Rule2026-12077
Endangered and Threatened Wildlife and Plants; Two Species Not Warranted for Listing as Endangered or Threatened Species
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Published
June 16, 2026
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (Service), announce findings that two species are not warranted for listing as endangered or threatened species under the Endangered Species Act of 1973, as amended (Act). After a thorough review of the best scientific and commercial data available, we find that it is not warranted at this time to list the Sangre de Cristo peaclam (Pisidium sanguinichristi) and black-backed tanager (Stilpnia peruviana). However, we ask the public to submit to us at any time any new information relevant to the status of either of the species mentioned above or their habitats.
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<title>Federal Register, Volume 91 Issue 115 (Tuesday, June 16, 2026)</title>
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[Federal Register Volume 91, Number 115 (Tuesday, June 16, 2026)]
[Rules and Regulations]
[Pages 36090-36094]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-12077]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FXES1111090FEDR-267-FF09E21000]
Endangered and Threatened Wildlife and Plants; Two Species Not
Warranted for Listing as Endangered or Threatened Species
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notification of findings.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce
[[Page 36091]]
findings that two species are not warranted for listing as endangered
or threatened species under the Endangered Species Act of 1973, as
amended (Act). After a thorough review of the best scientific and
commercial data available, we find that it is not warranted at this
time to list the Sangre de Cristo peaclam (Pisidium sanguinichristi)
and black-backed tanager (Stilpnia peruviana). However, we ask the
public to submit to us at any time any new information relevant to the
status of either of the species mentioned above or their habitats.
DATES: The findings in this document were made on June 16, 2026.
ADDRESSES: Detailed descriptions of the bases for these findings are
available on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a> under the
following docket numbers:
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Species Docket No.
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Sangre de Cristo peaclam..................... FWS-R2-ES-2026-1453
black-backed tanager......................... FWS-HQ-ES-2026-1454
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Those descriptions are also available by contacting the appropriate
person, as specified under FOR FURTHER INFORMATION CONTACT. Please
submit any new information, materials, comments, or questions
concerning these findings to the appropriate person, as specified under
FOR FURTHER INFORMATION CONTACT.
FOR FURTHER INFORMATION CONTACT:
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Species Contact Information
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Sangre de Cristo peaclam............... Mark Horner, New Mexico
Ecological Services Field
Office, 505-657-2054,
<a href="/cdn-cgi/l/email-protection#d1bcb0a3ba8eb9bea3bfb4a391b7a6a2ffb6bea7"><span class="__cf_email__" data-cfemail="fb969a8990a4939489959e89bb9d8c88d59c948d">[email protected]</span></a>.
black-backed tanager................... Rachel London, Manager, Branch
of Delisting and Foreign
Species, Ecological Services
Program, Headquarters, 703-358-
2171, <a href="/cdn-cgi/l/email-protection#0b796a68636e67546764656f64654b6d7c78256c647d"><span class="__cf_email__" data-cfemail="582a393b303d34073437363c3736183e2f2b763f372e">[email protected]</span></a>.
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the United States.
SUPPLEMENTARY INFORMATION:
Background
Under section 4(b)(3)(B) of the Act (16 U.S.C. 1533(b)(3)(B)), we
are required to make a finding on whether or not a petitioned action is
warranted within 12 months after receiving any petition that we have
determined contains substantial scientific or commercial information
indicating that the petitioned action may be warranted (``12-month
finding''). We must make a finding that the petitioned action is: (1)
not warranted; (2) warranted; or (3) warranted but precluded by other
listing activity. We must publish a notification of these 12-month
findings in the Federal Register.
Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations at part 424 of title 50 of the Code of Federal Regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or reclassifying species on the Lists of Endangered and
Threatened Wildlife and Plants (Lists). The Act defines ``species'' as
including 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. The Act defines an ``endangered
species'' as a species that is in danger of extinction throughout all
or a significant portion of its range (16 U.S.C. 1532(6)) 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 (16 U.S.C. 1532(20)). Under section
4(a)(1) of the Act, the Secretary of the Interior (Secretary) may
determine whether any species is an endangered species or a threatened
species because of any of the following 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.
These factors represent broad categories of natural or human-caused
actions or conditions that could have an effect on a species' continued
existence. In evaluating these actions and conditions, we look for
those that may have a negative effect on individuals of the species, as
well as other actions or conditions that may ameliorate any negative
effects or may have positive effects.
We use the term ``threat'' to refer in general to actions or
conditions that are known to or are reasonably likely to negatively
affect individuals of a species. The term ``threat'' includes actions
or conditions that have a direct impact on individuals (direct
impacts), as well as those that affect individuals through alteration
of their habitat or required resources (stressors). The term ``threat''
may encompass--either together or separately--the source of the action
or condition or the action or condition itself. However, the mere
identification of any threat(s) does not necessarily mean that the
species meets the statutory definition of an ``endangered species'' or
a ``threatened species.'' In determining whether a species meets either
definition, we must evaluate all identified threats by considering the
species' expected response and the effects of the threats--in light of
those actions and conditions that will ameliorate the threats--on an
individual, population, and species level. We evaluate each threat and
its expected effects on the species, then analyze the cumulative effect
of all of the threats on the species as a whole. We also consider the
cumulative effect of the threats in light of those actions and
conditions that will have positive effects on the species, such as any
existing regulatory mechanisms or conservation efforts. The Secretary
determines whether the species meets the definition of an ``endangered
[[Page 36092]]
species'' or a ``threatened species'' only after conducting this
cumulative analysis and describing the expected effect on the species.
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, which is
further described in the 2009 Memorandum Opinion on the foreseeable
future from the Department of the Interior, Office of the Solicitor (M-
37021, January 16, 2009; ``M-Opinion,'' available online at <a href="https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf">https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf</a>).
The foreseeable future extends as far into the future as the U.S. Fish
and Wildlife Service can make reasonably reliable predictions about the
threats to the species and the species' responses to those threats. We
need not identify the foreseeable future in terms of a specific period
of time. We will describe the foreseeable future on a case-by-case
basis, using the best scientific and commercial data available and
taking into account considerations such as the species' life-history
characteristics, threat projection timeframes, and environmental
variability. In other words, the foreseeable future is the period of
time over which we can make reasonably reliable predictions.
``Reliable'' does not mean ``certain;'' it means sufficient to provide
a reasonable degree of confidence in the prediction, in light of the
conservation purposes of the Act.
In conducting our evaluation of the five factors provided in
section 4(a)(1) of the Act to determine whether the Sangre de Cristo
peaclam or black-backed tanager meet the Act's definition of an
``endangered species'' or a ``threatened species,'' we considered and
thoroughly evaluated the best scientific and commercial data available
regarding the past, present, and future stressors and threats. We
reviewed the petition, information available in our files, and other
available published and unpublished information for the species. Our
evaluation may include information from recognized experts; Federal,
State, and Tribal governments; academic institutions; foreign
governments; private entities; and other members of the public.
In accordance with the regulations at 50 CFR 424.14(h)(2)(i), this
document announces the not-warranted findings on petitions to list the
two species. We have also elected to include brief summaries of the
analyses on which these findings are based. We provide the full
analyses, including the reasons and data on which the findings are
based, in the decisional files for the Sangre de Cristo peaclam and
black-backed tanager. Below, we describe the documents containing these
analyses.
The species assessment forms for the Sangre de Cristo peaclam and
black-backed tanager each contain more detailed biological information,
a thorough analysis of the listing factors, a list of literature cited,
and an explanation of why we determined that these species do not meet
the Act's definition of an ``endangered species'' or a ``threatened
species.'' To inform our status review, we completed a species status
assessment (SSA) report for the black-backed tanager. This SSA report
contains a thorough review of the taxonomy, life history, ecology,
current status, and projected future status for this species. No SSA
was completed for the Sangre de Cristo peaclam. This supporting
information can be found on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a>
under the appropriate docket number (see ADDRESSES, above).
Sangre de Cristo Peaclam
Previous Federal Actions
On June 25, 2007, we received a petition from Forest Guardians (now
WildEarth Guardians) to list 475 species, including the Sangre de
Cristo peaclam, as an endangered or threatened species under the Act.
On December 16, 2009, we published a 90-day finding (74 FR 66866) that
the petition presented substantial information indicating that listing
may be warranted for the Sangre de Cristo peaclam. This document
constitutes our 12-month finding on the June 25, 2007, petition to list
the Sangre de Cristo peaclam under the Act.
Summary of Finding
The Sangre de Cristo peaclam is a small freshwater clam thought to
occur exclusively in Middle Fork Lake, a cirque lake in the Sangre de
Cristo Mountains, Taos County, New Mexico, at nearly 11,000 feet (ft)
(3,353 meters (m)) elevation. The initial species' description claimed
that the Sangre de Cristo peaclam is found in mud along emergent
grasses in sheltered embayments along the edge and outlet of the lake
and suggested the species may occur in other portions of the southern
Rocky Mountains. However, surveys consisting of over 750 voucher
samples from Middle Fork Lake alone, including surveys initiated by the
New Mexico Department of Game and Fish in the mid-1990s, have failed to
find any additional occurrences. The 1987 description notes that the
Sangre de Cristo peaclam was locally abundant, a finding inconsistent
with subsequent sampling efforts.
Sphaeriid clams can be problematic to distinguish morphologically
due to a limited number of shared ancestral traits and high levels of
intraspecific phenotypic variation. Therefore, recent research has
focused on a genetic approach to potentially clarify the taxonomy of
the Sangre de Cristo peaclam. Whole body samples were collected from 14
sites in New Mexico and west Texas, including Middle Fork Lake. Two
independent genetic markers capable of accurately identifying a
species' uniqueness were then used to evaluate the validity of the
Sangre de Cristo peaclam as a distinct species.
The results showed that the genetic sequences from Middle Fork Lake
were effectively identical to those of both described and undescribed
species listed in GenBank, a publicly available genetic database. This
means there were very few differences in the genetic markers between
the Middle Fork Lake samples and species already described in the
scientific literature (e.g., Euglesa fallax, E. compressa, E.
variabilis, E. casertana, E. walkeri, E. floresiana, E. subtruncata,
Sphaerium lacustre, S. occidentale, and S. indicum). One genetic marker
from Middle Fork Lake matched (99-100 percent identical) samples from
San Gregorio and Pioneer Lakes, which are about 150 kilometers (km)
(93.2 miles (mi)) and 10 km (6.2 mi) away, and matched exclusively with
E. variabilis and E. casertana. Another genetic marker from Middle Fork
Lake also matched (99-100 percent identical) samples from eight other
locations in the region.
A phylogenetic analysis (i.e., an evolutionary tree that models the
relationships and common ancestors of a group of organisms based on
genetic data) of a combination of both markers showed analogous results
with multiple, well-supported clades (branches). The only monophyletic
clade (a branch with a single species) is from Perch Lake, which was
most closely related to an undescribed species and E. floresiana, E.
casertana or E. subtruncata. The samples from Middle Fork Lake are
found in two statistically supported clades, one of which also included
individuals from San Gregorio Lake, and the other of which also
included individuals from Pioneer Lake in northern New Mexico.
The results of the various genetic analyses strongly suggest that
the Sangre de Cristo peaclam is not supported as a valid taxon.
Instead, individuals that
[[Page 36093]]
had been previously identified as Sangre de Cristo peaclam are most
likely a member of either the most widely distributed non-marine
mollusk in the world, E. casertana, or E. variabilis, which occurs
throughout North America.
In conclusion, genetic evidence strongly indicates that the Sangre
de Cristo peaclam is not a valid taxon. Additionally, since the initial
species description in 1987, hundreds of samples have been examined
genetically or morphologically and have failed to identify any specimen
from Middle Fork Lake that are clearly Sangre de Cristo peaclam despite
claims that the species was locally abundant. Thus, we consider
specimens previously identified as Sangre de Cristo peaclam to actually
be a more widespread cosmopolitan species rather than a narrow endemic
limited to Middle Fork Lake. The best scientific data available present
clear evidence that the Sangre de Cristo peaclam is not a unique
species.
Thus, after assessing the best available information, we find that
the Sangre de Cristo peaclam is not supported as a valid taxon, but
rather a member of a widely dispersed cosmopolitan species, likely to
be E. casertana or E. variabilis. Therefore, the Sangre de Cristo
peaclam is not warranted for listing because it is not a listable
entity under the Act. A detailed discussion of the basis for these
findings can be found in the Sangre de Cristo peaclam species
assessment form and other supporting documents on <a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket No. FWS-R2-ES-2026-1453 (see
ADDRESSES, above).
Black-Backed Tanager
Previous Federal Actions
On May 6, 1991, we received a petition from the International
Council for Bird Preservation (now BirdLife International) to list 53
different bird species, including the black-backed tanager (Stilpnia
peruviana), as an endangered or threatened species under the Act. On
December 16, 1991, we published a 90-day finding that the petition
contained substantial information indicating that listing may be
warranted for all species (56 FR 65207). On May 21, 2004, we published
our resubmitted petition findings that listing the black-backed tanager
was warranted but precluded by higher priority actions, and we added
the entity to our list of candidate species (69 FR 29354). We
subsequently published 11 candidate notices of review between 2007 and
2025 which continued to find that the species was warranted but
precluded by higher priority actions (72 FR 20184, April 23, 2007; 73
FR 44062, July 29, 2008; 74 FR 40540, August 12, 2009; 76 FR 25150, May
3, 2011; 78 FR 24604, April 25, 2013; 81 FR 71457, October 17, 2016; 84
FR 54732, October 10, 2019; 86 FR 43470, August 9, 2021; 87 FR 26152,
May 3, 2022; 88 FR 41560, June 27, 2023; 90 FR 48912, October 31,
2025). At the time of the petition, the black-backed tanager was
classified as Tangara peruviana. However, the black-backed tanager was
later placed in the genus Stilpnia, and we now treat Tangara peruviana
as a synonym. This document constitutes our 12-month finding on the May
6, 1991, petition to list the black-backed tanager under the Act.
Summary of Finding
The black-backed tanager is endemic to the Atlantic Forest along
the southeastern coast of Brazil, and while the extent of the species'
historical range is not known, it is estimated to currently occupy 11
to 100 locations throughout an extant range that measures approximately
72,500 square kilometers (km\2\) (28,000 square miles (mi\2\)).
The black-backed tanager mainly occupies coastal sandbank forests,
restinga (coastal scrubland), and lowland forests (up to ~700 m (2,297
ft) in elevation), and its diet consists primarily of fruit, and to a
smaller extent, invertebrates found in canopy vegetation. The species
is also known to visit other habitat types when certain fruit-bearing
plants are ripening (e.g., secondary forest, edge habitat near
pastures, gardens, and orchards).
We have carefully assessed the best scientific and commercial data
available regarding the past, present, and future threats to the black-
backed tanager, and we evaluated all relevant factors under the five
listing factors, including any regulatory mechanisms and conservation
measures addressing these threats. The primary threat affecting the
black-backed tanager's biological status is habitat loss from
deforestation and sea level rise.
The black-backed tanager is ``not rare'' within suitable habitat,
but because the species breeds in coastal habitats, its viability is
closely tied to the persistence of these habitats within its range.
Protected areas overlap with 21.5 percent of the black-backed tanager's
extant range, and 49.4 percent of the remaining restinga within that
range. These protected areas maintain very low illegal deforestation
rates (0.08-0.1 percent) and provide adequate legal protection to the
black-backed tanager's remaining suitable habitat. However, small-scale
illegal deforestation has caused the loss of 0.69 percent of the
remaining restinga within the species' range since 2010. This equates
to an annual loss of approximately 0.05 percent of restinga within the
black-backed tanager's range, which if projected into the future, could
result in an additional loss of 1.25 percent of restinga habitat over
the next 25 years. However, because one of the main tree species that
black-backed tanagers feed on (Brazilian peppertree, Schinus
terebinthifolia) persists in disturbed environments, it is likely that
the species' viability will not be significantly impacted by small-
scale deforestation in the future. Furthermore, multiple ongoing
restoration efforts are actively restoring degraded habitat within the
black-backed tanager's range and contributing to improving the species'
current condition. So, while small-scale illegal deforestation may
continue to occur, the amount of deforested habitat is likely to be
offset in the future by these ongoing restoration initiatives such that
we expect the total amount of suitable habitat available for the
species to likely be stable or increasing.
Because the black-backed tanager mainly occupies coastal habitats,
both sea level rise and temperature increases resulting from climate
change are projected to impact the species' viability in the future.
Restingas are projected to be one of the more climactically stable
habitat types in the Atlantic Forest biome and are projected to lose 7
percent of their area by 2070 due to temperature increases resulting
from climate change. In addition, coastal Brazil is expected to
experience a median range of sea level rise of 0.22-0.25 m by 2050, for
shared socioeconomic pathway (SSP)2-4.5 and SSP5-8.5 respectively.
Because restingas consist mostly of pioneer plants, they may be able to
retreat further inland as sea levels rise. However, many restingas in
highly developed areas will be unable to retreat further inland due to
existing urban structures, removing the possibility that some restingas
within the black-backed tanager's range adapt to sea level rise.
Furthermore, it is unknown how restingas may tolerate increased
flooding and saltwater intrusion, both of which may lead to additional
habitat loss and degradation. The black-backed tanager is known to
opportunistically feed on ripening fruits in more inland areas and has
even established residency in some higher elevation areas. Therefore,
while it is unknown exactly how restingas will adapt to
[[Page 36094]]
changing environmental conditions, the species has demonstrated the
ability to persist in more inland habitats and is therefore likely
capable of withstanding small-scale losses of coastal habitat.
Considering the potential effects of additional small-scale habitat
loss, the likely stability or net gain of suitable habitat via
restoration efforts, and the species' ability to adapt to shifting
environmental conditions, the black-backed tanager will likely have
either stable or slightly reduced viability into the foreseeable
future.
We also evaluated whether the black-backed tanager is endangered or
threatened throughout a significant portion of its range. We did not
find any portion of the black-backed tanager's range for which both (1)
the portion is ``significant;'' and (2) the species is in danger of
extinction in that portion, either now or likely to become so within
the foreseeable future. Thus, after assessing the best available
scientific and commercial data available, we conclude that the black-
backed tanager is not in danger of extinction throughout a significant
portion of its range, or likely to become so within the foreseeable
future.
Based on the best scientific and commercial data available, we
determine that the black-backed tanager does not meet the 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
black-backed tanager is not warranted at this time. A detailed
discussion of the basis for this finding can be found in the black-
backed tanager species assessment form and other supporting documents
on <a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket No. FWS-HQ-ES-2026-1454
(see ADDRESSES, above).
Peer Review
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 in
listing actions under the Act, we solicited independent scientific
reviews of the information contained in the black-backed tanager SSA
report from three experts and received peer review from two independent
peer reviewers. Results of this structured peer review process can be
found at <a href="https://www.regulations.gov">https://www.regulations.gov</a> under Docket No. FWS-HQ-ES-2026-
1454. We incorporated the results of this review, as appropriate, into
the SSA report, which is the foundation for this finding. We did not
solicit peer review for the Sangre de Cristo peaclam because there was
no SSA drafted for the species.
New Information
We request that you submit any new information concerning the
taxonomy of, biology of, ecology of, status of, or stressors to the
Sangre de Cristo peaclam or black-backed tanager to the appropriate
person, as specified under FOR FURTHER INFORMATION CONTACT, whenever it
becomes available. New information will help us monitor these species
and make appropriate decisions about their conservation and status. We
encourage local agencies and stakeholders to continue cooperative
monitoring and conservation efforts.
References
A complete list of the references used in these petition findings
is available in the relevant species assessment form, which is
available on the internet at <a href="https://www.regulations.gov">https://www.regulations.gov</a> in the
appropriate docket (see ADDRESSES, above) and upon request from the
appropriate person (see FOR FURTHER INFORMATION CONTACT, above).
Authority
The authority for this action is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Brian R. Nesvik,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2026-12077 Filed 6-15-26; 8:45 am]
BILLING CODE 4333-15-P
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