Proposed Rule2021-27512
Endangered and Threatened Wildlife and Plants; Foothill Yellow-Legged Frog; Threatened Status With Section 4(d) Rule for Two Distinct Population Segments and Endangered Status for Two Distinct Population Segments
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
December 28, 2021
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (Service), propose to list four of six distinct population segments (DPSs) of the foothill yellow-legged frog (Rana boylii), a stream dwelling amphibian from Oregon and California, under the Endangered Species Act of 1973 (Act), as amended. This determination also serves as our 12-month finding on a petition to list the foothill yellow-legged frog. After a review of the best scientific and commercial information available, we find that listing the South Sierra and South Coast DPSs as endangered and the North Feather and Central Coast DPSs as threatened is warranted. Accordingly, we propose to list these four DPSs under the Act, with the South Sierra and South Coast DPSs listed as endangered species, and the North Feather and Central Coast DPSs listed as threatened species. Our proposal to list the North Feather and Central Coast DPSs as threatened species also includes a rule issued under section 4(d) of the Act for each of these two DPSs. If we finalize this proposed rule for these four DPSs, we will then add them to the List of Endangered and Threatened Wildlife and extend the Act's protections to them. We have determined that designation of critical habitat for these four DPSs is not determinable at this time. We have also determined that the North Coast DPS (in Oregon and northern California) and the North Sierra DPS (in Yuba, Sierra, Nevada, and Placer Counties, California) of the foothill yellow-legged frog do not warrant listing at this time.
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[Federal Register Volume 86, Number 246 (Tuesday, December 28, 2021)]
[Proposed Rules]
[Pages 73914-73945]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2021-27512]
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Vol. 86
Tuesday,
No. 246
December 28, 2021
Part III
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Foothill Yellow-Legged
Frog; Threatened Status With Section 4(d) Rule for Two Distinct
Population Segments and Endangered Status for Two Distinct Population
Segments; Proposed Rule
Federal Register / Vol. 86 , No. 246 / Tuesday, December 28, 2021 /
Proposed Rules
[[Page 73914]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R8-ES-2021-0108; FF09E21000 FXES1111090FEDR 223]
RIN 1018-BE90
Endangered and Threatened Wildlife and Plants; Foothill Yellow-
Legged Frog; Threatened Status With Section 4(d) Rule for Two Distinct
Population Segments and Endangered Status for Two Distinct Population
Segments
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
list four of six distinct population segments (DPSs) of the foothill
yellow-legged frog (Rana boylii), a stream dwelling amphibian from
Oregon and California, under the Endangered Species Act of 1973 (Act),
as amended. This determination also serves as our 12-month finding on a
petition to list the foothill yellow-legged frog. After a review of the
best scientific and commercial information available, we find that
listing the South Sierra and South Coast DPSs as endangered and the
North Feather and Central Coast DPSs as threatened is warranted.
Accordingly, we propose to list these four DPSs under the Act, with the
South Sierra and South Coast DPSs listed as endangered species, and the
North Feather and Central Coast DPSs listed as threatened species. Our
proposal to list the North Feather and Central Coast DPSs as threatened
species also includes a rule issued under section 4(d) of the Act for
each of these two DPSs. If we finalize this proposed rule for these
four DPSs, we will then add them to the List of Endangered and
Threatened Wildlife and extend the Act's protections to them. We have
determined that designation of critical habitat for these four DPSs is
not determinable at this time. We have also determined that the North
Coast DPS (in Oregon and northern California) and the North Sierra DPS
(in Yuba, Sierra, Nevada, and Placer Counties, California) of the
foothill yellow-legged frog do not warrant listing at this time.
DATES: We will accept comments received or postmarked on or before
February 28, 2022. Comments submitted electronically using the Federal
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59
p.m. Eastern Time on the closing date. We must receive requests for a
public hearing, in writing, at the address shown in FOR FURTHER
INFORMATION CONTACT by February 11, 2022.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: <a href="http://www.regulations.gov">http://www.regulations.gov</a>. In the Search box, enter the docket number or RIN
for this rulemaking (presented above in the document headings). For
best results, do not copy and paste either number; instead, type the
docket number or RIN into the Search box using hyphens. Then, click on
the Search button. On the resulting page, in the Search panel on the
left side of the screen, under the Document Type heading, check the
Proposed Rule box to locate this document. You may submit a comment by
clicking on ``Comment.''
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: FWS-R8-ES-2021-0108, U.S. Fish and Wildlife Service,
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on <a href="http://www.regulations.gov">http://www.regulations.gov</a>. This
generally means that we will post any personal information you provide
us (see Information Requested, below, for more information).
FOR FURTHER INFORMATION CONTACT: Michael Fris, Field Supervisor, U.S.
Fish and Wildlife Service, Sacramento Fish and Wildlife Office, 2800
Cottage Way, Sacramento, CA 95825; telephone 916-414-6700. Persons who
use a telecommunications device for the deaf (TDD) may call the Federal
Relay Service at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Act, a species 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 in 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 South
Sierra and South Coast DPSs meet the definition of an endangered
species and the North Feather and Central Coast DPSs meet the
definition of threatened species; therefore, we are proposing to list
them as such. We have determined that designation of critical habitat
for these four DPSs is not determinable at this time. We have
determined that listing the North Coast and North Sierra DPSs is not
warranted at this time. Both listing a species as an endangered or
threatened species and designating critical habitat can be completed
only by issuing a rule through the Administrative Procedure Act
rulemaking process.
What this document does. We propose to list two DPSs as endangered
species (South Sierra and South Coast DPSs) and two DPSs as threatened
species (North Feather and Central Coast DPSs) under the Act. We also
propose a rule under section 4(d) of the Act for each of those DPSs we
are proposing to list as threatened species.
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 the following threats are
driving the status of the foothill yellow-legged frog: Altered
hydrology (largely attributable to dams, water diversions, channel
modifications), nonnative species, and the effects of climate change
(exacerbating drought, high-severity wildfire, extreme flood
conditions). Other threats currently impacting the species include
disease and parasites, agriculture (including pesticide drift), mining,
urbanization (including development and roads) and recreation.
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. Due to a court-ordered
settlement agreement for completing our 12-month finding for the
species, we have not been able to obtain the necessary economic
information needed to develop a proposed critical habitat designation
for the foothill yellow-legged frog. Therefore, we find that
designation of critical habitat for this species is currently not
determinable. Once we obtain the necessary economic information, we
will propose a critical habitat designation for the species.
Information Requested
We intend that any final action resulting from this proposed rule
will be
[[Page 73915]]
based on the best scientific and commercial data available and be as
accurate and as effective as possible. Therefore, we request comments
or information from other governmental agencies, Native American
Tribes, the scientific community, industry, or any other interested
parties concerning this proposed rule.
We particularly seek comments concerning:
(1) The species' biology, range, and population trends, including:
(a) Biological or ecological requirements of the species, including
habitat requirements for feeding, breeding, and sheltering;
(b) Genetics and taxonomy;
(c) Historical and current range, including distribution patterns,
and the locations of any additional populations of this species;
(d) Historical and current population levels, and current and
projected population trends; and
(e) Past and ongoing conservation measures for the species and its
habitat and their effectiveness.
(2) Factors that may affect the continued existence of the species,
which may include habitat modification or destruction, overutilization,
disease, predation, the inadequacy of existing regulatory mechanisms,
or other natural or manmade factors.
(3) Biological, commercial trade, or other relevant data concerning
any threats (or lack thereof) to this species and existing regulations
that may be addressing those threats.
(4) Information on regulations that are necessary and advisable to
provide for the conservation of the foothill yellow-legged frog and
that the Service can consider in developing a 4(d) rule for the
species. In particular, we seek information concerning the extent to
which we should include any of the Act's section 9 prohibitions in the
4(d) rule or whether we should consider any additional exceptions from
the prohibitions in the 4(d) rule.
(5) The reasons why we should or should not designate habitat as
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et
seq.), including information to inform the following factors that the
regulations identify as reasons why designation of critical habitat may
be not prudent:
(a) The species is threatened by taking or other human activity and
identification of critical habitat can be expected to increase the
degree of such threat to the species;
(b) The present or threatened destruction, modification, or
curtailment of a species' habitat or range is not a threat to the
species, or threats to the species' habitat stem solely from causes
that cannot be addressed through management actions resulting from
consultations under section 7(a)(2) of the Act;
(c) Areas within the jurisdiction of the United States provide no
more than negligible conservation value, if any, for a species
occurring primarily outside the jurisdiction of the United States; or
(d) No areas meet the definition of critical habitat.
(6) Specific information on:
(a) The amount and distribution of foothill yellow-legged frog
habitat; and
(b) What areas, which are either (i) occupied at the time of
listing and that contain the physical or biological features essential
to the conservation of the species and which may require special
management considerations or protection; or (ii) unoccupied at the time
of listing and are essential for the conservation of the species, and
would, with reasonable certainty, contribute to the conservation of the
species.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include. Please
note that submissions merely stating support for, or opposition to, the
action under consideration without providing supporting information,
although noted, will not be considered in making a determination, as
section 4(b)(1)(A) of the Act directs that determinations as to whether
any species is an endangered or a threatened species must be made
``solely on the basis of the best scientific and commercial data
available.''
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
If you submit information via <a href="http://www.regulations.gov">http://www.regulations.gov</a>, your
entire submission--including any personal identifying information--will
be posted on the website. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Because we will consider all comments and information we receive
during the comment period, our final determinations may differ from
this proposal. Based on the new information we receive (and any
comments on that new information), we may conclude that the appropriate
listing status for any of the four DPSs is different than our
determinations identified in this proposal, including the possibility
that one or more of the DPSs may not warrant listing as either
endangered or threatened. In addition, we may change the parameters of
the prohibitions or the exceptions to those prohibitions in the 4(d)
rule if we conclude it is appropriate in light of comments and new
information we receive. For example, we may expand the prohibitions to
include prohibiting additional activities if we conclude that those
additional activities are not compatible with conservation of the
species. Conversely, we may establish additional exceptions to the
prohibitions in the final rule if we conclude that the activities would
facilitate or are compatible with the conservation and recovery of the
species.
Public Hearing
Section 4(b)(5) of the Act (16 U.S.C. 1531 et seq.) provides for a
public hearing on this proposal, if requested. Requests must be
received by the date specified in DATES. Such requests must be sent to
the address shown in FOR FURTHER INFORMATION CONTACT. We will schedule
a public hearing on this proposal, if requested, and announce the date,
time, and place of the hearing, as well as how to obtain reasonable
accommodations, in the Federal Register and local newspapers at least
15 days before the hearing. For the immediate future, we will provide
these public hearings using webinars that will be announced on the
Service's website, in addition to the Federal Register. The use of
these virtual public hearings is consistent with our regulations at 50
CFR 424.16(c)(3).
Previous Federal Actions
On July 11, 2012, we received a petition from the Center for
Biological Diversity to list 53 species of reptiles and amphibians,
including the foothill yellow-legged frog, as endangered or threatened
under the Act. On July 1, 2015, we published our finding that the
petition presented substantial scientific or commercial information
indicating that listing the foothill yellow-legged frog may be
warranted based on impacts to the species' habitat (Factor A) and other
natural or humanmade factors (Factor E) (80 FR 37568).
On August 30, 2016, we entered into a settlement agreement with the
Center
[[Page 73916]]
for Biological Diversity to complete our 12-month finding on the
foothill yellow-legged frog by September 30, 2020. We subsequently
requested and received an extension of our deadline to submit the 12-
month finding on the species to the Federal Register by December 15,
2021. This document fulfills our obligation under the settlement
agreement to complete a 12-month finding on the foothill yellow-legged
frog.
Supporting Documents
A species status assessment (SSA) team prepared an SSA report for
the foothill yellow-legged frog (Service 2021, entire). The SSA team
was composed of Service biologists, in consultation with other species
experts. The SSA report represents a compilation of the best scientific
and commercial data available concerning the status of the species,
including the impacts of past, present, and future factors (both
negative and beneficial) affecting the species. 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
sought and received the expert opinions of three appropriate
specialists regarding the SSA. We also sent the SSA report to numerous
Federal, State, Tribal, and private partners and stakeholders,
including scientists with expertise in foothill yellow-legged frog
ecology, river ecology, amphibian genetics, population modeling, and
public land management, for review. We received comments from 12 of
these partners including representatives from the U.S. Department of
Agriculture's U.S. Forest Service (Forest Service), U.S. Geological
Survey (USGS), Bureau of Land Management (BLM), National Park Service,
Oregon Department of Fish and Wildlife (ODFW), California Department of
Forestry and Fire Protection (CalFire), and researchers from the
University of California at Los Angeles. We did not receive comments
from any Tribal entities. Comments and feedback from partners and peer
reviewers were incorporated into the SSA report as appropriate and have
informed this proposed rule. A copy of the SSA report can be found on
<a href="http://www.regulations.gov">www.regulations.gov</a> at Docket No. FWS-R8-ES-2021-0108.
I. Proposed Listing Determination
Background
Below is a brief description of the foothill yellow-legged frog,
its habitat, distribution, and taxonomy; for a thorough discussion of
the ecology and life history of the species, please see the SSA report
(Service 2021, Chapter 2, pp. 14-33).
The foothill yellow-legged frog is a small- to medium-sized stream-
dwelling frog with fully webbed feet and rough pebbly skin. Coloring of
the species is highly variable but is usually light and dark mottled
gray, olive, or brown, with variable amounts of brick red. The foothill
yellow-legged frog is a stream-obligate species. Stream habitat for the
species is highly variable and keyed on flow regimes. The historical
range of the foothill yellow-legged frog extended from the Willamette
River drainage in Oregon south through the Sierra Nevada Mountains to
the Transverse Range, and down along the California Coast Range to at
least the Upper San Gabriel River in Los Angeles County, California.
The current distribution of the foothill yellow-legged frog generally
follows the historical distribution of the species except with range
contractions in the southern and, to a lesser extent, northern parts of
the species' range.
Taxonomy
The foothill yellow-legged frog currently retains its
classification as Rana boylii, ascribed in 1854 by S. F. Baird (Baird
1854, p. 62; Frost 2019, unpaginated). Prior to1955, the foothill
yellow-legged frog was part of a grouping of two Ranid subtaxa that
occurred in Oregon and California. The two subtaxa were subsequently
revised as two separate individual taxa in 1955 and identified as Rana
boylii (foothill yellow-legged frog) and Rana muscosa (mountain yellow-
legged frog) (Zweifel 1955, pp. 210, 273). The foothill yellow-legged
frog is now the only entity classified as Rana boylii (Zweifel 1968,
pp. 71.1-71.2).
Genetic Information
Subsequent to receipt of the petition to list the foothill yellow-
legged frog as a singular species, investigations into genetic
differences among populations of the foothill yellow-legged frog have
delineated the species into six currently identified genetic clades
(Peek 2018, entire). A clade is a group of organisms that includes a
common biological ancestor and all the lineal descendants. Two
rangewide assessments of foothill yellow-legged frog genomic datasets
revealed that the species is extremely differentiated following
biogeographical boundaries (McCartney-Melstad et al. 2018, p. 112; Peek
2018, p. 76). The foothill yellow-legged frog has deeper population
structure (stratification or separation between populations) than that
observed in any other anuran (i.e., frogs, toads, and tree frogs) with
similar data (McCartney-Melstad et al. 2018, p. 112). The California
Department of Fish and Wildlife (CDFW) in their recent status
determination classified the foothill yellow-legged frog as having six
unique, genetic clades (i.e., lineages) (CDFW 2019b, pp. 4, 13).
Additional information regarding the genetic clades can be found in the
SSA report (Service 2021, pp. 19-21). The six separate genetic clades
are identified as the North Coast, North Feather, North Sierra, South
Sierra, Central Coast, and South Coast clades in our analysis.
Distinct Population Segment Evaluation
Under the Act, the term species includes any subspecies of fish or
wildlife or plants, and any distinct population segment of any species
of vertebrate fish or wildlife which interbreeds when mature (16 U.S.C.
1532(16)). To guide the implementation of the distinct population
segment (DPS) provisions of the Act, we and the National Marine
Fisheries Service (National Oceanic and Atmospheric Administration--
Fisheries), published the Policy Regarding the Recognition of Distinct
Vertebrate Population Segments Under the Endangered Species Act (DPS
Policy) in the Federal Register on February 7, 1996 (61 FR 4722). Under
our DPS Policy, we use two elements to assess whether a population
segment under consideration for listing may be recognized as a DPS: (1)
The population segment's discreteness from the remainder of the species
to which it belongs, and (2) the significance of the population segment
to the species to which it belongs. If we determine that a population
segment being considered for listing is a DPS, then the population
segment's conservation status is evaluated based on the five listing
factors established by the Act to determine if listing it as either
endangered or threatened is warranted.
Under the Act, we have the authority to consider for listing any
species, subspecies, or, for vertebrates, any DPS of these taxa if
there is sufficient information to indicate that such action may be
warranted. Based on the information available regarding potential
discreteness and significance for the species, we determined it was
appropriate to review the status of the foothill yellow-legged frog by
first conducting a DPS analysis for the species.
Discreteness
Under our DPS Policy, a population segment of a vertebrate taxon
may be considered discrete if it satisfies either of the following
conditions: (1) It is markedly separated from other
[[Page 73917]]
populations of the same taxon as a consequence of physical,
physiological, ecological, or behavioral factors. Quantitative measures
of genetic or morphological discontinuity may provide evidence of this
separation; or (2) it is delimited by international governmental
boundaries within which differences in control of exploitation,
management of habitat, conservation status, or regulatory mechanisms
exist that are significant in light of section 4(a)(1)(D) of the Act.
For the foothill yellow-legged frog, we examined recent genetic
information and distribution of the species' populations as our means
of determining discreteness for potential DPSs.
There is substantial evidence that the foothill yellow-legged frog
is biogeographically divided into multiple clades with little or no
gene flow between the clades. Earlier studies provided strong evidence
that there are deep genetic divisions in this taxon (Dever 2007, pp.
168-173; Lind et al. 2011, pp. 269-284; Peek 2010, entire). Subsequent,
more in-depth and larger-scale genetic studies (McCartney-Melstead et
al. 2018, entire; Peek 2018, entire) confirmed the certainty and depth
of the phylogenetic (evolutionary history) structural divisions of the
foothill yellow-legged frog using population genomics (comparison of
DNA sequences of populations).
The results of the first study (McCartney-Melstead et al. 2018,
entire), which used several different analytical approaches, all
supported extremely differentiated clades in a spatially cohesive
pattern, and identified five reciprocally monophyletic clades (where
each clade shares more-recent common ancestors from one clade than it
shares with any other clade) associated with five different geographic
regions (identified herein as the North Coast, Central Coast, South
Coast, North Sierra, and South Sierra clades) (McCartney-Melstead et
al. 2018, p. 112).
The second genomic study (Peek 2018, entire) provided additional
geographic and genetic resolution to clade divisions by examining
genetic samples from 1,103 individual foothill yellow-legged frogs
across the extant range of the species and provided greater coverage of
localities in the northern Sierra Nevada range (Peek 2018, pp. 52-53).
Like the earlier study, multiple analytical methods were used to
quantify genetic structure. The study largely confirmed the five clades
described by previous research (McCartney-Melstead et al. 2018,
entire), but also identified another discrete group between the North
Sierra and North Coast clade that is identified herein as the North
Feather clade (Peek 2018, pp. 63-64). The extensive genomic data
available for this species, which are both more reliable and more
informative than morphological data, demonstrate discrete patterns of
biogeographical discontinuity across the taxon's range.
Some of the geographical boundaries that delineate the foothill
yellow-legged frog clades are fairly certain because of clear physical
barriers, such as the separation between the Sierra Nevada and Coastal
clades due to the Central Valley of California, the San Francisco Bay
between the North Coast and the Central Coast clades, or the separation
of the Central Coast and South Coast clades due to the Salinas Valley.
However, physical separation between clades in the Sierra Nevada and
separation of the Sierra Nevada clades from the North Coast clade were
not as physically apparent and were informed by continuous sampling
efforts in neighboring watersheds between clades. Where continuous
landscape-level sampling was unavailable, the clade boundaries were
estimated or inferred. Information is currently lacking for the precise
boundary separating the North Coast clade and the North Feather clade,
and the Central Coast clade from the South Coast clade. Therefore, we
relied upon the genetic information for assessment of discreteness in
this DPS analysis.
Meeting the first condition for discreteness, there are six
statistically-supported discrete genetic entities (Central Coast, South
Coast, South Sierra, North Sierra, North Feather, and North Coast)
within the range of the foothill yellow-legged frog (see figure below).
Two rangewide assessments of foothill yellow-legged frog genomic
datasets revealed that this taxon is extremely differentiated by
biogeographical boundaries (McCartney-Melstead et al. 2018, p. 112;
Peek 2018, p. 76). All six entities, or clades, are markedly separate
from each other, as evidenced by quantitative measures of genetic
discontinuity, and at least five of the clades are monophyletic groups
(McCartney-Melstead et al. 2018, p. 116). As a result, we have
determined that the foothill yellow-legged frog is comprised of six
discrete entities (North Coast, Central Coast, South Coast, North
Feather, North Sierra, and South Sierra) meeting the condition of
discreteness under our DPS policy.
BILLING CODE 4333-15-P
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[GRAPHIC] [TIFF OMITTED] TP28DE21.019
BILLING CODE 4333-15-C
Significance
Under our DPS Policy, once we have determined that a population
segment is discrete, we consider its biological and ecological
significance to the larger taxon to which it belongs. This
consideration may include, but is not limited to: (1) Evidence of the
persistence of the discrete population segment in an ecological setting
that is unusual or unique for the taxon, (2)
[[Page 73919]]
evidence that loss of the population segment would result in a
significant gap in the range of the taxon, (3) evidence that the
population segment represents the only surviving natural occurrence of
a taxon that may be more abundant elsewhere as an introduced population
outside its historical range, or (4) evidence that the discrete
population segment differs markedly from other populations of the
species in its genetic characteristics.
We evaluated each discrete population segment to see if it met the
conditions of significance under our DPS policy, and we have determined
that the six entities are significant to the foothill yellow-legged
frog.
The support for significance of the six DPSs is based, in part,
upon evidence that loss of any of these population segments would
result in a significant gap in the range of the taxon. The loss of
either the Central Coast or South Coast DPS would result in a
substantial change in the overall range and distribution of the taxon.
The loss of the South Coast DPS would shift the taxon's southwestern
range boundary northward by approximately 150-200 kilometers (km) (93-
125 miles (mi)). The loss of the Central Coast DPS would leave an
extensive separation of approximately 300 km (186 mi) and be a
significant gap in the species' range. The loss of the South Sierra DPS
would result in a considerable contraction of the taxon's range, making
the species' range shift approximately 180 km (112 mi) west and 340 km
(211 mi) north. The loss of the North Coast DPS would result in the
loss of more than half of the taxon's current range. The North Sierra
and North Feather DPSs occupy much smaller areas than the other DPSs.
However, based on the current range of each of these DPSs, the loss of
either would result in a 50-75 km (31-47 mi) gap in the range of the
taxon. Due to the species' limited dispersal ability from occupied
stream habitats, this gap would effectively prevent any potential
future gene flow between the DPSs remaining on either side of the gap.
The support for significance of the six DPSs is also based upon
evidence that each discrete population segment differs markedly from
all the others in its genetic characteristics. The loss of any of the
six DPSs would result in the loss of a discrete genetic clade. The DPSs
that are most genetically divergent, and thus contribute most to the
overall adaptive capacity of this taxon, are the Central Coast, South
Coast, and South Sierra DPSs (Peek 2018, p. 77). The North Feather and
North Sierra DPSs likely have unique adaptive potential in the face of
climate change because of their admixture history (interbreeding of
isolated populations) and intermediacy to the South Sierra and North
Coast DPSs. The North Coast DPS is also genetically valuable to the
taxon because it contains the greatest genetic diversity and is the
only DPS that shows a trajectory of increasing genetic diversity (Peek
2018, p. 74).
Distinct Population Segment Conclusion
Our DPS Policy directs us to evaluate whether populations of a
species are separate from each other to the degree they qualify as
discrete segments and whether those segments are significant to the
remainder of the species to which it belongs. Based on an analysis of
the best available scientific and commercial data, we conclude that the
North Coast, North Feather, North Sierra, South Sierra, Central Coast,
and South Coast clades of the foothill yellow-legged frog's range are
each discrete due to their marked genetic separation. Furthermore, we
conclude that each of the six clades of the foothill yellow-legged
frog's range is significant, based on evidence that a loss of any of
the population segments would result in a significant gap in the range
of the taxon and on evidence that the discrete population segments
differ markedly from other populations of the species in their genetic
characteristics. Therefore, we conclude that the six clades within the
foothill yellow-legged frog's range are both discrete and significant
under our DPS Policy and are, therefore, uniquely listable entities
under the Act.
Based on our DPS Policy (61 FR 4722; February 7, 1996), if a
population segment of a vertebrate species is both discrete and
significant relative to the taxon as a whole (i.e., it is a distinct
population segment), its evaluation for endangered or threatened status
will be based on the Act's definition of those terms and a review of
the factors enumerated in section 4(a) of the Act. Having found that
each of the six clades of the foothill yellow-legged frog's range meet
the definition of a distinct population segment, we then evaluated the
status of the six clades of the foothill yellow-legged frog to
determine whether any met the definition of an endangered or threatened
species under the Act. The figure below identifies the areas within the
foothill yellow-legged frog's historical range encompassed by the six
DPSs for the foothill yellow-legged frog.
Description of Foothill Yellow-Legged Frog Distinct Population Segments
Below is a general description of environmental and ecological
conditions for each DPS.
North Coast DPS: The North Coast DPS includes the range of the
foothill yellow-legged frog in northern California and central and
southwestern Oregon. This DPS occupies parts of the Cascade Range,
Klamath Mountains, central and southwest Oregon (including the
Willamette Valley), northern California Coast Range north of San
Francisco Bay, and a portion of the Sierra Nevada Mountains and
foothills to the borders of Plumas and Butte Counties, California. This
DPS covers the largest geographic area and has the greatest amount of
genetic diversity of the species, suggesting that habitat conditions
allow for populations within the DPS to be interconnected (McCartney-
Melstad et al. 2018, p. 121; Peek 2018, p. 76). In Oregon, the area has
the greatest precipitation and coolest temperatures within the species'
range (PRISM Climate Group 2012, 30-year climate dataset, entire;
Service 2021, table 3, p. 36). In California, the DPS is cooler and
wetter on average than the DPSs to the south but is about equal to that
of the North Sierra DPS (PRISM Climate Group 2012, 30-year climate
dataset, entire; Service 2021, table 3, p. 36). The DPS also contains
the most Level IV ecoregions (finest down-scaled ecosystems boundaries
based on biotic and abiotic factors as defined by Omerick and Griffith
2014, entire), as well as several ecoregions that are not found
anywhere else in the foothill yellow-legged frog's range, suggesting
that the environmental conditions for habitat within this DPS are
variable and not likely to be subject to rangewide environmental
influences.
North Feather DPS: The North Feather DPS is located primarily in
Plumas and Butte Counties, California. This DPS occupies the transition
zone between the northern Sierra Nevada, Southern Cascades Foothills,
and Tuscan Flows ecoregions. The DPS averages cooler and wetter
conditions than the DPSs to the south (PRISM Climate Group 2012, 30-
year climate dataset, entire; Service 2021, table 3, p. 36). The North
Feather DPS differs from the surrounding watersheds outside the areas
in terms of geology and aspect (Peek et al. 2019, p. 4638), and is the
only known area where the foothill yellow-legged frog and the
endangered Sierra Nevada yellow-legged frog (Rana sierrae) currently
coexist (Peek et al. 2019, p. 4637).
North Sierra DPS: The North Sierra DPS is located primarily in
Yuba, Sierra, Nevada, and Placer Counties, California. This DPS
occupies the transition zone between the northern and central
ecoregions of the Sierra Nevada Range. This transition zone is
characterized by a southward decrease in annual
[[Page 73920]]
precipitation, decrease in Douglas and white firs (Pseudotsuga
menziesii and Abies concolor), increase in ponderosa pine (Pinus
ponderosa), and geological shift from metamorphic rocks to volcanic and
granitic rocks (Environmental Protection Agency Level IV Ecoregions,
Griffith et al. (2016, entire)). Like the North Feather DPS, the North
Sierra DPS receives notably more precipitation than the South Sierra
DPS; however, the mean annual temperature in the North Sierra DPS is
more similar to that of the South Sierra DPS than that of the North
Feather DPS (PRISM Climate Group 2012, 30-year climate dataset, entire;
Service 2021, table 3, p. 36).
South Sierra DPS: The South Sierra DPS extends from the South Fork
American River sub-basin to the transition zone between the Sierra
Nevada and the Tehachapi Mountains that border the south end of the
California Central Valley. This DPS largely includes ecoregions that
are unique to the southern and central Sierra Nevada Range
(Environmental Protection Agency Level IV Ecoregions, Griffith et al.
(2016, entire)). The South Sierra DPS also shares an ecoregion
transition zone with the North Sierra DPS. In terms of average
precipitation and temperature, the South Sierra DPS is fairly dry and
warm, but it falls intermediately among the northern DPSs and the DPSs
south of San Francisco Bay (PRISM Climate Group 2012, 30-year climate
dataset, entire; Service 2021, table 3, p. 36).
Central Coast DPS: The Central Coast DPS extends south from the San
Francisco Bay through the Diablo Range and Coast Range (Santa Cruz
Mountains and Gabilan Mountains) east of the Salinas Valley,
California. On average, the Central Coast DPS receives the least amount
of annual precipitation of all the DPSs (PRISM Climate Group 2012, 30-
year climate dataset, entire; Service 2021, table 3, p. 36). The DPS
contains several unique ecoregions associated with the Diablo and Coast
Ranges. Although the mountain ranges of the Central Coast DPS are
geologically unique and separated from those of the South Coast DPS by
the Salinas Valley, there are several attributes such as overall
elevation, elevation grade, and some vegetation types (Environmental
Protection Agency Level IV Ecoregions, Griffith et al. (2016, entire))
which they share in common with the South Coast DPS mountain ranges.
Climatic and habitat conditions of the DPS are drier than all other
DPSs except for the South Coast DPS, which has conditions similar to
the Central Coast DPS, being warm and dry and containing waterways
similar in size and hydrological properties (PRISM Climate Group 2012,
30-year climate dataset, entire; Service 2021, table 3, p. 36).
South Coast DPS: The South Coast DPS extends along the coastal
Santa Lucia Range and the Sierra Madre Mountains in California.
Ecoregions that are unique to the South Coast DPS include those
associated with the Santa Lucia Range, Western Transverse Range, and
Southern California Lower Montane Shrub and Woodland (Environmental
Protection Agency Level IV Ecoregions, Griffith et al. (2016, entire)).
As stated above, the streams and rivers in the South Coast DPS share
similarities to many waterways in the Central Coast DPS. Waterways in
the South Coast and Central Coast DPSs tend to have flashier flows,
more ephemeral channels, and a higher degree of intermittency because
of the region's more variable, and lower amount of, precipitation
(Storer 1925, pp. 257-258; Gonsolin 2010, p. 54; Adams et al. 2017b, p.
10227). The South Coast and Central Coast DPSs receive the least amount
of annual precipitation and average the warmest temperatures within the
species' range (PRISM Climate Group 2012, 30-year climate dataset,
entire; Service 2021, table 3, p. 36).
Regulatory and Analytical Framework
Regulatory Framework
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species is an endangered species or a threatened species. 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 expected response by the species,
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 the
Service 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
[[Page 73921]]
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. For information regarding the foreseeable
future for the foothill yellow-legged frog, see Current and Future
Condition Analysis, below.
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 species, including an assessment of the potential
threats to the species. The SSA report does not represent a decision by
the Service on whether the species should be proposed for listing 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. The following is a summary
of the key results and conclusions from the SSA report; the full SSA
report can be found at Docket FWS-R8-ES-2021-0108 on <a href="http://www.regulations.gov">http://www.regulations.gov</a> and from the Sacramento Fish and Wildlife Office
(see FOR FURTHER INFORMATION CONTACT).
Our review of the foothill yellow-legged frog has determined that
it is made up of six DPSs; therefore, we assessed the biological
viability and regulatory status of each DPS separately. Because the
North Coast DPS of the foothill yellow-legged frog occurs in Oregon and
California, we split the North Coast DPS into a California and an
Oregon analysis unit due to varying levels of information and to better
understand if any management actions or habitat conditions may differ
between the two areas (Service 2021, Chapter 3, pp. 35-36). We later
combine the two analysis units to determine the status of the North
Coast DPS as a whole. When we discuss general biological or other
information regarding the species as a whole we use the term species.
When we discuss information pertaining to one of the six DPSs we use
the term DPS.
To assess the biological viability of each DPS of the foothill
yellow-legged frog, we used the three conservation biology principles
of resiliency, redundancy, and representation (Shaffer and Stein 2000,
pp. 306-310). Briefly, resiliency supports the ability of the DPS to
withstand environmental and demographic stochasticity (for example, wet
or dry, warm or cold years), redundancy supports the ability of the DPS
to withstand catastrophic events (for example, droughts, large
pollution events), and representation supports the ability of the DPS
to adapt over time to long-term changes in the environment (for
example, climate changes). In general, the more resilient and redundant
a DPS is and the more representation it has, the more likely it is to
sustain populations over time, even under changing environmental
conditions.
Using these principles, we identified each DPS's ecological
requirements for survival and reproduction at the individual,
population, and DPS levels, and described the beneficial and risk
factors influencing the DPS's viability.
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 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. In our development of the SSA and analysis of information, we
divided our analysis into separate analysis units due to the varying
degree of information throughout the species' range and other factors.
The analysis units coincide with those areas we are considering as DPSs
for the species except for the North Coast DPS which has been split
into two analysis units. In California, the analysis units match those
considered in the CDFW's evaluation for their status review and listing
under the California Endangered Species Act.
Summary of Biological Status and Threats
In this discussion, we review the biological condition of each DPS
and its resources, and the threats that influence each DPS's current
and future condition, in order to assess each DPS's overall viability
and the risks to that viability.
We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA report, we have not
only analyzed individual effects on each DPS, but we have also analyzed
their potential cumulative effects. We incorporate the cumulative
effects into our SSA analysis when we characterize the current and
future condition of each DPS. To assess the current and future
condition of each DPS, 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 each DPS, 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 DPS, our assessment integrates the cumulative effects of the
factors and replaces a standalone cumulative effects analysis.
Species Needs
Stream Habitat
The foothill yellow-legged frog is a stream-obligate species and is
primarily observed in or along the edges of streams (Zweifel 1955, p.
221; Kupferberg 1996a, p. 1339). Most foothill yellow-legged frogs
breed along mainstem water channels and overwinter along smaller
tributaries of the mainstem channel (Kupferberg 1996a, p. 1339; GANDA
2008, p. 20). Habitat within the stream includes rocky substrate mostly
free of sediments with interstitial spaces to allow for predator
avoidance. Stream morphology is a strong predictor of breeding habitat
because it creates the microhabitat conditions required for successful
oviposition (i.e., egg-laying), hatching, growth, and metamorphosis.
Foothill yellow-legged frogs that overwinter along tributaries often
congregate at the same breeding locations along the mainstem each year
(Kupferberg 1996a, p. 1334; Wheeler and Welsh 2008, p. 128). During the
nonbreeding season, the smaller tributaries, some of which may only
flow during the wet winter season, provide refuge while the larger
breeding channels may experience overbank flooding and high flows
(Kupferberg 1996a, p. 1339). Habitat elements that provide both refuge
from winter peak flows and adequate moisture for foothill yellow-legged
frogs include pools, springs, seeps, submerged root wads, undercut
banks,
[[Page 73922]]
and large boulders or debris at high-water lines (van Wagner 1996, pp.
74-75, 111; Rombough 2006b, p. 159).
The streams occupied by foothill yellow-legged frogs occur in a
wide variety of vegetation types including valley-foothill hardwood,
valley-foothill hardwood-conifer, valley-foothill riparian, ponderosa
pine, mixed conifer, mixed chaparral, and wet meadow (Hayes et al.
2016, p. 5). The extensive range of habitat types used by the foothill
yellow-legged frog demonstrates the species' non-specificity in regard
to vegetation type and macroclimate of the species' terrestrial habitat
component. While habitat conditions can be vastly different among these
stream sizes, and across the species' geographic range, only a narrow
range of abiotic conditions are tolerated by early life stages (i.e.,
eggs, tadpoles, and metamorphs) (Kupferberg 1996a, p. 1336; Bondi et
al. 2013, p. 101; Lind et al. 2016, p. 263; Catenazzi and Kupferberg
2018, pp. 1044-1045). The abiotic conditions that directly influence
the success of early life stages are those associated with stream
velocity, water depth, water temperature, and streambed substrate.
Foothill yellow-legged frogs also require stream flow regimes to have
or mimic natural flow patterns which includes high winter flows with a
slowly diminishing hydrograph with increasing water temperature and
decreasing flows into the spring and summer. Higher winter flows can
maintain and or increase breeding habitat by widening and diversifying
channel morphology, improving rocky substrate conditions, and
increasing sunlight (Lind et al. 1996, pp. 64-65; Lind et al. 2016, p.
269; Power et al. 2016, p. 719). The reduction in flows and increasing
water temperatures are also cues to initiate breeding. As a result,
foothill yellow-legged frogs rely on natural, predictable changes
during the hydrological cycle to optimize early life-stage growth and
survival (Kupferberg 1996a, p. 1332; Bondi et al. 2013, p. 100).
Food Resources
During their lifecycle foothill yellow-legged frogs feed on a
variety of plant and animals. During early development food sources
include algae, diatoms, and detritus that are scraped from submerged
rocks and vegetation (Ashton et al. 1997, p. 7; Fellers 2005, p. 535).
Juvenile and adult foothill yellow-legged frogs prey upon many types of
aquatic and terrestrial invertebrates including snails, moths, flies,
water striders, beetles, grasshoppers, hornets, and ants (Nussbaum et
al. 1983, p. 165).
Migration/Dispersal Routes and Connectivity
Adult foothill yellow-legged frogs primarily use waterway corridors
to migrate or disperse (Bourque 2008, p. 70) and make their movements
over multiple days (GANDA 2008, p. 22). While most foothill yellow-
legged frogs are found in, or very close to, water, juveniles and an
adult have also been observed moving through upland areas outside of
riparian corridors. The habitat characteristics needed by foothill
yellow-legged frogs for migration and dispersal are largely the same as
they are for upland and tributary habitat. However, movement routes do
not need to be moist for extended periods. Routes need to connect
breeding areas and overwintering habitat without exposing frogs to
large physical barriers (e.g., roads, development, reservoirs) or high
risk of predation. These migration and dispersal routes provide for
metapopulation connectivity and allows for ease of mobility (for post-
metamorphic frogs) within a metapopulation and between different
metapopulations. Both breeding/rearing and overwintering sites need to
be distributed across the metapopulation area. Foothill yellow-legged
frog occupancy (i.e., presence of breeding adults in a given area) must
also be well distributed, such that dispersers are able to repopulate
extirpated areas of the metapopulation. A resilient foothill yellow-
legged frog metapopulation should have a network of quality breeding/
rearing sites (often on or near the mainstem channel) and overwintering
sites (often on tributaries of the mainstem) that are connected by
habitat suitable for migration and dispersal (Section 4.9 Migration and
Dispersal Routes). An in-depth discussion of habitat and population
elements required for the foothill yellow-legged frog is in the SSA
report (Service 2021, Chapter 4 and Chapter 5).
Threats Influencing Current and Future Condition
Following are summary evaluations of the threats analyzed in the
SSA report for the foothill yellow-legged frog. The discussion focuses
on general threats impacting all DPSs, with some anecdotal evidence
regarding threats operating in particular DPSs. The specific threats
associated with each DPS are identified in the status discussion for
each DPS below and in the SSA report (Service 2021, Chapter 7, pp. 73-
122).
Those threats having the greatest impacts on the species or its
habitat include: Altered stream hydrology and flow regimes (Factor A)
associated with dams, surface water diversions, and channel
modifications and their impact on the species and its habitat;
predation and resource competition from nonnative species (Factor C and
Factor E, respectively), such as American bullfrogs (Lithobates
catesbeianus), smallmouth bass (Micropterus dolomieu), and crayfish
species (Pacifastacus spp.); disease (Factor C); habitat degradation,
loss, and fragmentation associated with wildfire (Factor A); the
effects of climate change, including increased temperatures, drying and
drought, and extreme flood events (Factor E); habitat modification and
altered hydrology as a result of conservation efforts for salmonid
species (colder water temperatures, timing and intensity of water
flows) (Factor E); habitat loss, degradation, and fragmentation (Factor
A), and direct negative effects to individuals (Factor E) from other
anthropogenic activities such as agriculture, mining, urbanization,
roads, and recreation. Within our threat discussion, we also evaluate
existing regulatory mechanisms (Factor D) and ongoing conservation
measures that may ameliorate threat impacts on the species.
Livestock grazing and timber harvest were discussed as potential
threats and potential beneficial influences in the recent status
assessment for the foothill yellow-legged frog in California (CDFW
2019b, pp. 64-65, 67). These activities were also considered in the
conservation assessment developed by the Forest Service and BLM as part
of their sensitive species program for the species in Oregon (Olson and
Davis 2009, pp. 18-20). While there is potential for harm to the
species (e.g., when grazing and timber practices cause excessive
erosion and sedimentation into streams), there are also potential
positive benefits to foothill yellow-legged frog habitat from these
practices (Olson and Davis 2009, pp. 18-20; CDFW 2019b, pp. 64-65, 67).
We captured and evaluated the potential negative impacts associated
with grazing and timber harvest (e.g., water impoundments for cattle,
erosion, logging roads) in our assessment of altered hydrology,
sedimentation, and roads. For full descriptions of all threats and how
they impact the species, please see the SSA report (Service 2021, pp.
72-121).
Altered Stream Hydrology and Flow Regimes
Foothill yellow-legged frog ecology and habitat needs are closely
tied to the natural hydrological cycle of the streams
[[Page 73923]]
they inhabit. Foothill yellow-legged frog breeding and recruitment are
dependent upon specific stream morphologies and upon predictable
hydrological patterns that are synchronized with other climatic cues
for foothill yellow-frog populations to be successful (Kupferberg
1996a, p. 1337). Strong stream flow events typical during winter under
natural flow regimes help maintain and create foothill yellow-legged
frog breeding habitat by widening and diversifying channel morphology,
improving rocky substrate conditions, removing sediment, and increasing
sunlight by limiting vegetation encroachment (Lind et al. 1996, pp. 64-
65; Lind et al. 2016, p. 269; Power et al. 2016, p. 719; GANDA 2018,
pp. 37-38). Dams, water management, and other waterway modifications
alter the hydrology, timing, temperature, and morphology of foothill
yellow-legged frog stream habitat (Service 2021, pp. 74-79).
Alterations to flow regimes also occur for hydropeaking (for energy
production) and recreational activities, such as spring and summer
releases for whitewater boating (Kupferberg et al. 2012, p. 518) (see
``Recreation,'' below). These pulse flows are generally much greater in
frequency and intensity as compared to other flow fluctuations and,
during spring and summer, can detrimentally affect early life stages of
foothill yellow-legged frog during breeding and rearing season (Greimel
et al. 2018, p. 92, Kupferburg et al. 2009c, Kupferburg et al., 2011b,
p.144). Therefore, alterations of stream hydrology and flows can have a
large influence on foothill yellow-legged frog distribution and
metapopulation dynamics (Hayes et al. 2016, pp. 24-25; Service 2021,
figure 21, p. 25).
The effects of altered streams also impede foothill yellow-legged
frog dispersal and metapopulation connectivity, which can prevent
recolonization of extirpated areas and cause genetic bottlenecks (Peek
2010, p. 44; Peek 2012, p. 15). Genetic comparisons among
subpopulations demonstrated that gene flow is decreased in regulated
river systems, even when the amount of regulation is low (Peek 2012, p.
15; Peek et al. 2021, p. 14).
Many population declines across the foothill yellow-legged frog's
range have been attributed to the altered flow regimes and habitat
fragmentation associated with water storage and hydropower dams
(Kupferberg et al. 2009c, p. ix). Where populations of foothill yellow-
legged frogs persist in these areas, breeding population densities were
more than five times smaller below dams than in free-flowing rivers
(based on breeding populations in the North Coast DPS, North Feather
DPS, and Central Coast DPS) (Kupferberg et al. 2012, p. 520). Dams and
impoundments, as well as historical use of splash dams (temporary
wooden dams created to facilitate transport of logs downstream) in the
North Coast DPS in Oregon, have also presumably caused extirpations of
the species and altered stream characteristics in some locations
(Miller 2010, pp. 14, 61-63, 70-71, table 2.9; Linnell and Davis 2021,
not paginated, figures 6 and 7).
Altered flow regimes and water diversions (as well as several
anthropogenic activities, such as mining, agriculture, overgrazing,
timber harvest, and poorly constructed roads), as described in greater
detail below, can cause or increase sedimentation in breeding habitat
for the foothill yellow-legged frog (Moyle and Randall 1998, pp. 1324-
1325). Increased sedimentation can increase turbidity, impact algae and
other food resources or impede foothill yellow-legged frog egg mass
attachment to substrate (Cordone and Kelley 1961, pp. 191-192; Ashton
et al. 1997, p. 13). Fine sediments can also fill interstitial spaces
between rocks, which provide shelter from high velocity flows, cover
from predators, and sources of aquatic invertebrate prey (Harvey and
Lisle 1998, pp. 12-14; Olson and Davis 2009, p. 11; Kupferberg et al.
2011b, pp. 147-149).
Predation
Foothill yellow-legged frogs can be negatively affected by several
native and nonnative animal species. The American bullfrog, native and
nonnative fish, and nonnative crayfish have all been linked to
impacting populations of foothill yellow-legged frogs (Olson and Davis
2009, pp. 17-18; Hayes et al. 2016, pp. 49-51). The following
discussion provides details on how these predatory species affect the
foothill yellow-legged frog at various life stages through predation
and competition.
American bullfrogs: American bullfrogs are considered a threat to
all six DPSs. Bullfrogs affect foothill yellow-legged frog populations
in several ways because they are simultaneously competitors, predators,
and disease vectors, and they impact life stages from tadpoles to
adults (see figure 23 in the SSA report, Service 2021, p. 80).
Bullfrogs impact foothill yellow-legged frogs by direct predation
(Crayon 1998, p. 232; Hothem et al. 2009, pp. 279-280) and indirectly
by reducing survival. In one experiment, the presence of bullfrog
tadpoles reduced foothill yellow-legged frog tadpole survival by 48
percent and mass at metamorphosis by 24 percent (Kupferberg 1997a, p.
1736). Additionally, the algal and macroinvertebrate assemblages
available to foothill yellow-legged frogs were significantly reduced
due to the presence of bullfrog tadpoles (Kupferberg 1996b, p. 2;
Kupferberg 1997a, p. 1736), which would negatively affect food sources
for foothill yellow-legged frog tadpoles, juveniles, and adults. The
spread of bullfrogs is facilitated by altered hydrology, land-use
change, drought, and increasing water temperatures (Moyle 1973, p. 21;
Fuller et al. 2011, pp. 210-211; Adams et al. 2017a, p. 13). Regulatory
mechanisms to manage importation and distribution of bullfrogs are
currently ineffective due to an inability to adequately enforce
regulations (CDFW 2014, pp. 11-12).
Fish: Fish such as smallmouth bass, green sunfish (Lepomis
cyanellus), mosquitofish (Gambusia affinis), and trout (Oncorhynchus,
Salmo, and Salvelinus spp.) are predators of foothill yellow-legged
frogs and may also potentially compete with them for invertebrate food
resources (Hayes et al. 2016, p. 51). However, of these fish,
smallmouth bass are the greatest threat to foothill yellow-legged
frogs. Adult smallmouth bass consume amphibian tadpoles (Kiesecker and
Blaustein 1998, pp. 776-787), as well as foothill yellow-legged frog
tadpoles and adults (Rombough 2006a, unpaginated; Paoletti et al. 2011,
p. 166). Smallmouth bass have been identified as a potential cause of
foothill yellow-legged frog declines and extirpations in Oregon
(Rombough 2006a, unpaginated; Olson and Davis 2009, pp. 13, 17).
The distribution of smallmouth bass in California includes the
entire South Coast DPS and lower elevation areas of the South Sierra,
North Sierra, and North Feather DPSs. Areas in the foothill yellow-
legged frog's range in the Salinas, Santa Clara, Central, and
Sacramento Valleys are also within the range of the smallmouth bass.
For the North Coast DPS, smallmouth bass occupy the Russian River,
Trinity, and Eel River drainages (Conservation Biology Institute 2011,
entire). In Oregon, smallmouth bass can be found in the entire range of
the North Coast DPS except the extreme southeastern portion near the
Klamath basin (Carey et al. 2011, p. 306).
Nonnative crayfish: Several nonnative crayfish species prey upon
early life stages of foothill yellow-legged frog. While the signal
crayfish (Pacifastacus leniusculus) is native to part of the
[[Page 73924]]
North Coast DPS (i.e., Oregon and northwestern corner of California),
it has been introduced into several areas within the coast ranges of
northern California and the Sierra Nevada (Wiseman et al. 2005, p. 162;
Pintor et al. 2009, p. 582; CDFW 2019b, p. 56). In both the native and
introduced range of the signal crayfish, the species preys upon
foothill yellow-legged frog egg masses, and likely contributes to
dislodging egg masses from substrate, potentially allowing them to be
transported to unsuitable habitat (Rombough and Hayes 2005, p. 163;
Wiseman et al. 2005, p. 162). Signal crayfish are prey upon foothill
yellow-legged frog tadpoles in laboratory settings (Kerby and Sih 2015,
p. 266), and observations of tail injuries in wild tadpoles suggest
crayfish predation also occurs in the wild (Rombough and Hayes 2005, p.
163; Wiseman et al. 2005, p. 162).
Disease
Foothill yellow-legged frogs can be negatively affected by
amphibian chytrid fungus (Batrachochytrium dendrobatidis (Bd)),
parasitic copepods, and Saprolegnia fungus (see figure 24 in the SSA
report, Service 2021, p. 83).
Bd is implicated in the declines or presumed extinctions of
hundreds of amphibian species (Scheele et al. 2019, p. 1). The spread
of Bd in the range of the foothill yellow-legged frog is presumably
linked to increased human use of habitat and the introduction of
nonnative bullfrogs, which are Bd reservoir hosts (Huss et al. 2013, p.
341; Adams et al. 2017b, pp. 10225-10226; Yap et al. 2018, pp. 1-2;
Byrne et al. 2019, p. 20386). The southern California precipitation
regime (i.e., alternation of extreme droughts and floods) may increase
the likelihood of disease outbreaks by causing favorable habitat
conditions for bullfrogs, warmer water temperatures, and increased
stress on foothill yellow-legged frogs (Adams et al. 2017b, p. 10228).
Bullfrog presence is a positive predictor of Bd prevalence and load in
foothill yellow-legged frogs (Adams et al. 2017a, p, 1). The Bd
pathogen has been documented within all DPSs (Yap et al. 2018, p. 5,
figure 1), and evidence of Bd prevalence suggests that Bd played a role
in the precipitous decline of the foothill yellow-legged frog in
southern California. Bd has been implicated in the decline of the
foothill yellow-legged frog in both the Central Coast DPS and South
Coast DPS (Adams et al. 2017b, p. 10224). Bd may also have sublethal
effects on foothill yellow-legged frogs. Foothill yellow-legged frogs
that tested positive for Bd had lower body mass to length ratios,
although the frogs showed no other signs of infection (Lowe 2009, pp.
180-181). Tadpole susceptibility experiments with other western anurans
documented species-specific effects of Bd exposure such as tadpole
lethargy (motionless at bottom of tank), disorientation, weak response
to prodding, and increased incidence of tadpole mouthpart deformities
(Blaustein et al. 2005, pp. 1464-1466).
Parasitism of foothill yellow-legged frogs by the Eurasian copepod,
Lernaea cyprinacea, is linked to malformations in tadpole and juvenile
foothill yellow-legged frogs (Kupferberg et al. 2009a, p. 529). In
addition to malformations, this parasite likely has other sublethal
effects on foothill yellow-legged frogs, such as stunted growth
(Kupferberg et al. 2009a, p. 529). Although direct foothill yellow-
legged frog mortality from this parasite has not been documented in the
wild, copepod parasitism may be responsible for mortality of tadpoles
in captivity (Kupferberg 2019, entire; Oakland Zoo 2019, p. 1; Rousser
2019, entire). The changes predicted by climate change models (i.e.,
increased summer water temperatures and decreased daily discharge) may
promote outbreaks of this parasite throughout the foothill yellow-
legged frog's range (Kupferberg et al. 2009a, p. 529).
The water fungus (Saprolegnia sp.) causes egg mortality in
amphibians of the Pacific Northwest (Blaustein et al. 1994, p. 251).
Fungal infections of foothill yellow-legged frog egg masses,
potentially from Saprolegnia but not confirmed, have been observed in
the mainstem Trinity River (North Coast DPS) (Ashton et al. 1997, pp.
13-14), in approximately 25 percent of egg masses during a study in the
South Fork Eel River (North Coast DPS) (Kupferberg 1996a, p. 1337), and
in 14 percent of egg masses during 2002 and nearly 50 percent of egg
masses during 2003 in the Cresta reach of the North Fork Feather River
(North Feather DPS) (GANDA 2004, p. 55). While fungal infections are
not a major source of mortality for foothill yellow-legged frogs, this
threat has had a strong effect in other amphibian populations
(Blaustein et al. 1994, pp. 251-253).
Habitat Loss, Degradation, and Fragmentation
Habitat loss, degradation, and fragmentation occurs throughout the
species' range and is attributed to numerous factors including
agricultural activities, mining, urbanization, roads, recreation, and
wildfire.
Agriculture/Pesticides: Agriculture is a source of threats to the
foothill yellow-legged frog because of agriculture's role in habitat
degradation, the contribution of pesticides and pollutants to the
environment, and its role as a driver of other threats such as altered
hydrology and spread of nonnative species (see figure 26 in the SSA
report, Service 2021, p. 88). Agricultural land uses have been linked
to declines in foothill yellow-legged frog populations due to the
impacts described above (Davidson et al. 2002, p. 1597; Lind 2005, pp.
19, 51, 62, table 2.2; CDFW 2019, p. 58). Foothill yellow-legged frog
presence is negatively associated with agriculture within 5 km (3.1 mi)
(Olson and Davis 2009, pp. 15, 22; Linnell and Davis 2021, not
paginated, figures 6 and 7).
The proximity of foothill yellow-legged frog habitat downwind of
the San Joaquin Valley (greatest use of airborne pesticides) suggests
that foothill yellow-legged frog declines in the South Sierra unit may
be linked to agricultural pesticide use (Davidson et al. 2002, p. 1594;
Davidson 2004, pp. 1900-1901; Bradford et al. 2011, p. 690). Water
samples from low elevations in the Sierra Nevada have had
concentrations of pesticides that were within the lethal range for
foothill yellow-legged frogs (Bradford et al. 2011, p. 690). Foothill
yellow-legged frog tadpoles are especially vulnerable to pesticides,
especially if pesticide exposure occurs in the presence of other
threats, such as competition or predation (Davidson et al. 2007,
entire; Sparling and Fellers 2007, entire; Sparling and Fellers 2009,
entire; Kerby and Sih 2015, entire). Impacts from pesticides include
reduced body size, slower development rate, and increased time to
metamorphosis as well as decreased development of natural anti-
microbial skin peptides (presumably a defense against the disease,
chytridiomycosis) (Davidson et al. 2007, p. 1774; Sparling and Fellers
2009, pp. 1698, 1701; Kerby and Sih 2015, pp. 255, 260).
Trespass Cannabis Cultivation: Trespass cannabis cultivation
(illegally establishing largescale cannabis farms) occurs throughout
the species' range, but the North Coast (California), Central Coast,
and South Coast DPSs may be most at risk from this threat (CDFW 2019b,
pp. 61-62). These unregulated activities impact the foothill yellow-
legged frog by destroying or degrading habitat, increasing water
diversion, increasing sedimentation, and introducing pesticides and
other chemicals that reduce water quality and impact the species (Bauer
et al. 2015, entire).
Mining Activities: Mining activities, including aggregate, hard-
rock, and suction-dredge mining, are sources of
[[Page 73925]]
threats to the foothill yellow-legged frog habitat because of their
role in habitat destruction and degradation, pollution, and expansion
of nonnative species (Hayes et al. 2016, pp. 52-54; Service 2021,
figure 29, p. 94). Hydraulic mining, although outlawed, has had and
continues to have long-lasting legacy effects and is still affecting
aquatic ecosystems in California, with the North Feather DPS and North
Sierra DPS being the most impacted (Hayes et al. 2016, pp. 52-54; CDFW
2019b, pp. 57-58). The immediate and legacy effects and extent of
mining practices are outlined in Table 8 of the SSA report (Service
2021, table 8, pp. 92-93), and include habitat destruction and
alteration, sedimentation, changes in stream morphology, decreased
stream heterogeneity, creation of ponded habitat (that supports
nonnative species), decreased water quality, and contamination. A
moratorium of suction-dredging in streams has currently been put in
place for California. However, the State is currently developing new
guidance and permitting processes for potentially reinitiating suction-
dredging activities (State Water Resources Control Board 2020, entire).
Oregon has restricted suction-dredging in the foothill yellow-legged
frog's range (National Genomics Center for Wildlife and Fish
Conservation 2021, entire).
Urbanization: Urbanization (development and roads) can affect
foothill yellow-legged frogs and their habitat through direct mortality
and from habitat destruction, degradation, and fragmentation.
Urbanization can also contribute to increased occurrence of pesticides
and pollutants being introduced to the environment and increases in
other threats such as altered hydrology, introduction and spread of
nonnative species, and assist in disease transmission (see figure 30 in
the SSA report, Service 2021, p. 95). Conversion or alteration of
natural habitats for urban land uses has been linked to declines in
foothill yellow-legged frog populations (Davidson et al. 2002, p. 1597;
Lind 2005, pp. 19, 51, 62, table 2.2). Foothill yellow-legged frog
presence is negatively associated with cities and road density
(Davidson et al. 2002, p. 1594; Olson and Davis 2009, p. 22). Increases
in urbanization and roads have been reportedly associated with foothill
yellow-legged frog extirpations in the South Coast DPS, possibly by
facilitating the spread of Bd and nonnative species (Adams et al.
2017b, p. 10227).
Recreational Activities: Some recreational activities can affect
foothill yellow-legged frogs in a variety of ways, depending on the
region and type of recreation. Impacts from recreation can be
localized, such as trampling or dislodging of egg masses, while others
are greater in extent or contribute to other threats. These greater
threats include off-highway vehicle use causing habitat degradation and
increased sedimentation (Olson and Davis 2009, p. 23), nonnative
sportfish stocking of smallmouth bass (see Predation) (ODFW 2009, pp.
8, 11; CDFW 2019a, entire), and altered hydrology due to whitewater
boating (Borisenko and Hayes 1999, pp. 18, 28; Kupferberg et al. 2012,
p. 518). Some dam operations include planned, short pulse flows during
the spring and summer to specifically provide recreation opportunities
for whitewater boaters (Kupferberg et al. 2012, p. 518). As with other
impacts associated with water management, the timing of these strong
unseasonal flows has coincided with the foothill yellow-legged frog
breeding and rearing season, leading to negative population-level
impacts in the North Feather DPS (Kupferberg et al. 2012, pp. 518, 520-
521, figure 3b).
Wildfire: Wildfire is a natural phenomenon throughout the range of
the foothill yellow-legged frog, and its occurrence and severity are
positively influenced by urbanization, roads, recreation, and the
effects of climate change. The effects on foothill yellow-legged frogs
from wildfire and its suppression are not well understood and have not
been directly studied (Hayes et al. 2016, p. 35, table 6; CDFW 2019b,
p. 71). The impacts of wildfire are also a function of the severity and
intensity of the wildfire, which can be extremely variable across the
landscape depending on topography and vegetation. Anecdotally, foothill
yellow-legged frog populations have survived low- to moderate-severity
wildfires (Lind et al. 2003, p. 27; CDFW 2019b, p. 71), and it is
suspected that low-severity fires do not have adverse effects on the
foothill yellow-legged frog (Olson and Davis 2009, p. 24). In fact,
wildfires may benefit habitat quality by decreasing canopy cover and
increasing habitat heterogeneity (Pilliod et al. 2003, pp. 171, 173;
Olson and Davis 2009, p. 24). Direct mortality from scorching is
unlikely, given the species' aquatic nature and the sightings of
foothill yellow-legged frogs immediately after wildfires (CDFW 2019b,
p. 71). In contrast, high-severity wildfires can greatly alter water
and habitat quality, remove all vegetative canopy, and reduce habitat
heterogeneity by burning vegetative and woody debris that foothill
yellow-legged frogs use for shelter. Short- and long-term effects of
severe wildfires include potentially harmful changes in water chemistry
and increased erosion and sedimentation from flooding (CDFW 2019b, pp.
71-72), which can destroy or degrade breeding habitat and interstitial
spaces. Furthermore, the use of fire retardants and suppressants during
wildland firefighting can affect amphibians by harming water quality
and by direct toxicity to amphibians and their food sources (Pilliod et
al. 2003, pp. 174-175; Service 2018, pp. 42-44). See the SSA report for
additional information regarding trends and impacts of wildfire
(Service 2021, section 7.9, pp. 100-109).
Effects of Climate Change
The effects of climate change are already having statewide impacts
in California and Oregon (Bedsworth et al. 2018, p. 13; Mote et al.
2019, p. ii, summary). Overall trends in climate conditions across the
foothill yellow-legged frog's range include increasing temperatures,
greater proportion of precipitation falling as rain instead of snow,
earlier snowmelt (influencing streamflow), and increased frequency,
duration, and severity of extreme events such as droughts, heat waves,
wildfires, and floods (OCCRI 2019, pp. 5-7, tables 2 and 3; Public
Policy Institute of California 2020, not paginated). A rangewide study
of occupancy found that foothill yellow-legged frog presence is
negatively related to the frequency of dry years and to precipitation
variability, suggesting that the species may already be declining due
to the effects from climate change (Lind 2005, p. 20).
Projected increases in temperature are likely to affect foothill
yellow-legged frogs differently in different parts of the range.
Warming temperatures are likely to have some positive effects in areas
where stream temperatures are typically colder, allowing for greater
foothill yellow-legged frog population growth rates and early life
stage survival (Kupferberg et al. 2011a, p. 72; Rose et al. 2020, p.
41). However, researchers observed an unexpected die-off (unknown
cause) of late-stage tadpoles that coincided with maximum daily
temperatures exceeding 25 degrees Celsius ([deg]C) (77 degrees
Fahrenheit ([deg]F)) (Kupferberg et al. 2011a, pp. 14, 58; Catenazzi
and Kupferberg 2018, pp. 43-44, figure 2). Temperatures greater than
the preferred thermal range may also have lethal or sublethal effects
on tadpoles and metamorphs from parasites (Kupferberg et al. 2009a, p.
529; Kupferberg et al. 2011a, p. 15). There may be additional negative
consequences to rising stream
[[Page 73926]]
temperatures, even where temperatures are currently cold. Increasing
temperatures may facilitate colonization by nonnative species (Fuller
et al. 2011, pp. 210-211; Kiernan et al. 2012, pp. 1480-1481). Bd
prevalence in bullfrogs was also found to be greater when water
temperature was warmer than 17 [deg]C (63 [deg]F) (Adams et al. 2017a,
pp. 12-13).
In California, a 25 to 100 percent increase in the frequency of
extreme dry-to-wet precipitation events (such as that of the 2012-2016
drought followed by the extremely wet winter of 2016-2017) is projected
during the 21st century (Swain et al. 2018, p. 427). This information
indicates that the threats of drought and extreme flood events may
increase by 25 to 100 percent in California. Increased frequency of
extreme heat events, drought, and extreme precipitation and floods
events are also projected to increase in Oregon (OCCRI 2019, pp. 5, 6,
13-14, tables 2 and 3). In order to assess future conditions, including
future climatic conditions for the foothill yellow-legged frog, we
developed a population viability analysis (PVA) (Rose et al. 2020,
entire) that used climate and habitat change information consistent
with current emission estimates such as those identified as
Representative Concentration Pathway (RCP) 4.5 and RCP 8.5 (see
Population Viability Analysis, below).
The projected changes in temperature, precipitation, and climate
variability may exacerbate the effects of other threats on the foothill
yellow-legged frog (Service 2021, figure 46, p. 11). The potential
interactions (between climate change effects and other threats) that
can negatively affect the foothill yellow-legged frog include:
<bullet> An increased risk to human safety from flooding and
increased risk of water shortages may necessitate more hydrological
alterations (e.g., dams, surface-water diversions, changes to water
releases, and channel modifications). While the effect of climate
change is only projected to increase surface water stress by up to 5
percent in the Oregon portion of the North Coast DPS's range by mid-
century, projected increases range from 5 to 30 percent in California
watersheds (Averyt et al. 2013, p. 7, figure 7). In California,
climate-induced surface water stress is projected to increase the most
in the South Sierra DPS and the least in the North Coast DPS (Averyt et
al. 2013, p. 7, figure 7).
<bullet> Increased frequency of drought, decreased spring/summer
streamflow, and warmer water temperature may benefit nonnative
predators and competitors such as bullfrogs and nonnative fish (Brown
and Ford 2002, pp. 332, 338-340, figure 3; Fuller et al. 2011, pp. 210-
211; Adams et al. 2017a, p. 13).
<bullet> Increased summer water temperatures and/or decreased daily
stream discharge and other increases in climate variability are
expected to increase copepod parasitism in foothill yellow-legged frogs
(Kupferberg et al. 2009a, p. 529) or exacerbate the effects of disease
outbreaks (Raffel et al. 2013, p. 147; Adams et al. 2017b, p. 10228).
<bullet> Observed and projected trends toward warmer and drier
wildfire seasons in the western United States are likely to continue
the trend toward higher-severity wildfires and larger burn areas (Parks
and Abatzoglou 2020, pp. 1, 5-6). This would result in additional loss,
degradation, fragmentation, and alteration of habitat, and secondary
impacts from increased sedimentation and flooding for the foothill
yellow-legged frog across its range.
Competing Conservation Interests
Many of the conservation activities that support native salmonid
fishes (e.g., natural flow management, prevention of sedimentation)
have positive influences on foothill yellow-legged frog habitat,
connectivity, and juvenile and adult survival (Service 2021, section
7.12, figure 45, p. 113). However, some measures that are taken to
improve habitat for cold-water salmonid fishes reduce habitat quality
for the foothill yellow-legged frog by decreasing stream temperature
and increasing tree canopy cover over streams. One of the management
techniques used to support salmonid recruitment is to release high
volumes of cold water from dams in the spring (to trigger spawning runs
or to flush smolts out to the ocean) (Kupferberg 1996a, p. 1342;
Kiernan et al. 2012, p. 1474). The timing of such flow events can
negatively affect foothill yellow-legged frog breeding and recruitment
(Kupferberg 1996a, pp. 1336-1337, 1342).
Current and Future Condition Analysis
In our analysis of the current and future condition, we assessed
resiliency for each DPS of the foothill yellow-legged frog by
evaluating the health and number of metapopulations for each DPS. A
healthy metapopulation is defined in terms of its abundance, level of
reproduction and recruitment, juvenile and adult survival, and
connectivity between populations. To assess the current representation
for the foothill yellow-legged frog, we considered the current
diversity of ecological conditions and the genetic makeup of each DPS
as a proxy for the DPS's adaptive capacity. Redundancy for the foothill
yellow-legged frog was measured by the quantity and spatial
distribution of resilient metapopulations across each DPS's range.
Generally speaking, the greater the number of healthy metapopulations
that are distributed (and connected) across the landscape, the greater
the DPS's ability to withstand catastrophic events and, thus, the
greater the DPS's overall viability.
Population Structure
Foothill yellow-legged frog distributions and movements across the
species' range and within each DPS exhibit the characteristics of
metapopulations (Lind 2005, p. 49; Kupferberg et al. 2009b, p. 132). A
metapopulation consists of a network of spatially separated population
units, or subpopulations, that interact at some level. Subpopulations
are subject to periodic extirpation from demographic or environmental
stochasticity, but then are naturally repopulated via colonization from
nearby subpopulations. Numerous metapopulations may occur within a
single stream reach or watershed depending on whether the
subpopulations are interacting with each other. Each DPS is made up of
numerous metapopulations. In our analysis for determining the range of
each DPS, we considered this metapopulation structure when determining
whether certain populations or segments interacted with each other and
helped define boundaries for the DPSs, especially where some other
natural or manmade barrier was not evident.
Historical Distribution
The historical distribution, as identified once the species was
established as a single taxon of the foothill yellow-legged frog
(Zweifel 1955, pp. 210, 273), extended from west of the crest of the
Cascade Mountains in the Willamette River drainage to the coast in
Oregon, south through the Coast Range to Los Angeles County,
California, and down the Sierra Nevada foothills and mountains to 5,000
feet (1,524 meters) (CDFW 2019, pp. 7-8; Service 2021, p. 16, Figure
2). Isolated populations or individuals had been identified in the
Sacramento (at Sutter Buttes) and Central Valleys (Mokelumne River
drainage) of California and in Baja California Norte, Mexico (San Pedro
Martir), but these locations were either isolated individuals or have
not been found again (Loomis 1965, pp. 78-79; Stebbins 2003, pp. 231-
233, 479). Based on our knowledge of foothill yellow-
[[Page 73927]]
legged frog genetic divergence at much smaller spatial scales of
isolation (McCartney-Melstad et al. 2018, p. 121; Peek 2018, p. 76),
the distant Mexico population once identified as foothill yellow-legged
frog, now considered extirpated, most likely was a different taxon.
In Oregon, past impacts from timber operations resulting in stream
alteration have reduced the historical range of the species in the
Willamette Valley and in the southeast portion (portions of Jackson
County) of the State (Olson and Davis 2009, p. 9-11). In California,
the historical range has also been reduced most likely from
hydrological alteration of habitat associated with water management
(Lind 2005, pp. 65, 68, figures 2.1 and 2.4).
Current Distribution, Occupancy, Abundance, and Population Trends
The current distribution of the foothill yellow-legged frog
generally follows the historical distribution of the species except
with range contractions in the southern and, to a lesser extent,
northern parts of the species' range as discussed above. Within areas
currently occupied, foothill yellow-legged frog distribution is
currently in a declining trend in several parts of the species' range
with the species having disappeared from more than half of its
historically-occupied locations (Lind 2005, pp. 38, 61, table 2.1).
Some areas in Oregon, especially in the northern and northwestern
portion of the species' range, have shown declines; however, recent
survey efforts have identified additional populations of the species in
some of these areas (National Genomics Center for Wildlife and Fish
Conservation 2021, entire).
There has not been any rangewide occupancy or population abundance
survey effort for the species, and some areas are more heavily surveyed
than others. Because of this variation in the available data, we use
presence in stream segments as an indicator of occupancy and spatial
connectivity of populations. In our review of occupancy, distribution,
and abundance, we used information from the California Natural
Diversity Database (CNDDB 2020, foothill yellow-legged frog
information) and other survey information obtained from Federal and
other academic and private resource entities throughout the species'
range. The factors we analyzed to determine the condition of a
population are (1) spatial and temporal trends in occupancy and reports
of population abundance where available, (2) connectivity and isolation
among occupied areas, (3) modeled risk of population decline that
incorporates demographic and environmental information, and (4) status
of threats and their effects (see chapter 8 of the SSA report, Service
2021, pp. 122-166).
Foothill yellow-legged frog occupancy varies widely among the DPSs,
with generally greater occupancy in the northern half of the range. The
North Sierra DPS has the greatest proportion of presumed occupied
stream segments (relative to the number of potential stream segments),
followed by the North Coast (in California) and North Feather DPSs.
Proportions of presumed occupied stream segments were much lower in the
rest of the DPSs with the South Coast DPS having the lowest proportion
of presumed occupied segments, followed by the South Sierra DPS (see
table 10 in the SSA report, Service 2021, p. 125).
Based on historical and current occurrence data (Element
Occurrences) for California (CDFW 2020, entire), 67-70 percent of all
known occurrence locations are presumed to be occupied by the foothill
yellow-legged frog in the North Coast DPS (in California), North
Feather DPS, and North Sierra DPS (Service 2021, Table 10, p. 125). In
contrast, less than 45 percent of known occurrence locations are
presumed occupied in the South Sierra DPS, Central Coast DPS, and South
Coast DPS (Service 2021, Table 10, p. 125). Based on patterns of
current occupancy by decade of most recent detections (Service 2021,
figures 47-53, pp. 127-139), occupied area appears to be declining in
parts of each of the DPSs but less so in the northern California and
southern Oregon portions of the taxon's range (North Coast DPS). There
are large regions in both the northern part of the range (northern
Oregon) (North Coast DPS in Oregon) and in the southern half of the
species' range (South Sierra DPS, Central Coast DPS, and South Coast
DPS) that have not had any reported observations of foothill yellow-
legged frogs for two or more decades. Foothill yellow-legged frogs are
mostly extirpated in the South Coast DPS and currently occur only in
two streams. Table 1 below identifies the percentage of occurrence
records considered occupied (2000-2020) in California. Comparable
Element Occurrence data are not available for the North Coast Oregon
analysis unit. For our analysis of Oregon, we looked to other sources
of information on occurrences (Service 2021, pp. 127-144).
Table 1--Percentage of Extant Occurrence Records (CDFW 2020) by Analysis
Unit
------------------------------------------------------------------------
Analysis unit 2000-2020 (percent)
------------------------------------------------------------------------
North Coast, Oregon...................... Not Available.
North Coast, California.................. 67.
North Feather............................ 70.
North Sierra............................. 70.
South Sierra............................. 43.
Central Coast............................ 42.
South Coast.............................. 8.
------------------------------------------------------------------------
Population Viability Analysis
In addition to our assessments of occupancy, abundance, and trends,
using occurrence information, we worked with USGS researchers to
complete a rangewide population viability analysis (PVA) for the
foothill yellow-legged frog (Rose et al. 2020, entire). We used the
information from the PVA to inform both the species' current condition
(Service 2021, chapter 8, pp. 122-166) and potential future condition
(Service 2021, chapter 9, pp. 167-193). The methods and information
used for developing the models used in the PVA are described in section
8.4 of the SSA report (Service 2021, pp. 146-152). The results of the
PVA focus on identifying patterns in risk attributed to areas having a
greater than or equal to 50 percent decline within and between analysis
units and characterize this as the `risk of decline.'
The `risk of decline' results from the PVA reflect many of the
geographical patterns that we described above for occupancy data
(Service 2021, section 8.2, pp. 123-139). A summary of the PVA results
for the current condition of foothill yellow-legged frog populations
within the boundaries of the DPSs combined with our analysis of
occupancy information is discussed below.
The North Sierra DPS has both the lowest average relative risk of
decline and the greatest proportion of presumed occupied stream
segments (relative to stream segments that have the potential to be
occupied). The North Feather DPS has a medium-high average relative
risk of decline and an intermediate proportion of occupied stream
segments (relative to potential stream segments). Within the North
Coast DPS, stream segments in northern California and southwestern
Oregon have lower risks of decline, compared to streams near the San
Francisco Bay area and the northern and eastern extents of the species'
range in Oregon. The southern analysis units (Central Coast DPS, South
Coast DPS, and South Sierra DPS) exhibit the strongest patterns of
declining occupancy, with all stream segments
[[Page 73928]]
within each DPS having either a medium or high relative risk of
decline.
Chapter 9 of the SSA report (Service 2021, pp. 167-193) discusses
the potential change in magnitude and extent of threats and the
species' response to those threats into the future. We have determined
that the effects of climate change and its impact on increasing
temperatures, changes to precipitation and hydrology, and influence on
wildfire and drought, as well as the continued regulated flows from
managed streams, will drive threats on the species and affect its
status into the future. The timeframe of our analysis for these threats
is approximately 40 years. This period represents our best
understanding of the projected future environmental conditions related
to threats associated with climate change that would impact the species
(increasing temperatures, greater proportion of precipitation falling
as rain instead of snow, earlier snowmelt (influencing streamflow), and
increased frequency, duration, and severity of extreme events such as
droughts, heat waves, wildfires, and floods). The 40-year timeframe was
also used in our PVA as part of its analysis on determining risk for
the species into the future (Rose et al. 2020, entire). Although we
possess climate and habitat change projections that go out beyond 40
years, there is greater uncertainty between these model projections in
the latter half of the 21st century and how the effects of the modeled
changes will affect the species' response when projected past 40 years.
Accordingly, we determined that the foreseeable future extends only 40
years for the purpose of this analysis and we rely upon projections out
to approximately 2060 for predicting changes in the species'
conditions. This timeframe allows us to be more confident in assessing
the impact of climate and habitat changes on the species. Therefore,
based on the available climate and modeling projections and information
we have on the species, we have determined 2060 as the foreseeable
future timeframe for the foothill yellow-legged frog.
Our assessment of future condition interprets the effects that the
future changes to threats would potentially have on foothill yellow-
legged frog resiliency, representation, and redundancy. In order to
accomplish our review, three plausible future scenarios were considered
and each DPS's future resiliency, redundancy, and representation under
each scenario was assessed. As discussed above, we used information
from a PVA (Rose et al. 2020, pp. 22-27) to assist us in determining
the potential condition of foothill yellow-frog populations into the
future. Although there are an infinite number of possible future
scenarios, the chosen scenarios (i.e., lower change scenario, mean
change scenario, and higher change scenario) reflect a range of
reasonable scenarios based on the current understanding of climate
change models, threats, and foothill yellow-legged frog ecology. The
environmental conditions in each future scenario are plausible in that
they are not meant to represent the lowest and highest projections of
what is possible. Rather, the lower change and higher change scenarios
are at the lower and upper ends of confidence intervals from climate
change projections, land cover models, and stream temperature models
(Rose et al. 2020, pp. 22-23). Environmental conditions for the three
future scenarios are based on published studies that used ensembles of
global climate models (Isaak et al. 2017, p. 9188; Swain et al. 2018,
p. 427; Sleeter et al. 2019, p. 3336). For the projections of spatially
explicit covariates (i.e., land cover and stream temperature),
downscaled regional climate model data were used (Isaak et al. 2017, p.
9186; Sleeter et al. 2019, p. 3339). The information from these studies
reflects the best scientific and commercial information available for
projections of land cover (Sleeter et al. 2019; Sleeter and Kreitler
2020, unpublished data), stream temperature (Isaak et al. 2017), and
climate variability (Swain et al. 2018) within the range of the
foothill yellow-legged frog.
Descriptions of each scenario and the anticipated effects of each
scenario on resiliency, representation, and redundancy for each
foothill yellow-legged frog DPS is in the SSA report (Service 2021,
Table 17, sections 9.3-9.5, pp. 171, 174-193) and is summarized below.
Resiliency
Resiliency is having sufficiently robust populations for the
species to withstand stochastic events (i.e., events arising from
random factors). For the foothill yellow-legged frog, we determined
that resiliency is a function of metapopulation health and the
distribution and connectivity among metapopulations and subpopulations.
To determine if foothill yellow-legged frog populations were resilient,
we first assessed spatial and temporal trends in occupancy and
abundance. We then assessed structural and functional connectivity
among occupied areas. We also evaluated results from a study that
modeled the risk of >=50 percent decline in occupied stream segments
using demographic and environmental information. Finally, we related
our results to information from scientific literature, reports, and
species experts. Table 2 below summarizes the current condition and
future conditions of resiliency for each of the foothill yellow-legged
frog DPSs. In the SSA report and the table below, we split the North
Coast DPS into a California and an Oregon analysis unit. These two
analysis units are later combined for determination of the status of
this DPS as a whole. The current condition column reflects the current
resiliency of the analysis unit. The current resiliency of each DPS was
characterized as having an intact, reduced, substantially reduced, or
extensively reduced condition. Under each future scenario, we assessed
how the following resiliency measures would change from current
condition: (1) Occupancy and abundance, (2) connectivity, (3) modeled
risk of population decline, and (4) status of threats. Because changes
to environmental conditions under the future scenarios were reflected
by environmental covariates in the PVA (see Service 2021, section 9.2
(Scenarios); Table 17), we were able to forecast the magnitudes of
changes in resiliency by comparing the modeled risk of decline (Rose et
al. 2020, entire) under current conditions to modeled risk under the
three future scenarios. The lower, mean, and higher change scenario
columns represent any changes from each DPS's current resiliency. For
this analysis, ``functional extirpation'' is defined as such extensive
reduction in condition that extirpation of the entire unit is likely to
eventually occur as remnant populations experience normal environmental
and demographic fluctuations. For additional detail on current and
future conditions of the DPSs, see the SSA report (Service 2021,
chapters 8 and 9, pp. 122-193).
[[Page 73929]]
Table 2--Resiliency of the Seven Foothill Yellow-Legged Frog Analysis Units
----------------------------------------------------------------------------------------------------------------
Lower change Mean change Higher change
Analysis unit Current condition scenario scenario scenario
----------------------------------------------------------------------------------------------------------------
North Coast DPS (Oregon)...... Intact Resiliency.. Slightly reduced Slightly reduced Markedly reduced
from current. from current. from current.
North Coast DPS (California).. Intact Resiliency.. Slightly reduced Markedly reduced Greatly reduced
from current. from current. from current.
Risk of
functional
extirpation.
North Feather DPS............. Reduced Resiliency. No change.......... Markedly reduced Greatly reduced
from current. from current.
Risk of Risk of
functional functional
extirpation. extirpation or
extirpation.
North Sierra DPS.............. Intact Resiliency.. Slightly reduced Markedly reduced Greatly reduced
from current. from current. from current.
South Sierra DPS.............. Substantially Slightly reduced Markedly reduced Greatly reduced
Reduced Resiliency. from current. from current. from current.
Risk of Risk of
functional functional
extirpation or extirpation or
extirpation. extirpation.
Central Coast DPS............. Substantially Slightly reduced Markedly reduced Greatly reduced
Reduced Resiliency. from current. from current. from current.
Risk of Risk of
functional functional
extirpation or extirpation or
extirpation. extirpation.
South Coast DPS............... Extensively Reduced Slightly reduced Markedly reduced Greatly reduced
Resiliency. from current. Risk from current. from current.
of extirpation. Risk of Risk of
extirpation. extirpation.
----------------------------------------------------------------------------------------------------------------
Representation
Representation describes the ability of a species to adapt to
changing environmental conditions. This includes both near-term and
long-term changes in its physical (e.g., climate conditions, habitat
conditions, habitat structure, etc.) and biological (e.g., pathogens,
competitors, predators, etc.) environments. This ability of a species
to adapt to these changes is often referred to as ``adaptive
capacity.'' To assess the current condition of representation for the
foothill yellow-legged frog, we considered the current diversity of
ecological conditions and of genetic material throughout the range of
the species.
There are considerable ranges of ecological conditions under which
foothill yellow-legged frogs occur. As discussed in the SSA Report
(Service 2021, Section 2.7 and CHAPTER 3), there are substantial
differences in latitude, elevation, precipitation, average temperature,
and vegetative community across the species' range. Parts of the
foothill yellow-legged frog range also differ in terms of species
composition and in hydrology (rain-fed versus snow-fed systems).
Exemplary of these different ecological conditions, foothill yellow-
legged frog tadpoles from snow-fed Sierra Nevada populations have
higher intrinsic growth rates than tadpoles from rain-fed coastal
populations, likely due to their constraint to a shorter rearing season
in the Sierra Nevada (Catenazzi and Kupferberg 2017, pp. 1255, 1260-
1261).
As described in the SSA report (Service 2021, Section 2.6), two
rangewide assessments of foothill yellow-legged frog genomic datasets
revealed that this taxon is extremely differentiated following
biogeographical boundaries (McCartney-Melstad et al. 2018, p. 112; Peek
2018, p. 76). The clades that are most genetically divergent (i.e.,
South Sierra, Central Coast, and South Coast clades), and thus could
contribute most to the overall adaptive capacity of this taxon
(McCartney-Melstad et al. 2018, p. 120; Peek 2018, p. 77), are also the
clades with the lowest levels of population resiliency. The South
Sierra and Central Coast clades have substantially reduced resiliency
and the South Coast clade has extensively reduced resiliency (SSA
Report (Service 2021, Section 8.5)). The reduced resiliency in these
clades, means that the foothill yellow-legged frog is especially
vulnerable to loss of this genetic diversity. The Central Coast and
South Coast clades are the most genetically divergent, indicating that
a significant amount of the taxon's overall genetic diversity would be
lost if either clade were extirpated. The Central Coast and South Coast
clades are also ecologically unique because they have lower annual
precipitation and higher mean annual temperatures than elsewhere in the
range of the species (PRISM Climate Group 2012, 30-year climate
dataset; Table 3) and the region hosts the highest freshwater endemism
of anywhere in the species' California range (Howard et al. 2013, p.
5).
While not as at risk of extirpation, the northern Sierra clades
(i.e., North Feather and North Sierra clades) might also have unique
adaptive potential in the face of climate change because of their
admixture history and intermediacy to the South Sierra and North Coast
clades (McCartney-Melstad et al. 2018, p. 121). The genetic clade that
is comprised of the two North Coast units is also genetically valuable
to the foothill yellow-legged frog because it contains the greatest
genetic diversity and is the only part of the range that shows a
trajectory of increasing genetic diversity (McCartney-Melstad et al.
2018, pp. 120-121; Peek 2018, p. 74). The North Coast clade also
potentially provides connectivity and a large latitudinal gradient for
responding to the effects of climate change.
While the foothill yellow-legged frog clearly has a range of
genetically divergent populations, it has likely already lost a lot of
diversity due to large extirpations in the southern analysis units. The
species is also at risk of further losses amidst trends toward
decreasing occupancy and decreasing connectivity. The foothill yellow-
legged frog is exhibiting an overall trend of decreasing genetic
diversity in spite of the trend of increasing genetic diversity in the
North Coast clade (McCartney-Melstad et al. 2018, pp. 120-121; Peek
2018, p. 74).
The trend of decreasing genetic diversity in the foothill yellow-
legged frog may be leading to losses in adaptive capacity (i.e.,
ability to adapt to change). Loss of adaptive capacity lowers the
species' viability because the decrease in ability to adapt to change
increases extinction risk in the face of future changes. For foothill
yellow-legged frog conservation, McCartney-Melstad et al. (2018, p.
122) strongly recommended that each of the major genetic groups be
managed as independent recovery units. Peek (2018, p. 77) also
recommended that conservation actions should prioritize protecting
foothill yellow-legged frogs in the Central Coast, South Coast, and
South Sierra clades because they are simultaneously the most distinct,
divergent, and at-risk populations.
Redundancy
Redundancy describes the ability of a species to withstand
catastrophic events. To assess redundancy for each analysis unit, we
considered the (1) quantity of occupied stream segments (proxy for
subpopulations) (SSA Report (Service 2021,Table 10)), (2) spatial
distribution of occupied stream
[[Page 73930]]
segments (SSA Report (Service 2021, Figure 55)), and (3) population
level factors such as connectivity, relative risk of decline, and level
of threats. These factors were assessed in terms of their potential
influence on the ability of foothill yellow-legged frog metapopulations
to survive and recover after a plausible catastrophic event. For
example, isolation of occupied stream segments or lack of functional
connectivity in an analysis unit, could prevent recolonization of
extirpated areas after a massive die-off or temporary habitat
destruction.
At the analysis unit scale of redundancy, long-term viability after
a catastrophic event would likely be possible in the North Coast clade
(North Coast California and North Coast Oregon units) and might be
possible in the North Sierra clade. In the North Coast clade, there are
large numbers of occupied streams and there are numerous occupied
stream segments that both are in the low risk of decline category and
are distributed widely across the geographical area (SSA Report
(Service 2021, Figure 55)). Furthermore, resiliency is intact in both
of the two analysis units that comprise this clade. Resiliency is also
intact in the North Sierra clade because there are numerous occupied
stream segments that both are in the low risk of decline category and
are distributed widely across the geographical area (SSA Report
(Service 2021, Figure 55)). However, the North Sierra clade has less
redundancy than the North Coast clade because the North Sierra clade is
small in size and has poor functional connectivity, which could prevent
recolonization after catastrophic events.
The North Feather DPS occupies a relatively small area and several
streams or occurrences have been extirpated from past impacts (eastern
portion of range, southwestern area near Lake Oroville, and some
occurrences in northern Butte County) (CDFW 2020, dataset, entire;
Service 2021, figure 49, p. 131). The North Feather DPS also has the
highest average relative risk of population decline with only 16 (15
percent) of the 109 analyzed stream segments in the low risk category
and 34 stream segments (31 percent) in the high risk category. Overall
abundance of foothill yellow-legged frogs for the North Feather DPS is
largely unknown, but egg mass densities are very low in the two
regulated stream reaches that have long-term monitoring (Rose et al.
2020, pp. 63-64, table 1). For example, sections of the Cresta reach of
the North Feather River that historically had relatively high numbers
of foothill yellow-legged frog egg masses did not have egg masses or
were extremely reduced for several years (2006-2017) (CDFW 2019, p. 31;
Dillingham 2019, p. 7). As a result, redundancy is limited in the North
Feather DPS. The North Feather DPS is not only the smallest clade, but
its occupied stream segments are not well-distributed over the
geographical area (SSA Report (Service 2021, Figure 55)). The extant
North Feather populations occupy an area small enough that a large
catastrophic event, such as a high-severity wildfire or drought, could
result in functional extirpation. Furthermore, the North Feather DPS
has reduced resiliency because of poor occupancy and relatively high
risk of population decline.
Redundancy is poor in the South Sierra and Central Coast clades.
Both the South Sierra and Central Coast clades have substantially
reduced resiliency because of poor occupancy, poor connectivity,
relatively high risk of decline, and substantial threats. A single
catastrophic event would be unlikely to extirpate the entirety of
either unit, but the patchy distribution of occurrences (SSA Report
(Service 2021, Figure 55)) and limited connectivity would make it
extremely unlikely that extirpated areas would be recolonized
naturally.
Redundancy within the South Coast clade is nearly zero. Not only is
the resiliency in this clade extensively reduced, but there are only
two known populations (SSA Report (Service 2021, Section 8.2)) in the
South Coast clade. These two populations (comprised of seven stream
segments) are also very close in proximity (SSA Report (Service 2021,
Figure 55)). These streams are located close to one another, but the
foothill yellow-legged frog populations within them appear to have lost
genetic connectivity. Although the stream flows are not regulated by
dams, the risk of population decline continues to be medium or high
under current conditions due to the combination of threats identified
above altering habitat and impacting the DPS. Furthermore, the close
proximity of the stream segments to each other makes the South Coast
DPS especially vulnerable to extirpation from a single catastrophic
event.
Overall Current and Future Condition
As discussed above, we used the information from the PVA to inform
both the species' current condition (Service 2021, chapter 8, pp. 122-
166) and potential future condition (Service 2021, chapter 9, pp. 167-
193). The PVA assessed how the following measures would change from
current condition: (1) Occupancy and abundance, (2) connectivity, (3)
modeled risk of population decline, and (4) status of threats under
each future scenario. Because changes to environmental conditions under
the future scenarios were reflected by environmental covariates in the
PVA (see Service 2021, section 9.2 (Scenarios); Table 17), we were able
to forecast the magnitudes of changes in resiliency by comparing the
modeled risk of decline (Rose et al. 2020, entire) under current
conditions to modeled risk under the three future scenarios. The
results of the analysis showed that the average risk of population
decline for each analysis unit increased under the three future
scenarios (Rose et al. 2020, p. 39). Under current conditions and all
future scenarios, the average relative risk of decline was highest in
the South Sierra and Central Coast units and was lowest in the North
Coast Oregon, North Coast California, and North Sierra units (Table 3
below and Service 2021, Tables 18 and 19). Under the lower change
scenario, decreases in resiliency, compared to current conditions, were
small in most analysis units. However, decreases in resiliency were
more dramatic under the mean and higher change scenarios. These
dramatic declines in resiliency put several analysis units at risk of
unit-wide extirpation or functional extirpation (i.e., such extensive
reduction in condition that extirpation of the entire unit is likely to
eventually occur as remnant populations experience normal environmental
and demographic fluctuations) under the mean and higher change
scenarios (SSA Report (Service 2021, Table 19)). One of the analysis
units (South Coast unit) is at risk of unit-wide extirpation under all
three of the future scenarios.
[[Page 73931]]
Table 3--Relative Risk of Decline Summary for Current Condition and Three Future Scenarios
----------------------------------------------------------------------------------------------------------------
Risk of decline
-------------------------------------------------------------------------------
Analysis unit Lower change Mean change Higher change
Current condition scenario scenario scenario
----------------------------------------------------------------------------------------------------------------
North Coast Oregon.............. Low............... Medium............ Medium............ Medium.
North Coast California.......... Medium............ Medium............ Medium............ Medium.
North Feather................... Medium............ Medium............ High.............. High.
North Sierra.................... Low............... Low............... Medium............ Medium.
South Sierra.................... Medium............ High.............. High.............. High.
Central Coast................... Medium............ Medium............ High.............. High.
South Coast..................... Medium............ Medium............ Medium............ High.
----------------------------------------------------------------------------------------------------------------
Conservation Efforts and Regulatory Mechanisms
Several initiatives and conservation efforts are in place and being
implemented for foothill yellow-legged frog conservation including
measures for rearing (headstarting), nonnative species removal,
development of reintroduction feasibility studies, and habitat
conservation planning for the species (Service 2021, table 9, pp. 117-
120). Headstarting (hatching eggs and rearing into releasable frogs)
has been started on the North Feather River. The program has just been
started and the extent from headstarting is limited to a portion of the
range of the North Feather DPS. Also benefitting the species (through
regulatory protection) is the decision by the California Fish and Game
Commission to list five foothill yellow-legged frog genetic clades
(referred to as analysis units in this document) under the California
Endangered Species Act. In February 2020, the California Fish and Game
Commission adopted the findings of the CDFW to list the South Coast,
Central Coast, and South Sierra clades as endangered and list the North
Feather and North Sierra clades as threatened under the California
Endangered Species Act (Commission 2020, p. 1). Another regulatory
benefit that applies to breeding and rearing habitat is the 2009
moratorium on suction-dredge mining in California. However, benefits to
the foothill yellow-legged frog from the moratorium have not been
studied, and permitting processes are in development so that the
moratorium may be lifted (State Water Resources Control Board 2020,
entire).
The foothill yellow-legged frog is listed as a sensitive species by
the BLM and the Forest Service under their Sensitive Species program.
These agencies define sensitive species as those species that require
special management consideration to promote their conservation and
reduce the likelihood and need for future listing under the Act. Any
actions conducted by the Forest Service or BLM would need to take into
consideration impacts to sensitive species and, if possible, implement
best management practices to limit impacts to the species or its
habitat. In addition, the species in northern portions of California
and the species' range in Oregon on National Forest or BLM lands
currently receive protection through conservation measures and best
management practices under the Northwest Forest Plan's Survey and
Manage program (USDA-USDOI 2001, entire). These measures reduce or
eliminate impacts to habitat for the foothill yellow-legged frog and
areas occupied by the species during road construction and maintenance
activities as well as any vegetation management actions which assist in
the reduction of threats associated with wildfire on BLM and Forest
Service lands.
The Federal Energy Regulatory Commission (FERC) issues licenses for
the operation of nonfederal hydropower projects. Within the range of
the foothill yellow-legged frog, numerous hydropower projects require
FERC licensing to operate. Part of the licensing process includes
consideration of recommendations for the protection of fish and
wildlife. Some FERC license requirements have included measures to help
protect and conserve foothill yellow-legged frogs including actions
such as collection of data, implementation of modified flow regimes to
mimic more natural conditions, and other standard best management
practices.
Two joint Federal and State habitat conservation plans (HCPs) and
California State natural community conservation plans (NCCPs) (Santa
Clara Valley HCP/NCCP and East Contra Costa HCP/NCCP) have been
approved and implemented for the foothill yellow-legged frog as a
covered species and assist in local population and habitat conservation
(Jones & Stokes 2006, entire; ICF International 2012, entire). Both
HCP/NCCPs are in the northern portion of the Central Coast DPS's range.
Another Federal HCP has been issued to the Humboldt Redwood (formerly
Pacific Lumber) Company. The Humboldt Redwood Company (HRC) HCP covers
areas within the range of the North Coast DPS in Humboldt County and
includes adaptive management strategies designed to maintain viability
in populations of foothill yellow-legged frogs and other covered
aquatic herpetofauna (HRC 2015, entire).
Due to the limited nature of existing conservation efforts and no
rangewide planning or coordination, the current conservation efforts
are localized. In addition, several ongoing efforts are preliminary
steps to on-the-ground conservation (e.g., feasibility research) and
other efforts have not had enough time to verify long-term success
(e.g., population headstarting) or determine if and how the condition
of a foothill yellow-legged frog population may have improved (e.g.,
bullfrog removal) (Service 2021, section 7.15, pp. 116-121). Therefore,
large scale conservation efforts are not known to be currently
outweighing any of the threats described above at the species or DPS
level, but may reduce some effects at the individual or smaller
localized population level.
Determination of Status for the Foothill Yellow-Legged Frog
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of an ``endangered species'' or
a ``threatened species.'' The Act defines an ``endangered species'' as
a species in danger of extinction throughout all or a significant
portion of its range, and a threatened species as a species 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 a species meets the definition of 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)
[[Page 73932]]
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.
In determining potential future threats facing the six DPSs, we
evaluated various future conditions based on projections of changes in
threats. Our timeframe for review looked out approximately 40 years
based on the effects of climate change and information developed for
the PVA. This was our timeframe for our threats analysis of future
conditions for the six DPS to determine if they were likely to become
endangered within the foreseeable future (i.e., if they meet the Act's
definition of ``threatened species'') throughout their ranges.
Status of the South Sierra DPS and the South Coast DPS of the Foothill
Yellow-Legged Frog Throughout All of Their Ranges
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
to the South Sierra and South Coast DPSs of the foothill yellow-legged
frog and their habitat. Below we summarize our assessment of status of
the South Sierra DPS and South Coast DPS under the Act.
South Sierra DPS: Threats are numerous and severe for the South
Sierra DPS and include altered hydrology (Factor A), agriculture
(including airborne pesticide drift) (Factor A), illegal cannabis
cultivation (Factor A), predation by nonnative species (Factor C),
disease and parasites (Factor C), mining (Factor A), urbanization
(including development and roads (Factor A), recreation (Factor E),
severe wildfire (Factor A), drought (Factor E), extreme flooding
(Factor E), the effects of climate change (e.g., increased
temperatures, variability in precipitation events, increased drought
frequency) (Factor E), and inadequacy of regulatory mechanisms (Factor
D). After evaluating threats to the DPS and assessing the cumulative
effect of the threats under the Act's section 4(a)(1) factors, we
conclude that under current conditions, resiliency, redundancy and
representation are substantially reduced due to existing range
contractions and the DPS's extensive extirpations and patchy
distribution within and between stream segments. Both structural and
functional connectivity are also poor in the South Sierra DPS. While
exact abundances are largely unknown, populations within the DPS are
relatively small and isolated and are impacted by numerous threats that
are of such extent and magnitude that they are making the South Sierra
DPS currently more susceptible to loss from stochastic or catastrophic
events. The South Sierra DPS also has a high average risk of decline
with no stream segments in lower risk categories under current
conditions. As a result, we find that the magnitude and imminence of
threats facing the South Sierra DPS of the foothill yellow-legged frog
place the DPS in danger of extinction now, and therefore a threatened
status is not appropriate. Thus, after assessing the best scientific
and commercial information available, we determine that the South
Sierra DPS of the foothill yellow-legged frog is in danger of
extinction throughout all of its range.
South Coast DPS: There are numerous, severe threats to the South
Coast DPS of the foothill yellow-legged frog including altered
hydrology (Factor A), drought (Factor E), nonnative species (Factor C),
disease and parasites (Factor C), urbanization (including development
roads) (Factor A), and recreation (Factor E), illegal cannabis
cultivation (Factor A), extreme floods (Factor E), severe wildfire
(Factor A), the effects of climate change (e.g., increased
temperatures, precipitation variability, increased drought frequency
and duration) (Factor E), and inadequacy of regulatory mechanisms
(Factor D). After evaluating threats to the DPS and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we conclude that under current conditions, resiliency,
redundancy, and representation are poor for the South Coast DPS.
Foothill yellow-legged frogs are mostly extirpated in this DPS and
currently occur only in two streams. These streams are located close to
one another, but the foothill yellow-legged frog populations within
them appear to have lost genetic connectivity. Although the stream
flows are not regulated by dams, the risk of population decline
continues to be medium or high under current conditions due to the
combination of threats identified above altering habitat and impacting
the DPS. Furthermore, the close proximity of the stream segments to
each other makes the South Coast DPS especially vulnerable to
extirpation from a single catastrophic event. Like the other DPSs
within the southern portion of the species' range, the area associated
with the South Coast DPS is subject to reduced precipitation and
drying, which (1) shortens the hydroperiod and negatively affects
habitat elements that are hydrology-dependent; (2) limits recruitment,
survival, and connectivity; and (3) exacerbates the effects of other
threats, such as predation and wildfire. In addition, the current
occupancy within the DPS is extremely low and the threats acting on the
DPS are of such extent and magnitude to currently cause significant
declines. As a result, we find that the magnitude and imminence of
threats facing the South Coast DPS of the foothill yellow-legged frog
place the DPS in danger of extinction now, and therefore a threatened
status is not appropriate. Thus, after assessing the best scientific
and commercial information available, we determine that currently the
South Coast DPS of the foothill yellow-legged frog is in danger of
extinction throughout all of its range.
Status of the South Sierra DPS and South Coast DPS Throughout a
Significant Portion of Their Ranges
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. We have determined that the South Sierra DPS and the South
Coast DPS of the foothill yellow-legged frog are in danger of
extinction throughout all of their ranges, and accordingly we did not
undertake an analysis of any significant portion of the range for these
two DPSs. Because both DPSs warrant listing as endangered throughout
all of their ranges, our determination does not conflict with the
decision in Center for Biological Diversity v. Everson, 2020 WL 437289
(D. DC 2020), in which the court vacated the aspect of the Final Policy
on Interpretation of the Phrase ``Significant Portion of its Range'' in
the Endangered Species Act's Definitions of ``Endangered Species'' and
``Threatened Species'' (79 FR 37578; July 1, 2014) that provided the
Service does not undertake an analysis of significant portions of a
species' range if the species warrants listing as threatened throughout
all of its range.
Determination of Status for the South Sierra DPS and South Coast DPS
Our review of the best available scientific and commercial
information indicates that the South Sierra DPS and the South Coast DPS
meet the Act's definition of endangered species. Therefore, we propose
to list the South Sierra DPS and the South Coast DPS as endangered
species in accordance with sections 3(6) and 4(a)(1) of the Act.
[[Page 73933]]
Status of the North Feather DPS and Central Coast DPS of the Foothill
Yellow-Legged Frog Throughout All of Their Ranges
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
to the North Feather and Central Coast DPSs of the foothill yellow-
legged frog and their habitat. Below we summarize our assessment of
status of the North Feather DPS and Central Coast DPS under the Act.
North Feather DPS: Numerous threats are currently acting on the
North Feather DPS. The North Feather DPS is within the most
hydrologically altered part of the foothill yellow-legged frog's range
(Factor A) and potentially is among the most impacted by the latent
effects from historical mining (Hayes et al. 2016, pp. 53-54) (Factor
A). Other threats to the DPS include nonnative species (bullfrogs and
crayfish) (Factor C), impacts to habitat (agriculture, urbanization,
severe wildfire) (Factor A), recreation (Factor E), the effects of
climate change (Factor E), and inadequacy of regulatory mechanisms
(Factor D). After evaluating threats to the DPS and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we conclude that under current conditions, resiliency,
redundancy, and representation for the North Feather DPS are reduced.
The North Feather DPS occupies a relatively small area and several
streams or occurrences have been extirpated from past impacts (eastern
portion of range, southwestern area near Lake Oroville, and some
occurrences in northern Butte County) (CDFW 2020, dataset, entire;
Service 2021, figure 49, p. 131). The North Feather DPS also has the
highest average relative risk of population decline with only 16 (15
percent) of the 109 analyzed stream segments in the low risk category
and 34 stream segments (31 percent) in the high risk category. Overall
abundance of foothill yellow-legged frogs for the North Feather DPS is
largely unknown, but egg mass densities are very low in the two
regulated stream reaches that have long-term monitoring (Rose et al.
2020, pp. 63-64, table 1). For example, sections of the Cresta reach of
the North Feather River that historically had relatively high numbers
of foothill yellow-legged frog egg masses did not have egg masses or
were extremely reduced for several years (2006-2017) (CDFW 2019, p. 31;
Dillingham 2019, p. 7).
Under current conditions, resiliency in the North Feather DPS is
reduced, largely because of the DPS's occupation of a small geographic
area, range contraction, the relatively high risk of the DPS's decline,
and the area's high degree of hydrological alteration. However, the
North Feather DPS still currently contains a relatively high proportion
of occurrence records with 42 percent of all known occurrences being
from the 2010-2020 timeframe (Service 2021, table 10, figure 49, pp.
125, 131). As a result, occupancy for the North Feather DPS is good,
based on a majority of records being within the 2000-2020 timeframe,
but abundance is low where there has been population monitoring.
Current redundancy is limited in the North Feather clade. The North
Feather DPS not only occupies the smallest area, but its occupied
stream segments are not well-distributed over the geographical area it
occupies. Current representation of the DPS is most likely reduced due
to past loss of populations.
In 2001, the FERC issued an order to the licensee responsible for
flow regulation on the Cresta and Poe reaches of the North Feather
River (Rock Creek-Cresta Hydroelectric Project (FERC Project No. 1962)
Pacific Gas and Electric Company (PG&E)). The order required PG&E to
develop a plan to ensure recreational and pulse flow releases did not
negatively impact the foothill yellow-legged frog. The order also
required the establishment of an Ecological Resources Committee (ERC)
to evaluate effects of flows and provide adaptive management strategies
if flows had a negative impact on the foothill yellow-legged frog
populations within the two reaches. In 2006, flow releases for
recreational boating were discontinued on the Cresta reach due to
possible impacts from flows resulting in low foothill yellow-legged egg
masses that year. In 2009 and again in 2014, modified flow programs
were implemented to mimic natural flow regimes by reducing flows in
spring and summer (April through the foothill yellow-legged frog's
breeding season) (GANDA 2018, pp. 1-2). We expect these measures to
continue due to the establishment of the ERC on monitoring impacts to
foothill yellow-legged frog populations on the two reaches. As a
result, there are some signs of improved abundance since 2018, in the
Cresta reach of the North Feather River following the above described
modifications of the regulated flow regime to more natural conditions.
Additional conservation efforts have been implemented to improve
abundance of the North Feather DPS including in-situ and ex-situ
rearing of foothill yellow-legged frogs for reintroduction (GANDA 2018,
pp. 1-3, 13, table 2; Dillingham 2019, pp. 7-9; Rose et al. 2020, pp.
63-64, 76, table 1, figure 4). The Forest Service has noted habitat
improvements in breeding areas of the Cresta reach and expects
abundances and breeding activity to continue to increase in response to
conservation efforts associated with in-situ and ex-situ rearing
efforts (Dillingham 2019, pp. 7-9). In addition, the environmental
condition of streams in the range of the North Feather DPS exhibit
colder stream temperatures. These cooler water temperatures, although
not currently preferable for the foothill yellow-legged frog, may help
to provide climatic resiliency during periods of hot weather that may
increase stream temperatures and may extend breeding and rearing
timeframes. In addition, the existing conservation efforts to improve
populations and regulatory measures to benefit habitat conditions as
described above currently document improvements to the DPS's overall
current condition. After evaluating threats to the species and
assessing the cumulative effect of the threats under the section
4(a)(1) factors, we have determined that despite the current condition
of the DPS being reduced, the population and habitat factors used to
determine the resiliency, representation, and redundancy for the DPS
have not been reduced to such a degree to consider the North Feather
DPS currently in danger of extinction throughout its range.
However, threat conditions in the future are likely to
substantially impact populations of the North Feather DPS. Because of
the current cold stream temperatures, future climatic conditions that
may increase stream temperatures may potentially benefit many of the
North Feather DPS populations; however, the negative effects of
increases in streamflow variability due to climate change (i.e.,
drought/flood events, snow/rain events) and residual environmental
stochasticity likely outweigh the benefit of any warmer stream
temperatures. Increased water demand and anticipated additional
regulation to an already highly regulated hydrologic condition of the
DPSs habitat will further limit the DPS's capability to maintain
adequate population sizes to support the DPS's metapopulation
structure. Nonnative species (bullfrogs and crayfish) will continue to
impact the DPS and their impacts may increase as temperatures warm,
allowing for spread of warm water species such as bullfrogs and
smallmouth bass. Trends indicate that the amount of area severely
burned annually by wildfires has been
[[Page 73934]]
growing sharply in the range of the North Feather DPS (Service 2021,
figures 38 and 39, pp. 105-106) and negative consequences from
wildfire-related sedimentation to foothill yellow-legged frog
reproduction have been documented in this DPS (Service 2021, pp. 86-
87). The populations of the North Feather DPS occupy an area small
enough that a large catastrophic event, such as a severe wildfire or
prolonged drought, could result in a severe reduction in population
size and extent for the DPS. Future resiliency for the North Feather
DPS will be markedly reduced as a result of these increases in threats
and increases in the synergistic effects of threat interactions. Thus,
the projected increases in average relative risk of decline under
future conditions under the mean change scenario are likely to decrease
occupancy, abundance, and connectivity, with resiliency being markedly
reduced from the DPS's current condition, putting the North Feather DPS
at risk of functional extirpation or extirpation within 40 years.
As a result of the DPS having a large percentage (42 percent) of
recently occupied occurrences (2010-2020) within the occupied stream
segments, and implementation of conservation measures to reduce the
effects of altered stream hydrology and provide for an increase in
populations, we have determined that the current condition of the DPS,
although reduced, still exhibits sufficient resiliency, redundancy, and
representation and would provide for, at a minimum, pockets of
favorable conditions that allow the North Feather DPS to currently
sustain its existing populations. However, future impacts from the
threats facing the DPS are likely to cause declines in the DPS's
population size and distribution. Thus, after assessing the best
available information, we conclude that the North Feather DPS of the
foothill yellow-legged frog is not currently in danger of extinction
but is likely to become in danger of extinction within the foreseeable
future throughout all of its range.
Central Coast DPS: Numerous threats are currently acting on the
Central Coast DPS including altered hydrology (Factor A), disease
(Factor C), drought (Factor A), nonnative bullfrogs (Factor C), impacts
to habitat (urbanization (including development and roads),
agriculture, trespass cannabis cultivation, extreme floods, and
wildfire) (Factor A), recreation (Factor E), the effects of climate
change (Factor E), and inadequacy of regulatory mechanisms (Factor D).
Human land use and population (urban development) in the northern
portions of the DPS's range are high, and the proportion of forest and
shrub cover across the DPS's range is low, with large areas being made
up of lower elevation open oak woodlands or foothill grassland
habitats. Seasonal precipitation within the range of the Central Coast
DPS is extremely variable year-to-year, making stream habitat for the
Central Coast DPS subject to drying. This, in turn, shortens the
breeding season; negatively affects habitat elements that are
hydrology-dependent; limits recruitment, survival, and connectivity;
and exacerbates the effects of other threats (e.g., wildfire, drought,
nonnative predators, disease, and the effects of climate change).
However, this variability has also resulted in the Central Coast area
of California (including the area occupied by the Central Coast DPS)
containing a high number of freshwater species that have evolved
adaptations to their environment (Howard et al. 2013, p. 5). Below we
summarize the resiliency, redundancy, and representation of the Central
Coast DPS.
The Central Coast DPS has undergone historical range contraction in
portions of its northern (Contra Costa, Alameda, San Mateo, and
northern Santa Cruz Counties) and central (southern Santa Clara and
northern San Benito Counties) regions. Currently, two clusters of
stream segments have had recent (2000-2020) detections of the species,
one cluster in the southern part and one cluster in the northern part
of the DPS's range (Service 2021, figure 52, p. 137). Population size
and abundance for the Central Coast DPS have been historically, and
continue to be, small, with those populations in unregulated streams
being larger and more productive (Service 2021, pp. 136-137 (8.2
Central Coast)). The southern cluster appears to have functional and
genetic connectivity (McCartney-Melstad et al. 2018, p. 117, figure 3),
which assists in maintaining the cluster's metapopulation integrity.
The southern cluster also has fewer human-caused threats (urbanization,
high-level recreation) due to its distance away from highly human-
populated areas and its location on public lands (BLM's Clear Creek
Management Area (CCMA)). Populations within the CCMA in San Benito and
Fresno Counties are being monitored and managed by BLM, and currently
appear to be self-sustaining (BLM 2014, pp. 4-77, 99-100). The northern
cluster is proximate to highly urbanized areas of the south San
Francisco Bay area and San Jose, California. The northern cluster also
exhibits some genetic differentiation among subpopulations, indicating
a lack of functional connectivity (McCartney-Melstad et al. 2018, p.
117, figure 3). However, two HCP/NCCPs (East Contra Costa and Santa
Clara Valley) (Jones & Stokes 2006, entire; ICF Jones & Stokes 2009,
entire) that identify the foothill yellow-legged frog as a covered
species have been approved and implemented. These plans assist in
ameliorating the current threats acting on the northern populations of
the Central Coast DPS and help conserve the DPS and its habitat within
their jurisdictional boundaries.
Current resiliency of the Central Coast DPS is substantially
reduced due to past impacts limiting connectivity between populations
and existing populations having smaller population abundance and
breeding (Rose et al. 2020, p. 63, table 1). The average risk of
population decline for the Central Coast DPS is considered high and
numerous threats are currently acting on the DPS (altered hydrology,
drought, nonnative species, disease, and urbanization). The current
overall redundancy for the Central Coast DPS is considered adequate to
maintain the existing populations of the DPS. This is because the
Central Coast DPS has numerous occupied stream segments that are
spatially distributed across the DPS's range, and those stream segments
exhibit variable environmental conditions providing for, at a minimum,
refugia for the population. As a result of this distribution, the
likelihood that a single catastrophic event would impact a significant
proportion of the Central Coast DPS's populations to the point of
extirpation or functional extirpation is extremely small. Current
representation for the Central Coast DPS is considered sufficient to
maintain its adaptive capacity. The Central Coast DPS has evolved in an
area with high climatic variability and is most likely adapted to
environmental changes. The Central Coast DPS is also one of the most
genetically divergent for the foothill yellow-legged frog, indicating
that the DPS still contains a significant amount of the taxon's overall
genetic diversity.
In the future, the average risk of decline for the existing
populations is expected to increase by 14 percent and the number of
populations at high risk of decline are expected to increase by 69
percent, under the mean change scenario. These changes are a result of
increases in threats such as climate-induced demand for surface waters
that is projected to increase by 5 to 20 percent (from 1900-1970
levels) by mid-century (2050) (Averyt et al. 2013, p. 7, figure 7).
Future increases in severe wildfires are expected. Despite wildfire
trends in the Central Coast DPS being
[[Page 73935]]
stable between 1950 and 2018 (Service 2021, Figure 38), recent events
such as the fires in 2020 in the San Mateo-Santa Cruz Unit (CZU)
(35,009 hectares (ha) (86,509 acres (ac)) (Santa Cruz and San Mateo
Counties) and Santa Clara Unit (SCU) (160,508 ha (396,624 ac)) (Santa
Clara, Alameda, Stanislaus Counties) Lightning Complex are examples of
expected increasing trends in wildfire activity in the future (CALFIRE
2021, entire). Under the lower change scenario, the Central Coast DPS's
resiliency would be slightly reduced. Under the mean change scenario,
resiliency would be markedly reduced from current condition due to
reductions in population numbers and distribution (reduction in
redundancy). This reduction in resiliency under the mean change
scenario would put the Central Coast DPS at risk of functional
extirpation or extirpation in 40 years.
After evaluating threats to the Central Coast DPS and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we find that the Central Coast DPS of the foothill yellow-
legged frog currently sustains numerous populations and contains
habitat distributed throughout the DPS's range (redundancy). These
widely distributed populations provide for the genetic and ecological
representation for the DPS across its range. Therefore, the current
resiliency, redundancy, and representation are sufficient to prevent
the current threats acting on the Central Coast DPS from causing it to
be in danger of extinction anywhere within its range. Thus, the Central
Coast DPS of the foothill yellow-legged frog is not currently in danger
of extinction throughout its range, and therefore, the Central Coast
DPS does not meet the Act's definition of endangered. However, based on
our projections of future occupancy (which are currently low and show
poor connectivity), modeled risk of decline assessments from the PVA,
and the existing and increased threats in the future on the DPS from
increasing water demand, increases in wildfire frequency and intensity
due to climate change conditions will further impact abundance and
connectivity of populations and cause the DPS's habitat to become
increasingly less able to support foothill yellow-legged frog
populations into the future. Thus, after assessing the best available
information, we conclude that the Central Coast DPS of the foothill
yellow-legged frog is likely to become in danger of extinction within
the foreseeable future throughout all of its range.
Status of the North Feather DPS and Central Coast DPS of the Foothill
Yellow-Legged Frog Throughout a Significant Portion of Their Ranges
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. The court in Center for Biological Diversity v. Everson,
2020 WL 437289 (D.D.C. Jan. 28, 2020) (Center for Biological
Diversity), vacated the aspect of the Final Policy on Interpretation of
the Phrase ``Significant Portion of Its Range'' in the Endangered
Species Act's Definitions of ``Endangered Species'' and ``Threatened
Species'' (79 FR 37578; July 1, 2014) that provided that the Service
does not undertake an analysis of significant portions of a species'
range if the species warrants listing as threatened throughout all of
its range. Therefore, we proceed to evaluating whether the North
Feather DPS or Central Coast DPS is endangered in a significant portion
of its range--that is, whether there is any portion of either DPSs'
range for which both (1) the portion is significant; and (2) the
species is in danger of extinction in that portion. Depending on the
case, it might be more efficient for us to address the ``significance''
question or the ``status'' question first. We can choose to address
either question first. Regardless of which question we address first,
if we reach a negative answer with respect to the first question that
we address, we do not need to evaluate the other question for that
portion of either DPS's range.
Following the court's holding in Center for Biological Diversity,
we now consider whether there are any significant portions of the
species' range where either DPS is in danger of extinction now (i.e.,
endangered). In undertaking this analysis for the North Feather DPS and
Central Coast DPS, we choose to address the status question first--we
consider information pertaining to the geographic distribution of both
the species and the threats that the two DPSs face to identify any
portions of either DPS's range where either is endangered.
For North Feather DPS and Central Coast DPS, we considered whether
the threats are geographically concentrated in any portion of the DPS's
ranges at a biologically meaningful scale. We examined the following
threats for the North Feather DPS: Altered stream hydrology, latent
effects from historical mining, nonnative species, impacts to the DPS's
habitat (agriculture, urbanization, wildfire), recreation, and the
effects of climate change, including cumulative effects. For the
Central Coast DPS, we examined: Altered stream hydrology, disease,
drought, nonnative species, impacts to habitat (urbanization (including
roads and recreation), agriculture, trespass cannabis cultivation,
extreme floods, and wildfire), and the effects of climate change,
including cumulative effects. The major driving forces of altered
stream hydrology, wildfire, disease, nonnative species, and the effects
of climate change are occurring throughout each DPS at similar levels
and we did not find a concentration of any of these threats in any
portion of either the North Feather or Central Coast DPS's range at a
biologically meaningful scale.
Thus, there are no portions of the North Feather DPS's or Central
Coast DPS's range where the threats facing the species are concentrated
to a degree where the species in that portion would have a different
status from its overall DPS status. Therefore, no portion of the North
Feather DPS's or Central Coast DPS's range provides a basis for
determining that the North Feather DPS or Central Coast DPS is in
danger of extinction in a significant portion of its range. We
determine that the two DPSs are likely to become in danger of
extinction within the foreseeable future throughout all of their
ranges. This does not conflict with the courts' holdings in Desert
Survivors v. U.S. Department of the Interior, 321 F. Supp. 3d 1011,
1070-74 (N.D. Cal. 2018), and Center for Biological Diversity v.
Jewell, 248 F. Supp. 3d 946, 959 (D. Ariz. 2017) because, in reaching
this conclusion, we did not need to consider whether any portions are
significant and therefore did not apply the aspects of the Final
Policy's definition of ``significant'' that those court decisions held
were invalid.
Determination of Status for the North Feather DPS and Central Coast DPS
of the Foothill Yellow-Legged Frog
Our review of the best scientific and commercial information
available indicates that the North Feather DPS and Central Coast DPS of
the foothill yellow-legged frog are likely to become endangered species
within the foreseeable future throughout their ranges and thus meet the
Act's definition of threatened species. Therefore, we propose to list
the North Feather DPS and Central Coast DPS of the foothill yellow-
legged frog as threatened species in accordance with sections 3(20) and
4(a)(1) of the Act.
[[Page 73936]]
Status of the North Coast DPS and North Sierra DPS of the Foothill
Yellow-Legged Frog Throughout All of Their Ranges
We have carefully assessed the best scientific and commercial
information available regarding the past, present, and future threats
to the North Coast DPS and the North Sierra DPS of the foothill yellow-
legged frog and its habitat. Below we summarize our assessment of
status of the North Coast DPS and the North Sierra DPS under the Act.
In the SSA report, we provided information regarding the current and
future conditions of the North Coast DPS in Oregon and California as
separate analysis units. To be consistent, we describe the conditions
of the Oregon and California portions of the DPS separately below, but
we combine these analyses and present the DPS as one entity for our
determination of overall status under the Act.
North Coast DPS (Oregon): The major threats that are affecting the
foothill yellow-legged frog in the North Coast DPS in Oregon include
altered hydrology (Factor A), nonnative species (Factor C), agriculture
(including water diversion and fluctuation caused by irrigation)
(Factor A), mining (Factor A), urbanization (including development and
roads) (Factor A), and recreation (Factor E).
Current conditions of the North Coast DPS in Oregon include legacy
impacts from historical habitat loss and alteration of habitat and
resulting range contraction. The current extent of the DPS's range in
Oregon has been fragmented and the populations remaining have lost some
connectivity, with smaller populations sometimes being isolated.
Evidence of this isolation has been supported by genetic research that
found the DPS in Oregon subdivided into three genetic groups based on
locality (McCartney-Melstad et al. 2018, p. 117, figure 3). Abundance
information also appears to indicate the fragmented populations are
lower in abundance than past abundance estimates (Borisenko and Hayes
1999, pp. 20-21; Olson and Davis 2009, p. 26). Although occupancy and
connectivity are poor for the DPS in Oregon as a whole, there appear to
be some strongholds for the foothill yellow-legged frog (Service 2021,
figure 55, p. 151). The areas in the central and southwestern portions
of the DPS in Oregon appear to be most stable with numerous occupied
stream segments that are both close together and at a relatively low
risk of decline. According to the PVA, the average relative risk of
population decline in the North Coast DPS in Oregon is the second-
lowest across all DPSs. In addition, the majority of stream segments in
this unit are in the low relative risk of decline category. This is
partly because most stream segments in Oregon do not have regulated
flows which are associated with dams. In addition, conservation efforts
such as rangewide conservation planning and habitat connectivity
prioritization are focusing management on the North Coast DPS in Oregon
(Service 2021, table 9, pp. 117-120). Although habitat impacts
resulting from present-day threats are currently negatively affecting
the North Coast DPS in Oregon, the DPS in Oregon still has a sufficient
degree of resiliency, redundancy, and representation, due to the
lessened magnitude and extent of threats acting on the DPS, such that
we do not consider these present-day effects to place the species in
danger of extinction.
North Coast DPS-California: Altered stream hydrology (Factor A) is
among the most impactful threats to the North Coast DPS in California.
Other major threats that likely have or are contributing to localized
declines in the DPS in California include nonnative species (Factor C),
habitat impacts from agriculture, mining, and urbanization (including
development and roads) (Factor A), and recreation (Factor E). Trespass
cannabis cultivation (Factor A) is also an extensive threat in the
North Coast DPS in California (CDFW 2019b, pp. 97-98). Illegal water
diversions and pesticides for illegal cannabis are reportedly linked to
local declines of foothill yellow-legged frogs in the Eel River and
South Fork Trinity River (Service 2019, p. 33).
Despite several documented local extirpations, the North Coast DPS
in California contains the most abundant foothill yellow-legged frog
populations and the majority (1,443 of 2,425 for the species) of stream
segments that have had recent (2000-2020) detections of the species
(Service 2021, Table 10, Figure 48). Stream segments with recent
detections also have good connectivity and are distributed over a large
area. The North Coast DPS in California also contains a large number of
stream segments (382) in the low risk of decline category. In addition,
conservation efforts such as rangewide conservation planning and other
regulatory measures to manage streams to benefit the North Coast DPS
are currently being implemented in California (Service 2021, table 9,
pp. 117-120). Although habitat impacts resulting from present-day
threats are currently negatively affecting the North Coast DPS in
California, the DPS in California still has a sufficient degree of
resiliency, redundancy, and representation, due to the health and
number of populations and magnitude and extent of threats acting on the
DPS, such that we do not consider these present-day effects to place
the DPS in danger of extinction.
After assessing the best scientific and commercial information
available, and based on the information on the North Coast DPS's
overall current condition above, we have determined that the North
Coast DPS (in California and Oregon) of the foothill yellow-legged frog
is not currently in danger of extinction throughout all of its range.
Below, we review the North Coast DPS's future condition and status.
Future Condition of the North Coast DPS: Over the next 40 years
(our timeframe of foreseeable future), the projected increases in risk
of decline and the increasing risk of serious threats indicate that the
resiliency of the North Coast DPS will decrease in the future (Service
2021, table 19, pp. 180-181). This decline is expected to be largely
related to the altered stream hydrology (in California) in the mainstem
river systems and threats associated with severe wildfire events
exacerbated by changes in climatic conditions. However, the North Coast
DPS in Oregon has the lowest risk of decline under the mean and higher
change scenarios and has the second-lowest risk of decline under the
lower change scenario. In addition, the percent forest and shrub cover
for the entire DPS is projected to change very little by 2060 (less
than 0.3 percent of total area under the mean change scenario) in the
North Coast DPS overall (California and Oregon data summarized
together) (Sleeter and Kreitler 2020, unpublished data). This would
result in a relatively stable upland habitat conditions for the DPS
over this timeframe. This DPS overall is also likely to be more
resilient to projected changes in climate variables (i.e., stream
temperature and annual streamflow). For example, projected increases in
stream temperature could increase population growth rates in those
streams that tend to be cooler than in the rest of the species' range.
In addition, although resiliency for the North Coast DPS will be
reduced, the reduction will not be significantly different from current
condition. This is mostly because the North Coast DPS has a large
number of occupied stream segments, contains populations with high
abundances, is distributed relatively uniformly across a large
geographic area, and has good connectivity between populations, making
it able to withstand the anticipated variation and increase of
[[Page 73937]]
stochastic events. Regulatory mechanisms such as the Forest Service's
and BLM's Sensitive Species Program and habitat management programs
under the Northwest Forest Plan which provides for species management
and habitat protection for activities on their lands will continue to
be implemented for a large portion of the DPS. As a result, the North
Coast DPS's resiliency would most likely be only slightly reduced from
the threats it will face in the foreseeable future over the next 40
years due to its heightened current condition. Therefore, due to the
DPS's current and projected high occupancy level, its abundance,
connectivity, and distribution of populations within the DPS as well as
implementation of measures to reduce threats, we have determined that
the North Coast DPS will continue to have a sufficient degree of
resiliency, redundancy, and representation such that we do not
anticipate the future threats to limit the DPS's ability to maintain
populations in the wild.
After review of the threats identified above and cumulative effects
facing the North Coast DPS, as well as existing conservation measures,
we conclude that threats have likely impacted individuals or localized
populations of the North Coast DPS. However, the magnitude and extent
of these impacts into the future will not significantly impact the
resiliency, representation, or redundancy for the DPS or result in a
decline in the overall distribution or general demographic condition of
the DPS such that it is likely to become in danger of extinction in the
foreseeable future throughout the DPS's range.
North Sierra DPS: The major threats that likely have or are
contributing to declines of the foothill yellow-legged frog in the
North Sierra DPS include altered stream hydrology (Factor A), nonnative
species (Factor C), habitat impacts (agriculture, mining, urbanization
(including development and roads) (Factor A) and recreation (Factor E),
and the effects of climate change (Factor E). The North Sierra DPS is
in the most hydrologically altered part of the foothill yellow-legged
frog's range and contains a high density of hydropower dams (CDFW
2019b, p. 97). While the North Sierra DPS has a high proportion of
forest and shrub cover (86 percent), it may be affected by agricultural
activities (vineyards) adjacent to habitat in the foothill portions of
the northern Central Valley (Service 2021, supplementary figure 1, p.
224). The northern Sierra Nevada (North Feather and North Sierra DPSs)
is also suspected to be the most impacted from the latent effects from
historical mining (Hayes et al. 2016, pp. 53-54).
Despite the threats acting on the North Sierra DPS, its populations
have the lowest risk of decline across the DPS's range due to it having
a large proportion of occupied streams containing populations that are
both robust and stable. The majority (65 percent) of the DPS's 278
analyzed stream segments are currently in the low relative risk
category. The North Sierra DPS is made up of a dense network of
occupied stream segments that are distributed across the range of the
DPS. There are few documented extirpations of occurrences in the North
Sierra DPS. As a result, the resiliency, redundancy, and representation
across the DPS are considered sufficient to reduce the impact of
threats and currently maintain populations in the wild.
In the future, the North Sierra DPS is expected to decline due to
alterations associated with regulated water flows. However, these
declines are not expected to impact the North Sierra DPS to such a
degree that populations would be significantly impacted. The PVA
determined that the North Coast DPS would have the lowest risk of
decline under the lower change scenario and the second-lowest risk of
decline under the mean and higher change scenarios. As a result, we
expect resiliency, redundancy, and representation across the DPS to
remain sufficient for the DPS to maintain populations in the wild into
the foreseeable future.
We have reviewed the current threats identified above and
cumulative effects facing the North Coast and North Sierra DPSs, and
evaluated the condition of the resiliency, representation, and
redundancy for each of the DPSs. Based on the favorable conditions
currently measured by the resiliency, redundancy and representation
across the DPSs, the threats acting on the two DPSs are not of such
magnitude, extent, and imminence that they are causing the two DPSs to
be in danger of extinction now throughout their ranges.
The future threats acting on and driving the status of the two DPSs
include altered hydrology (either through stream flows or past stream
alterations) and the effects of climate change, which may result in
increased hydrological changes or severity of habitat loss from
wildfire impacts. We anticipate that, although the risk of decline will
increase due to the threats acting on the two DPSs into the future, the
two DPSs' resiliency, representation, and redundancy are projected to
sufficiently reduce the effect of future impacts to such a degree that
populations of both DPSs would be able maintain viability into the
future.
Thus, after assessing the best scientific and commercial
information available, we conclude that the North Coast DPS (in
northern California and Oregon) and the North Sierra DPS (located
primarily in Yuba, Sierra, Nevada, and Placer Counties, California) are
not currently in danger of extinction and not likely to become in
danger of extinction within the foreseeable future throughout their
respective ranges.
Status of the North Coast DPS and North Sierra DPS of the Foothill
Yellow-Legged Frog Throughout a Significant Portion of Their Range
Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. Having determined that the North Coast DPS and North Sierra
DPS are not in danger of extinction or likely to become so in the
foreseeable future throughout all of their respective ranges, we now
consider whether either may be in danger of extinction or likely to
become so in the foreseeable future in a significant portion of their
respective ranges--that is, whether there is any portion of the DPSs'
ranges for which it is true that both (1) the portion is significant;
and (2) the DPS is in danger of extinction now or likely to become so
in the foreseeable future in that portion. Depending on the case, it
might be more efficient for us to address the ``significance'' question
or the ``status'' question first. We can choose to address either
question first. Regardless of which question we address first, if we
reach a negative answer with respect to the first question that we
address, we do not need to evaluate the other question for that portion
of the DPS's range.
In undertaking this analysis for the North Coast DPS and North
Sierra DPS, we choose to address the status question first--we consider
information pertaining to the geographic distribution of both the DPSs
and the threats that the DPSs face to identify any portions of the
range where the DPSs are endangered or threatened.
For the North Coast DPS and North Sierra DPS, we considered whether
the threats are geographically concentrated in any portion of the DPSs'
ranges at a biologically meaningful scale. We examined the following
threats: Hydrological alteration of streams (Factor A), latent effects
from historical mining (Factor A), predation from nonnative species
(bullfrogs and crayfish) (Factor C), other impacts to
[[Page 73938]]
habitat (agriculture, urbanization, severe wildfire) (Factor A),
recreation (Factor E), and the effects of climate change (Factor E),
including cumulative effects. In our analysis, we did not find any
portion of either the North Coast DPS's range or the North Sierra DPS's
range where the threats identified above are currently acting at a
biologically meaningful scale such that any portion of the DPSs' ranges
may be endangered, or where threats are likely to act on either DPS
into the future such that any portion may be threatened. Occupied
stream segments are distributed throughout each of the DPSs, and
connectivity in the majority of each DPS is considered to be good
except within the Oregon portion of the North Coast DPS. However, the
Oregon portion also has fewer regulated streams, and populations,
although small, are in a low risk of decline both now and into the
future. Therefore, no portion of the two DPSs' ranges provides a basis
for determining that either DPS is in danger of extinction now or
likely to become so in the foreseeable future in a significant portion
of its range, and we find that the DPSs are not in danger of extinction
now or likely to become so in the foreseeable future in any significant
portion of their ranges. This does not conflict with the courts'
holdings in Desert Survivors v. U.S. Department of the Interior, 321 F.
Supp. 3d 1011, 1070-74 (N.D. Cal. 2018), and Center for Biological
Diversity v. Jewell, 248 F. Supp. 3d 946, 959 (D. Ariz. 2017) because,
in reaching this conclusion, we did not need to consider whether any
portions are significant and therefore did not apply the aspects of the
Final Policy's definition of ``significant'' that those court decisions
held were invalid.
Determination of Status of the North Coast DPS and North Sierra DPS of
the Foothill Yellow-Legged Frog
Our review of the best scientific and commercial information
available indicates that the North Coast DPS and North Sierra DPS of
the foothill yellow-legged frog do not meet the Act's definition of an
endangered species or a threatened species in accordance with sections
3(6) and 3(20) of the Act. Therefore, we find that listing the North
Coast DPS and North Sierra DPS of the foothill yellow-legged frog under
the Act is not warranted at this time.
Available Conservation Measures
Conservation measures provided to species listed as endangered or
threatened species under the Act include recognition, recovery actions,
requirements for Federal protection, and prohibitions against certain
practices. Recognition through listing results in public awareness, and
conservation by Federal, State, Tribal, and local agencies, private
organizations, and individuals. The Act encourages cooperation with the
States and other countries and calls for recovery actions to be carried
out for listed species. The protection required by Federal agencies and
the prohibitions against certain activities are discussed, in part,
below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Section 4(f) of the Act calls for the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The recovery planning process involves the
identification of actions that are necessary to halt or reverse the
species' decline by addressing the threats to its survival and
recovery. The goal of this process is to restore listed species to a
point where they are secure, self-sustaining, and functioning
components of their ecosystems.
Recovery planning consists of preparing draft and final recovery
plans, beginning with the development of a recovery outline and making
it available to the public within 30 days of a final listing
determination. The recovery outline guides the immediate implementation
of urgent recovery actions and describes the process to be used to
develop a recovery plan. Revisions of the plan may be done to address
continuing or new threats to the species, as new substantive
information becomes available. The recovery plan also identifies
recovery criteria for review of when a species may be ready for
reclassification from endangered to threatened (``downlisting'') or
removal from protected status (``delisting''), and methods for
monitoring recovery progress. Recovery plans also establish a framework
for agencies to coordinate their recovery efforts and provide estimates
of the cost of implementing recovery tasks. Recovery teams (composed of
species experts, Federal and State agencies, nongovernmental
organizations, and stakeholders) are often established to develop
recovery plans. When completed, the recovery outline, draft recovery
plan, and the final recovery plan will be available on our website
(<a href="http://www.fws.gov/endangered">http://www.fws.gov/endangered</a>), or from our Sacramento Fish and
Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
If any of the DPSs identified above are listed, funding for
recovery actions will be available from a variety of sources, including
Federal budgets, State programs, and cost-share grants for non-Federal
landowners, the academic community, and nongovernmental organizations.
In addition, pursuant to section 6 of the Act, the State of California
would be eligible for Federal funds to implement management actions
that promote the protection or recovery of the DPSs. Information on our
grant programs that are available to aid species recovery can be found
at: <a href="https://www.fws.gov/grants">https://www.fws.gov/grants</a>.
Although the four DPSs are only proposed for listing under the Act
at this time, please let us know if you are interested in participating
in recovery efforts for this species. Additionally, we invite you to
submit any new information on this species whenever it becomes
available and any information you may have for recovery planning
purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7(a) of the Act requires Federal agencies to evaluate their
actions with respect to any species that is proposed or listed as an
endangered or threatened species and with respect to its critical
habitat, if any is designated. Regulations implementing this
interagency cooperation provision of the Act are codified at 50 CFR
part 402. Section 7(a)(4) of the Act requires Federal agencies to
confer with the Service on any action that is likely to jeopardize the
continued existence of a species proposed for listing or result in
destruction or adverse modification of proposed critical habitat. If a
species is listed subsequently, section 7(a)(2) of the Act requires
Federal agencies to ensure that activities they authorize, fund, or
carry out are not likely to jeopardize the continued existence of the
species or destroy or adversely modify its critical habitat. If a
Federal action may affect a listed species or its
[[Page 73939]]
critical habitat, the responsible Federal agency must enter into
consultation with the Service.
Examples of Federal agency actions within the species' habitat
within the DPSs that may require conference or consultation or both, as
described in the preceding paragraph, include but are not limited to
management and any other landscape-altering activities on Federal lands
administered by the U.S. Fish and Wildlife Service, Forest Service,
BLM, and National Park Service; issuance of section 404 Clean Water Act
(33 U.S.C. 1251 et seq.) permits by the U.S. Army Corps of Engineers;
construction and maintenance of roads, bridges, or highways by the
Federal Highway Administration; water management and conveyance
activities by the Bureau of Reclamation; and licensing for hydropower
and safety of dams by the FERC.
South Sierra DPS and South Coast DPS--Proposed Endangered Status
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply to endangered wildlife.
The prohibitions of section 9(a)(1) of the Act, codified at 50 CFR
17.21, make it illegal for any person subject to the jurisdiction of
the United States to take (which includes harass, harm, pursue, hunt,
shoot, wound, kill, trap, capture, or collect; or to attempt any of
these) endangered wildlife within the United States or on the high
seas. In addition, it is unlawful to import; export; deliver, receive,
carry, transport, or ship in interstate or foreign commerce in the
course of commercial activity; or sell or offer for sale in interstate
or foreign commerce any species listed as an endangered species. It is
also illegal to possess, sell, deliver, carry, transport, or ship any
such wildlife that has been taken illegally. Certain exceptions apply
to employees of the Service, the National Marine Fisheries Service,
other Federal land management agencies, and State conservation
agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits are codified at 50 CFR 17.22. With regard to
endangered wildlife, a permit may be issued for the following purposes:
For scientific purposes, to enhance the propagation or survival of the
species, and for incidental take in connection with otherwise lawful
activities. The statute also contains certain exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of the
species proposed for listing.
Because activities being implemented in the range of the species
are variable and have variable impacts depending on the nature of the
project, we are unable at this time to identify any specific activities
within the range of the species that would not constitute a violation
of section 9, as effects of any actions on the species are fact-pattern
specific. However, actions whose effects do not extend into foothill
yellow-legged frog habitat are unlikely to result in section 9
violations.
Based on the best available information, the following activities
may result in a violation of section 9 of the Act if they are not
authorized in accordance with applicable law; this list is not
comprehensive:
Activities that the Service believes could potentially harm the
foothill yellow-legged frog and result in ``take'' include, but are not
limited to:
(1) Unauthorized handling or collecting of the species;
(2) Destruction/alteration of the species' habitat by discharge of
fill material, draining, ditching, tiling, pond construction, stream
channelization or diversion, or diversion or alteration of surface or
ground water flow;
(3) Inappropriate livestock grazing that results in direct or
indirect destruction of riparian habitat;
(4) Pesticide applications in violation of label restrictions;
(5) Introduction of nonnative species that compete with or prey
upon foothill yellow-legged frogs, such as the introduction of
nonnative bullfrogs or nonnative fish; and
(6) Modification of the channel or water flow of any stream or
removal or destruction of vegetation or stream substrate in any body of
water in which the foothill yellow-legged frog is known to occur.
Questions regarding whether specific activities would constitute a
violation of section 9 of the Act should be directed to the Sacramento
Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
North Feather DPS and Central Coast DPS--Proposed Threatened Status
It is our policy, as published in the Federal Register on July 1,
1994 (59 FR 34272), to identify to the maximum extent practicable at
the time a species is listed, those activities that would or would not
constitute a violation of section 9 of the Act. The intent of this
policy is to increase public awareness of the effect of a proposed
listing on proposed and ongoing activities within the range of the
species proposed for listing. The discussion below regarding protective
regulations under section 4(d) of the Act for the proposed threatened
North Feather DPS and Central Coast DPS complies with our policy.
II. Proposed Rule Issued Under Section 4(d) of the Act for the North
Feather DPS and the Central Coast DPS of the Foothill Yellow-Legged
Frog
Background
Section 4(d) of the Act contains two sentences. The first sentence
states that the Secretary shall issue such regulations as she deems
necessary and advisable to provide for the conservation of species
listed as threatened. The U.S. Supreme Court has noted that statutory
language like ``necessary and advisable'' demonstrates a large degree
of deference to the agency (see Webster v. Doe, 486 U.S. 592 (1988)).
Conservation is defined in the Act to mean the use of all methods and
procedures which are necessary to bring any endangered species or
threatened species to the point at which the measures provided pursuant
to the Act are no longer necessary. Additionally, the second sentence
of section 4(d) of the Act 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 section
9(a)(2), in the case of plants. Thus, the combination of the two
sentences of section 4(d) provides the Secretary with wide latitude of
discretion to select and promulgate appropriate regulations tailored to
the specific conservation needs of the threatened species. The second
sentence grants particularly broad discretion to the Service when
adopting the prohibitions under section 9.
The courts have recognized the extent of the Secretary's discretion
under this standard to develop rules that are appropriate for the
conservation of a species. For example, courts have upheld rules
developed under section 4(d) as a valid exercise of agency authority
where they prohibited take of threatened wildlife, or include a limited
taking prohibition (see Alsea Valley
[[Page 73940]]
Alliance v. Lautenbacher, 2007 U.S. Dist. Lexis 60203 (D. Or. 2007);
Washington Environmental Council v. National Marine Fisheries Service,
2002 U.S. Dist. Lexis 5432 (W.D. Wash. 2002)). Courts have also upheld
4(d) rules that do not address all of the threats a species faces (see
State of Louisiana v. Verity, 853 F.2d 322 (5th Cir. 1988)). As noted
in the legislative history of the Act, ``once an animal is on the
threatened list, the Secretary has an almost infinite number of options
available to him [or her] with regard to the permitted activities for
those species. He [or she] may, for example, permit taking, but not
importation of such species, or he [or she] may choose to forbid both
taking and importation but allow the transportation of such species''
(H.R. Rep. No. 412, 93rd Cong., 1st Sess. 1973).
Exercising this authority under section 4(d), we have developed
proposed rules that are designed to address the conservation needs of
the North Feather DPS and Central Coast DPS of the foothill yellow-
legged frog. Although the statute does not require us to make a
``necessary and advisable'' finding with respect to the adoption of
specific prohibitions under section 9, we find that these rules as a
whole satisfy the requirement in section 4(d) of the Act to issue
regulations deemed necessary and advisable to provide for the
conservation of the North Feather DPS and Central Coast DPS of the
foothill yellow-legged frog. As discussed above under Summary of
Biological Status and Threats, we have concluded that the North Feather
DPS and Central Coast DPS of the foothill yellow-legged frog are likely
to become in danger of extinction within the foreseeable future
throughout their respective ranges primarily due to threats associated
with altered stream hydrology, nonnative species, impacts to habitat
(agriculture, mining, urbanization, roads, recreation), disease,
drought, extreme floods, high-severity wildfire, and the exacerbation
of threats from the effects of climate change. The provisions of this
proposed 4(d) rule would promote conservation of the North Feather DPS
and Central Coast DPS of the foothill yellow-legged frog by encouraging
management of the species' stream habitat and landscape in ways that
meet both resource management considerations and the conservation needs
of the species. The provisions of this proposed rule are one of many
tools that we would use to promote the conservation of the North
Feather DPS and Central Coast DPS of the foothill yellow-legged frog.
This proposed 4(d) rule would apply only if and when we make final the
listing of the North Feather DPS and Central Coast DPS of the foothill
yellow-legged frog as threatened species.
Section 7(a)(2) of the Act requires Federal agencies, including the
Service, to ensure that any action they fund, authorize, or carry out
is not likely to jeopardize the continued existence of any endangered
species or threatened species or result in the destruction or adverse
modification of designated critical habitat of such species. In
addition, section 7(a)(4) of the Act requires Federal agencies to
confer with the Service on any agency action which is likely to
jeopardize the continued existence of any species proposed to be listed
under the Act or result in the destruction or adverse modification of
proposed critical habitat.
If a Federal action may affect a listed species or its critical
habitat, the responsible Federal agency (action agency) must enter into
consultation with the Service. Examples of actions that are subject to
the section 7 consultation process are actions on State, Tribal, local,
or private lands that require a Federal permit (such as a permit from
the U.S. Army Corps of Engineers under section 404 of the Clean Water
Act, a license from the Federal Energy Regulatory Commission under the
Federal Power Act, or a permit from the Service under section 10 of the
Act) or that involve some other Federal action (such as funding from
the Federal Highway Administration, Federal Aviation Administration, or
the Federal Emergency Management Agency). Federal actions not affecting
listed species or critical habitat--and actions on State, Tribal,
local, or private lands that are not federally funded, authorized, or
carried out by a Federal agency--do not require section 7 consultation.
This obligation does not change in any way for a threatened species
with a species-specific 4(d) rule. Actions that result in a
determination by a Federal agency of ``not likely to adversely affect''
continue to require the Service's written concurrence and actions that
are ``likely to adversely affect'' a species require formal
consultation and the formulation of a biological opinion.
Provisions of the Proposed 4(d) Rule for the North Feather DPS and the
Central Coast DPS of the Foothill Yellow-Legged Frog
This proposed 4(d) rule would provide for the conservation of the
North Feather DPS and Central Coast DPS of the foothill yellow-legged
frog by prohibiting the following activities, except as otherwise
authorized or permitted: Import or export; take; possession and other
acts with unlawfully taken specimens; delivery, receipt,
transportation, or shipment in interstate or foreign commerce in the
course of commercial activity; or sale or offer for sale in interstate
or foreign commerce. These prohibitions mirror those prohibitions
afforded to endangered species under section 9(a)(1) of the Act.
In addition to the prohibited activities identified above, we also
provide standard and other exceptions to those prohibitions for certain
activities as described below.
We note that the long-term viability of the North Feather DPS and
Central Coast DPS of the foothill yellow-legged frog, as with many
wildlife species, is intimately tied to the condition of their habitat.
As described in our analysis of the species' status, one of the major
threats to the North Feather DPS and Central Coast DPS of the foothill
yellow-legged frog's continued viability is habitat loss, degradation,
and fragmentation resulting from past or current anthropogenic impacts
or from catastrophic wildfires. The potential for an increase in
frequency and severity of catastrophic wildfires from the effects of
climate change subsequently increases the risk to the species posed by
this threat. An additional threat is the occurrence of nonnative
species that may predate upon and compete for resources with the
foothill yellow-legged frog.
We have determined that actions taken by forest management entities
in the range of the North Feather DPS and Central Coast DPS of the
foothill yellow-legged frog for the purpose of reducing the risk or
severity of catastrophic wildfires and protecting stream habitat, even
if these actions may result in some short-term or low level of
localized negative effect to North Feather DPS and/or Central Coast DPS
of the foothill yellow-legged frog, will further the goal of reducing
the likelihood of either DPS becoming endangered, and will also likely
contribute to their conservation and long-term viability. This includes
measures approved by the Service, to conduct wildfire prevention
activities, non-emergency suppression activities, and other
silviculture best management practices that are in accordance with an
established forest or fuels management plan and that include measures
that minimize impacts to the species and its habitat.
In addition, habitat restoration efforts that specifically provide
for the habitat needs of the North Feather DPS and Central Coast DPS of
the foothill yellow-legged frog as approved by the Service
[[Page 73941]]
and include measures that minimize impacts to the species and its
habitat are appropriate for an exception. These activities would most
likely have some limited short-term impacts but overall would provide
for conservation of the two DPSs. Habitat restoration efforts focused
on other species (e.g., salmonid species) are not included in this
exception without written approval from the Service.
Removal and restoration of trespass cannabis cultivation sites as
approved by the Service are excepted from prohibitions. These
activities would benefit the foothill yellow-legged frog, especially in
the Central Coast DPS area. Trespass cannabis cultivation sites cause
several issues for the foothill yellow-legged frog including water
diversion, pollution, sedimentation, and introduction of pesticides and
fertilizers to streams occupied by the foothill yellow-legged frog.
When these sites are found, they often require reclamation (waste
cleanup and removal of fertilizers, pesticides, and debris) and
restoration to precultivation conditions. Cleanup of these sites may
involve activities that may cause localized, short-term disturbance to
the North Feather DPS and Central Coast DPS of the foothill yellow-
legged frog. However, the removal of pesticides and other chemicals
that can affect the North Feather DPS or Central Coast DPS of the
foothill yellow-legged frog and the surrounding environment is
encouraged. Removal and restoration of trespass cannabis cultivation
sites is expected to have long-term benefits for resiliency of the
North Feather DPS and Central Coast DPS.
Nonnative species removal would significantly increase the
viability of the foothill yellow-legged frog. As discussed above,
bullfrogs, nonnative fish, and nonnative crayfish contribute to
foothill yellow-legged frog predation and increase competition for
resources. Bu
[…truncated; see source link]Indexed from Federal Register on December 28, 2021.
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.