
-----------------------------------------------------------------------
50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Threatened Species
Status With Section 4(d) Rule for Cactus Ferruginous Pygmy-Owl; Final
Rule
Federal Register / Vol. 88 , No. 138 / Thursday, July 20, 2023 /
Rules and Regulations
[[Page 46910]]
-----------------------------------------------------------------------
DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R2-ES-2021-0098; FF09E21000 FXES1111090FEDR 234]
RIN 1018-BF25
Endangered and Threatened Wildlife and Plants; Threatened Species
Status With Section 4(d) Rule for Cactus Ferruginous Pygmy-Owl
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
-----------------------------------------------------------------------
SUMMARY: We, the U.S. Fish and Wildlife Service (Service), determine
threatened species status under the Endangered Species Act of 1973
(Act), as amended, for the cactus ferruginous pygmy-owl (Glaucidium
brasilianum cactorum), a bird subspecies found in Mexico, southern
Arizona, and southern Texas. This rule adds the subspecies to the List
of Endangered and Threatened Wildlife. We also finalize a rule under
the authority of section 4(d) of the Act that provides measures that
are necessary and advisable to provide for the conservation of this
subspecies. We concluded that designation of critical habitat is
prudent and determinable at this time. Critical habitat will be
proposed in a separate rule-making.
DATES: This rule is effective August 21, 2023.
ADDRESSES: This final rule is available on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. Comments and materials we received, as well as
supporting documentation we used in preparing this rule, are available
for public inspection at <a href="https://www.regulations.gov">https://www.regulations.gov</a> at Docket No. FWS-
R2-ES-2021-0098.
FOR FURTHER INFORMATION CONTACT: Heather Whitlaw, Field Supervisor,
U.S. Fish and Wildlife Service, Arizona Ecological Services Field
Office, 9828 N 31st Ave., Phoenix, AZ 85051; telephone 602-242-0210.
Individuals in the United States who are deaf, deafblind, hard of
hearing, or have a speech disability may dial 711 (TTY, TDD, or
TeleBraille) to access telecommunications relay services. Individuals
outside the United States should use the relay services offered within
their country to make international calls to the point-of-contact in
the United States.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, a species,
subspecies, or distinct vertebrate population segment warrants listing
if it meets the definition of an endangered species (in danger of
extinction throughout all or a significant portion of its range) or a
threatened species (likely to become endangered within the foreseeable
future throughout all or a significant portion of its range). If we
determine that a species warrants listing, we must list the species
promptly and designate the species' critical habitat to the maximum
extent prudent and determinable. We have determined that the cactus
ferruginous pygmy-owl meets the definition of a threatened subspecies;
therefore, we are listing it as such. We have determined that the
designation of critical habitat for the cactus ferruginous pygmy-owl is
prudent and determinable, and we will propose designation in a separate
rule. Listing a species as an endangered or threatened species can be
completed only by issuing a rule through the Administrative Procedure
Act rulemaking process (5 U.S.C. 551 et seq.).
What this document does. This rule lists the cactus ferruginous
pygmy-owl as a threatened subspecies under the Act and adds it to the
List of Endangered and Threatened Wildlife. This rule also finalizes a
rule issued under section 4(d) of the Act (hereafter, referred to as a
``4(d) rule'').
The basis for our action. Under the Act, we may determine that a
species is an endangered or threatened species because of any of five
factors: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or educational purposes; (C)
disease or predation; (D) the inadequacy of existing regulatory
mechanisms; or (E) other natural or manmade factors affecting its
continued existence. We have determined that threats to the cactus
ferruginous pygmy-owl include: (1) Habitat loss and fragmentation from
urbanization, invasive species, and agricultural or forest production;
and (2) climate change (effects from current and future changes in
climate) and climate conditions (effects from current and past
climate), resulting in hotter, more arid conditions throughout much of
the subspecies' geographic range. The 4(d) rule would generally
prohibit the same activities as prohibited for an endangered species
but would allow exemptions for specific types of education and outreach
activities already permitted under a Migratory Bird Treaty Act permit,
surveying and monitoring conducted in Arizona under a state scientific
activity permit issued by the state, and habitat restoration and
enhancement activities that improve habitat conditions for the cactus
ferruginous pygmy-owl.
Section 4(a)(3) of the Act requires the Secretary of the Interior
(Secretary) to designate critical habitat concurrent with listing to
the maximum extent prudent and determinable. Section 3(5)(A) of the Act
defines critical habitat as (i) the specific areas within the
geographical area occupied by the species, at the time it is listed, on
which are found those physical or biological features (I) essential to
the conservation of the species and (II) which may require special
management considerations or protections; and (ii) specific areas
outside the geographical area occupied by the species at the time it is
listed, upon a determination by the Secretary that such areas are
essential for the conservation of the species. Section 4(b)(2) of the
Act states that the Secretary must make the designation on the basis of
the best scientific data available and after taking into consideration
the economic impact, the impact on national security, and any other
relevant impacts of specifying any particular area as critical habitat.
As stated in the proposed listing rule (86 FR 72547, December 22,
2021), we have determined that the designation of critical habitat for
the cactus ferruginous pygmy-owl is prudent and will be proposed in a
separate rule.
Previous Federal Actions
As described in Previous Federal Actions of our proposed listing
rule for the cactus ferruginous pygmy-owl (86 FR 72547, December 22,
2021), we received a petition dated March 15, 2007, from the Center for
Biological Diversity and Defenders of Wildlife (CBD, DOW; petitioners)
requesting that we list the cactus ferruginous pygmy-owl as an
endangered or threatened species under the Act (CBD and DOW 2007,
entire). On October 5, 2011, we published in the Federal Register (76
FR 61856) a 12-month finding on the petition to list the pygmy-owl as
endangered or threatened. Using the currently accepted taxonomic
classification of the pygmy-owl (Glaucidium brasilianum cactorum), we
found that listing the pygmy-owl was not warranted throughout all or a
significant portion of its range, including the petitioned and other
potential distinct population segment (DPS) configurations. We were
litigated on this decision (Case 4:12-cv-00627-CKJ), and the court
found in favor of the
[[Page 46911]]
plaintiffs and remanded the 2011 12-month finding on the 2007 petition
to list the pygmy-owl (Case 4:14-cv-02506-RM). Under a court
settlement, we developed a new 12-month finding and published our
proposed rule to list the pygmy-owl on December 22, 2021 (86 FR 72547).
Peer Review
A species status assessment (SSA) team prepared an SSA report for
the cactus ferruginous pygmy-owl. The SSA team was composed of Service
biologists, in consultation with other species and subject-matter
experts. The SSA report represents a compilation of the best scientific
and commercial data available concerning the status of the subspecies,
including the impacts of past, present, and future factors (both
negative and beneficial) affecting the subspecies.
In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), and our August 22,
2016, memorandum updating and clarifying the role of peer review of
listing actions under the Act, we solicited independent scientific
review of the information contained in the SSA report. As discussed in
the proposed rule, we sent the SSA report to five independent peer
reviewers and received three responses. The peer reviews can be found
at <a href="https://regulations.gov">https://regulations.gov</a>. We also sent the SSA report to 13 partners,
including Tribes and scientists with expertise in land management,
pygmy-owl and raptor ecology, and climate science, for review. We
received review from 11 partners, including State and Federal agencies,
universities, and nonprofit organizations. In preparing the proposed
rule, we incorporated the results of these reviews, as appropriate,
into the SSA report, which was the foundation for the proposed rule and
this final rule.
Summary of Changes From the Proposed Rule
Since the publication of the December 22, 2021, proposed rule to
list the cactus ferruginous pygmy-owl as threatened with a 4(d) rule
(86 FR 72547), we have made the following changes:
(1) Per requests from commenters, we have revised the provisions of
the 4(d) rule. We updated and clarified our description of the habitat
restoration and enhancement exception to clarify that this exception
does not include vegetation management along roadways or fuels
management that includes the removal of trees and large shrubs. We also
provided additional clarity and guidance on what types of projects
would be excepted under the 4(d) rule and which would require
coordination with and approval from the Service. These changes included
additional clarification regarding conditions under which prescribed
fire may be excepted under the 4(d) rule and specific guidance on how
to coordinate with us prior to habitat restoration and enhancement
projects to ensure that projects qualify for exception under the 4(d)
rule.
(2) In the preamble, we now include a more detailed discussion of
the DPS analysis we undertook, including a description of any pertinent
new information we have received since our 2011 12-month finding (76 FR
61856, October 5, 2011).
(3) Based upon new reports we received from the Arizona Game and
Fish Department during the comment period, we updated the biological
information for the subspecies related to surveys, distribution,
occupancy, and genetic differentiation (AGFD 2021b, pers. comm.;
Cobbold et al. 2021, entire; Cobbold et al. 2022a, entire; Cobbold et
al. 2022b, entire). This information did not alter any significant
findings in the proposed rule.
(4) A number of commenters provided us with additional references
to consider as we finalized this rule. We considered these references
and other references we found while responding to public comments and
have incorporated them and any associated information in the final rule
and SSA report as appropriate. See the Summary of New Information Since
the 2011 12-Month Finding section below for an explanation of where
these new references are included in issues relevant to our finding and
determination.
(5) We added a summary of the new information and changes that have
occurred since our 2011 12-month finding to clarify the factors that
contributed to a different determination in this final listing rule.
This summary is found in Summary of New Information Since the 2011 12-
Month Finding, below.
(6) In response to a comment received during the public comment
period, we completed additional analysis on the effects of certain land
uses in Texas and Arizona over the past decade (2010-2020) on pygmy-owl
habitat using additional sources of information to the source used by
the commenter. This further analysis can be found in appendix 6 of the
SSA report (Service 2022a, appendix 6).
Summary of New Information Since the 2011 12-Month Finding
This final listing rule results in a different finding than our
2011 12-month finding. This change in finding is based on an additional
decade of threats and land-use changes, as well as climate change,
acting on the landscape within the range of the pygmy-owl. We also used
a different approach in assessing the status of the pygmy-owl
throughout its range. We developed a species status assessment for the
pygmy-owl using the best available information and a team of experts,
including subject-matter experts, representing a range of agencies,
Tribal entities, and conservation partners, supported by new spatial
data and modeling developed subsequent to our 2011 12-month finding (76
FR 61856, October 5, 2011). Below we summarize the new information
available since 2011 upon which our 2021 proposed listing rule (86 FR
72547, December 22, 2021) was based. We have also updated our
discussion of the DPS finding to include information subsequent to our
2011 12-month finding (see Distinct Vertebrate Population Segment,
below).
Taxonomic Classification
Additional genetic sampling was conducted in Mexico by the Arizona
Game and Fish Department (AGFD) (Cobbold et al. 2022b, entire). While
these additional data add to the baseline information we used to
evaluate the status of the pygmy-owl, these results did not change our
finding that we lack sufficient information to adopt the proposed
taxonomic classification (change taxonomic classification to Glaucidium
ridgwayi cactorum with associated change in distribution) described by
Proudfoot et al. (2006a, entire; 2006b, entire) and discussed in the
2011 12-month finding (76 FR 61856, October 5, 2011). Therefore, no
change to the taxonomic classification of the pygmy-owl has occurred
since our 2011 12-month finding.
Rangewide Distribution
The taxonomic classification of the pygmy-owl did not change; thus,
the general geographic distribution of the pygmy-owl did not change and
is the same as described in the 2011 12-month finding (76 FR 61856,
October 5, 2011). However, the analysis in our current finding divided
the overall range of the pygmy-owl into five separate analysis units.
Using this smaller scale analysis, we were able to discuss the
condition of pygmy-owl populations and their habitat within each
analysis unit, which is a finer resolution analysis than we
[[Page 46912]]
used in 2011. This more detailed analysis can be found in the SSA
report (Service 2022a, entire), which includes a detailed description
of each analysis unit. We also accessed additional pygmy-owl locations
across the range of the pygmy-owl that we did not use in 2011 via the
Global Biodiversity Information Facility, which included location data
from such sources as eBird, iNaturalist, and museum specimens (GBIF
2020, unpaginated).
Climate Change
The decade that passed between our 2011 12-month finding (76 FR
61856, October 5, 2011) and our proposed listing rule (86 FR 72547,
December 22, 2021) has been characterized by ongoing climate impacts to
pygmy-owl populations and their habitats (Bagne and Finch 2012, entire;
Coe et al. 2012, entire; Jiang and Yang 2012, entire; Romero-Lankao, et
al. 2014, p. 1443; Melillo et al. 2014, entire; USGCRP 2018, chapters
23 and 25). Impacts resulting from climate change such as ongoing
drought (habitat and prey impacts), increased temperatures (decreased
productivity), reduced vegetation health and associated impacts to
pygmy-owl prey availability, and increased fire occurrence (habitat and
prey impacts) have resulted in negative effects to pygmy-owl abundance
and distribution, as well as in loss of habitat and increased habitat
fragmentation (Melillo et al. 2014, entire; Vermote et al. 2014,
unpaginated; Cook et al. 2015, p. 6; Easterling et al. 2017, pp. 207-
230; USGCRP 2018, chapters 23 and 25; Gonzalez et al. 2018, entire;
Breshears et al. 2018, p. 1; Williams et al. 2020, p. 317, IPCC 2022,
entire).
Enough time has passed since the early predictions of impacts of
climate change that we have seen evidence of those predicted impacts on
vegetation communities across the range of the pygmy-owl. Generally,
these impacts have been in line with or worse than what was predicted.
New climate models and projections and updated information in general
were available for our analysis. These projections continue to predict
impacts at the same or increasing levels upon the landscape in areas
where the pygmy-owl occurs. This information is discussed in greater
detail in Climate Change and Climate Conditions, below. Additionally,
we included climate scientists in our peer and partner review of the
climate section of the pygmy-owl SSA report, and they provided input
and updated citations regarding our discussion of climate effects that
are included in the SSA report and this final listing rule.
Rangewide Habitat Loss
With the exception of climate change, there is not a single threat
leading to habitat loss across the range of the pygmy-owl. However,
habitat loss is occurring across every portion of the range of the
pygmy-owl. Each of the five analysis units is experiencing varying
degrees of pygmy-owl habitat loss that, when considered together,
result in rangewide habitat loss (Thomas et al. 2012, p. 43; Lyons et
al. 2013, p. 8; Vo 2013, unpaginated; TDC 2019, entire; Texas Land
Trends 2019, entire; Wied et al. 2020, entire; Mesa-Sierra et al. 2022,
unpaginated; Burquez 2022, pers. comm.). The 2011 12-month finding did
not assess local habitat impacts at the level of individual analysis
units. These more specific descriptions of threats and impacts by
analysis unit can be found in the SSA report (Service 2022a, appendix
5) and in Summary of Current Condition of the Subspecies, below.
Status in Arizona
As in 2011, pygmy-owls continue to be absent from Pinal County and
around Tucson where they were found as recently as the early 2000s
(Ingraldi 2020, pers. comm.). Additionally, based on survey efforts in
2020 and 2021, pygmy-owls can no longer be found reliably in Organ Pipe
Cactus National Monument for the first time since records have been
kept (Ingraldi 2020, pers. comm.; AGFD 2021b, pers. comm.). Personal
communication with Tribal staff indicates that pygmy-owls continue to
be found on the Tohono O'odham Nation, although comprehensive surveys
have not been conducted and information on specific locations of pygmy-
owls is not released by the Tohono O'odham Nation (Verwys 2020 and
2021, pers. comm.). Currently, the known abundance of owls is higher in
Altar Valley than it was in 2011, likely due to increased survey and
monitoring under the Pima County Multi-Species Conservation Plan and by
the AGFD (Flesch 2018a, entire; Ingraldi 2020, pers. comm.; PCOSC 2021,
entire). However, occupancy in the Altar Valley appears to be down in
2022, potentially in response to the dry winter of 2021-2022 and
ongoing drought conditions (AGFD 2022, unpublished data; Service 2022b,
unpublished data; NDMC 2022, unpaginated).
Threats related to climate change have increased, including fire
(Inciweb 2022, unpaginated), invasive species, degraded vegetation
condition, and reduced prey availability due to drought and impacted
hydrology including the loss of surface and ground water (BOR 2021,
entire; NDMC 2022, unpaginated). Development continues to impact
habitat particularly in areas of northwest Tucson and Pinal County.
While there is not a direct correlation between acres of pygmy-owl
habitat lost and human population growth, it is reasonable to find
that, as human population grows, the amount of native habitat lost or
fragmented will increase. We looked at recent population growth and
projections in Arizona as an indication for future urbanization (OEO
2018, unpaginated; U.S. Census Bureau 2021a, unpaginated; EBRC 2021,
unpaginated). New, taller border walls have been constructed along all
border areas occupied by pygmy-owls in Arizona (DHS 2020, unpaginated).
As discussed in the SSA report, the impacts of this border
infrastructure on pygmy-owls have not been studied but represent a
potential barrier to pygmy-owl movements along and across the border.
We considered a new analysis of Arizona pygmy-owl occupancy (Flesch
et al. 2017, entire). This report includes an analysis of factors
contributing to pygmy-owl occupancy in Arizona, as well as factors to
consider in designing and implementing pygmy-owl conservation actions.
In addition, a climate change study that was published since our 2011
12-month finding predicts a reduction in saguaros (Carnegiea gigantea)
in the Sonoran Desert (Thomas et al. 2012, p. 43). Saguaros are the key
nesting substrate for pygmy-owls in the Sonoran Desert of Arizona.
Status in Texas
Threats to the pygmy-owl and pygmy-owl habitat from drought, as
well as fire, freezes, and hurricanes (Harvey in 2017, Hanna in 2020,
and Ida in 2021) have all continued in Texas over the past decade (EPA
2016, unpaginated; Bhatia et al. 2019, entire; Inciweb 2022,
unpaginated; Bond 2022, unpaginated; NDMC 2022, unpaginated; NIFC 2022,
unpaginated; NWS 2022, unpaginated). Many of these effects are the
result of climate change (Romero-Lankao, et al. 2014, p. 1459; EPA
2016, unpaginated; Gonzalez et al. 2018, entire). Urbanization and
agricultural development in both Texas and northeastern Mexico (Texas
Land Trends 2019, entire; USGS 2022, unpaginated; Texas Comptroller
2020, unpaginated) have continued, likely resulting in increased
isolation of the Texas population from those in Mexico. No recent
surveying or monitoring has been conducted in Texas. However, given
current habitat conditions as outlined in the SSA report, the declines
in pygmy-owls and pygmy-owl habitat
[[Page 46913]]
documented in the 2011 12-month finding have likely continued,
resulting in reduced abundance of pygmy-owls. For example, the Texas
Parks and Wildlife Department recently changed the conservation status
rank for ferruginous pygmy-owl in Texas from S3:vulnerable to
S2:imperiled (TPWD 2022, unpaginated). In addition, the number and
distribution of pygmy-owls in the Lower Rio Grande Valley has declined
since 1988, likely due to the ongoing loss of riparian habitats along
the Rio Grande (Leslie 2016, entire).
Status in Northern Sonora
Our understanding of the habitat needs for pygmy-owls in the
Sonoran Desert has improved since 2011 as a result of ongoing research
in northern Sonora (Flesch 2014, entire; Flesch et al. 2015, entire;
Flesch 2017, entire; Flesch et al. 2017, entire; Cobbold et al. 2021,
entire; Cobbold et al 2022a, entire). The abundance of pygmy-owls in
northern Sonora has declined with increasing drought (Flesch et al.
2017, entire; Flesch 2021, entire). Abundance and densities of pygmy-
owls are, in general, higher farther south in Sonora in thornscrub and
tropical dry forests and lower in the northern part of northwest Mexico
(Cobbold et al. 2021, entire; Cobbold et al. 2022a, entire). These data
are consistent with previous findings (Flesch 2003, entire). Threats
resulting in reduced vegetation condition and increased habitat
fragmentation have been documented (Flesch 2014, entire; Flesch et al.
2015, entire; Flesch et al. 2017, entire; Flesch 2021, entire). In
2012, a climate change study was published predicting a reduction in
saguaros in the Sonoran Desert (Thomas et al. 2012, p. 43). Saguaros
are the key nesting substrate for pygmy-owls in the Sonoran Desert of
northern Sonora. In addition, a retired Service biologist who led the
Sonoran Joint Venture provided updated information on the status of
land use and impacts to pygmy-owls in Sonora (Mesta 2020, pers. comm.).
Status in Remainder of Mexico
There are no recent pygmy-owl survey or monitoring data for the
remainder of Mexico, so we continue to have no recent, verified data on
abundance or occupancy. We used eBird, iNaturalist, and museum specimen
records to get a general scope of occurrences in these areas, but did
not use these records to estimate abundance (GBIF 2020, unpaginated;
Johnston et al. 2021, p. 1266). Ten additional years of threats acting
on these population groups have impacted the landscape and habitat of
the pygmy-owl in these areas including extraction of natural resources,
increases in invasive species, use of pesticides, and the effects of
climate change such as drought and increased evapotranspiration
(Enr[iacute]quez and Vazquez-Perez 2017, p. 546, DataMexico 2021,
unpaginated; Murray-Tortarolo 2021; entire; Mesa-Sierra et al. 2022,
unpaginated). Specifically, habitat loss and fragmentation has
increased since 2011 as a result of wood harvesting, agriculture,
population growth and urbanization, and other land uses (CONAPO 2014,
p. 25; Enr[iacute]quez and Vazquez-Perez 2017, p. 546; DataMexico 2021,
unpaginated; Burquez 2022, pers. comm.). Increases in hurricanes in
northeastern Mexico (EPA 2016, entire) have resulted in impacts to
pygmy-owl habitat. We also received additional information related to
the status of the pygmy-owl in Mexico such as the lack of research and
data, lack of land use planning and government oversight, other
threats, establishment of preserve areas, and cultural significance
(Enr[iacute]quez and Vazquez-Perez 2017, p. 546; Enr[iacute]quez 2021,
pers. comm.).
Conservation Actions
Implementation of the Pima County Multi-Species Conservation Plan
has resulted in additional surveys for pygmy-owls on lands controlled
by Pima County in Arizona. Additional pygmy-owl habitat has been
protected through conservation planning and habitat acquisition and
protection as part of implementing this large, regional Pima County
Habitat Conservation Plan (Pima County 2016, entire; Flesch 2018a,
entire; PCOSC 2021, entire). Investigation of captive-breeding and
release to establish new pygmy-owl population groups and to augment
existing population groups has continued in Arizona (AGFD 2015,
entire). The Altar Valley Watershed Plan has been developed and will
contribute to the enhancement of pygmy-owl habitat in Altar Valley,
Arizona (Altar Valley Watershed Working Group 2022, entire).
Factor A--The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
We evaluated new information related to the effects of present and
future climate change on vegetation on which the pygmy-owl depends
(Bagne and Finch 2012, entire; Coe et al. 2012, entire; Jiang and Yang
2012, entire; Flesch 2014, pp. 113-116; Melillo et al. 2014, entire;
Romero-Lankao, et al. 2014, p. 1443; Flesch et al. 2015, entire;
Pearce-Higgins et al. 2015, entire; Deguines et al. 2017, entire;
Flesch et al. 2017, entire; USGCRP 2018, chapters 23 and 25). The
incidence of fires, particularly in Arizona and Texas, has increased
since 2011 (Inciweb 2022, unpaginated). While there is not a direct
correlation between acres of pygmy-owl habitat lost and human
population growth, it is reasonable to find that, as human population
grows, the amount of native habitat lost or fragmented will increase.
We used updated population growth estimates in the SSA report and this
final rule (Brinkhoff 2016, unpaginated; HHS 2017, unpaginated; OEO
2018, unpaginated; INEGI 2021, unpaginated; CONAPO 2014, p. 25; TDC
2019, entire; Pinal County 2019, p. 126; Gonzales 2020, unpaginated;
DataMexico 2021, unpaginated; Service 2022a, chapter 7). We also looked
at more recent information from Mexico related to habitat loss and
fragmentation, which showed that land uses continue to impact pygmy-owl
habitat and the occupancy and productivity of pygmy-owls
(Enr[iacute]quez and Vazquez-Perez 2017, p. 546; Flesch et al. 2017,
entire). We have also included recent information on the effects of
buffelgrass on the ecosystems and habitats used by pygmy-owls (Lyons et
al. 2013, p. 8; Vo 2013, entire, Wied et al. 2020, p. 47; ASDM 2022,
unpaginated). We also considered new information showing that pygmy-owl
occupancy decreases in areas of increased roadway size, agricultural
development, and other factors causing pygmy-owl habitat disturbance
(Flesch 2017, p. 5; Flesch et al. 2017, entire; Flesch 2021, pp. 12-
14).
Factor B--Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
We have observed a recent increase in visitation by birders (2019
to present) to known pygmy-owl territories (Flesch 2018b, pers. comm.,
Vaughan 2019, pers. comm.), but we have not studied how that activity
has affected occupancy and productivity. We also evaluated more recent
information on the impacts of researchers on birds (Gibson et al. 2015,
pp. 404-406; Herzog et al. 2020, p. 891).
Factor C--Disease or Predation
We are not aware of any additional information regarding the
effects of disease and predation on pygmy-owls since what was included
in our 2011 12-month finding.
Factor D--The Inadequacy of Existing Regulatory Mechanisms
Typically, work funded or implemented by Federal agencies complies
with a number of environmental laws such as the National Environmental
Policy Act and
[[Page 46914]]
the Endangered Species Act. However, under the Real ID Act, the U.S.
Department of Homeland Security (DHS) waived environmental compliance
for much of the border infrastructure work completed recently in
Arizona and Texas (Fischer 2019, unpaginated; USCBP 2020, unpaginated).
This work included the construction of taller border fencing with
lights and associated access roads contributing to habitat loss and
fragmentation.
Factor E--Other Natural or Manmade Factors Affecting the Species'
Continued Existence
A new potential threat to pygmy-owls was identified subsequent to
our 2011 12-month finding as reported in a study that documented
pesticides in pygmy-owl feathers and blood (Arrona-Rivera et al. 2016,
entire). We also evaluated new information related to climate and
weather impacts on pygmy-owls that affect productivity in pygmy-owls as
well as pygmy-owl prey species (Flesch 2014, pp. 113-116; Flesch et al.
2015, entire; Pearce-Higgins et al. 2015, entire; Deguines et al. 2017,
entire; Flesch et al. 2017, entire). We considered a more recent
publication on the potential for small population size to increase
extinction risk and the types of information needed to model such risk
(Benson et al. 2016, pp. 1-2, 8). During the development of the pygmy-
owl SSA report, we sought peer and partner review specifically on our
climate change analysis. The responses we received from climate experts
were used to update our SSA report and are included in more detail in
this final rule.
Additionally, we considered more recent information related to
updated climate models, downscaled climate predictions, and information
on drought (Bagne and Finch 2012, entire; Coe et al. 2012, entire;
Jiang and Yang 2012, entire; Romero-Lankao, et al. 2014, p. 1443;
Melillo et al. 2014, entire; Cook et al. 2015, p. 6; Wang et al. 2016,
pp. 6-7; Dewes et al. 2017, p. 17; Easterling et al. 2017, entire;
Diffenbaugh et al. 2017, entire; Gonzalez et al. 2018, entire;
Christensen et al. 2018, p. 5409; Breshears et al. 2018, p. 6; Williams
et al. 2020, p. 317; Bradford et al. 2020, entire; BOR 2021, entire).
Furthermore, additional IPCC reports have been published since 2011, as
well as National Climate Assessments, and we have included these in our
climate analysis related to this final rule and the pygmy-owl SSA
report (IPCC 2014b, entire; Melillo et al. 2014, entire; USGCRP 2018,
chapters 23 and 25; IPCC 2022, entire). We also have new information
indicating that climate extremes may be more important than averages
(Germain and Lutz 2020, entire) and further evidence that climate has
become, and is projected to become, more extreme within the range of
the pygmy-owl (Bagne and Finch 2012, entire; Cook et al. 2015, p. 6;
Diffenbaugh et al. 2017, entire; Easterling et al. 2017, entire; BOR
2021, entire). Additionally, since our 2011 12-month finding, a climate
change study was published predicting a reduction in saguaros in the
Sonoran Desert (Thomas et al. 2012, p. 43). Saguaros are the key
nesting substrate for pygmy-owls in the Sonoran Desert.
Overall Status and Needs of Pygmy-Owls
Subsequent to our 2011 12-month finding, the IUCN published a Red
List Update for the ferruginous pygmy-owl (Glaucidium brasilianum) and,
although the status remained the same as the 2009 Red List status
(Least Concern), the Update acknowledged rangewide declines in the
ferruginous pygmy-owl (BirdLife International 2016, unpaginated). We
also reviewed and incorporated the updated Birds of North America
ferruginous pygmy-owl account (now Birds of the World) (Proudfoot et
al. 2020, entire). Additionally, new information has been published
further supporting the importance of woodland vegetation and large,
unfragmented habitat patches in the Sonoran Desert (Flesch et al. 2015,
entire).
Additional Sources of Information
The following includes a list of information sources that were
included subsequent to the proposed rule: AdaptWest Project 2015,
unpaginated; AdaptWest Project 2022, unpaginated; Altar Valley
Watershed Working Group 2022, entire; AGFD 2021b, pers. comm.; AGFD
2022, unpublished data; ASDM 2022, unpaginated; Arrona-Rivera et al.
2016, entire; Bhatia et al. 2019, entire; BirdLife International 2016,
unpaginated; Blackie et al. 2014, entire; Bond 2022, unpaginated;
Bradford et al. 2020, entire; Breshears et al. 2018, entire;
Buffelgrass Working Group 2008, entire; BOR 1947, unpaginated; BOR
2021, entire; Burquez 2022, pers. comm.; Burquez and Martinez-Yrizar
1997, entire; Christensen et al. 2018, entire; Cobbold et al. 2021,
entire; Cobbold et al. 2022a, entire; Cobbold et al. 2022b, entire;
Cook et al. 2001, entire; Deguines et al. 2017, entire; Dewes et al.
2017, entire; Diffenbaugh et al. 2017, entire; Easterling et al. 2017,
entire; Enr[iacute]quez et al. 2017, entire; Flesch 2003, entire;
Flesch 2014, entire; Flesch 2017, entire; Flesch 2018a, entire; Flesch
2018b, pers. comm., Flesch 2021, entire; Flesch et al. 2010, entire;
Germain and Lutz 2020, entire; Gonzalez et al. 2018, entire; Gonzales
2020, unpaginated; Gornish and Howery 2019, entire; Herzog et al. 2020,
entire; Inciweb 2022, unpaginated; IPCC 2014b, entire; IPCC 2022,
entire; Johnson et al. 2004, entire; Johnston et al. 2021, entire;
Keith 2007, entire; Lesli 2016, entire; Marris 2006, entire; Mays 1996,
entire; Melillo et al. 2014, entire; Meltz and Copeland 2007, entire;
Mesa-Sierra et al. 2022, entire; Mesta 2020, pers. comm.; Murray-
Tortarolo 2021, entire; NDMC 2022, unpaginated; NIFC 2022, unpaginated;
INEGI 2021, unpaginated; NWS 2022, unpaginated; Pearce-Higgins et al.
2015, unpaginated; PCOSC 2021, entire; Pinal County 2019, entire;
Romero-Lankao et al. 2014, entire; Texas Comptroller 2020, unpaginated;
TDC 2019, entire; Texas Land Trends 2019, entire; TPWD 2022,
unpaginated; U.S. Census Bureau 2021b, unpaginated; DHS 2020,
unpaginated; U.S. NDMC 2022, unpaginated; EPA 2016, unpaginated;
Service 2022b, unpaginated; USGCRP 2018, entire; USGS 2022,
unpaginated; EBRC 2021, unpaginated; Valdez et al. 2006, entire;
Vaughan 2019, pers. comm.; Vermote et al. 2014, unpaginated; Verwys
2020, pers. comm.; Verwys 2021, pers. comm.; Walker and Pavlakovish-
Kochi 2003, entire; Wang et al. 2016, entire; Wied et al. 2020, entire.
I. Final Listing Determination
Background
A thorough review of the taxonomy, life history, and ecology of the
cactus ferruginous pygmy-owl is presented in the SSA report. We
summarize this information here.
The cactus ferruginous pygmy-owl is a diurnal, nonmigratory
subspecies of ferruginous pygmy-owl and is found from central Arizona
south to Michoac[aacute]n, Mexico, in the west and from south Texas to
Tamaulipas and Nuevo Leon, Mexico, in the east. Pygmy-owls eat a
variety of prey including birds, insects, lizards, and small mammals,
with the relative importance of prey type varying throughout the year.
The pygmy-owl is a small bird, approximately 17 centimeters (cm)
(6.7 inches (in)) long. Generally, male pygmy-owls average 58 grams (g)
to 66 g (2.0 to 2.3 ounces (oz)) and females average 70 g to 75 g (2.4
to 2.6 oz). The pygmy-owl is reddish brown overall, with a cream-
colored belly streaked with reddish brown. The crown is lightly
streaked, and a pair of dark
[[Page 46915]]
brown or black spots outlined in white occurs on the nape, suggesting
eyes (Oberholser 1974, p. 451). The species lacks obvious ear tufts
(Santillan et al. 2008, p. 154), and the eyes are yellow. The tail is
relatively long for an owl and is reddish brown in color, with darker
brown bars. Males have pale bands between the dark bars on the tail,
while females have darker reddish bands between the dark bars.
Cactus ferruginous pygmy-owls are secondary cavity nesters, nesting
in cavities of trees and columnar cacti, with nesting substrate varying
throughout its range. Pygmy-owls can breed in their first year and
typically mate for life, with both sexes breeding annually. Clutch size
can vary from two to seven eggs with the female incubating the eggs for
28 days (Johnsgard 1988, p. 162; Proudfoot and Johnson 2000, p. 11).
Fledglings disperse from their natal sites about 8 weeks after they
fledge (Flesch and Steidl 2007, p. 36). Pygmy-owls live on average 3 to
5 years but have been documented to live 7 to 9 years in the wild
(Proudfoot 2009, pers. comm.) and 10 years in captivity (Abbate 2009,
pers. comm.).
Pygmy-owls are found in a variety of vegetation communities,
including Sonoran desertscrub and semidesert grasslands in Arizona and
northern Sonora, thornscrub and tropical dry forests in southern Sonora
south to Michoac[aacute]n, Tamaulipan brushland in northeastern Mexico,
and live oak forest in Texas. At a finer scale, the pygmy-owl is a
creature of edges found in semi-open areas of thorny scrub and
woodlands in association with giant cacti and in scattered patches of
woodlands in open landscapes, such as tropical dry forests and riparian
communities along ephemeral, intermittent, and perennial drainages
(K[ouml]nig et al. 1999, p. 373). It is often found at the edges of
riparian and xeroriparian drainages and even habitat edges created by
villages, towns, and cities (Abbate et al. 1999, pp. 14-23; Proudfoot
and Johnson 2000, p. 5).
The taxonomy of Glaucidium is complicated and has been the subject
of much discussion and investigation. Following delisting of the pygmy-
owl in 2006 (71 FR 19452, April 14, 2006), we were petitioned to relist
the pygmy-owl (CBD and DOW 2007, entire). The petitioners requested a
revised taxonomic consideration for the pygmy-owl based on Proudfoot et
al. (2006a, p. 9; 2006b, p. 946) and K[ouml]nig et al. (1999, pp. 160,
370-373), classifying the northern portion of Glaucidium brasilianum's
range as an entirely separate species, G. ridgwayi, and recognizing two
subspecies of G. ridgwayi: G. r. cactorum in western Mexico and Arizona
and G. r. ridgwayi in eastern Mexico and Texas. Other recent studies
proposing or supporting the change to G. ridgwayi for the northern
portion of G. brasilianum's range have been published in the past 20
years (Navarro-Sig[uuml]enza and Peterson 2004, p. 5; Wink et al. 2008,
pp. 42-63; Enr[iacute]quez et al. 2017, p. 15).
As we evaluated the cactus ferruginous pygmy-owl's current status,
we found that, although there is genetic differentiation at the far
ends of the pygmy-owl's distribution represented by Arizona and Texas,
uncertainty continues with regard to how this pattern is represented in
the southern portion of the range. This latter area represents the
boundary between the petitioners' two proposed subspecies (cactorum and
ridgwayi within the proposed reclassification of the species ridgwayi),
which raises the question of whether there is adequate data to support
a change in species classification and define the eastern and western
distributions as separate subspecies as proposed by Proudfoot et al.
(2006a, entire; 2006b, entire). The Arizona Game and Fish Department
(AGFD) completed additional pygmy-owl genetic sampling in the southern
portion of the pygmy-owl's range in Mexico in 2022 (Cobbold et al.
2022b, entire). This work did not collect samples far enough south into
southern Mexico and Central America to resolve the proposed taxonomic
change of Proudfoot et al. (2006a, entire; 2006b, entire), but it did
confirm that genetic differentiation does occur across the range of
what is currently classified as the subspecies cactorum, and that this
pattern of differentiation is the result of isolation by distance
(Cobbold et al. 2022b, entire). Additionally, this updated analysis and
additional genetic sampling did seem to answer the question of whether
the Transvolcanic Belt of Mexico at the southern end of the pygmy-owl's
range presents a barrier to gene flow across this area.
Based on additional sampling conducted specifically in the area of
the Transvolcanic Belt, an area hypothesized to be a potential barrier
to movement and gene flow, pygmy-owl samples collected north and south
of, as well as within, the Transvolcanic Belt clustered in a single
genetically related group (Cobbold et al. (2022b, p. 16). This finding
suggests a high degree of gene flow between these population groups.
Consequently, the results suggest that the Mexican Transvolcanic Belt
does not represent a dispersal barrier to pygmy-owl population groups
located on either side of the geological feature within the sampled
areas. Additionally, genetic differentiation followed a pattern of
isolation by distance, a model under which the strongest differences in
genetic structure are expected to occur at the extremities of a
species' or subspecies' range (Cobbold et al. 2022b, p. 15). Between
the extremities, there is gradual genetic differentiation, rather than
abrupt changes, across the range. Sudden changes would be more likely
to represent dispersal barriers and, therefore, boundaries between
different genetic groupings. Although these datasets show that there
are genetic differences across the range of the pygmy-owl, they do not
provide adequate evidence of genetic differentiation along the gradient
from Arizona to Texas that would warrant the taxonomic changes
recommended by Proudfoot et al. (2006a, entire, and 2006b, entire). In
particular, sample sizes in the southern portion of the range remain
low. Samples in this portion of the range are critical to determining
if there are indeed two distinct subspecies of pygmy-owl. While future
work and studies may clarify and resolve these issues, we will continue
to use the currently accepted distribution of G. brasilianum cactorum
as described in the 1957 American Ornithologists' Union (now the
American Ornithological Society) checklist and various other
publications (Friedmann et al. 1950, p. 145; Oberholser 1974, p. 452;
Johnsgard 1988, p. 159; Millsap and Johnson 1988, p. 137).
Regulatory and Analytical Framework
Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations in title 50 of the Code of Federal Regulations set forth
the procedures for determining whether a species is an endangered
species or a threatened species, issuing protective regulations for
threatened species, and designating critical habitat for endangered and
threatened species. In 2019, jointly with the National Marine Fisheries
Service, the Service issued a final rule that revised the regulations
in 50 CFR part 424 regarding how we add, remove, and reclassify
endangered and threatened species and the criteria for designating
listed species' critical habitat (84 FR 45020; August 27, 2019). On the
same day, the Service also issued final regulations that, for species
listed as threatened species after September 26, 2019, eliminated the
Service's general protective regulations automatically applying to
threatened species the prohibitions that section 9 of the Act
[[Page 46916]]
applies to endangered species (84 FR 44753; August 27, 2019).
The regulations that are in effect and therefore applicable to this
final rule are 50 CFR part 424, as amended by (a) revisions that we
issued jointly with the National Marine Fisheries Service in 2019
regarding both the listing, delisting, and reclassification of
endangered and threatened species and the criteria for designating
listed species' critical habitat (84 FR 45020; August 27, 2019); and
(b) revisions that we issued in 2019 eliminating for species listed as
threatened species are September 26, 2019, the Service's general
protective regulations that had automatically applied to threatened
species the prohibitions that section 9 of the Act applies to
endangered species (84 FR 44753; August 27, 2019).
The Act defines an ``endangered species'' as a species that is in
danger of extinction throughout all or a significant portion of its
range, and a ``threatened species'' as a species that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act requires that we
determine whether any species is an endangered species or a threatened
species because of any of the following factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
These factors represent broad categories of natural or human-caused
actions or conditions that could have an effect on a species' continued
existence. In evaluating these actions and conditions, we look for
those that may have a negative effect on individuals of the species, as
well as other actions or conditions that may ameliorate any negative
effects or may have positive effects.
We use the term ``threat'' to refer in general to actions or
conditions that are known to or are reasonably likely to negatively
affect individuals of a species. The term ``threat'' includes actions
or conditions that have a direct impact on individuals (direct
impacts), as well as those that affect individuals through alteration
of their habitat or required resources (stressors). The term ``threat''
may encompass--either together or separately--the source of the action
or condition or the action or condition itself.
However, the mere identification of any threat(s) does not
necessarily mean that the species meets the statutory definition of an
``endangered species'' or a ``threatened species.'' In determining
whether a species meets either definition, we must evaluate all
identified threats by considering the species' expected response and
the effects of the threats--in light of those actions and conditions
that will ameliorate the threats--on an individual, population, and
species level. We evaluate each threat and its expected effects on the
species, then analyze the cumulative effect of all of the threats on
the species as a whole. We also consider the cumulative effect of the
threats in light of those actions and conditions that will have
positive effects on the species, such as any existing regulatory
mechanisms or conservation efforts. The Secretary determines whether
the species meets the definition of an ``endangered species'' or a
``threatened species'' only after conducting this cumulative analysis
and describing the expected effect on the species now and in the
foreseeable future.
The Act does not define the term ``foreseeable future,'' which
appears in the statutory definition of ``threatened species.'' Our
implementing regulations at 50 CFR 424.11(d) set forth a framework for
evaluating the foreseeable future on a case-by-case basis. The term
``foreseeable future'' extends only so far into the future as we can
reasonably determine that both the future threats and the species'
responses to those threats are likely. In other words, the foreseeable
future is the period of time in which we can make reliable predictions.
``Reliable'' does not mean ``certain''; it means sufficient to provide
a reasonable degree of confidence in the prediction. Thus, a prediction
is reliable if it is reasonable to depend on it when making decisions.
It is not always possible or necessary to define foreseeable future
as a particular number of years. Analysis of the foreseeable future
uses the best scientific and commercial data available and should
consider the timeframes applicable to the relevant threats and to the
species' likely responses to those threats in view of its life-history
characteristics. Data that are typically relevant to assessing the
species' biological response include species-specific factors such as
lifespan, reproductive rates or productivity, certain behaviors, and
other demographic factors.
Analytical Framework
The SSA report documents the results of our comprehensive
biological review of the best scientific and commercial data regarding
the status of the subspecies, including an assessment of the potential
threats to the subspecies. The SSA report does not represent our
decision on whether the subspecies should be listed as an endangered or
threatened species under the Act. However, it does provide the
scientific basis that informs our regulatory decisions, which involve
the further application of standards within the Act and its
implementing regulations and policies.
To assess cactus ferruginous pygmy-owl viability, we used the three
conservation biology principles of resiliency, redundancy, and
representation (Shaffer and Stein 2000, pp. 306-310). Briefly,
resiliency is the ability of the subspecies to withstand environmental
and demographic stochasticity (for example, wet or dry, warm or cold
years), redundancy is the ability of the subspecies to withstand
catastrophic events (for example, droughts, large pollution events),
and representation is the ability of the subspecies to adapt over time
to both near-term and long-term changes in its physical and biological
environment (for example, climate conditions, pathogens). In general,
species viability will increase with increases in resiliency,
redundancy, and representation (Smith et al. 2018, p. 306). Using these
principles, we identified the subspecies' ecological requirements for
survival and reproduction at the individual, population, and subspecies
levels, and described the beneficial and risk factors influencing the
species' viability.
In the context of the Act, resiliency, redundancy, and
representation are influenced by the five listing factors described in
the Act. Conversely, the measures of resiliency, redundancy, and
representation can indicate the extent to which any or all of the five
listing factors are influencing the viability and status of a species
in the context of the Act. This relationship between resiliency,
redundancy, and representation and the five listing factors is
described in more detail in the Threats, Current Condition, Future
Scenarios, and Determination of Cactus Ferruginous Pygmy-owl Status
sections of this final rule.
The SSA process can be categorized into three sequential stages.
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the
[[Page 46917]]
historical and current condition of the species' demographics and
habitat characteristics, including an explanation of how the species
arrived at its current condition. The final stage of the SSA involved
making predictions about the species' responses to positive and
negative environmental and anthropogenic influences. Throughout all of
these stages, we used the best available information to characterize
viability as the ability of a species to sustain populations in the
wild over time. We use this information to inform our regulatory
decision.
The following is a summary of the key results and conclusions from
the SSA report; the full SSA report can be found at Docket No. FWS-R2-
ES-2021-0098 at <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Summary of Biological Status and Threats
In this discussion, we review the biological condition of the
cactus ferruginous pygmy-owl and its resources, and the threats that
influence the subspecies' current and future condition, in order to
assess the subspecies' overall viability and the risks to that
viability. The overall geographic range of the pygmy-owl is very large
(approximately 140,625 square miles [364,217 square kilometers]) and
covers two countries, the United States and Mexico. To assist in our
analysis, we divided the overall geographic range of the pygmy-owl into
five analysis units based upon biological, vegetative, political,
climatic, geographical, and conservation differences. The five analysis
units are: Arizona, northern Sonora, western Mexico, Texas, and
northeastern Mexico. We analyzed each of these analysis units
individually and also analyzed the viability of the subspecies in its
entire range.
Threats
We reviewed the potential risk factors, and their applicable
listing factor, that could be affecting the resiliency, redundancy, and
representation of the pygmy-owl now and in the future including:
climate change and climate condition (Factor E), habitat loss and
fragmentation (Factor A), human activities and disturbance (Factors B
and E), waived or ineffective regulatory mechanisms (Factor D), human-
caused mortality (Factors B and E), disease and predation (Factor C),
and small population size (Factor E). In this final rule, we will
discuss only those factors in detail that could meaningfully impact the
status of the subspecies. Those risks that are not known to have
effects on pygmy-owl populations, such as disease, are not discussed
here but are evaluated in the SSA report. The primary risk factors
affecting the current and future status of the pygmy-owl are: (1)
Habitat loss and fragmentation (Factor A), and (2) climate change and
climate conditions (Factor E). We acknowledge, however, that all of the
threats discussed in this final rule and the SSA report can exacerbate
or contribute to these two primary threats and that it is important to
consider all of the known threats to pygmy-owl populations. For a
detailed description of the threats analysis, please refer to the SSA
report (Service 2022a, chapter 7).
Habitat Loss and Fragmentation
Pygmy-owls require habitat elements, such as mature woodlands, that
include appropriate cavities for nest sites, adequate structural
diversity and cover, and a diverse prey base. Urbanization, invasive
species, and agricultural or forest production are all causing a
reduction in the extent of habitat and an increase in habitat
fragmentation throughout the geographic range of the subspecies. In
response to a comment we received during the public comment period and
prior to finalizing this rule, we completed some additional analysis on
the effects of certain land uses in Texas and Arizona over the past
decade (2010-2020) on pygmy-owl habitat. The commenter provided results
of an analysis they did on changes in land cover within the pygmy-owl
analysis areas during the time period of 2010-2015 and suggested that
the impacts to pygmy-owl habitat were not as great as we presented in
the proposed rule and SSA report. Because it is important to consider
the scope, scale, and the factors included in different sources of
data, we conducted additional analysis using data sources that provided
the same type of data that the commenter used in their analysis. This
allowed us to compare the results of additional sources of data with
the results presented by the commenter. This additional analysis does
not change the outcome of our listing decision, but it does provide
additional support for our finding that areas of important pygmy-owl
habitat have been lost or modified and habitat fragmentation has
continued, at least in Texas and Arizona, during this time period. This
further analysis can be found in appendix 6 of the SSA report (Service
2022a, appendix 6).
Urbanization
Urbanization causes permanent impacts on the landscape that
potentially result in the loss and alteration of pygmy-owl habitat.
Residential, commercial, and infrastructure development replace and
fragment areas of native vegetation resulting in the loss of available
pygmy-owl habitat and habitat connectivity needed to support pygmy-owl
dispersal and demographic support (exchange of individuals and rescue
effect) of population groups.
Urbanization can also have detrimental effects on wildlife habitat
by increasing the channelization or disruption of riverine corridors,
the proliferation of exotic species, and the fragmentation of remaining
patches of natural vegetation into smaller and smaller pieces that are
unable to support viable populations of native plants or animals (Ewing
et al. 2005, pp. 1-2; Nabhan and Holdsworth 1998, p. 2). Human-related
mortality (e.g., shooting, collisions, and predation by pets) also
increases as urbanization increases (Banks 1979, pp. 1-2; Churcher and
Lawton 1987, p. 439). Development of roadways and their contribution to
habitat loss and fragmentation is a particularly widespread impact of
urbanization (Nickens 1991, p. 1). Data from Arizona and Mexico
indicate that roadways and other open areas lacking cover affect pygmy-
owl dispersal (Abbate et al. 1999, p. 54; Flesch and Steidl 2007, pp.
6-7; Flesch 2017, p. 5; Flesch et al. 2017, entire; Flesch 2021, pp.
12-14). Nest success and juvenile survival were also lower at pygmy-owl
nest sites closer to large roadways, suggesting that habitat quality
may be reduced in those areas (Flesch and Steidl 2007, pp. 6-7; Flesch
2017, p. 5).
From 2010 to 2020, various land uses, including urbanization, have
resulted in the loss of pygmy-owl habitat in Arizona and Texas (Service
2022a, appendix 6), and this loss and fragmentation of pygmy-owl
habitat is likely to continue. While there is not a direct correlation
between acres of pygmy-owl habitat lost and human population growth, it
is reasonable to conclude that, as human population grows, the amount
of native habitat lost or fragmented will increase. From 2010 to 2020,
population growth rates increased in all Arizona counties where the
pygmy-owl has recently occurred: Pima (9.3 percent); Pinal (25.7
percent); and Santa Cruz (13 percent) (OEO 2018, unpaginated). Many
cities and towns within the historical distribution of the pygmy-owl in
Arizona experienced substantial growth between April 2010 and July
2019: Casa Grande (20.7 percent); City of Eloy (17.8 percent); City of
Florence (7.7 percent); Town of Marana (41.9 percent); Town of Oro
Valley (12.2 percent); and the Town of
[[Page 46918]]
Sahuarita (20.9 percent) (U.S. Census Bureau 2021a, unpaginated). Urban
expansion and human population growth trends in Arizona are expected to
continue into the future. The Maricopa-Pima-Pinal Counties area of
Arizona is expected to grow by as much as 132 percent between 2005 and
2050, creating rural-urban edge effects across thousands of acres of
pygmy-owl habitat (AECOM 2011, p. 13). Additionally, a wide area from
the international border in Nogales, through Tucson, Phoenix, and north
into Yavapai County (called the Sun Corridor ``Megapolitan'' Area) is
projected to have 11,297,000 people by 2050, a 132 percent increase
from 2005 (AECOM 2011, p. 13). If build-out occurs as expected, it will
encompass a substantial portion of the current and historical
distribution of the pygmy-owl in Arizona.
In Texas, the pygmy-owl occurred in relatively high abundance until
approximately 90 percent of the mesquite-ebony woodlands of the Rio
Grande delta were cleared in 1910-1950 (Oberholser 1974, p. 452).
Currently, most of the pygmy-owl habitat occurs on private ranch lands,
and, therefore, the threat of habitat loss and fragmentation of the
remaining pygmy-owl habitat due to urbanization may be reduced in some
areas of Texas. However, urbanization and agriculture along the United
States-Mexico border are likely to continue to isolate the Texas
population of pygmy-owls by restricting movements between Texas and
northeastern Mexico (TDC 2019, entire; Texas Land Trends 2019, entire;
USGS 2022, unpaginated).
The United States-Mexico border region has a distinct demographic
pattern of permanent and temporary development related to warehouses,
exports, and other border-related activities, and patterns of
population growth in this area of northern Mexico has accelerated
relative to other Mexican States (Pineiro 2001, pp. 1-2). The Sonoran
border population has been increasing faster than that State's average
and faster than Arizona's border population; between 1990 and 2000, the
population in the Sonoran border municipios increased by 33.4 percent,
compared to Sonora's average (21.6 percent) and the average increase of
Arizona's border counties (27.8 percent). Growth of urban areas in
Texas is expected to result in a decrease of rural land uses, further
fragmenting habitats in this region (Texas Land Trends 2019, entire).
Urbanization has increased habitat conversion and fragmentation, which,
along with immigration, population growth, and resource consumption,
were ranked as the highest threats to the Sonoran Desert Ecoregion
(Nabhan and Holdsworth 1998, p. 1). This pattern focuses development,
and potential barriers or impediments to pygmy-owl movements, in a
region that is important for demographic support (immigration events
and gene flow) of pygmy-owl population groups, including movements such
as dispersal.
Significant human population expansion and urbanization in the
Sierra Madre foothill corridor may represent a long-term risk to pygmy-
owls in northeastern Mexico. From 2010 to 2015 the population in
Tamaulipas increased by 8 percent to 3,527,735, and the population in
Nuevo Le[oacute]n increased by 24 percent to 5,784,442 (DataMexico
2021, unpaginated). Such increasing urbanization results in the
permanent removal of pygmy-owl habitat reducing habitat availability
and, more significantly, increases habitat fragmentation affecting the
opportunity for pygmy-owl movements within northeastern Mexico and
between Mexico and Texas. Habitat removal in northeastern Mexico is
widespread and nearly complete in northern Tamaulipas (Hunter 1988, p.
8). Demographic support (rescue effect) of pygmy-owl population groups
is threatened by ongoing loss and fragmentation of habitat in this
area. Urbanization has the potential to permanently alter the last
major landscape linkage between the pygmy-owl population in Texas and
those in northeastern Mexico (Tewes 1993, pp. 28-29).
Human population growth in Sinaloa, Nayarit, Colima, and Jalisco,
Mexico, is ongoing. From 2010 to 2015, the population in Sinaloa grew
at a rate of 9.3 percent, Nayarit grew at a rate of 13.9 percent,
Jalisco grew at a rate of 13.6 percent, and Colima grew at a rate of
12.4 percent (DataMexico 2021, unpaginated). Growth rates in these
areas will likely have some concurrent spread of urbanization despite
the fact that most of the growth is taking place in the large cities
rather than in the rural areas (Brinkhoff 2016, unpaginated).
Additionally, these Mexican States have other threats to pygmy-owl
habitat occurring, such as agricultural development and deforestation,
that, in combination with habitat lost to urbanization, represent
threats to the continued viability of the pygmy-owl in this area
(Blackie et al. 2014, p. 1; Burquez 2022, pers. comm.; Mesa-Sierra et
al. 2022, entire).
Invasive Species
The invasion of nonnative vegetation, particularly nonnative
grasses, has altered the natural fire regime over the Sonoran Desert
ecoregion of the pygmy-owl range, in particular, but invasive species
impact native habitats in other pygmy-owl analysis units as well (Esque
and Schwalbe 2002, p. 165; Lyons et al. 2013, p. 71; Wied et al. 2020,
entire). In areas composed entirely of native species, ground
vegetation density is mediated by barren spaces that do not allow fire
to carry across the landscape. However, in areas where nonnative
species have become established, the fine fuel load is continuous, and
fire is capable of spreading quickly and efficiently (Esque and
Schwalbe 2002, p. 175; Wied et al. 2020, p. 48). As a result, fire has
become a significant threat to the native vegetation of the Sonoran
Desert. Sonoran Desert vegetation is not fire adapted, and many such
vegetative communities in Arizona are no longer in a natural or
historical state. Instead, these vegetative communities and their fire
dynamics have been inalterably changed by nonnative grasses and forbs,
and in some areas by woody shrubs and trees (Gornish and Howery 2019,
entire). Nonnative plant communities are problematic not only for
imperiled species such as the pygmy-owl, but also for land managers
whose goals include forest stewardship and wildfire mitigation for
public safety and natural resource protection. The Arizona Wildfire
Risk Assessment Portal estimates that a substantial portion of the
pygmy-owl range in Arizona (2,433,763 ha; 6,013,959 acres) has a
moderate to high risk of experiencing adverse effects of wildfire in
the foreseeable future. As discussed elsewhere in this final rule and
in our SSA report, such adverse effects include the destruction of
roosting and nesting substrate provided by mature trees and columnar
cacti. Using conservative estimates from post-fire monitoring performed
by the Tonto National Forest, the Arizona Department of Forestry and
Fire Management (ADFFM) concluded that over 30 million saguaros could
be lost and unlikely to regenerate if a large portion of the area under
risk were to burn (ADFFM 2022, pers. comm.).
Nonnative annual plants prevalent within the Sonoran range of the
pygmy-owl include Bromus rubens and B. tectorum (brome grasses),
Schismus spp. (Mediterranean grasses), and Sahara mustard (Brassica
tournefortii) (Esque and Schwalbe 2002, p. 165; ASDM 2021,
unpaginated). However, the nonnative species that is currently one of
the greatest threats to vegetation communities in Arizona and Texas in
the United States and northeastern and northwestern Mexico is the
perennial Cenchrus ciliaris (buffelgrass), which is
[[Page 46919]]
prevalent and increasing throughout much of the range of the pygmy-owl
(Burquez and Quintana 1994, p. 23; Van Devender and Dimmit 2006, p. 5;
Lyons et al. 2013, pp. 68-69; Wied et al. 2020, pp. 47-48).
Buffelgrass is not only fire-tolerant (unlike native Sonoran Desert
plant species) but is actually fire-promoting (Halverson and Guertin
2003, p. 13; Lyons et al. 2013, p. 71). Invasion sets in motion a
grass-fire cycle where nonnative grass provides the fuel necessary to
initiate and promote fire. Nonnative grasses recover more quickly than
native grass, tree, and cacti species and cause a further
susceptibility to fire (D'Antonio and Vitousek 1992, p. 73; Schmid and
Rogers 1988, p. 442). While a single fire in an area may or may not
produce long-term reductions in plant cover or biomass, repeated
wildfires in a given area, due to the establishment of nonnative
grasses, are capable of ecosystem type-conversion from native
desertscrub to nonnative annual grassland (Wied et al. 2020, p. 48).
These repeated fires may render the area unsuitable for pygmy-owls and
other native wildlife due to the loss of trees and columnar cacti and
reduced diversity of cover and prey species (Brooks and Esque 2002, p.
336; Wied et al. 2020, p. 48).
The distribution of buffelgrass has been supported and promoted by
governments on both sides of the United States-Mexico border as a
resource to increase range productivity and forage production (Lyons et
al. 2013, p. 65). A 2006 publication estimates that 143,504 ha (3.5
million ac) have been converted to buffelgrass in Sonora, and that
between 1990 and 2000, there was an 82 percent increase in buffelgrass
coverage (Franklin et al. 2006, pp. 62, 66, 67). Following
establishment, buffelgrass fuels fires that destroy Sonoran
desertscrub, thornscrub, and, to a lesser extent, tropical dry forest;
the disturbed areas are quickly converted to open savannas composed
entirely of buffelgrass, which removes pygmy-owl nest substrates and
generally renders areas unsuitable for future occupancy by pygmy-owls.
Buffelgrass is now fully naturalized in most of Sonora, southern
Arizona, and some areas in central and southern Baja California
(Burquez-Montijo et al. 2002, p. 131) and now commonly spreads without
human cultivation (Burquez et al. 1998, p. 26; Perramond 2000, p. 131;
Arriaga et al. 2004, pp. 1509-1511).
Because of the significance of the issue of buffelgrass invasion in
Arizona, the Governor of Arizona formed the Arizona Invasive Species
Advisory Council in 2005, and the Southern Arizona Buffelgrass Working
Group developed the Southern Arizona Buffelgrass Strategic Plan in 2008
(Buffelgrass Working Group 2008, entire) in order to coordinate the
control of buffelgrass. Because of its negative impacts to native
ecosystems, buffelgrass was declared a noxious weed by the State of
Arizona in March 2005. This buffelgrass working group is now led by the
Arizona-Sonora Desert Museum (ASDM). The ASDM is currently mapping the
extent, and control, of buffelgrass in southern Arizona in an effort to
inform and direct management activities (ASDM 2022, unpaginated). These
efforts are helping to manage buffelgrass invasion in southern Arizona.
Similar issues occur in Texas. Buffelgrass is now one of the most
abundant nonnative grasses in South Texas, and a prevalent invasive
grass within the range of the pygmy-owl. During the 1950s, Federal and
State land management agencies promoted buffelgrass as a forage grass
in South Texas (Smith 2010, p. 113; Lyons et al. 2013, p. 69).
Buffelgrass is very well adapted to the hot, semi-arid climate of South
Texas due to its drought resistance and ability to aggressively
establish in heavily grazed landscapes (Smith 2010, p. 113; Wied et al.
2020, p. 48). Despite increasing awareness of the ecological damage
caused by nonnative grasses, buffelgrass is still planted in areas
affected by drought and overgrazing to stabilize soils and to increase
rangeland productivity. Prescribed burning used for brush control
typically promotes buffelgrass forage production in South Texas
(Hamilton and Scifres 1982, p. 11). Buffelgrass often creates
homogeneous monocultures by out-competing native plants for essential
resources (Lyons et al. 2013, p. 8). Furthermore, buffelgrass produces
phytotoxins in the soil that inhibit the growth of neighboring native
plants (Vo 2013, unpaginated). With regard to pygmy-owl habitat, the
loss of trees and canopy cover and the creation of dense ground cover
resulting from buffelgrass conversion reduces nest cavity availability,
cover for predator avoidance and thermoregulation, and prey
availability. Overall, buffelgrass is the dominant herbaceous cover on
10 million ha (24,710,538 acres) in southern Texas and northeastern
Mexico (Wied et al. 2020, p. 47).
The impacts of buffelgrass establishment and invasion are
substantial for the pygmy-owl in the United States and Mexico because
conversion results in the loss of important habitat features,
particularly columnar cacti and trees that provide nest sites.
Buffelgrass also reduces habitat diversity by creating monocultures of
buffelgrass and out-competing native vegetation species (Lyons et al.
2013, pp. 66-67; Wied et al. 2020, p. 48), which decreases prey
availability for the pygmy-owl by decreasing the habitat compositional
and structural diversity. Buffelgrass invasion and the subsequent fires
eliminate most columnar cacti, trees, and shrubs of the desert
(Burquez-Montijo et al. 2002, p. 138). This elimination of trees,
shrubs, and columnar cacti from these areas is a potential threat to
the survival of the pygmy-owl in the northern part of its range, as
these vegetation components are necessary for roosting, nesting,
protection from predators, and thermal regulation. Invasion and
conversion to buffelgrass also negatively affect the diversity and
availability of prey species in these areas (Franklin et al. 2006, p.
69; Avila-Jimenez 2004, p. 18; Burquez-Montijo et al. 2002, pp. 130,
135).
Buffelgrass is adapted to dry, arid conditions and does not grow in
areas with high rates of precipitation or high humidity, above
elevations of 1,265 m (4,150 ft), or in areas with freezing
temperatures. Areas that support pygmy-owls south of Sonora and
northern Sinaloa typically are wetter and more humid, and conditions
are not as favorable for the invasion of buffelgrass. Surveys completed
in Sonora and Sinaloa in 2006 noted buffelgrass was present in Sonora
and northern Sinaloa, but the more southerly locations were noted as
sparse or moderate (Van Devender and Dimmitt 2006, p. 7). However,
because buffelgrass was first introduced to Mexico in Tamaulipas and
Neuvo Leon, and then subsequently to Sonora and Sinaloa (Lyons et al.
2013, pp. 68-69), buffelgrass and its associated impacts are found in
all five of the pygmy-owl analysis units used in our analysis for this
final rule.
Agricultural Production and Wood Harvesting
Agricultural development and wood harvesting can result in
substantial impacts to the availability and connectivity of pygmy-owl
habitat. Conversion of native vegetation communities to agricultural
fields or pastures for grazing has occurred within historical pygmy-owl
habitat in both the United States and Mexico, and not only removes
existing pygmy-owl habitat elements, but also can affect the long-term
ability of these areas to return to native vegetation communities once
agricultural activities cease. Wood harvesting has a direct effect on
the
[[Page 46920]]
amount of available cover and nest sites for pygmy-owls and is often
associated with agricultural development. Wood harvesting also occurs
to supply firewood and charcoal, and to provide material for cultural
and decorative wood carvings.
In Arizona, although new agricultural development is limited, the
effects to historical habitat are still evident. Many areas that
historically supported meso- and xeri-riparian habitat have been
converted to agricultural lands, and associated groundwater pumping has
affected the hydrology of these valleys (Jackson and Comus 1999, pp.
233, 249). These riparian areas are important pygmy-owl habitat,
especially within drier upland vegetation communities like Sonoran
desertscrub and semi-desert grasslands.
Habitat fragmentation as a result of agricultural development has
also occurred within Texas. Brush-clearing, pesticide use, and
irrigation practices associated with agriculture have had detrimental
effects on the Lower Rio Grande Valley (Jahrsdoerfer and Leslie 1988,
p. 1). From the 1920s until the early 1970s, over 90 percent of pygmy-
owl habitat in the Lower Rio Grande Valley of Texas was cleared for
agricultural and urban expansion (Oberholser 1974, p. 452). The Norias
Division of the King Ranch in southern Texas has been at the center of
most research on pygmy-owls in Texas (Mays 1996, entire; Proudfoot
1996, entire), but has been isolated by agricultural expansion, which
has restricted pygmy-owl dispersal (Oberholser 1974). This expansion
has resulted in loss of pygmy-owl habitat connectivity between pygmy-
owl population groups in Texas and in Mexico. From 2010 to 2020,
various land uses, including agricultural development and wood
harvesting, have resulted in some loss of pygmy-owl habitat in Arizona
and Texas (Service 2022a, Appendix 6), and this loss and fragmentation
of pygmy-owl habitat is likely to continue based on population growth
projections (HHS 2017, unpaginated; OEO 2018, unpaginated; TDC 2019,
entire; Pinal County 2019, p. 126; Gonzales 2020, unpaginated).
Historically, agriculture in Sonora, Mexico, was restricted to
small areas with shallow water tables, but it had, nonetheless,
seriously affected riparian areas by the end of the nineteenth century.
For example, in the Rio Mayo and Rio Yaqui coastal plains, nearly 1
million ha (2.5 million ac) of mesquite, cottonwood, and willow
riparian forests and coastal thornscrub disappeared after dams upriver
started to operate (Burquez and Martinez-Yrizar 2007, p. 543). Other
Mexican States within the range of the pygmy-owl show similar potential
for habitat loss. For example, in Tamaulipas, areas under irrigation
increased from 174,400 to 494,472 ha (431,000 to 1.22 million ac)
between 1998 and 2004, with an area of 668,872 ha (1.65 million ac)
equipped for irrigation. However, agricultural development in the
States of Colima, Jalisco, Nayarit, and Nuevo Leon had decreases in the
amount of irrigated lands over the same period (FAO 2007, unpaginated).
There is some evidence that historical agricultural practices by
indigenous peoples and early settlers provided and potentially enhanced
available pygmy-owl habitat in Arizona, primarily through the
development of irrigation canals that promoted the presence of woody
vegetation (BOR 1947, unpaginated; Johnson et al. 2004, p. 139).
However, more recent agricultural developments typically remove areas
of native vegetation resulting in pygmy-owl habitat loss and
fragmentation over relatively large areas, causing reductions in ground
and surface waters impacting riparian systems important to the pygmy-
owl and pygmy-owl prey species, and resulting in habitat fragmentation
and loss of habitat connectivity for the pygmy-owl. While the loss and
fragmentation of habitat is more of an historical impact in Arizona and
Texas, some agricultural development continues in these areas and some
historical impacts are still evident. In Mexico, agricultural
development is an ongoing threat to pygmy-owl habitat (Burquez 2022,
pers. comm.).
Wood harvesting is also a potential threat to pygmy-owl habitat.
Ironwood (Olneya tesota) and mesquite (Prosopis spp.) are harvested
throughout the Sonoran Desert for use as charcoal, fuelwood, and
carving (Burquez and Martinez Yrizar 2007, p. 545). For instance, by
1994, 202,000 ha (500,000 ac) of mesquite had been cleared in northern
Mexico to meet the growing demand for mesquite charcoal (Haller 1994,
p. 1). Flesch (2021, pp. 11, 13) noted that pygmy-owl habitat impacts
from charcoal operations are still occurring in Sonora. Unfortunately,
woodcutters and charcoal makers used large, mature mesquite and
ironwood trees growing in riparian areas (Taylor 2006, p. 12), which is
the tree class that is of most value as pygmy-owl habitat. Loss of
leguminous trees results in long-term effects to the soil as these
trees add organic matter, fix nitrogen, and add sulfur and soluble
salts, affecting overall habitat quality and quantity (Rodriguez-Franco
and Aguirre 1996, p. 6-47). Ironwood and mesquite trees are important
nurse plant species for saguaros, the primary nesting substrate for
pygmy-owls in the northern portion of their range (Burquez and Quintana
1994, p. 11). Declining tree populations in the Sonoran Desert as a
result of commercial uses and land conversion threatens other plant
species and may alter the structure and composition of the vertebrate
and invertebrate communities as well (Bestelmeyer and Schooley 1999, p.
644). This has implications for pygmy-owl prey availability because
pygmy-owls rely on a seasonal diversity of vertebrate and invertebrate
prey species; loss of tree structure and diversity reduces prey
diversity and availability.
Once common in areas of the Rio Grande delta, significant habitat
loss and fragmentation due to woodcutting have now caused the pygmy-owl
to be a rare occurrence in this area of Texas. Oberholser (1974, p.
452) concluded that agricultural expansion and subsequent loss of
native woodland and thornscrub habitat, begun in the 1920s, preceded
the rapid demise of pygmy-owl populations in the Lower Rio Grande
Valley of southern Texas. Because much of the suitable pygmy-owl
habitat in Texas occurs on private ranches, habitat areas are subject
to potential impacts that are associated with ongoing ranch activities
such as grazing, herd management, fencing, pasture improvements,
construction of cattle pens and waters, road construction, and
development of hunting facilities. Brush-clearing, in particular, has
been identified as a potential factor in present and future declines in
the pygmy-owl population in Texas (Oberholser 1974, p. 452).
Conversely, ranch practices that enhance or increase pygmy-owl habitat
to support ecotourism can contribute to conservation of the pygmy-owl
in Texas (Wauer et al. 1993, p. 1076).
Habitat fragmentation in northeastern Mexico is extensive, with
only about two percent of the ecoregion remaining intact, and no
habitat blocks larger than 250 square km (96.5 square mi), and no
significant protected areas (Cook et al. 2001, p. 4). Fire is often
used to clear woodlands for agriculture in this area of Mexico, and
many of these fires are not adequately controlled. There may be fire-
extensive related effects to native plant communities (Cook et al.
2001, p. 4); however, there is no specific information available for
how much area may be affected by this activity.
Areas of dry subtropical forests, important habitat for pygmy-owls
in southwestern Mexico, have been used by humans through time for
settlement
[[Page 46921]]
and various other activities (Trejo and Dirzo 2000, p. 133; Blackie et
al. 2014, pp. 1-2). The long-term impact of this settlement has
converted these dry subtropical forests into shrublands and savannas
lacking large trees, columnar cacti, and cover and prey diversity that
are important pygmy-owl habitat elements. In Mexico, tropical dry
forest is the major type of tropical vegetation in the country,
covering over 60 percent of the total area of tropical vegetation.
About 8 percent (approximately 160,000 square km (61,776 square mi)) of
this forest remained intact by the late 1970s, and an assessment made
at the beginning of the present decade suggested that 30 percent of
these tropical forests have been altered and converted to agricultural
lands and cattle grasslands (Trejo and Drizo 2000, p. 134; Mesa-Sierra
et al. 2022, unpaginated). Tropical dry forests, such as Selva baja
caducifolia and Bosque tropical caducifolio, are the most important
reservoir of biodiversity along the Pacific coast of Mexico (Burquez
2022, pers. comm.). Extensive reductions in these habitats have
occurred in the past. For instance, extensive irrigation systems have
been developed along the coasts of Sinaloa and Nayarit, and in more
localized areas in Jalisco, Michoac[aacute]n, and Guerrero. These and
other land-transformation pressures affecting tropical dry forests have
not diminished with time (Burquez 2022, pers. comm.).
Summary of Habitat Loss and Fragmentation
In summary, pygmy-owls require habitat elements such as mature
woodlands that include appropriate cavities for nest sites, adequate
structural diversity and cover, and a diverse prey base. These habitat
elements need to be available across the geographic range of the pygmy-
owl and spatially arranged to allow connectivity between habitat
patches. Pygmy-owl habitat loss and fragmentation have affected, and
are continuing to affect, pygmy-owl viability throughout its range.
These threats vary in scope and intensity throughout the pygmy-
owl's geographic range, and specific threats are a more significant
issue in certain parts of the range than in others. For example, in
Arizona and Northern Sonora, pygmy-owl habitat loss and fragmentation
resulting from urbanization, changing fire regimes due to the invasion
of buffelgrass, and agricultural development and woodcutting are
significant threats that have negatively affected pygmy-owl habitat. In
Texas, historical loss of habitat has reduced the pygmy-owl range, and,
in Texas and other areas of the pygmy-owl's range, these past impacts
continue to affect the current extent of available pygmy-owl habitat,
because of the extended time it takes for these lands to recover.
Therefore, even if habitat destruction ceases, the negative effects of
past land use are expected to continue in many of these areas into the
future, and this will be a cumulative impact with current impacts from
invasive species, agricultural development, and other land use
practices (Texas Land Trends 2019, entire; Wied et al. 2020, entire;
DHS 2020, unpaginated; USGS 2022, unpaginated).
One of the most pressing issues for the U.S.-Mexico border is the
impact of illegal human and vehicular traffic through these unique and
environmentally sensitive areas. Many of these locations now bear the
scars of wildcat trails, abandoned refuse, and trampled vegetation
(Marris 2006, p. 339; Walker and Pavlakovich-Kochi 2003, p. 15). Trails
and roadways remove pygmy-owl habitat features; noise and disturbance
from people and vehicles disrupt important behaviors; and there is an
increased risk of fire in important habitats resulting from cooking and
warming fires, as well as signal fires used by cross-border immigrants
and smugglers.
For the remainder of the pygmy-owl's range and habitat in Mexico
(northeastern Mexico and south of Sonora), data available for our
analysis were limited. Available data that we considered regarding
population growth and land use patterns indicates that human population
growth throughout Mexico is occurring (INEGI 2021, unpaginated; CONAPO
2014, p. 25; DataMexico 2021, unpaginated). Historical loss of pygmy-
owl habitat in northeastern Mexico has occurred, and recent increases
in agricultural development are occurring in Tamaulipas (FAO 2007,
unpaginated). Tropical dry forests, one of the most biologically
significant vegetation communities in Mexico and important pygmy-owl
habitat, has been significantly reduced and is continuing to be lost
(Burquez 2022 pers. comm.; Mesa-Sierra et al. 2022, unpaginated).
This information indicates that the impacts to pygmy-owl habitat
discussed herein may be having different levels of effects on the
populations of pygmy-owls throughout their range and, while not every
activity is occurring in every analysis unit, every analysis unit is
experiencing habitat loss and fragmentation (Service 2022a, appendix
5). Enr[iacute]quez and Vazquez-Perez (2017, p. 546) indicate that,
during the last 50 years, Mexico has seen drastic changes in land uses
due to rapid urbanization and industrialization, which has been poorly
planned. The result has been impacts to the natural environment,
including the degradation and loss of biological diversity in Mexico.
There has been limited work in Mexico, however, to understand what the
direct impacts of these threats are on owl population losses and
changes in distribution and abundance of subspecies in the long term
(Enr[iacute]quez and Vazquez-Perez 2017, p. 546).
Habitat loss and fragmentation will impact both the eastern and
western populations of pygmy-owls through reduced size and number of
suitable blocks of nesting habitat and nest cavity availability, loss
and reduction of habitat connectivity and the ability of pygmy-owls to
move across the landscape to provide demographic and genetic rescue,
loss and reduction of prey availability, and the increase of potential
threats related to predation, pesticides, and human disturbance.
Climate Change and Climate Conditions
Enough time has passed since the early predictions of impacts of
climate change that we have seen evidence of those predicted impacts on
vegetation communities across the range of the pygmy-owl (Vermote et
al. 2014, unpaginated; Romero-Lankao, et al. 2014, p. 1459; Williams et
al. 2020, p. 317; IPCC 2022, entire). New climate models and
projections, updated Normalized Difference Vegetation Index (NDVI)
datasets, and an assessment examining pygmy-owl's vulnerability to
climate change have been completed since our analysis in the 2011
pygmy-owl 12-month finding (Bagne and Finch 2012, pp. 67-73; Coe et al.
2012, entire; Jiang and Yang 2012, entire; IPCC 2014b, entire; Romero-
Lankao, et al. 2014, entire; Melillo et al. 2014, entire; Vermote et
al. 2014, unpaginated; AdaptWest Project 2015, unpaginated; Cook et al.
2015, entire; Pascale et al. 2017, p. 806; USGCRP 2018, chapters 23 and
25; Gonzalez et al. 2018, entire; Christensen et al. 2018, p. 5409; BOR
2021, entire; AdaptWest Project 2022, unpaginated; IPCC 2022, entire).
These projections continue to predict impacts at the same or increasing
levels upon the landscape in areas where the pygmy-owl occurs.
In the SSA report, the proposed rule, and this final listing rule,
we used newer modeling related to climate that was not used in our 2011
12-month finding, and this change reduced the subjectivity of our
approach to evaluate the effects to pygmy-owl habitat effects
[[Page 46922]]
(Vermote et al. 2014, unpaginated; AdaptWest Project 2015, unpaginated;
Wang et al. 2016, pp. 6-7; Dewes et al. 2017, p. 17; Diffenbaugh et al.
2017, entire; AdaptWest Project 2022, unpaginated; Service 2022a,
chapter 6, appendices 2 and 3). Furthermore, additional IPCC reports
have been published since 2011, as well as National Climate
Assessments, and we have included the appropriate information found in
these sources in our climate analysis to ensure that we considered the
most current and best information available. These sources represent
the current understanding of the evidence and effects of climate change
(IPCC 2014b, entire; Melillo et al. 2014, entire; USGCRP 2018, chapters
23 and 25; IPCC 2022, entire).
Climate change projections within the geographic range of the
pygmy-owl show that increasing temperatures, decreasing precipitation,
and increasing intensity of weather events are likely (Karmalkar et al.
2011, entire; Bagne and Finch 2012, entire; Coe et al. 2012, entire;
and Jiang and Yang 2012, entire; BOR 2021; p. 23). Climate influences
pygmy-owl habitat conditions and availability through the loss of
vegetation cover, reduced prey availability, increased predation,
reduced nest site availability, and vegetation community change. The
majority of the current range of the pygmy-owl occurs in tropical or
subtropical vegetation communities, which may be reduced in coverage if
climate change results in hotter, more arid conditions. Extended
drought has and continues to affect vegetation communities used by the
pygmy-owl in the United States (NDMC 2022, unpaginated). Additionally,
models predict that the distribution of suitable habitat for saguaros,
the primary pygmy-owl nesting substrate within the Sonoran Desert
ecoregion, will substantially decrease over the next 50 years under a
moderate climate change scenario (Weiss and Overpeck 2005, p. 2074;
Thomas et al. 2012, p. 43).
Climate change scenarios project that drought will occur more
frequently and increase in severity, with a decrease in the frequency
and increase in severity of precipitation events (Seager et al. 2007,
p. 9; Cook et al. 2015, p. 6; Pascale et al. 2017, p. 806; Williams et
al. 2020, p. 317; BOR 2021, p. 23). Drought and changes to the timing
and intensity of precipitation events may reduce available cover and
prey for pygmy-owls adjacent to riparian areas through scouring flood
events and reduced moisture retention. The extent to which changing
climatic patterns will affect the pygmy-owl is better understood
following the past decade of observations in the field. For example, in
northern Sonora, the summer monsoon's precipitation (or lack thereof)
has a significant effect on whether or not juvenile pygmy-owls reach
adulthood, as the lizards preferred by these owls are more abundant
when summer precipitation does not fall below normal levels. Climate
change has made the amount of summer precipitation more variable than
it used to be. Average summer monsoons in the Sonoran Desert produce
2.43 inches of rain. In years like 2019 and 2020, however, when summer
rainfall was significantly below average (0.66 inches and 1.0 inches
respectively), there was less prey for juveniles to eat as they entered
adulthood, and thus fewer owls survived. In years like 2015-2016, when
the amount of precipitation from the summer monsoon was above average,
more juveniles survived to adulthood and owl population levels in those
years did not decline (Flesch 2021, entire).
Synergistic interactions are likely to occur between the effects of
climate change and habitat fragmentation and loss. Climate change
projections indicate that conditions will likely favor increased
occurrence and distribution of nonnative, invasive species and
alteration of historical fire regimes. Climate change may also affect
the viability of the pygmy-owl through precipitation-driven changes in
plant and insect biomass, which in turn influence abundance of lizards,
small mammals, and birds (Jones 1981, p. 111; Flesch 2008, p. 5; Flesch
et al. 2015, p. 26). Decreased precipitation generally reduces plant
cover and insect productivity, which in turn reduces the abundance and
availability of pygmy-owl prey species. Similarly, increased
temperatures reduce pygmy-owl prey activity due to increased energetic
demands of thermoregulation and a decreased availability of prey and
cover (Flesch 2014, p. 116; Flesch et al. 2015, p. 26). These indirect
effects on prey availability and direct effects on prey activity affect
nestling growth, development, and survival. When decreased
precipitation affects food supply and increased temperature affects
prey activity, reduced pygmy-owl productivity is likely to result in
reduced pygmy-owl resiliency (Flesch et al. 2015, p. 26).
A recent downscaled hydroclimate study reported predicted climate
impacts within the range of the pygmy-owl in Arizona (BOR 2021,
entire). In general, the scenarios for the greenhouse gas emissions
model that approximates our current trajectory predicts that monsoonal
rain will be reduced, as well as more highly variable. Temperatures
will also increase significantly during both winter (between 1.88
[deg]Fahrenheit (F) and 3.20 [deg]F) and summer (between 2.59 [deg]F
and 3.34 [deg]F). As a result, streamflow throughout the area covered
by this effort, including the Avra and Altar valleys, which are
occupied by pygmy-owls, is likely to be reduced, which would negatively
impact infiltration into the aquifer. These changes are likely to
impact pygmy-owls and their prey species in a variety of ways, many of
them negative. For example, increased evapotranspiration and reduced
soil moisture could negatively impact prey species that pygmy-owls
depend on, reduce the amount and/or quality of vegetation necessary for
roosting, thermoregulation, and predator avoidance, amplify fire risk
and concomitant compromise of necessary woodland vegetation and
availability of mature saguaro cacti, as well as lead to reduced
nestling fitness if nest cavity temperatures rise too high (Flesch et
al. 2015, p. 26; Service 2022a, chapter 6; Flesch 2021, entire).
Climate change can also influence natural events, such as hurricanes
and tropical storms, which can modify and fragment pygmy-owl habitats,
primarily through loss of woody cover, as evidenced in Texas and
northeastern Mexico (Hurricane Harvey in 2017, Hurricane Hanna in 2020,
and Hurricane Ida in 2021). Historical and ongoing threats to the
pygmy-owl from habitat loss and fragmentation as well as from climate
change and climate conditions, have shaped the current habitat and
population conditions of the subspecies throughout its range.
In summary, climate change and its associated change in conditions
on the landscape will impact both the eastern and western pygmy-owl
populations through habitat loss and fragmentation, reduced nest cavity
availability, reduced prey populations, lower productivity, and reduced
survivability.
Current Condition
To assess resiliency, we evaluated six components that broadly
related to the subspecies' population demography or physical
environment and for which we had data sufficient to conduct the
analysis. We assessed each analysis unit's physical environment by
examining three components determined to have the most influence on the
subspecies: habitat intactness, prey availability, and vegetation
health and cover (Flesch 2017, entire). We also assessed each analysis
unit's demography through abundance, occupancy, and evidence of
reproduction. We established
[[Page 46923]]
parameters for each component by evaluating the range of existing data
and separating those data into categories based on our understanding of
the subspecies' demographics and habitat. Using the demographic and
habitat parameters, we then categorized the overall condition of each
analysis unit. We provide a summary of each of the six factors below
and describe them in detail in the SSA report (Service 2022a, entire).
Demographic Factors
Abundance: Larger populations have a lower risk of extinction than
smaller populations (Pimm et al. 1988, pp. 773-775; Trombulak et al.
2004, p. 1183). Small populations are less resilient and more
vulnerable to the effects of demographic, environmental, and genetic
stochasticity, and have a higher risk of extinction than larger
populations (Trombulak et al. 2004, p. 1183). Small populations may
experience increased inbreeding, loss of genetic variation, and
ultimately a decreased potential to adapt to environmental change
(Trombulak et al. 2004, p. 1183; Harmon and Braude 2010, p. 125; Benson
et al. 2016, pp. 1-2). The abundance of pygmy-owls within each analysis
unit must be high enough to support persistence of pygmy-owl population
groups (multiple breeding pairs of pygmy-owls within relatively
discrete geographic areas) within the analysis unit. This persistence
of population groups is accomplished by having adequate patches of
habitat to support multiple nesting pairs of pygmy-owls and their
offspring, having adequate habitat connectivity to support
establishment of additional territories by dispersing young, and having
a supply of floaters (unpaired individuals of breeding age) within each
pygmy-owl population group to offset loss of breeding adults and to
provide potential mates for dispersing juveniles. In order to compare
the resiliency of the individual analysis units, we estimated the
general magnitude of the abundance of pygmy-owls within each analysis
unit (Service 2022a, chapter 6 and table 4.2). However, these estimates
of the magnitude of abundance should not be construed as actual
population estimates (see Summary of Current Condition of the
Subspecies below).
Occupancy: Sufficiently resilient pygmy-owl populations must occupy
large enough areas such that stochastic events and environmental
fluctuations that affect individual pygmy-owls, or population groups of
pygmy-owls, do not eliminate the entire population. Pygmy-owls are
patchily distributed across the landscape in population groups of
nesting owls. Each of these population groups must contain a high
enough abundance of pygmy-owls to enable the population group to
persist on the landscape over time. Enough occupied population groups
of pygmy-owls must also exist on the landscape, with interconnected
habitat supporting movement among population groups, so that each
population group can receive or exchange individuals with any given
adjacent population group.
Pygmy-owl occupancy is an indicator of habitat conditions as well
as demographic factors, such as reproduction and survival. Habitats
that support a high abundance of pygmy-owls are better able to provide
floaters and available mates to dispersing pygmy-owls from adjacent
populations. These floaters are able to serve as replacement breeders
if either or both members of an existing breeding pair are lost.
Observations indicate that if a site is occupied by a breeding pair,
they will breed. Survival of adults also affects occupancy, as some
occupied sites will be abandoned if one of the adult breeders perishes.
These sites can be reoccupied in the future when floaters or dispersing
birds move into the area.
Evidence of reproduction: Adequately resilient pygmy-owl
populations must also reproduce and produce a sufficient number of
young such that recruitment equals or exceeds mortality. Current
population size and abundance reflects previous influences on the
population and habitat, while reproduction and recruitment reflect
population trends that may be stable, increasing, or decreasing in the
future. Adequately resilient populations of the pygmy-owl must have
sufficient abundance to replace members of breeding pairs that have
been lost and to support persistent population groups of nesting pygmy-
owls through dispersal. However, the necessary reproductive rate needed
for a self-sustaining population is unknown. Additionally, key
demographic parameters of pygmy-owl populations (e.g., survival, life
expectancy, lifespan, productivity, etc.) are unknown throughout most
of the geographic range. Due to the lack of information on demographic
parameters of reproduction, recruitment, and survival, we broadly
considered evidence of reproduction to include any evidence of
reproduction (e.g., active nests, presence of eggs or nestlings,
fledglings, etc.), as well as persistence of occupied territories and
population groups in an area over a sufficient amount of time to
indicate evidence of reproduction. Thus, evidence of reproduction on a
consistent basis over time likely indicates a sufficiently resilient
population.
Habitat intactness: Adequately resilient pygmy-owl populations need
intact habitat that is large enough to support year-round occupancy, as
well as connectivity between habitat patches to enable dispersal. As
the baseline for our analysis of habitat intactness, we modeled
suitable vegetation types across the range of the pygmy-owl that
provide habitat for the pygmy-owl (Service 2022a, chapter 6 and
appendix 1). We know that the modeled suitable vegetation does not
equal pygmy-owl habitat and that the acres of suitable vegetation are
greater than the actual acres of pygmy-owl habitat. However, modeled
suitable vegetation does provide a surrogate for acres of pygmy-owl
habitat. Pygmy-owls are patchily distributed across much of their
geographic range. These pygmy-owl population groups are dependent on
interchange of individuals in order to maintain adequate abundance and
genetic diversity on the landscape. Habitat connectivity is crucial to
maintaining pathways for the interchange of individuals among pygmy-owl
population groups (Flesch 2017, entire).
Prey availability: Adequate prey availability is a key component
for maintaining resiliency in pygmy-owl populations. Year-round prey
availability is essential throughout the range of the pygmy-owl, with
portions of the geographic range characterized by seasonal variability
in available prey resources. The abundance of many of these prey
species is influenced by annual and seasonal precipitation through
increases and decreases in vegetation cover and diversity, which also
influences insect abundance and availability. Sufficiently resilient
pygmy-owl populations require adequate precipitation to support year-
round prey availability. This includes appropriately timed
precipitation to support seasonally available prey such as lizards,
insects, and small mammals.
Vegetation cover: Sufficiently resilient pygmy-owl populations
require adequate vegetation to provide cover for predator avoidance,
thermoregulation, hunting, and nest cavities. Of primary importance for
cover is the presence of woody vegetation canopy. Maintenance of the
health and vigor of this woody cover is a key component to maintaining
resiliency of pygmy-owl populations.
Summary of Current Condition of the Subspecies
Currently, the cactus ferruginous pygmy-owl occurs from southern
Arizona, south to Michoac[aacute]n in the
[[Page 46924]]
western portion of its range, and from southern Texas to Tamaulipas and
Nuevo Leon in the eastern portion of its range. For our analysis, we
divided the pygmy-owl's overall range into five analysis units:
Arizona, northern Sonora, western Mexico, Texas, and northeastern
Mexico (see Figure 1). In order to compare the resiliency of the
individual analysis units, we estimated the general magnitude of the
abundance of pygmy-owls within each analysis unit (Service 2022a,
chapter 6 and table 4.2). This estimated magnitude of abundance is one
of the demographic factors used to evaluate the resiliency of each
analysis unit. These estimates of the magnitude of abundance should not
be construed as actual population estimates. We lack sufficient data to
make any statistically meaningful population estimates for any of the
analysis units. Rather, these estimates of the magnitude of pygmy-owl
abundance are used as a tool to compare the general abundance of pygmy-
owls in each analysis unit.
The primary factors currently affecting the condition of cactus
ferruginous pygmy-owl populations include changing climate conditions,
and habitat fragmentation and loss. The threats contributing to or
resulting from these two primary factors do not occur consistently
across all analysis units, but all analysis units are being impacted by
one or more of the threats discussed in this final rule and the SSA
report (see Service 2022a, appendix 5 for a more detailed discussion of
the particular threats impacting each analysis unit). Information from
the northern Sonora analysis unit provides evidence of what factors
contribute to the viability of pygmy-owl populations. Flesch (2014, pp.
114-117) showed that, at least in the northern portion of the western
pygmy-owl population, pygmy-owl abundance was consistently higher and
varied less in areas with more nest cavities, more riparian vegetation,
and lower land-use intensity, suggesting these factors are important
drivers of pygmy-owl habitat quality. We have also identified which of
the five listing factors identified in the Act are influencing the
current condition of the pygmy-owl.
Resiliency
The Arizona analysis unit currently has the lowest pygmy-owl
abundance of all analysis units, which is estimated to be in the low
hundreds. Habitat fragmentation and loss from urbanization and
increases in invasive species such as buffelgrass, have reduced the
availability and connectivity of habitat in this analysis unit (Factor
A). Additionally, climate conditions have reduced prey availability and
vegetative cover through increased temperatures and drought (Factor E).
These factors result in a reduced capacity for this analysis unit to
withstand stochastic events and result in a low resiliency currently.
The northern Sonora analysis unit has an estimated pygmy-owl
abundance in the high hundreds. However, this analysis unit is affected
by habitat fragmentation from urbanization, agricultural development,
and associated infrastructure (Flesch 2021, pp. 12-14) (Factor A).
These stressors increase water use and, in conjunction with climate
conditions, result in a reduction in the quality and availability of
pygmy-owl habitat (Factor A). Abundance of pygmy-owls in the Sonoran
Desert in northwest Mexico, for example, declined about 19-27 percent
over a 12-year period, and change in owl abundance was highly
associated with variation in precipitation and temperature (Factor E).
In addition, hot, dry conditions influence the behavior and health of
prey species the owl relies upon for food. For example, lizards are
both less abundant and move less frequently as temperatures rise,
making it more difficult for owls to spot and capture them (Flesch
2021, entire).
Based on moderate owl abundance and some decrease in habitat
availability and connectivity, the northern Sonora analysis unit has a
moderate level of population resiliency. Information from surveys and
monitoring in 2021 in the northern Sonora analysis unit indicated a
decline in pygmy-owl occupancy and an increase in habitat loss and
fragmentation (Flesch 2021, pp. 12-14) and is evidence of decreasing
resiliency in this analysis unit.
The western Mexico analysis unit is estimated to have tens of
thousands of pygmy-owls. This analysis unit has some habitat
fragmentation from urbanization, agricultural development, and
deforestation of the tropical dry forests (Factor A). Overall, the
western Mexico analysis unit has high population resiliency due to high
abundance of pygmy-owls and generally healthy vegetation cover, likely
as a result of higher levels of precipitation in the region than in
other parts of the pygmy-owl's range.
The Texas analysis unit has an estimated pygmy-owl abundance in the
high hundreds. Land ownership within this analysis unit has resulted in
habitat fragmentation (Factor A) and, due to agricultural development
and wood harvesting within the Rio Grande Valley, this analysis unit is
somewhat genetically isolated from the rest of the geographic range of
the subspecies (Factor E). Due to moderate pygmy-owl abundance,
fragmentation of habitat, and some genetic isolation, the Texas
analysis unit has a moderate level of population resiliency.
The northeast Mexico analysis unit is estimated to have tens of
thousands of pygmy-owls. However, this unit has high levels of habitat
fragmentation due to urbanization and agricultural development (Factor
A). Overall, the northeast Mexico analysis unit has a moderate level of
population resiliency with some capacity to withstand stochastic
events. Rangewide, current condition of the pygmy-owl populations
indicate that three analysis units are maintaining a moderate level of
population resiliency, one analysis has low resiliency, and one
analysis unit has high resiliency.
Representation
Resiliency, and the factors that drive resiliency, also contribute
to the pygmy-owl's representation on the landscape. Pygmy-owls occupy a
diversity of habitat types throughout the geographic range of the
subspecies and maintain substantial genetic diversity. The subspecies'
adaptive potential (representation) is currently high due to genetic
and ecological variability across the range. There is substantial
genetic diversity across the range (Proudfoot et al. 2006a, entire;
2006b, entire; Cobbold et al. 2022b, entire) due to isolation-by-
distance and geographic barriers. Additionally, across the range, the
pygmy-owl occupies a diverse range of ecological settings as a result
of geographic gradients of vegetation, climate, elevation, topography,
and other landscape elements. Such ecological diversity could help the
pygmy-owl adapt to and survive future environmental changes, such as
warming temperatures or decreased precipitation from climate change.
Redundancy
We assessed the number and distribution of population groups across
the pygmy-owl's geographic range as a measure of its redundancy. While
the abundance and densities of pygmy-owls are lower in some analysis
units, these portions of the range still contribute in a meaningful way
to the overall pygmy-owl population. Each analysis unit within the
geographic range of the subspecies maintains a network of population
groups that are connected both within and between analysis units. These
population groups have the potential to recolonize areas where other
population groups are lost to catastrophic events. All analysis units
[[Page 46925]]
contribute to the total rangewide population, and population groups
within each analysis unit provide population support for that analysis
unit and adjacent portions of the range. If an analysis unit is self-
sustaining, it provides redundancy across the range, and may provide
emigrants to support adjacent analysis units.
Exchange of individual cactus ferruginous pygmy-owls occurs among
population groups within the Arizona, northern Sonora, and Texas
analysis units, and between the Arizona and northern Sonora analysis
units (Abbate et al. 2000, p. 30; Flesch and Steidl 2007, p. 37;
Proudfoot et al. 2020, unpaginated; AGFD 2022, unpublished data).
Habitat fragmentation and reduced vegetation health, as a result of
ongoing drought and various land uses, have resulted in the extirpation
of population groups in Arizona and Texas (Factor A), but redundancy
was exhibited in the northern Sonora analysis unit when drought
conditions eased and historically occupied areas were reoccupied
(Flesch et al. 2017, p. 12). However, abundance has once again declined
in northern Sonora and increased habitat loss and fragmentation likely
are decreasing pygmy-owl habitat connectivity within this analysis unit
and likely between the northern Sonora and Arizona analysis units
(Factor A) because both analysis units are experiencing similar
conditions (Flesch et al. 2017, entire; Flesch 2021, p. 9).
Despite existing habitat fragmentation, exchange of individual
pygmy-owls occurs between population groups and between some analysis
units is still occurring (Abbate et al. 2000, p. 30; Flesch and Steidl
2007, p. 37; Proudfoot et al. 2020, unpaginated; AGFD 2022, unpublished
data). Habitat types used by pygmy-owls vary across the range, with
some vegetation types being restricted to certain portions of the
geographic range. It is important to maintain pygmy-owl populations
throughout the range to provide redundancy to adjacent populations in
similar habitat conditions. Due to the broad geographic distribution
and network of population groups that are connected within and between
some analysis units throughout most of its range, the pygmy-owl has
some ability to recolonize following catastrophic events (Flesch et al.
2017, p. 12) and is considered to have adequate redundancy.
BILLING CODE 4333-15-P
[[Page 46926]]
[GRAPHIC] [TIFF OMITTED] TR20JY23.000
Figure 1. Cactus ferruginous pygmy-owl's range in the United States and
Mexico, including the five analysis units used in the species status
assessment.
BILLING CODE 4333-15-C
Future Scenarios
In our SSA report, we defined viability as the ability of a species
to sustain populations in the wild over time. To help address
uncertainty associated with the degree and extent of potential future
stressors and their impacts on species' needs, we assessed the
principles of resiliency, redundancy, and representation using three
plausible future scenarios that represent a reasonable range of
outcomes that we expect could occur. We developed these scenarios by
identifying information on the following primary factors anticipated to
affect the cactus ferruginous pygmy-owl in the future: climate change,
habitat loss and fragmentation, and ongoing conservation efforts
(Flesch 2017, entire). The three scenarios capture the range of
uncertainty in the changing landscape and how the pygmy-owl would
likely respond to changing conditions.
[[Page 46927]]
We used the best available data and models to project out 30 years
into the future (i.e., 2050). This is appropriate because, as we
discuss later in the document, we define 30 years as the foreseeable
future for our analysis of pygmy-owl viability and whether the species
is a threatened species. We chose this timeframe based on the
subspecies' lifespan and observed cycles in population abundance, as
well as the time period where we could reasonably project certain land
use changes and urbanization patterns relevant to the pygmy-owl and its
habitat. The majority of existing projections of urbanization and
population growth within the geographic range of the pygmy-owl extend
to 2050. Because urbanization and development are some of the primary
drivers of habitat loss and fragmentation, we extended our analysis as
far as we could reasonably project these changes and the subspecies'
response to those changes. Additionally, the average lifespan of a
pygmy-owl is 3 to 5 years. Thus, over a 30-year timeframe, we would
expect 8 to 10 generations of pygmy-owls to be produced, which should
be an adequate amount to assess the long-term effects of both threats
and conservation actions. Because the primary avenue through which
pygmy-owls move across the landscape is through the dispersal of
juveniles, it can take multiple generations to provide adequate
exchange of individuals to elicit detectable changes at the population
group and analysis unit scales. Including multiple generations of
pygmy-owls also allows adequate time to account for lags in demographic
factors resulting from changes in environmental conditions. Therefore,
we conclude that this number of generations is sufficient to assess the
effective levels of resiliency, redundancy, and representation.
Monitoring of pygmy-owl occupancy and productivity also indicates
that, at least in Arizona and northern Sonora, 30 years is an adequate
time period to document abundance cycles driven by climate conditions.
Monitoring in both Arizona and northern Sonora from the mid-1990s to
the present time showed a period of decline in occupancy and
productivity, primarily due to drought, followed by an increase in
productivity and occupancy during years of better precipitation such
that abundance and occupancy recovered to nearly the original levels
(Flesch et al. 2017, p. 12; Ingraldi 2020, pers. comm.; Service 2022a,
entire). For more information on the models and their projections,
please see the SSA report (Service 2022a, entire). Below, we also
identify which of the five listing factors identified in the Act are
influencing the pygmy-owl under each future scenario.
Under Scenario 1 (continuation of current trends), we projected no
significant changes to the rate of habitat loss and fragmentation
within the subspecies' range (Factor A). For this scenario, we
considered that climate change would track Representative Concentration
Pathway (RCP) 4.5, which is one of four alternative trajectories for
carbon dioxide emissions set forth by the International Panel on
Climate Change (IPCC 2014a, pp. 8-9). Specifically, RCP 4.5 is an
intermediate scenario where carbon dioxide emissions continue to
increase through 2040, but then stabilize and begin to decline. This
scenario would result in atmospheric carbon dioxide levels between 580
and 720 parts per million (ppm) between 2050 and 2100, well above
current rates of approximately 415 ppm, and would represent an
approximately 2.5 [deg]Celsius (C) increase in global mean temperature
relative to the period 1861--1880 (IPCC 2014a, p. 9) (Factor E). We
also considered that current conservation efforts, such as captive
rearing, would continue to be limited in their efficacy, due to limited
resources for agencies and other conservation partners to expand
implementation. However, we would expect conservation efforts to
improve modestly with continued efforts to identify appropriate and
effective methodologies and protocols that mitigate the primary
limitations to the success of releasing captive-reared pygmy-owls.
Additionally, climate change will continue to affect the suitability of
conditions at release sites (poor habitat conditions, reduced prey
availability, etc.) for captive-reared pygmy-owls, likely limiting the
effectiveness of pygmy-owl releases unless those effects can be
mitigated through project protocols (Factor E).
Under these conditions, we do not anticipate that any of the
factors used to evaluate resiliency would improve and, in fact,
vegetation intactness would be reduced due to continued development
(Factor A). Northeastern Mexico is projected to maintain its current
level of pygmy-owl abundance because, relative to the current
condition, substantial changes to habitat conditions are not expected,
primarily because our analysis indicates reduced impacts from climate
change on remaining habitat relative to other analysis units. Because
of this, the northeastern Mexico analysis unit is expected to maintain
a moderate level of population resiliency under this scenario.
Conditions in the Arizona analysis unit would continue to decline due
to continued habitat fragmentation and climate change (Factor A), and
resiliency would remain low. Resiliency in the remaining three analysis
units, northern Sonora, western Mexico, and Texas, would decline due to
continued loss of pygmy-owl habitat, reduced habitat intactness, and a
reduction in cover and prey availability for cactus ferruginous pygmy-
owls (Factor A). Overall, current levels of population redundancy and
representation would be maintained rangewide, but at a reduced rate.
All analysis units would remain occupied; however, representation
within each analysis unit would likely decline at the population-group
scale.
Under Scenario 2 (worsening or increased effects scenario), we
projected increased rates of habitat loss and fragmentation when
compared to the current condition and over and above that projected
under Scenario 1, leading to a decline in pygmy-owl habitat conditions
(Factor A). For this scenario, we considered that climate change would
track RCP 8.5, which is the highest greenhouse gas emission scenario.
Under this scenario, atmospheric carbon dioxide concentrations are
projected to exceed 1,000 ppm between 2050 and 2100 and would represent
a 4.5 [deg]C increase in global mean temperature (IPCC 2014a, p. 9)
(Factor E). We also assumed that conservation efforts that are
currently underway would not be effective or would not be implemented.
Increased habitat loss and fragmentation would result in the
greatest effect on overall resiliency through a reduction in abundance
and occupancy of pygmy-owls. Increased development and urbanization
would result in increased permanent losses of habitat (Factor A).
Indirect effects to vegetation and prey availability as a result of
climate change would also occur (Factor E). Due to increased habitat
fragmentation, such as agricultural development, as well as a reduction
in vegetation health from drought (Factor A), resiliency in the western
Mexico analysis unit is projected to decline. Under this scenario,
climate change and increased habitat fragmentation from urbanization
and agricultural development lead to the loss of some population groups
within the Texas, Arizona, and northern Sonora analysis units (Factor
A, Factor E). The resultant decline would decrease representation and
redundancy within these analysis units. In particular, the Texas and
Arizona analysis units would become more vulnerable to extirpation
because of low
[[Page 46928]]
pygmy-owl abundance and occupancy driven by reduced habitat quality as
a result of drought and high levels of habitat fragmentation from
ongoing urbanization and agricultural development (Factor E, Factor A).
Genetic representation would be reduced through the loss of population
groups or analysis units and the subsequent reduction of gene flow
(Factor E). Overall, there would be a reduction in resiliency,
representation, and redundancy within most analysis units, and the
likelihood of maintaining long-term viability would be considerably
reduced.
Under Scenario 3 (improving or reduced effects scenario), we
project that habitat loss and fragmentation would continue, but at a
reduced rate (Factor A). For this scenario, we considered that climate
change would track RCP 4.5 (Factor E), and conservation efforts that
are currently underway would be effective. We did not include other
planned conservation efforts in this scenario because we are not aware
of any that would significantly influence the viability of the
subspecies.
Despite effective conservation actions in portions of the range,
the viability of pygmy-owl populations would continue to decline within
all five analysis units due to the ongoing effects of habitat loss,
fragmentation, and climate change (Factor A, Factor E). The positive
effects of conservation actions would remain localized, and the
negative effects of the ongoing threats would outweigh these local
benefits to individual population groups at the scale of the entire
analysis unit. Resiliency would remain low in the Arizona analysis unit
and would decline in both the northern Sonora and western Mexico
analysis units due to a reduction in habitat quality as a result of
climate change (Factor E). We would expect pygmy-owl habitat
fragmentation from urbanization, deforestation, and agricultural
development (Factor A) to continue under this scenario, though at a
slower rate because of increased efforts to address the impacts from
climate change and to improve land use decisions, as well as
implementing habitat-related conservation actions. Resiliency would
remain in moderate condition for the Texas and northeastern Mexico
analysis units. Although habitat conditions are expected to continue to
decline due to drought and climate change (Factor E), we do not expect
a large decline in pygmy-owl occupancy and abundance in Texas and
northeastern Mexico. Under this scenario, each analysis unit remains
occupied and contributes to the representation and redundancy across
the range of the pygmy-owl. However, within each analysis unit, threats
continue, albeit at a reduced rate, and the resiliency of population
groups would decline in three of the five analysis units. Thus, within
analysis units, representation and redundancy is likely to decrease at
the population-group scale.
Cumulative Effects
We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA report, we have
analyzed not only individual effects on the subspecies but also their
potential cumulative effects. We incorporate the cumulative effects
into our SSA analysis when we characterize the current and future
condition of the subspecies. To assess the current and future condition
of the subspecies, we undertake an iterative analysis that encompasses
and incorporates the threats individually and then accumulates and
evaluates the effects of all the factors that may be influencing the
subspecies, including threats and conservation efforts. Because the SSA
framework considers not just the presence of the factors, but to what
degree they collectively influence risk to the entire subspecies, our
assessment integrates the cumulative effects of the factors and
replaces a standalone cumulative effects analysis.
Conservation Efforts and Regulatory Mechanisms
In this section, we discuss regulatory mechanisms and conservation
actions that potentially have influenced or will likely influence the
current and future viability of the cactus ferruginous pygmy-owl.
Federal Protections
The pygmy-owl is protected under the Migratory Bird Treaty Act
(MBTA) (16 U.S.C. 703-712). The MBTA prohibits ``take'' of any
migratory bird. However, unlike the Act, there are no provisions in the
MBTA preventing habitat destruction unless direct mortality or
destruction of an active nest also occurs. Approximately 31 percent of
the pygmy-owl's historical geographic range in the United States is
federally owned, with federally-owned lands making up approximately 40
percent of pygmy-owl habitat in Arizona. However, a substantial extent
of the known currently occupied habitat occurs on State Trust lands in
Arizona and on private lands in Texas. Other Federal regulations and
policies such as the Clean Water Act (33 U.S.C. 1251 et seq.), the
military's integrated natural resources management plans (INRMPs, such
as the one for the Barry M. Goldwater Range) (Uken 2008, pers. comm.),
and National Park Service policy provide varying levels of protection,
but they have not, to this date, been effective in protecting the
pygmy-owl from further decline as National Park Service owned lands
comprise only a small portion of the range of the pygmy-owl.
Regulations under and implementation of the Clean Water Act help
provide protections for a range of riparian habitat that is important
to the pygmy-owl. Court actions and changes in regulations have
decreased the potential scope of protections for riparian habitats
within the range of the pygmy-owl. The 2006 Rapanos Supreme Court
decision restricts the linear extent of jurisdiction to watercourses
having a ``significant nexus'' with a Traditionally Navigable Water.
This means that after the Court's decision was implemented starting in
2008, fewer watercourses were deemed jurisdictional. This ruling has
had the effect of further reducing past protections of riparian
habitats. This limitation in the extent of federal jurisdiction
particularly affected ephemeral streams in the pygmy-owl's Arizona
habitat. Based on the individual approved jurisdictional determinations
in Pima County by the U.S. Army Corps of Engineers, it is likely that
most of the Avra-Altar system, which supports pygmy-owl occupancy, will
be found to lack significant nexus to the Colorado River system, which
means that these habitats will not receive the same analysis and
protection that they received in the past under the Clean Water Act
(Meltz and Copeland 2007, entire; Keith 2007, entire).
As a result of the implementation of the 2005 Real ID Act (Division
B of Pub. L. 109-13), the U.S. Department of Homeland Security (DHS)
has waived application of the Act and other environmental laws in the
construction of border infrastructure, including areas occupied by the
pygmy-owl (73 FR 5272, January 29, 2008). As recently as 2020, DHS
waived environmental compliance for the construction of border walls
along the U.S.-Mexico border in Arizona and Texas (Fischer 2019,
unpaginated; USCBP 2020, unpaginated). Consequently, pygmy-owl habitat
has been lost and fragmented along most of the border area in Arizona,
as well as in Texas. Of particular concern is the potential for border
infrastructure to reduce habitat connectivity into occupied pygmy-owl
habitat in Mexico (Flesch et al. 2010, pp. 177-179).
[[Page 46929]]
State Protections
The pygmy-owl is included on the State of Arizona's list of species
of concern (AGFD 2021a, p. 16). Arizona statutes (ARS Title 17) only
protect individual pygmy-owls and their nests or eggs and do not
address destruction or alteration of pygmy-owl habitat. The State of
Texas lists the pygmy-owl as threatened (Texas Administrative Code,
title 31, part 2, chapter 65, subchapter G, rule 65.175; TPWD 2009,
unpaginated; TPWD 2022, unpaginated). This designation allows permits
to be issued for the taking, possession, propagation, transportation,
sale, importation, or exportation of pygmy-owls if necessary to
properly manage that species but, similar to Arizona, does not provide
any habitat protections (Texas Park and Wildlife Code, chapter 67,
section 67.0041).
Texas and Arizona state law prohibit any take (incidental or
otherwise) of state-listed or protected species. In both states,
species may only be handled by persons possessing a scientific activity
permit, scientific permit for research, or other form of authorization
from the State. While state laws in both Texas and Arizona prohibit the
capture, trap, take, or kill, or attempt to capture, trap, take, or
kill of protected wildlife, like the pygmy-owl, they provide no
protection to their habitats.
Protections in Mexico
Within Mexico, the distribution of owls is large and includes
multiple States. The administration of land use in Mexico depends on
the national government, which implements Natural Protected Areas and
other Federal programs, and also the policies of each State and even
municipal governments (Enr[iacute]quez 2021, pers. comm.). This system
represents a wide range of management, conservation, and natural
resource use approaches that affect pygmy-owl conservation, resulting
in inconsistent policies and inconsistent implementation of
conservation activities. No laws or regulations in Mexico specifically
protect pygmy-owls and pygmy-owl habitat. Further complicating the
conservation of the pygmy-owl in Mexico is the sheer diversity of
entities involved in managing land use in Mexico, each with its own
mission, goals, and objectives, many of which are not related to
natural resource conservation. Thus, development and application of
regulations and land-management activities that promote the
conservation of pygmy-owls in Mexico is difficult and exceedingly
complicated (Enr[iacute]quez 2021, pers. comm.).
Conservation Efforts
Cactus ferruginous pygmy-owl conservation activities have occurred
sporadically over the past three decades in both the United States and
in northern Sonora in Mexico. Initial conservation efforts developed
effective and safe protocols for studying the cactus ferruginous pygmy-
owl and on gathering basic life-history information. Efforts expanded
in the late 1990s and early 2000s to include important pygmy-owl work
in Arizona, Texas, and northern Sonora. For the past two decades,
studies have been irregular and focused primarily on monitoring known
territories, although work continues on the pygmy-owl captive-breeding
pilot project, as described below.
Surveying and Monitoring
AGFD initiated surveys to determine the extent of cactus
ferruginous pygmy-owl occurrences in Arizona in 1992, when the cactus
ferruginous pygmy-owl was first petitioned to be listed under the Act.
Survey and monitoring work by a variety of entities continued through
2006, when the subspecies was delisted. Prior to delisting, survey and
monitoring efforts were focused within Pima and Pinal Counties to
document the occupancy pattern of cactus ferruginous pygmy-owls in
areas of land use changes, primarily urban development. After the
pygmy-owl was delisted in 2006, Service and AGFD biologists continued
to conduct a small number of monitoring surveys. In 2020, AGFD
coordinated a comprehensive survey effort within the recently occupied
areas of Arizona, with the help of numerous partners, to gather data on
the current abundance and distribution of the cactus ferruginous pygmy-
owl in Arizona to inform this listing decision. Specifically, this
effort included surveys to document distribution, territory occupancy
monitoring, and some nest searches to document reproduction. This
latest effort provided data on current distribution of the pygmy-owl in
Arizona and the number of occupied territories, as well as some
information on the number of active nesting territories (Ingraldi 2020,
pers. comm.; AGFD 2021b, pers. comm.). These data are incorporated into
the SSA report. However, these efforts did not provide any information
on productivity or survival at these sites. Despite the changing
regulatory environment and inconsistent availability of resources,
survey and monitoring activities provide important information on the
abundance and distribution of pygmy-owl across its range and, with that
information, managers can more effectively and efficiently work to
conserve the pygmy-owl.
Nest Box Trials
Because cactus ferruginous pygmy-owls are secondary cavity nesters
(birds that nest in cavities excavated by other bird species), the
number of available cavities may influence the viability of cactus
ferruginous pygmy-owls on the landscape (Proudfoot 1996, p. 68). Using
nest boxes as a management tool may enhance the viability of cactus
ferruginous pygmy-owls by increasing cavity availability and reducing
predation. Nest boxes also enhance access to the owls during nesting,
which facilitates research. Research in Texas demonstrated successful
use of artificial nest structures by cactus ferruginous pygmy-owls
(Proudfoot et al. 1999, pp. 5-6). In response to concerns about cavity
availability, two nest box trials were conducted in Arizona in 1998 and
2006. No cactus ferruginous pygmy-owls used the nest boxes in these
studies, but low cavity availability was confirmed based on high use of
the nest boxes by other species, including screech owls. No additional
nest box studies have been undertaken in Arizona, and the nest box
study in Texas is no longer active. The information on nest box use in
Texas has contributed to the conservation of the pygmy-owl in Texas.
Additional research is needed in other parts of the pygmy-owl's range
to understand the effectiveness, or lack thereof, of using nest boxes
as a conservation tool for pygmy-owls.
Captive-Breeding and Population Augmentation
The AGFD initiated a pygmy-owl captive-breeding feasibility study
in partnership with the Wild at Heart raptor care facility in Cave
Creek, Arizona, in 2006. Since then, Wild at Heart has researched and
tested protocols for a managed breeding program for cactus ferruginous
pygmy-owls. In 2017, the Phoenix Zoo became the second captive-breeding
site for pygmy-owls in Arizona and part of the managed breeding program
when it entered into partnership with the Service and the AGFD. Both
the AGFD and the Service oversee this program.
The goal of the managed breeding program for the cactus ferruginous
pygmy-owl is to develop appropriate protocols for the husbandry and
breeding of captive pygmy-owls to provide individuals to augment
existing population groups or establish new population groups in areas
where suitable habitat exists in Arizona (AGFD 2015, entire). To date,
these efforts have
[[Page 46930]]
demonstrated: (a) Successful capture and transport of wild cactus
ferruginous pygmy-owls; (b) safe, healthy, and stress-free captive
facilities; (c) the development of appropriate care, feeding, and
maintenance protocols; (d) successful breeding; and (e) appropriate
care and development of young-of-the-year birds. Three pilot releases
of captive-bred pygmy-owls have been implemented since the inception of
this program. This effort establishes the first formal captive-breeding
for the subspecies and provides the groundwork for evaluation of this
strategy in wild cactus ferruginous pygmy-owl population augmentation.
These pilot releases have not resulted in the establishment of new
pygmy-owl territories or population groups, but they have contributed
valuable information to developing appropriate release strategies and
protocols to improve the potential for conservation benefits to the
pygmy-owl in the future. For example, high mortality rates of released
captive-bred pygmy owls as a result of weather, prey availability,
predation, habitat conditions, and lack of pre-release conditioning all
likely contributed to past failures. However, an adaptive management
approach is being used to address such mortality factors and improve
methodology. The partners involved in this project are committed to the
continuation of this effort into the future.
Conservation Planning
When the pygmy-owl was listed previously, several municipalities
located within current or historical pygmy-owl activity areas explored
or implemented habitat conservation plans (HCPs) under the Act to
address potential conflicts between development projects and
requirements of the Act. These HCP plans included the Sonoran Desert
Conservation Plan (Multi-Species Conservation Plan) developed by Pima
County (Pima County 2016, entire), the Town of Marana HCP (Town of
Marana 2009, entire), and the City of Tucson's Avra Valley (City of
Tucson 2019, entire) and Southlands HCPs (City of Tucson 2013, entire).
Each of these four HCP efforts identified the cactus ferruginous pygmy-
owl as one of the covered species within their plans. However, most of
these plans have yet to be completed: to date, only the Pima County HCP
has been completed and implemented. Pima County is currently conducting
ongoing surveys and monitoring of pygmy-owl territories on county-
managed lands and has set aside pygmy-owl habitat as part of their
conservation-lands system in compliance with their HCP. The
establishment of these conservation lands is an important contribution
to pygmy-owl conservation in Pima County, but continuing efforts are
needed to address other threats such as habitat impacts from climate
change. Pima County's efforts are expected to continue for the 30-year
life of their permit (through 2046) and longer if the County renews the
permit.
Another ongoing conservation planning effort that has the potential
to support pygmy-owl conservation in the Altar Valley of southern
Arizona is the Altar Valley Watershed Management Plan. This plan (being
developed by the Altar Valley Conservation Alliance with numerous
partners and participants) builds upon existing efforts within the
Altar Valley to restore and enhance the watershed. The plan will
describe stewardship practices and identify a series of high-priority
projects that maximize positive impacts on the land. Projects related
to watershed restoration have already been implemented at three ranches
in the Altar Valley. These projects have included one-rock dams and
other structures to stabilize waterways, road grading to promote water
harvesting, and enhancement of grasslands through invasive species
control to promote infiltration and reduce runoff and sedimentation.
These actions improve vegetation health through increased water
infiltration and reduced loss of soil and vegetation due to erosion.
These benefits improve riparian vegetation along drainages enhancing
pygmy-owl habitat conditions and connectivity. Ranches within the Altar
Valley of southern Arizona have maintained open space and contributed
to the conservation of pygmy-owls for over 20 years. Overall, the
conservation planning efforts implemented to date have contributed to
the conservation of the pygmy-owl through protecting or enhancing
important pygmy-owl habitat in Arizona and providing a path towards
long-term habitat viability and maintenance.
In Mexico, Federal, State, and municipal protected areas comprise
approximately 11 percent of the historical pygmy-owl range in Mexico.
These areas can work well as conservation strategies for the cactus
ferruginous pygmy-owl. There is now a new option for protected areas
called Voluntary Conservation Areas ([Aacute]reas Destinadas
Voluntariamente a la Conservaci[oacute]n; ADVA), which are areas
identified for conservation. These ADVA could be a potential
conservation strategy for the pygmy-owl in the future with improved
design, management, and enforcement (Burquez and Martinez-Yrizar 1997,
p. 378; Valdez et al. 2006, p. 272; Burquez and Martinez-Yrizar 2007,
p. 546; Enr[iacute]quez 2021, pers. comm.).
Summary of Comments and Recommendations
In the proposed rule published on December 22, 2021 (86 FR 72547),
we requested that all interested parties submit written comments on the
proposal by February 22, 2022. We also contacted appropriate Federal
and State agencies, scientific experts and organizations, and other
interested parties and invited them to comment on the proposal.
Newspaper notices inviting general public comment were published in the
Arizona Daily Star and Corpus Christi Caller-Times. We held a public
hearing on January 25, 2022. All substantive information received
during comment periods has either been incorporated directly into this
final determination or is addressed below.
Peer Reviewer Comments
As discussed in Peer Review above, we received comments from three
peer reviewers. We reviewed all comments we received from the peer
reviewers, including comments on substantive issues and new information
contained in the SSA report. The peer reviewers generally concurred
with our methods and conclusions, and provided additional information,
clarifications, and suggestions to improve the final SSA report. Peer
reviewer comments are addressed in the following summary and were
incorporated into the final SSA report as appropriate.
(1) Comment: One peer reviewer commented that the construction of
the border wall will cause substantive ecological damage and function
as a barrier to many terrestrial animals. However, the peer reviewer
finds the idea that the border wall would be an impediment or barrier
to pygmy-owls to be unfounded.
Our response: No studies have specifically looked at how border
walls and associated infrastructure may affect pygmy-owl movements. We
do not currently know if these structures will be a barrier or an
impediment on pygmy-owls. However, observations in the field indicate
that barriers similar to the border wall may affect pygmy-owl movement
patterns. Pygmy-owl flight patterns are generally less than 30 m (100
ft) and typically only 1.5 to 3.0 m (5 to 11 ft) above the ground
(Flesch and Steidl 2007, p. 35; AGFD 2008, pers. comm.). Flesch et al.
(2010, pp. 7-9) show that the vegetation gaps, in association with the
tall fences, may limit transboundary movements by pygmy-owls. The
fences and vehicle
[[Page 46931]]
barriers along the border, when considered in conjunction with patrol
roads, drag roads, and vegetation removal, result in a combination of
unvegetated area with a raised structure in the middle causing an
impediment to pygmy-owl movement. Observations reported in the
literature show that pygmy-owls avoid crossing open areas associated
with roadways (Abbate et al. 1999, p. 54; Flesch and Steidl 2007, pp.
6-7; Flesch 2017, p. 5; Flesch et al. 2017, entire; Flesch 2021, pp.
12-14). Given other known impediments to pygmy-owl movements, it is
likely border infrastructure could affect cross-border movements by
pygmy-owls, at least at some border locations. The SSA report discusses
factors that logically could result in some impact to pygmy-owl cross-
border movements. However, pygmy-owls are capable flyers and easily
navigate small openings in their normal day-to-day behaviors. Pygmy-
owls are sometimes observed very high in trees, at or above the height
of border infrastructure. Therefore, the border wall itself may not
affect all cross-border movements, depending on the crossing site
characteristics. However, the border wall in conjunction with lighting,
patrol and interdiction activities, and vegetation clearing present
more factors potentially deterring pygmy-owl movements. This issue
needs more research and monitoring to determine whether and how such
border infrastructure affects pygmy-owl movements.
(2) Comment: A peer reviewer expressed concern in considering the
eastern and western populations to be the same subspecies. The peer
reviewer expressed concerns about considering each of these to be
redundant populations because, with no evidence of interchange between
the two populations, each population would be unable to provide rescue
to the other population.
Our response: This issue was investigated by Proudfoot et al.
(2006a, entire; 2006b, entire) and K[ouml]nig et al. (1999, entire),
who concluded the eastern and western populations may comprise two
separate subspecies. This information, in combination with the
historical descriptions of distributions for the subspecies cactorum,
as discussed in the SSA report, provided some general evidence that
reclassification of this subspecies could have merit. However, after
reviewing the best available information, we find that the evidence of
delineating the range of these subspecies is uncertain and
inconsistent. Peer reviewers of our 2011 12-month finding pointed out
that a combination of factors, including morphological, vocal, and
genetic, need to be considered in greater depth, with additional
sampling and analysis of existing samples, to determine if the
petitioned taxonomic classification should be accepted, and we are in
agreement with these comments.
Given the uncertainty and lack of clarification found in the best
available scientific and commercial information, we rely on the
``biological expertise of the Department and the scientific community
concerning the relevant taxonomic group'' (50 CFR 424.11(a)) and the
``standard taxonomic distinctions (50 CFR 424.11(a)). Additional
genetic sampling and analysis in 2021 through AGFD, while providing
additional samples and an updated analysis of Proudfoot et al.'s
(2006a, entire, and 2006b, entire) work, did not provide compelling
evidence to change our conclusions regarding the taxonomic
classification of the cactus ferruginous pygmy-owl (Cobbold et al.
2022b, entire) (see also Background above). We do not yet have enough
information to say whether pygmy-owls at the far ends of their
distribution (Texas and Arizona) represent different subspecies, but
the work by Cobbold et al. (2022b, entire) suggests there is likely
some degree of redundancy between the eastern and western populations
of the pygmy-owl at the southern end of the range. In other words,
cactus ferruginous pygmy-owls in the southern portion of the range are
more similar to each other than to pygmy-owls in the northern extremes
of the range in Arizona and Texas. See also our response to comment 8
below.
(3) Comment: One peer reviewer pointed out that the influence
diagram in the SSA report (figure 4.1) was missing some linkages and
suggested careful consideration of additional linkages that may need to
be added.
Our response: We acknowledge that there are numerous other
connections not shown in the influence diagram in the SSA report.
However, we have simplified the graphic to illustrate the most
important influences on the subspecies. We have added the two
additional connections suggested by the reviewer and added
clarification in the SSA report acknowledging the complicated and
interconnected nature of stressors, habitat, individuals, and
population resiliency.
Federal Agency Comments
(4) Comment: The Forest Service stated that a critical habitat
designation would help to define areas in which to restrict wood
harvesting within the Coronado National Forest.
Our response: We will be publishing a proposed rule to designate
critical habitat as a separate action and will solicit public comments
on the critical habitat designation at that time. Our intent is to
publish a proposed critical habitat rule within 1 year of this final
listing rule.
Comments From States
(5) Comment: The Arizona Department of Forestry and Fire Management
and the Arizona Department of Transportation expressed concerns about
prohibitions on prescribed fire in the Sonoran Desert and thinning of
woody plants, specifically as it relates to fire management, invasive
species management, and for public safety along roadways. The Arizona
Department of Transportation requested that vegetation management and
brush removal within the recovery zone of roads and other strategic
locations be included as an exception in the 4(d) rule.
Our response: We acknowledge and understands the importance of
managing vegetation strategically along roadways and for fire and
invasive species management that can promote the conservation of native
species and their habitats. However, a broad exception under a 4(d)
rule for such activities would prevent us from working with partners to
conduct these activities in a way that minimizes effects to the pygmy-
owl and its habitat. The design of projects such as these are dependent
upon a number of site-specific factors requiring unique recommendations
and approaches so that pygmy-owl-specific measures can be incorporated.
We have a number of tools in place to reduce consultation workloads for
action agencies, including programmatic consultations, which would
allow for strategic planning of vegetation projects while allowing
adequate planning and review. We look forward to the opportunity to
work collaboratively with partners in Arizona and Texas to help conduct
necessary vegetation management projects while also ensuring that
effects to listed species are considered and minimized.
(6) Comment: The Texas Parks and Wildlife Department (TPWD) and
Arizona Department of Transportation requested increased clarification
for which habitat restoration projects would be excepted under the 4(d)
rule.
Our response: We have provided additional clarity for which habitat
projects are excepted under the 4(d) rule and which would require a
section 7 consultation. This additional clarification can be found
under Provisions of the 4(d) Rule below.
[[Page 46932]]
(7) Comment: The TPWD requested additional information regarding
the potential to use the State permitting process for surveying and
monitoring activities.
Our response: Discussion of this issue with TPWD has revealed they
are only authorized to permit activities that involve direct handling
of protected species, and, therefore, they do not permit the types of
activities excepted under the 4(d) rule for pygmy-owls, according to
Texas State Parks and Wildlife Code (Sec. 43.021). For this reason, we
will still require a Federal section 10 permit for pygmy-owl activities
in Texas.
(8) Comment: The Texas Comptroller of Public Accounts and the AGFD
questioned the validity of the subspecies' taxonomy and stated that the
Service should first address the taxonomic uncertainty prior to making
a listing decision.
Our response: As discussed in Background and Peer Reviewer
Comments, above, and extensively in the SSA report (Service 2022a,
Section 2.1-2.2), we rely on the currently accepted taxonomy when
making listing decisions. Although there have been proposed revisions
to the pygmy-owl taxonomy, these revisions have not been accepted by
the American Ornithological Society, the recognized authority for avian
taxonomic classification. Therefore, we have analyzed the cactus
ferruginous pygmy-owl as currently described (Glaucidium brasilianum
cactorum).
(9) Comment: The Texas Comptroller of Public Accounts stated that
pygmy-owl habitat in Texas makes up only five percent of the range of
the subspecies and that the population there is most likely secure.
They also state that the population in Texas is greater than that of
Arizona.
Our response: When analyzing the status of a species throughout its
range, we do not focus only on the portions of the species' range
within one State. Therefore, the percentage of the range within each
State in a species' range is not directly relevant to its status
throughout its range. We agree that the population in Texas is likely
greater than that in Arizona and have acknowledged that fact in this
rule. Although populations in one State may be higher than another, we
analyze the status of the species throughout all or a significant
portion of its range when making listing decisions. We rely on the
current and future conditions, and the threats and stressors acting on
the species and its habitat, to determine whether or a not a species is
in danger now or likely to become endangered in the foreseeable future
throughout all, or a significant portion of its range, not within each
State in which it occurs. Although pygmy-owls in Texas still occur
within rural private lands, much of the range of the pygmy-owl in Texas
has been developed and connectivity to Mexico has been significantly
reduced. The pygmy-owl has been listed as a Species of Greatest
Conservation Need by TPWD since 2005, and in 2020, TPWD downgraded the
ranking of the subspecies from vulnerable to imperiled. TPWD, the State
authority for managing the wildlife in Texas, was closely involved in
the development of the SSA for the pygmy-owl and provided data for this
species in Texas. For these reasons, we do not conclude that the
species is secure in Texas for the foreseeable future.
(10) Comment: The Texas Comptroller of Public Accounts stated that
the information used in the SSA report may have been best available but
was incomplete and outdated. They stated that the Service should not
make a listing decision without robust population and habitat data.
Our response: When making listing decisions, we are required to
rely on the best available information. The Act does not require that
we conduct our own research and monitoring before making a listing
determination. Often, we are required to make listing decisions based
on incomplete or outdated information, as many of the species we
analyze are rare and it is difficult to get adequate sample sizes for
study or analysis. For these reasons, many of these species are not
thoroughly studied. We do not delay providing protections to species
while awaiting additional data and, while we would welcome new
information not included in our SSA report, to date our analysis
includes the best available information for the pygmy-owl.
(11) Comment: The AGFD and other commenters stated that the Service
did not provide adequate support linking projected future human
population growth to direct effects to the status of the pygmy-owl. The
commenters stated that the Service needed direct information related to
the subspecies' status before, during, and after this human population
growth to demonstrate an effect to the subspecies.
Our response: We acknowledge that we do not have an extensive set
of quantified empirical data for a detailed analysis of the effects of
urbanization and development on pygmy-owls and pygmy-owl habitat. There
have been no specific studies quantifying the effects to pygmy-owls and
their habitat from urban development. However, as presented in Appendix
6 of the SSA Report (Service 2022a, Appendix 6), the data we have
indicate that substantial areas of habitat within the range of the
pygmy-owl have been lost due to urban growth and development
(approximately 100,000 acres cumulatively in the Arizona and Texas
analysis units over the past 10 years), and it is reasonable to predict
that such loss will continue as population growth and development
patterns trend upward into the future and more suitable habitat is
converted for urban development. We used the best available information
on population growth and development projects to project potential
losses of pygmy-owl habitat into the future.
Additionally, in response to a comment we received during the
public comment period, we completed additional analysis on land cover
changes within pygmy-owl habitat in Texas and Arizona over the past
decade (2010-2020). The commenter provided an analysis on changes in
land cover within the pygmy-owl analysis areas during the time period
of 2010-2015 and suggested that the impacts to pygmy-owl habitat were
not as great as we presented in the proposed rule and SSA report. The
commenter's data sources were different than what we used in the SSA,
but the commenter presented a reasonable issue with regard to the data
presented. Because it is important to consider the scope, scale, and
the factors included in different sources of data, we conducted
additional analysis using data sources that provided the same type of
data that the commenter used in their analysis. This allowed us to
compare the results of additional sources of data with the results
presented by the commenter. This additional analysis provides different
results than presented by the commenter, but this outcome is expected
because of differing time periods, categories of land cover and land
use, and the scope and scale of the data.
Both analyses provide useful information to consider as we evaluate
the status of the pygmy-owl. Neither analysis changed the outcome of
our listing decision or our assessment of the effects of human
population growth on the pygmy-owl. Our analysis showed greater impacts
to pygmy-owl habitat than the data provided by the commenter and
supported our finding that some areas of pygmy-owl habitat have been
lost or modified and habitat fragmentation has continued, at least in
Texas and Arizona, during this time period. Our further analysis
related to the impacts of various land uses on pygmy-owl habitat over
the past decade
[[Page 46933]]
can be found in appendix 6 of the SSA report (Service 2022a, appendix
6).
(12) Comment: The AGFD claimed that agricultural development should
not be considered a current threat to the pygmy-owl in Arizona as the
effects of agricultural development occurred primarily historically.
Our response: Agricultural development was primarily a historical
threat to the distribution of pygmy-owls in Arizona (Stromberg 1993,
pp. 117-119; Jackson and Comus 1999, pp. 215-255). However,
agricultural development is still a local impact to pygmy-owls in
Arizona and is impacting habitat connectivity and pygmy-owl movements
in some parts of Arizona, primarily in Pima and Pinal Counties (Service
2022a, Appendix 6). Additionally, agricultural development is currently
resulting in ongoing pygmy-owl habitat loss and fragmentation in Texas
and in all the analysis units in Mexico. The best available information
indicates it is a current and projected threat to pygmy-owl habitat.
Public Comments
(13) Comment: One commenter stated that the Service did not explain
why the proposed 4(d) rule was not analyzed under the National
Environmental Policy Act.
Our response: As stated under National Environmental Policy Act (42
U.S.C. 4321 et seq.) below and in the proposed rule, regulations
adopted pursuant to section 4(a) of the Act are exempt from the
National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.) and do
not require an environmental analysis under NEPA. We published a notice
outlining our reasons for this determination in the Federal Register on
October 25, 1983 (48 FR 49244). This includes listing, delisting, and
reclassification rules, as well as critical habitat designations and
species-specific protective regulations promulgated concurrently with a
decision to list or reclassify a species as threatened. The courts have
upheld this position (e.g., Douglas County v. Babbitt, 48 F.3d 1495
(9th Cir. 1995) (critical habitat); Center for Biological Diversity v.
U.S. Fish and Wildlife Service., 2005 WL 2000928 (N.D. Cal. Aug. 19,
2005) (concurrent 4(d) rule)).
(14) Comment: Two commenters stated that grazing is not beneficial
nor adequately managed and should not be included in the 4(d) rule.
Our response: As discussed in the proposed rule, we considered
mechanisms to ensure livestock grazing is conducted in a manner that
promotes the conservation of the pygmy-owl. While developing our
proposed rule, we determined that livestock grazing requires local
management that can address the specific conditions of each individual
operation and, therefore, including a broad, general exception for
grazing within the 4(d) rule would not be beneficial to the subspecies.
We are not currently allowing any exceptions from section 9
prohibitions for livestock grazing. Therefore, future livestock grazing
actions with a Federal nexus that may affect the pygmy-owl will require
a section 7 consultation with the Service.
(15) Comment: One commenter requested clarification of the phrase
``accelerate the time horizon'' that was used in our discussion of the
concentration of threats within the Sonoran Desert Ecoregion.
Our response: To provide additional clarity, we have removed the
statement ``accelerate the time horizon'' from our discussion in Status
Throughout a Significant Portion of Its Range below. In summary, we
found that the Sonoran Desert Ecoregion has a concentration of threats
to the pygmy-owl; however, we determined that these threats did not
rise to the level of those that would place the pygmy-owl in danger of
extinction now in that portion of its range. Therefore, we determined
that the pygmy-owl's status within the Sonoran Desert Ecoregion is the
same as the rangewide status of threatened.
(16) Comment: One commenter stated that the Service did not conduct
a regulatory flexibility analysis for the 4(d) rule to determine if the
proposed action would affect small entities. The commenter stated that
the issuance of a 4(d) rule is a distinct regulatory action from the
listing of a species under section 4(a) of the Act.
Our response: In 1982, Congress added to the Act the requirement
that classification decisions be made ``solely on the basis of the best
scientific and commercial data available.'' In addition, the Conference
Report accompanying those amendments made clear that one purpose of
adding that language was to ensure that requirements like those in E.O.
12866 do not apply to classification decisions. Specifically, it states
that economic considerations have no relevance to determinations
regarding the status of species and the economic analysis requirements
of Executive Order 12291 [the predecessor of E.O. 12866], and such
statutes as the Regulatory Flexibility Act and the Paperwork Reduction
Act, will not apply to any phase of the listing process. H.R. Conf.
Rep. No. 97-835, at 20. Section 4(d) requires that the Service issue
regulations deemed necessary and advisable to provide for the
conservation of a species whenever any species is listed as a
threatened species. We consider this 4(d) rule to be a necessary and
advisable phase of the listing process to put in place protections for
this threatened species.
(17) Comment: Two commenters stated that the proposed rule did not
explain the need to extend all section 9 prohibitions for endangered
species to the pygmy-owl and did not adequately explain why the 4(d)
rule was necessary and advisable.
Our response: As discussed in Final Rule Issued Under Section 4(d)
of the Act below, in promulgating regulations under section 4(d) of the
Act, we have broad discretion to select appropriate provisions tailored
to the specific conservation needs of threatened species. The second
sentence of section 4(d) states that the Secretary ``may by regulation
prohibit with respect to any threatened species any act prohibited
under section 9(a)(1), in the case of fish or wildlife, or 9(a)(2), in
the case of plants.'' The use of the word ``may,'' along with the
absence of any specific standards, in the second sentence grants us
particularly broad discretion to put in place prohibitions with respect
to threatened species that section 9 prohibits with respect to
endangered species. We have found that in most cases, it is necessary
and advisable to apply to a threatened species: (1) all of the general
prohibitions that apply to endangered species under section 9 and then
(2) tailor the exceptions to those prohibitions to address the specific
conservation needs of the species. We often lack a complete
understanding of the causes of a species' decline and affording a
threatened species protections that are similar to the protections for
an endangered species should help provide the necessary tools over time
as we learn more about the species' status and threats. In this
instance, we have determined that it is necessary and advisable to
extend all section 9 prohibitions to the pygmy-owl (see Final Rule
Issued Under Section 4(d) of the Act below) and that doing so
accomplishes our goal of putting in place protections that will both
prevent the species from becoming endangered and promote its recovery.
As new information becomes available, we have the option to revise
species-specific rules accordingly.
(18) Comment: We received several comments pertaining to critical
habitat designation for the pygmy-owl.
Our response: We are working on a proposed critical habitat rule
and will address comments pertaining to critical habitat designation
during the public comment period for that proposed rule.
[[Page 46934]]
(19) Comment: Two commenters stated that a court determined the
Service's interpretation of the phrase ``significant portion of its
range'' was unlawful (Ctr. For Biological Diversity v. Jewell, 248 F.
Supp. 3d 946 [D. Ariz. 2017]; 248 F. Supp. 3d at 955-58), and in the
vacatur and remand of the 2011 pygmy-owl finding (76 FR 61856, October
5, 2011), the court's ruling addressed only the ``significant portion
of the range'' policy and that, on remand, the Service did not need to
address any other aspect of the 2011 finding.
Our response: The court's decision in 2017 vacated and remanded the
entire 12-month finding. Additionally, in the 10 years since our
previous decision, there has been new information, as outlined in
Summary of New Information Since 2011 Finding. Therefore, we were
required to revisit our previous finding and assess all new information
to ensure we are making a listing determination based on the best
available information.
(20) Comment: Two commenters indicated that the Service included no
information regarding recent, specific rangewide habitat losses that
would cause pygmy-owl habitat conditions to have declined since the
2011 12-month finding.
Our response: As discussed in the SSA report (Service 2022a,
chapter 7) and clarified in this rule, substantial new information on
the status of the pygmy-owl has become available since our 2011
finding. Our analysis shows that, while the same threats may not be
occurring in all analysis units, every analysis unit within the range
of the pygmy-owl is experiencing ongoing threats. Threats in each
analysis unit have resulted in past pygmy-owl habitat loss and are
likely to result in additional pygmy-owl habitat loss and fragmentation
into the future. It would not be reasonable to conclude that ongoing
threats to habitat that demonstrably caused habitat losses in the past
are not continuing to cause habitat losses now and into the foreseeable
future. Additionally, we updated the threats section based on
references and comments provided during the public comment period and
on updated references found while developing our response to comments.
Thus, we used the best available information to determine that, while
most rangewide habitat losses are not caused by a single threat, the
combination of threats in all analysis units results in rangewide
impacts to pygmy-owl habitat.
(21) Comment: Two commenters interpreted the information found in
the SSA report and proposed rule as indicating that pygmy-owl
population estimates are greater in the proposed rule and SSA report
than in the Service's 2011 12-month finding (76 FR 61856, October 5,
2011).
Our Response: The population estimates to which the commenters
referred (Service 2022a, table 4.2) are not actual population estimates
but, rather, an estimate of the general magnitude of pygmy-owl
abundance within each analysis unit. Thus, these estimates of the
magnitude of abundance in the SSA should not be interpreted as precise
population estimates, but rather as a tool to compare the general
abundance of pygmy-owls in each analysis unit. As explained in the SSA
report, we lack actual, quantitative pygmy-owl abundance data, even in
those analysis units where some survey and monitoring activities have
occurred. The actual abundance of pygmy-owls is unknown for every
analysis unit, particularly for the western Mexico and northeastern
Mexico analysis units. However, the best available information
indicates that abundance, distribution, or both have declined in the
three analysis units where survey and monitoring data do exist
(Arizona, Texas, and Northern Sonora), and anecdotal information
suggests this is true for the other analysis units in Mexico. We have
clarified this point in the SSA report (Service 2022a, Section 6.2) and
this final rule (see Summary of Current Condition of the Subspecies).
(22) Comment: Several commenters pointed out that listing the
pygmy-owl is not warranted because nearly 90 percent of the pygmy-owl's
range is in Mexico, where the subspecies is considered common and faces
few serious threats.
Our response: While the majority of the pygmy-owl's overall
geographic range is found in Mexico, the owls and owl habitat in the
United States contributes to the viability of the subspecies as a
whole, and it is on the overall viability of the subspecies that we
make listing determinations. We used the best available information to
estimate the magnitude of pygmy-owl abundance; while we estimate that
the pygmy-owl occurs in higher densities in the western Mexico and
northeastern Mexico, we have the least information on pygmy-owl
abundance and density from these areas of the range. Additionally, the
pygmy-owls in those regions face a number of serious threats, such as
urbanization, deforestation, and climate change. As described in the
SSA report (Service 2022a, entire) and this final rule, we find that
the best available information supports our finding that, while the
threats may vary across the range of the pygmy-owl, there are
substantial threats affecting the pygmy-owl's viability in all five of
the described analysis units, including the three analysis units found
in Mexico.
(23) Comment: Two commenters stated that pygmy-owls in Arizona
should be listed as endangered, either due to a significant portion of
the range in Arizona being endangered or as a distinct population
segment (DPS). One commenter believed that the population in Arizona is
isolated from Sonora and may be discrete. They also stated that Arizona
should qualify as a DPS due to its unusual ecological setting.
Our response: There are innumerable ways to divide up a species'
range; however, we only analyze configurations that we find may meet
the definition of a DPS or a significant portion of the range. We
analyzed multiple potential configurations for both a significant
portion of the range and DPS but discussed in the proposed rule only
those that we felt were reasonable under our policy and guidance.
We determined that Arizona does not constitute a significant
portion of the range of the pygmy-owl because it makes up only 12
percent of the total pygmy-owl range, contains a small proportion of
the total number of pygmy-owls, and contains a similar habitat to that
found elsewhere in the range. See Status Throughout a Significant
Portion of Its Range for our full analysis.
We also found that Arizona is not a valid DPS. Under our DPS
policy, a population must be both discrete and significant to be
considered a DPS. We agree that under our DPS policy (61 FR 4722,
February 7, 1996) the pygmy-owl in Arizona would likely meet the
discreteness condition through the presence of the international
border. However, the Arizona population of pygmy-owls does not meet the
significance requirement. Under this condition, we assess the
biological and ecological significance of the population and can
consider, among other factors, a population segment in an ecological
setting unusual or unique for the taxon, evidence that the loss of the
discrete population would result in a significant gap in the range,
evidence that the discrete population segment represents the only
surviving natural occurrence of a taxon that may be more abundant
elsewhere as an introduced population outside its historic range, or
evidence that the discrete population segment differs markedly from
other populations of the subspecies in its genetic
[[Page 46935]]
characteristics. There is no evidence that the Arizona population is
genetically separate from the remainder of the range. This population
does not occur in a unique or unusual setting as it has a similar
ecological setting to habitat in Northern Sonora, comprising primarily
Sonoran Desert vegetation. The loss of the Arizona population would
create a gap in the range of the pygmy-owl, but not a significant one.
Because this population is on the northern extreme of the pygmy-owl
range, the gap that would result would be on the periphery of its
range. While the court acknowledged the presence of this gap in the
range, it found that this gap would not be significant to the species
as a whole and we agree based on the best available data. In looking at
the best available data and considering the pygmy-owl population
segment in Arizona, we determined that it does not meet the
significance condition of our DPS policy. For additional discussion of
our DPS analyses see, Distinct Vertebrate Population Segment below. For
an in-depth discussion of the DPS analysis for Arizona, see also our
final rule to delist the Arizona DPS of the pygmy-owl (71 FR 19452,
April 14, 2006).
(24) Comment: We received several comments stating the pygmy-owl is
endangered in the Sonoran Desert ecoregion, which constitutes a
significant portion of the range of the pygmy-owl. One commenter stated
that the Service should have analyzed the eastern and western
populations of the pygmy-owl as a DPS, and we should have then found
the Sonoran Desert was a significant portion of the range of the
western DPS.
Our response: To clarify our analysis of whether it would make
sense to separately analyze a potential eastern and western population
DPS, we have added additional discussion under Analysis of Potential
Distinct Population Segments, below. Although the Sonoran Desert
ecoregion is a unique ecological setting, this region does not have a
different status from the rest of the range. We have determined that
the subspecies is in danger of extinction in the foreseeable future
throughout its range. Therefore, when examining the populations in the
Sonoran Desert Ecoregion, we looked to determine if this region had a
different status from the rest of the range. The Sonoran Desert
Ecoregion currently supports an abundance of pygmy-owls in the high
hundreds and a moderate amount of intact, suitable vegetation (Service
2022a, chapter 6). Consequently, these factors are currently
maintaining an overall moderate level of resiliency in this portion of
the range. There is currently habitat connectivity with evidence of
pygmy-owl movement among population groups, providing redundancy
throughout the Sonoran Desert Ecoregion. Representation is currently
being maintained through pygmy-owl occupancy of a variety of vegetation
types throughout the Sonoran Desert Ecoregion with gene flow among
these population groups. Although threats may be more concentrated in
this region, this ecoregion is not in danger of extinction now, but is
likely to become so in the foreseeable future and has the same status
as the rest of the range. Therefore, we determined that, although the
Sonoran Desert ecoregion has a concentration of threats and may
constitute a significant portion of the range, the population of pygmy-
owls there is not currently in danger of extinction and has the same
status as the subspecies rangewide. When assessing a potential
significant portion of the range, we can choose to first address the
question of whether a portion has a different status than the species
rangewide or whether a portion is significant. In this instance, we
addressed the status question first and determined that the Sonoran
Desert Ecoregion does not have a different status than the subspecies
rangewide and, therefore, did not need to move on to address the
question of significance of this portion. For additional discussion of
our analyses see Status Throughout a Significant Portion of Its Range
and Distinct Vertebrate Population Segment below.
(25) Comment: Several commenters stated they believed the pygmy-owl
in the Sonoran Desert Ecoregion met the criteria for a DPS.
Our response: Our policy (61 FR 4722, February 7, 1996) requires
that a DPS be markedly separate from other populations of the same
taxon. There are no physical, geographic, or behavioral barriers that
separate the petitioned Sonoran Desert DPS from the rest of the pygmy-
owl's range to the south. Although there may be some impediments to
movement in central Sonora, this situation does not prevent movements
of pygmy-owls between northern and southern Sonora. Genetic
differentiation is a result of isolation by distance. This finding is
supported by genetic sampling (Cobbold et al. 2022b, entire; Proudfoot
2006a, entire). The Sonoran Desert Ecoregion does differ ecologically
from the remainder of the areas within its range. However, as described
above and in Distinct Vertebrate Population Segment below, the best
available scientific and commercial data do not indicate that this
ecological difference has resulted in any morphological, physiological,
or genetic differentiation within pygmy-owl populations in the Sonoran
Desert and that these populations are not markedly separated from
populations to the south.
(26) Comment: One commenter requested that the Service clarify and
justify criteria used to make decisions pertaining to distinct
population segments and a significant portion of the range.
Specifically, the commenter mentioned our discussion of the Sonoran
Desert as a potential DPS whereby we assert that connectivity occurs
between the Sonoran Desert ecoregion and southern Sonora, as evidenced
by genetic sampling. The commenter requested additional clarification
on how much restriction of gene flow would be required for these
populations to be considered discrete. The commenter also requested the
benchmarks used to determine whether a geographical extent was
significant or not.
Our response: Neither the Act nor our regulations provide or
require benchmarks or thresholds for determining whether a population
or portion of the range should be considered a distinct population
segment or a significant portion of the range. Our DPS policy (61 FR
4722) provides guidance for analyzing areas as potential DPSs; however,
we have broad discretion to make science-based decisions on a species-
by-species basis, including whether to analyze specific areas as
potential DPSs or significant portions of the species' range. In this
instance, the best available data show that there is enough genetic
exchange between the Sonoran Desert ecoregion and southern Sonora to
maintain gene flow (Proudfoot et al. 2006a, entire; 2006b, entire;
Cobbold et al. 2022b, entire). For additional information on our DPS
analysis, see our responses to comments 25 and 26. Because we
determined that the Sonoran Desert Ecoregion does not meet the
discreteness condition of our DPS policy (76 FR 61856, October 5,
2011), we did not further analyze its significance under the policy.
For additional discussion of our analyses see Status Throughout a
Significant Portion of Its Range and Distinct Vertebrate Population
Segment below.
(27) Comment: One commenter stated that, under the most likely
future scenario in the SSA report, the increased effects scenario,
there would be a high probability of extirpation within the next 30
years in portions of the subspecies' range.
[[Page 46936]]
Our response: Given the complexity of and the limited data
available on the future influences and subspecies' responses to those
influences, we did not base our listing decision on any one scenario
but rather considered the range of plausible future conditions and risk
to the subspecies. Although we do acknowledge that threats to the
subspecies are not consistent across the range, we have determined
through our DPS and significant portion of the range analyses that
those areas either do not meet the criteria for a DPS or significant
portion of the range, or that the species is not currently in danger of
extinction in any of those areas. See comments 25, 26, 27, and Status
Throughout a Significant Portion of Its Range and Distinct Vertebrate
Population Segment below.
(28) Comment: One commenter stated that the Service did not apply
the five-factor test required by section 4(a) of the Act but instead
used the three R's principles of resiliency, redundancy, and
representation.
Our response: As discussed under Regulatory and Analytical
Framework, we are required to determine if a species is an endangered
species or threatened species because of any of the five factors listed
in the Act. These factors represent broad categories of natural or
human-caused actions or conditions that could have an effect on a
species' continued existence. However, the mere identification of a
threat under one of these factors does not necessarily mean that a
species meets the statutory definition of an endangered or threatened
species. We must evaluate each threat and its expected effects on the
species, and then analyze the cumulative effect of all the threats on
the species as a whole. We examined the following threats to the cactus
ferruginous pygmy-owl: Climate change and climate condition (Factor E),
habitat loss and fragmentation (Factor A), human activities and
disturbance (Factors B and E), waived or ineffective regulatory
mechanisms (Factor D), human-caused mortality (Factors B and E),
disease and predation (Factor C), and small population size (Factor E),
and we determined that the primary threats to the subspecies are
climate change and climate condition, and habitat loss and
fragmentation.
The supporting Species Status Assessment (SSA) report documents the
results of our comprehensive biological review of the best scientific
and commercial data regarding the status of the subspecies, including
an assessment of these potential threats to the subspecies. The SSA
report does not represent our decision on whether the subspecies should
be proposed for listing as an endangered or threatened species under
the Act. In the SSA, we use the conservation biology principles of
resiliency, redundancy, and representation to assess the viability of
the subspecies. This biological assessment does not replace the
additional application of the standards within the Act. Rather, it
provides the scientific basis that informs our regulatory decisions,
which involve the further application of the standards within the Act
and its implementing regulations and policies. We found that, based on
analysis in the SSA regarding the projected future condition of the
species, the cactus ferruginous pygmy-owl is likely to become an
endangered species in the foreseeable future primarily due to Factors A
and E.
(29) Comment: One commenter stated that we should have used a
shorter timeframe when analyzing future conditions of the pygmy-owl and
suggested timeframes of 10 years and 20 years.
Our response: The Service has wide discretion when determining the
appropriate timeframes when analyzing future scenarios and projecting
future conditions of a species. As discussed in Future Scenarios above,
we chose a 30-year timeframe to adequately capture natural variation
and fluctuations in owl populations such as described in Flesch et al.
2017 (entire) and because it was the timeframe where we could make
reasonably reliable predictions about the threats to the species.
(30) Comment: One commenter indicated that we overemphasized the
effect of buffelgrass on pygmy-owls. The commenter stated that
buffelgrass occurs primarily on slopes, which are not generally used by
pygmy-owls.
Our response: Our analysis shows that the extent of the current
distribution of buffelgrass and the rate at which that distribution is
and can expand, as well as the detrimental effects to native vegetation
communities, do indeed result in negative impacts to the viability of
pygmy-owl populations. These impacts include loss of nest cavity
substrates, reduction in woody vegetation cover, loss of habitat
connectivity, and reduction in prey diversity and availability. While
buffelgrass certainly seems to thrive on slopes, it also occurs on
bajadas and on the valley floor in areas that support pygmy-owl
habitat. The literature is clear that buffelgrass is an invasive threat
to all vegetation communities that provide pygmy-owl habitat (Esque and
Schwalbe 2002, p. 165; Lyons et al. 2013, p. 71; Wied et al. 2020,
entire). See also Invasive Species above and the SSA report (Service
2022a, chapter 7). Thus, we did not overemphasize this effect.
(31) Comment: Two commenters stated that pygmy-owl populations in
the Altar Valley in Arizona have remained relatively stable and that,
since there are pygmy-owls in captivity, they are not at risk of
extinction.
Our response: Listing determinations are made on the entire
listable entity, rather than a single population within that listable
entity. Though controlled propagation has a supportive role in the
recovery of some listed species, the intent of the Act is ``to provide
a means whereby the ecosystems upon which endangered species and
threatened species depend may be conserved.'' Controlled propagation is
not a substitute for addressing factors responsible for an endangered
or threatened species' decline and the presence of individuals of the
species in captivity does not mean that a species is not in danger of
extinction. Our first priority is to recover wild populations in their
natural habitat wherever possible, without resorting to the use of
controlled propagation. This position is fully consistent with the Act.
As discussed in Determination of Cactus Ferruginous Pygmy-owl Status
below, we have determined that the pygmy-owl is not in danger of
extinction now but is likely to become so in the foreseeable future
throughout its range.
(32) Comment: Two commenters felt that instead of a critical
analysis of the best available data, the proposed rule relies on
opinion and a subjective categorization of the future impacts of
threats to the pygmy-owl. They stated that the SSA report lacks
sufficient specific, relevant data that can be objectively analyzed.
Our response: As with most uncommon or rare species that the
Service evaluates under our authorities, information, particularly
quantitative data, is limited for the pygmy-owl. In our analysis of the
status of the pygmy-owl, we used specific, quantifiable information
wherever available. Where such information was not available, we relied
on expert elicitation and review, as well as the best professional
judgment of the biologists and scientists working on our review of the
status of the pygmy-owl. Our assessment of the future impacts of
threats to the pygmy-owl is based on reasonable and plausible scenarios
of future climate change, habitat fragmentation and loss, conservation
efforts, and the subspecies' responses to these influences. We do not
agree with the commenters' statements that this finding relies on
opinions or subjective categorization of future
[[Page 46937]]
impacts of the threats to pygmy-owls. Instead, we based this assessment
on the best scientific and commercial data available, which includes
habitat data and modeling (see Service 2022a, appendices 1, 4, and 6),
climate data analysis (see Service 2022a, appendix 2), available
scientific literature (see Literature Cited for Service 2022a and this
final rule), and direct input from experts. We used the best available
scientific and commercial data to develop plausible and representative
factors and categories on which to evaluate the current condition of
the subspecies, as well as future scenarios that represent a range of
plausible futures. These are not speculative or subjective but based on
the best available information alongside expert elicitation as
described in the SSA report. Our methods for assessing the future
resiliency, redundancy, and representation of the subspecies were
selected given the nature of the best available information and are
described in detail in chapters 6 and 8 of the SSA report (Service
2022a, chapters 6 and 8). Additionally, the pygmy-owl SSA report went
through a peer and partner review process as described under Peer
Review.
(33) Comment: Two commenters stated that the discussions of human
population growth and development, and the potential for pygmy-owl
habitat loss and fragmentation, were simplistic and failed to fully
evaluate potential regional growth patterns and land use that influence
habitat suitability for pygmy-owl.
Our response: Due to lack of specific and quantitative data on
where human population growth and development would occur, we used
regional growth and development projections, as these are the best
available information on the subject at this time. There is much
uncertainty about where future development projects will occur in the
foreseeable future within the range of the pygmy-owl; therefore, it is
difficult to project the specific areas of pygmy-owl habitat that will
be affected. However, our analysis shows that the condition of all five
analysis units will decline in the future, some to low condition, thus
requiring that areas of suitable, intact pygmy-owl habitat outside of
those currently occupied by pygmy-owls will be needed to maintain or
improve the pygmy-owl's viability throughout its range. Therefore,
understanding and considering the effects that future population growth
and development will have includes not only areas currently occupied by
pygmy-owls, but also unoccupied areas of pygmy-owl habitat that will be
needed to sustain future viability of pygmy-owl populations. Our
approach allowed us to evaluate all areas of suitable vegetation in a
consistent manner across the range of the pygmy-owl and included
consideration of areas of projected human population growth across the
range of the pygmy-owl.
(34) Comment: One commenter felt the Service erroneously emphasized
the need for undeveloped and unfragmented habitat and provided some
information suggesting that pygmy-owls appear quite tolerant of human
activity, even in some of the least productive habitats within its
range.
Our response: As the commenter pointed out, the best available
information does include some analysis of the level of development
tolerated by pygmy-owls. However, the information provided by the
commenter comes from one specific population group in the Arizona
analysis unit, and this population group is currently extirpated with
the last detection of pygmy-owl in this population group occurring in
2006. Surveys and monitoring in this area over the past 16 years have
not detected any pygmy-owls. Substantial development and habitat
fragmentation have occurred in this area over this time period,
reducing the potential for pygmy-owls to disperse into this area and
establish home ranges in the remaining habitat. As a result, we
conclude that the poor condition of this population supports our
determination that pygmy-owls have limited tolerance for development
and fragmentation.
Conversely, the pygmy-owl population group southwest of this
population group is characterized by large areas of undeveloped habitat
and reduced levels of fragmentation and has maintained, and even
increased, abundance of pygmy-owls. Additionally, pygmy-owl research in
northern Sonora has also shown the detrimental impacts of development
on habitat occupancy by pygmy-owls (Flesch 2021, entire). Pygmy-owls
can exist in areas that have a relatively low level of habitat
disturbance and development, but the presence of large blocks of
nesting habitat and unfragmented dispersal corridors is necessary for
the long-term viability of pygmy-owl populations and population groups.
Thus, the best available information does not support the commenter's
suggestion that pygmy-owls appear quite tolerant of human activity,
even in some of the least productive habitats within its range.
(35) Comment: One commenter stated that the ordinal ranking scale
we used for our analyses of suitable vegetation and habitat intactness
did not allow for the nuances of habitat selection by individual pygmy-
owls that has been observed in the field and that these analyses risk
biasing the analyses towards undisturbed lands. The commenter stated
that more rigorous analysis should have been conducted.
Our response: Field observations are extremely valuable in gaining
insights about the life history and habitat use of a species. However,
these data are sporadic and are largely unavailable across the range of
the pygmy-owl. Therefore, although the information from such studies
informed our models, fine-resolution data are not available at a scale
that would inform a rangewide analysis of pygmy-owl habitat. As
acknowledged in our SSA report (Service 2022a, section 6.1), our
analyses required us to make several educated assumptions. As noted in
the report, we lack specific habitat measurements related to the needs
of the pygmy-owl (for example, canopy cover, tree density and height,
species composition, structural diversity, patch size, and cavity
availability required by the pygmy-owl) across its range. Therefore, we
determined what available data sources and datasets were appropriate
surrogates for pygmy-owl habitat requirements that we could apply
consistently across the entire range of the pygmy-owl. Under this
approach, we used the best available information in the form
[…truncated; see source link]Indexed from Federal Register on July 20, 2023.
This is legal information, not legal advice. Laws vary by jurisdiction and change frequently. Always verify current law with official sources and consult a licensed attorney in your jurisdiction for advice on your specific situation.