[Federal Register Volume 88, Number 199 (Tuesday, October 17, 2023)]
[Rules and Regulations]
[Pages 71644-71682]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-22377]
[[Page 71643]]
Vol. 88
Tuesday,
No. 199
October 17, 2023
Part II
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; Removal of 21 Species
From the List of Endangered and Threatened Wildlife; Final Rule
Federal Register / Vol. 88, No. 199 / Tuesday, October 17, 2023 /
Rules and Regulations
[[Page 71644]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FF08E22000 FXES111309FEDR 234]
RIN 1018-BC98
Endangered and Threatened Wildlife and Plants; Removal of 21
Species From the List of Endangered and Threatened Wildlife
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Final rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service or USFWS), are
removing 21 species from the Federal List of Endangered and Threatened
Wildlife due to extinction. This action is based on a review of the
best available scientific and commercial information, which indicates
that these species are no longer extant and, as such, no longer meet
the definition of an endangered species or a threatened species under
the Endangered Species Act of 1973, as amended (Act).
DATES: This rule is effective November 16, 2023.
ADDRESSES: The proposed rule and this final rule, the comments we
received on the proposed rule, and supporting documents are available
at https://www.regulations.gov under the following docket numbers:
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Species Docket No.
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Kauai akialoa............................. FWS-R1-ES-2020-0104
Kauai nukupuu............................. FWS-R1-ES-2020-0104
Kauai [revaps]o[revaps]o (honeyeater)..... FWS-R1-ES-2020-0104
Large Kauai thrush (kam[revaps]a)......... FWS-R1-ES-2020-0104
Maui akepa................................ FWS-R1-ES-2020-0104
Maui nukupuu.............................. FWS-R1-ES-2020-0104
Molokai creeper (kakawahie)............... FWS-R1-ES-2020-0104
Po[revaps]ouli (honeycreeper)............. FWS-R1-ES-2020-0104
Bridled white-eye......................... FWS-R1-ES-2020-0104
Little Mariana fruit bat.................. FWS-R1-ES-2020-0104
San Marcos gambusia....................... FWS-R2-ES-2020-0105
Scioto madtom............................. FWS-R3-ES-2020-0106
Flat pigtoe............................... FWS-R4-ES-2020-0107
Southern acornshell....................... FWS-R4-ES-2020-0107
Stirrupshell.............................. FWS-R4-ES-2020-0107
Upland combshell.......................... FWS-R4-ES-2020-0107
Green blossom (pearly mussel)............. FWS-R4-ES-2020-0108
Tubercled blossom (pearly mussel)......... FWS-R4-ES-2020-0108
Turgid blossom (pearly mussel)............ FWS-R4-ES-2020-0108
Yellow blossom (pearly mussel)............ FWS-R4-ES-2020-0108
Bachman's warbler......................... FWS-R4-ES-2020-0110
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FOR FURTHER INFORMATION CONTACT:
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Species Contact information
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Bridled white-eye, Kauai akialoa, Kauai Earl Campbell, Field
nukupuu, Kauai [revaps]o[revaps]o Supervisor, Pacific Islands
(honeyeater), large Kauai thrush Fish and Wildlife Office, 300
(kama), little Mariana fruit bat, Maui Ala Moana Boulevard, Suite 3-
akepa, Maui nukupuu, Molokai creeper 122, Honolulu HI 96850,
(kakawahie), and po[revaps]ouli Telephone: 808-792-9400.
(honeycreeper).
Bachman's warbler...................... Thomas McCoy, Field Supervisor,
South Carolina Field Office,
176 Croghan Spur, Charleston,
SC 29407, Telephone: 843-300-
0431.
Flat pigtoe, southern acornshell, James Austin, Deputy Field
stirrupshell, and upland combshell. Supervisor, Mississippi Field
Office, 6578 Dogwood View
Parkway, Suite A, Jackson, MS
39213, Telephone: 601-321-
1129.
Green blossom (pearly mussel), Daniel Elbert, Field
tubercled blossom (pearly mussel), Supervisor, Tennessee Field
turgid blossom (pearly mussel), and Office, Interior Region 2--
yellow blossom (pearly mussel). South Atlantic-Gulf
(Tennessee), 446 Neal Street,
Cookeville, TN 38506,
Telephone: 931-528-6481.
San Marcos gambusia.................... Karen Myers, Field Supervisor,
Austin Ecological Services
Field Office, 1505 Ferguson
Lane, Austin, TX 78754,
Telephone: 512-490-0057.
Scioto madtom.......................... Patrice Ashfield, Field
Supervisor, Ohio Ecological
Services Field Office, 4625
Morse Road, Suite 104,
Columbus, OH 43230, Telephone:
614-416-8993.
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Individuals in the United States who are deaf, deafblind, hard of
hearing, or have a speech disability may dial 711 (TTY, TDD, or
TeleBraille) to access telecommunications relay services. Individuals
outside the United States should use the relay services offered within
their country to make international calls to the point-of-contact in
the United States.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Section 4 of the Act (16 U.S.C.
1533) and its implementing regulations in title 50 of the Code of
Federal Regulations (50 CFR part 424) set forth the procedures for
adding species to,
[[Page 71645]]
removing species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants in 50 CFR part 17. Under
our regulations at 50 CFR 424.11(e)(1), a species shall be delisted if,
after conducting a status review based on the best scientific and
commercial data available, we determine that the species is extinct.
The 21 species in this final rule are currently listed as endangered or
threatened; we are delisting them due to extinction. We can only delist
a species by issuing a rule to do so.
What this document does. We are removing 21 species from the List
of Endangered and Threatened Wildlife (List) due to extinction.
While our September 30, 2021, proposed rule (86 FR 54298) proposed
to delist 23 species, this rule makes final the delisting of only 21 of
those. Elsewhere in this issue of the Federal Register, we withdraw our
proposed delisting of Phyllostegia glabra var. lanaiensis, which was
part of our September 30, 2021, proposed rule.
The basis for our action. We have determined that the 21 species
that are the subjects of this rule should be removed from the List
because the best available information indicates that they are extinct.
Peer review. In accordance with our policy, ``Notice of Interagency
Cooperative Policy for Peer Review in Endangered Species Act
Activities,'' which was published on July 1, 1994 (59 FR 34270) and our
August 22, 2016, Director's Memorandum ``Peer Review Process,'' we
sought the expert opinion of 28 appropriate and independent specialists
for 13 species in this rule. We requested those experts review the
scientific data and interpretations for each species or group of
species for which the associated 5-year review had not been peer
reviewed prior to publication of the proposed rule (86 FR 54298;
September 30, 2021). For the eight southeastern mussel species, the 5-
year reviews were peer reviewed prior to the publication of the
proposed rule. In certain cases, species were grouped together for peer
review based on similarities in biology or geographic occurrences. We
sent copies of the 5-year species status reviews to the peer reviewers
immediately following the proposed rule's publication in the Federal
Register. The purpose of such review is to ensure that our decisions
are based on scientifically sound data, assumptions, and analysis. We
received feedback from 16 of the 28 peer reviewers contacted. We have
incorporated the results of these reviews, as appropriate, into the
appropriate assessment forms and this final rule. Additionally, we have
provided our responses to peer review feedback below, under Summary of
Comments and Recommendations.
Summary of Changes From the Proposed Rule
In preparing this final rule, we reviewed and fully considered all
applicable comments we received during the comment period from the peer
reviewers and the public on the proposed rule to delist 23 species due
to extinction. In this final rule, we are delisting 21 species due to
extinction.
Due to new surveys conducted, we are withdrawing our proposed rule
to remove Phyllostegia glabra var. lanaiensis from the List of
Endangered and Threatened Plants; the document withdrawing the proposed
delisting of P. glabra var. lanaiensis is published elsewhere in this
issue of the Federal Register.
On July 7, 2022, we published in the Federal Register (87 FR 40477)
a 6-month extension of the final determination on whether to delist the
ivory-billed woodpecker (Campephilus principalis). That document also
reopened the public comment period on the proposed delisting of the
ivory-billed woodpecker. We extended the final determination on the
proposed delisting of this species due to substantial disagreement
among scientists knowledgeable about the species regarding the
sufficiency or accuracy of the available data relevant to the
determination. In a separate, future publication, we will either
finalize the delisting of the ivory-billed woodpecker due to extinction
or withdraw the proposed delisting of this species and retain the
species' status as an endangered species.
Lastly, in the proposed rule regulation Sec. 17.95 for the Eleven
Mobile River Basin Mussel Species Critical Habitat designation, we had
identified the orange-nacre mucket under the name Lampsilis perovalis.
We have corrected this to the name the species was listed under,
Hamiota perovalis.
Summary of Comments and Recommendations
In the proposed rule published on September 30, 2021 (86 FR 54298),
we requested that all interested parties submit written comments on the
proposal by November 29, 2021. We also contacted appropriate State
agencies, scientific experts and organizations, and other interested
parties and invited them to comment on the proposal. A newspaper notice
inviting the public to provide comments was published in USA Today on
October 8, 2021. We received a request for a public hearing for the
ivory-billed woodpecker on November 10, 2021. A newspaper notice
inviting the public to provide comments at the public hearing was
published in USA Today on January 11, 2022. A public hearing was
conducted on January 26, 2022. All applicable substantive information
we received during the comment period has been incorporated directly
into this final determination and the appropriate species assessment
forms or is addressed below.
Of the public comments we received on the proposed rule, the
majority concerned the ivory-billed woodpecker. We will address those
comments in a separate, future publication. Of the public comments
related to the other 22 species, two included substantive comments that
are summarized below and incorporated into this final rule and the
associated species assessment forms, as appropriate.
Peer Reviewer Comments
In accordance with our 1994 peer review policy, we solicited expert
opinion from knowledgeable individuals with scientific expertise that
included familiarity with these species and their habitat, biological
needs, and threats. As stated above, we sought peer review for species
whose 5-year reviews had not been previously peer reviewed. We reviewed
all comments received from peer reviewers for substantive issues and
new information regarding these species. The reviewers made suggestions
and comments that strengthened our analysis and improved this final
rule.
For the Bachman's warbler, we sent the 5-year reviews to a total of
three peer reviewers. We received responses from all three reviewers.
Peer reviewers provided additional information on the biological
background information of the species. We have incorporated the
information into both this rule and the supporting documents.
For the Scioto madtom, we sent the 5-year review to a total of
three peer reviewers. We received responses from all three reviewers.
Peer reviewers provided clarification on the results of prior surveys
that were conducted. We have incorporated the information into this
rule and the supporting documents.
For the San Marcos gambusia, we sought the expert opinions of three
specialists with expertise in biology, habitat, and threats to the
species, and we received responses from all three experts. Two peer
reviewers confirmed that San Marcos gambusia should be delisted due to
extinction, and the third peer reviewer had minor editorial
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comments that were incorporated, where appropriate, into this rule and
the supporting documents. The peer reviewers did not provide any
additional substantial information that would influence a change in our
decision from the proposed rule.
For the Hawaiian and Mariana Islands species, we sought the expert
opinion of a total of 11 individuals with expertise in the biology,
habitat, and threats to the species. Six reviewers provided comments
and feedback. We have organized and addressed those comments below.
Little Mariana Fruit Bat
(1) Comment: One peer reviewer noted that the related, larger-
bodied Mariana fruit bat (called fanihi in the Chamorro language) moves
between Rota and Guam, stating that Rota has larger populations of the
species compared to Guam, but that large groups of fanihi can be
observed on Guam when Rota experiences storms. The reviewer wondered
whether, similarly, the little Mariana fruit bat could be present on
Rota and move between Rota and Guam.
Response: We conclude that it is extremely unlikely that the little
Mariana fruit bat has persisted undetected on Rota or Guam considering
the tremendous amount of effort that has gone into monitoring the
fanihi on those islands.
(2) Comment: One peer reviewer asked how environmental threats such
as typhoons might impact little Mariana fruit bat populations and
hypothesized that if the little Mariana fruit bat and the fanihi were
to have roosted together, the fanihi may have contributed to the
decline of the little Mariana fruit bat by outcompeting for resources
following typhoon or other similar environmental events.
Response: We noted possible vulnerabilities of the little Mariana
fruit bat to typhoons and other environmental factors under ``Threats
Evaluation'' in the species' 5-year review (USFWS 2019, p. 4). If the
little Mariana fruit bat exhibited traits similar to that of other
Pteropus spp., including low fecundity, it would have been susceptible
to most large-scale disturbances to its habitat, particularly typhoons.
However, too little is known about the little Mariana fruit bat's
biology for us to speculate about the outcome of possible competition
with the fanihi for resources following events such as typhoons.
(3) Comment: One peer reviewer asked about the potential for using
genetics to determine whether the bats present on Guam and Rota
represent a single species and whether the little Mariana fruit bat is
truly extinct on both islands.
Response: As noted in our 5-year review for the little Mariana
fruit bat, genetic analysis of skin samples of Pteropus spp. concluded
that the species was genetically distinct (Almeida et al. 2014,
entire). We would welcome any new genetic information about the fanihi
or the little Mariana fruit bat should it become available, but in the
absence of this information, we conclude that the best available
information indicates that the little Mariana fruit bat is extinct.
Hawaiian Islands Bird Species
(4) Comment: One peer reviewer mentioned that the referenced
searches for po[revaps]ouli in K[imacr]pahulu Valley (1997-1999) relied
primarily on existing trails from which it is not possible to
adequately survey the entire area of rainforest habitat where
po[revaps]ouli could still potentially persist. The reviewer further
stated that K[imacr]pahulu Valley (and much of the east Maui
rainforest) has many steep gulches and frequently dense and
impenetrable vegetation and stream beds, and the area is very difficult
to cover adequately on foot, adding further difficultly to survey
efforts.
Response: Specific searches to locate Maui's rarest forest birds
were undertaken in 1967 and 1981 in K[imacr]pahulu Valley, and variable
circular-plot (VCP) counts were conducted in 1980, 1992, and 1996 along
Hawaii Forest Bird Survey (HFBS) transects in rainforests of Maui's
east region (Reynolds and Snetsinger 2001, p. 139). Variable circular
plot (VCP) studies are surveys conducted at pre-established stations
along transects. A surveyor counts all birds seen and heard during an
8-minute count period and estimates the distance from the count station
to each bird seen or heard. From this information, the VCP studies
estimate the number of birds in a surveyed area, along with a
confidence interval for the estimate. Despite these searches, the
po[revaps]ouli has never been found in K[imacr]pahulu Valley and is
known historically only from the Hanawi Natural Area Reserve (NAR) of
northeast Maui (Scott et al. 1986, p. 183), where it was most recently
observed in 2003 and 2004 (USFWS 2006, pp. 2-153-2-154). Collectively,
the weight of evidence indicates that the po[revaps]ouli is extinct.
(5) Comment: One peer reviewer indicated that po[revaps]ouli is
extremely cryptic and moves quietly through the understory and canopy.
This species could easily be missed by inexperienced observers not
familiar with the bird's behavior and is even easy to miss for
experienced observers searching in known occupied habitat.
Response: After the continued existence of five to six
po[revaps]ouli was confirmed in 1994-1995 in the K[umacr]hiwa drainage
of Hanawi NAR, thorough surveys of the species' historical range were
conducted from 1995 to 1997, with 81 sightings of five individual
po[revaps]ouli (Baker et al. 2001, p. 144). In 1997, only three
individual birds were found in three separate territories, and one
individual was color-banded in 1997. The po[revaps]ouli was last
observed in 2003 and 2004 (USFWS 2006, pp. 2-153-2-154) and despite
extensive time in the area from 2006 to 20011, no other birds have been
located since these surveys. Using 2004 as the last reliable
observation record for po[revaps]ouli, 2005 is estimated to be the year
of extinction, with 2008 as the upper 95 percent confidence bound on
that estimate (Elphick et al. 2010, p. 620). It is extremely unlikely
that the po[revaps]ouli has persisted undetected considering extensive
search efforts to document presence of the species on Maui.
(6) Comment: One peer reviewer indicated that extensive searches
for birds on the island of Maui were not conducted at elevations where
higher presence of avian disease is expected, based on the assumption
that rare bird species would not persist because of the threat of avian
malaria.
Response: The Rare Bird Search (RBS) on east Maui was conducted at
elevations as low as 3,280 feet (1,000 meters), which is well within
the zone of higher prevalence of avian malaria (Reynolds and Snetsinger
2001, p. 134). We have added this information to the species accounts
of the Maui forest birds in this final rule.
(7) Comment: One peer reviewer indicated that the traditional VCP
survey methods are not effective for detecting rarer, patchily
distributed birds and particularly ineffective for a species like the
po[revaps]ouli, which vocalizes infrequently and sounds similar to both
Maui parrotbill (Pseudonestor xanthophrys) and Maui creeper
(Paroreomyza montana). The reviewer further stated that confirmation of
po[revaps]ouli is primarily visual, which can be quite challenging
given its dark coloration, the dense vegetation it inhabits, and the
frequently inclement rainy/misty survey conditions.
Response: The VCP survey method does have limited effectiveness for
detection of po[revaps]ouli. Because of this, we relied strongly on
information from other sources including RBS and field studies
conducted in Hanawi NAR in
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the area of the only known historical population of po[revaps]ouli.
Collectively, the weight of evidence indicates that the po[revaps]ouli
is extinct.
(8) Comment: One peer reviewer asked that we better define what is
meant by ``extensive presence'' and ``qualified observers'' in
reference to personnel conducting forest bird research in the field.
Response: While working on Maui parrotbill (also called kiwikiu)
recovery from 2006 to 2011, personnel with the Maui Forest Bird
Recovery Project (MFBRP) spent thousands of person hours (i.e.,
extensive presence) in the area of the last po[revaps]ouli sightings.
These personnel (i.e., qualified observers) who conducted this field
work were highly trained to be able to detect all species of Hawaiian
forest birds by sight and sound.
(9) Comment: One peer reviewer recommended exploring some of the
newer survey design methods and analyses (e.g., occupancy estimation)
for rare species and to further develop and optimize sampling protocols
for rarer bird species like po[revaps]ouli, Maui akepa, and Maui
nukupuu.
Response: Exploring possible application of different survey design
methods and analyses and further developing and optimizing sampling
protocols for rarer bird species will be taken into consideration for
future survey and sampling efforts. However, we determined that the
methods we used to determine absence of rare species are robust, and we
have high confidence in our conclusion that the Hawaiian forest birds
that are addressed in this rule are extinct.
(10) Comment: One peer reviewer indicated that the three types of
surveys/searches used to detect po[revaps]ouli each have their own
inherent strengths and weaknesses. The commenter stated that although
the protocols for two of the surveys/searches (VCP and RBS) are
described, protocols and analytical techniques for additional surveys
conducted within Hanawi NAR and elsewhere on east Maui are not
described.
Response: The third type of survey/search is best described as the
long-term presence of qualified personnel doing field work in an area
where rare species could still persist. While working on Maui
parrotbill (kiwikiu) recovery from 2006 to 2011, personnel with the
MFBRP spent thousands of person hours in the area of the last
po[revaps]ouli sightings. Much of this consisted of active searches for
kiwikiu, observations of this species when it was detected, and other
types of conservation work in the area. Personnel who conducted field
work were highly trained to be able to detect all species of Hawaiian
forest birds by sight and sound. After thousands of hours of working in
the Hanawi NAR in areas where po[revaps]ouli, Maui akepa, and Maui
nukupuu were last detected, and no detections of these species
occurred, MFBRP was strongly confident that po[revaps]ouli, Maui akepa,
and Maui nukupuu are no longer present (Mounce 2021, pers. comm.).
Public Comments
Flat Pigtoe, Stirrupshell, Southern Acornshell, Upland Combshell
(11) Comment: One commenter indicated that we prematurely concluded
that the mussel species are extinct, stating that the species could
possibly be found in places that have not yet been surveyed. The
commenter asked that we study the species longer before they are
declared extinct and removed from the List.
Response: We deemed each of the species (flat pigtoe, stirrupshell,
southern acornshell, and upland combshell) extinct based on significant
alteration of all known historical habitat and lack of detections
during numerous surveys conducted throughout each species' range.
For the flat pigtoe, surveys in historical habitat over the past
three decades have failed to locate the species, and all historical
habitat is impounded or modified by channelization and impoundments
(USFWS 2015, p. 5). No live or freshly dead shells have been observed
since the species was listed in 1987. Surveys between 1990-2001, and in
2002, 2003, 2009, 2011, and 2015, of potential habitat throughout the
historical range, including intensive surveys of the Gainesville
Bendway, where adequate habitat and flows may still occur below the
Gainesville Dam on the Tombigbee River in Alabama, have failed to find
any live or dead flat pigtoes (USFWS 2000, p. 81). Lack of finding the
flat pigtoe despite extensive survey efforts in many habitats indicate
that the species is extinct.
For the stirrupshell, over the past three decades, repeated surveys
(circa 1988, 1998, 2001, 2002, 2003, 2006, 2011) of unimpounded habitat
in the Sipsey and Tombigbee Rivers, including intensive surveys of the
Gainesville Bendway, have failed to find any evidence of stirrupshell
(Service 2009, p. 6; Service 2015, p. 7). The stirrupshell was also
known from the Alabama River; however, over 92 hours of dive- bottom
time were expended searching appropriate habitats for imperiled mussel
species between 1997-2007 without encountering the species (Service
2009, p. 6), and a survey of the Alabama River in 2011 also did not
find stirrupshell (Service 2015, p. 5). Surveys of the Black Warrior
River in 1993 and from 2009-2012 (16 sites) focused on finding
federally listed and State conservation concern priority mussel species
but did not find any stirrupshells (Miller 1994, pp. 9, 42; McGregor et
al. 2009, p. 1; McGregor et al. 2013, p. 1). The stirrupshell has not
been found alive in the Black Warrior River or the Alabama River since
the early 1980s (Service 1989, p. 3). The stirrupshell has not been
collected alive since the Sipsey River was surveyed in 1978 (Service
1989, p. 4); one freshly dead shell was last collected from the Sipsey
River in 1986 (Service 2000, p. 85). In the Tombigbee River, the
stirrupshell has not been collected alive since completion of the
Tennessee-Tombigbee Waterway in 1984 (Service 2015, p. 7). Mussel
surveys within the Tombigbee River drainage during 1984-2015 failed to
document the presence of the stirrupshell (Service 2015, p. 8). Lack of
finding the stirrupshell despite extensive survey efforts in many
habitats indicate that the species is extinct.
For the southern acornshell, many well-planned, comprehensive
surveys by experienced State and Federal biologists have not been able
to locate extant populations of southern acornshell (Service 2000, p.
57; Service 2008, p. 20; Service 2018, p. 7). Both the 2008 and 2018 5-
year reviews reference multiple surveys by experienced Federal, State,
and private biologists--17 survey reports from 1993-2006 and 6 survey
reports from 2008-2017--and despite these repeated surveys of
historical habitat in both the Coosa and Cahaba River drainages, no
living animals or fresh or weathered shells of the southern acornshell
have been located (Service 2008, p. 19; Service 2018, p. 6). The most
recent records for the southern acornshell were from tributaries of the
Coosa River in 1966-1968 and 1974, and the Cahaba River in 1938 (58 FR
14330 at 14331, March 17, 1993; Service 2008, p. 19; Service 2018, p.
5). No living populations of the southern acornshell have been located
since the 1970s (Service 2000, p. 57; Service 2008, p. 20; Service
2018, p. 7). No live or freshly dead shells have been observed since
the species was listed in 1987 (Service 2009, p. 6; Service 2015, p.
7). A freshly dead shell was last collected from the lower Sipsey River
in 1986 (Service 2000, p. 85). Lack of finding the southern acornshell
despite extensive survey efforts in many
[[Page 71648]]
habitats indicate that the species is extinct.
For the upland combshell, the species was last collected in the
Black Warrior River drainage in the early 1900s; in the Coosa River
drainage in 1986, from the Conasauga River near the Georgia/Tennessee
State line; and the Cahaba River drainage in the early 1970s (58 FR
14330 at 14331, March 17, 1993; Service 2000, p. 61; Service 2018, p.
5). Both the 2008 and 2018 5-year reviews reference multiple surveys by
experienced Federal, State, and private biologists--18 survey reports
from 1993-2006 and 10 survey reports from 2008-2017--and despite these
repeated surveys of historical habitat in the Black Warrior, Cahaba,
and Coosa River drainages, no living animals or fresh or weathered
shells of the upland combshell have been located (Service 2008, p. 19;
Service 2018, p. 5). The most recent records for the upland combshell
are many decades old: from tributaries of the Black Warrior in early
1900s, from the Cahaba River drainage in the early 1970s, and from the
Coosa River drainage in the mid-1980s (58 FR 14330 at 14331, March 17,
1993; Service 2008, p. 19; Service 2018, p. 5). No living populations
of the upland combshell have been located since the mid-1980s (Service
2000, p. 61; Service 2008, p. 20; Service 2018, p. 7). Lack of finding
the upland combshell despite extensive survey efforts in many habitats
indicate that the species is extinct.
Background
Section 4(c) of the Act (16 U.S.C. 1531 et seq.) requires the
Secretary of the Interior to publish and maintain lists of endangered
and threatened species. This includes delisting species that are
extinct based on the best scientific and commercial data available. The
Service can decide to delist a species due to extinction on its own
initiative, as a result of a 5-year review under section 4(c)(2) of the
Act, or because we are petitioned to delist.
Congress made clear that an integral part of the statutory
framework is for the Service to make delisting decisions when
appropriate and to revise the Lists of Endangered and Threatened
Wildlife and Plants accordingly. For example, section 4(c)(1) of the
Act requires the revision of the Lists of Endangered and Threatened
Wildlife and Plants to reflect recent determinations, designations, and
revisions. Similarly, section 4(c)(2) requires review of those Lists at
least every 5 years; determination(s), based on those reviews, whether
any species should be delisted or reclassified; and, if so, the
application of the same standards and procedures as for listings under
sections 4(a) and 4(b) of the Act. Finally, to make a finding that a
particular action is warranted but precluded, the Service must make two
determinations: (1) That the immediate proposal and timely promulgation
of a final regulation is precluded by pending proposals to determine
whether any species is endangered or threatened; and (2) that
expeditious progress is being made to add qualified species to either
of the Lists and to remove species from the Lists (16 U.S.C.
1533(b)(3)(B)(iii)). Delisting species that will not benefit from the
Act's protections because they are extinct allows us to allocate
resources responsibly for on-the-ground conservation efforts, recovery
planning, 5-year reviews, and other protections for species that are
extant and will therefore benefit from those actions.
Regulatory and Analytical 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.
In 2019, jointly with the National Marine Fisheries Service, the
Service issued a final rule that revised the regulations in 50 CFR part
424 regarding how we add, remove, and reclassify endangered and
threatened species and the criteria for designating listed species'
critical habitat (84 FR 45020; August 27, 2019).
Under the Act, we must review the status of all listed species at
least once every 5 years. We must delist a species if we determine, on
the basis of the best available scientific and commercial data, that
the species is neither a threatened species nor an endangered species.
Our regulations at 50 CFR 424.11(e) identify three reasons why we might
determine that a listed species is neither an endangered species nor a
threatened species: (1) The species is extinct; (2) the species does
not meet the definition of an endangered species or a threatened
species; or (3) the listed entity does not meet the statutory
definition of a species.
In this final rule, we use the commonly understood biological
definition of ``extinction'' as meaning that no living individuals of
the species remain in existence. A determination of extinction will be
informed by the best available information to indicate that no
individuals of the species remain alive, either in the wild or
captivity. This is in contrast to ``functional extinction,'' where
individuals of the species remain alive, but the species is no longer
viable and/or no reproduction will occur (e.g., any remaining females
cannot reproduce, only males remain, etc.).
In our analyses, we attempted to minimize the possibility of either
(1) prematurely determining that a species is extinct where individuals
exist but remain undetected, or (2) assuming the species is extant when
extinction has already occurred. Our determinations of whether the best
available information indicates that a species is extinct included an
analysis of the following criteria: detectability of the species,
adequacy of survey efforts, and time since last detection. All three
criteria require taking into account applicable aspects of species'
life history. Other lines of evidence may also support the
determination and be included in our analysis.
In conducting our analyses of whether these species are extinct, we
considered and thoroughly evaluated the best scientific and commercial
data available. We reviewed the information available in our files, and
other available published and unpublished information. These
evaluations may include information from recognized experts; Federal,
State, and Tribal governments; academic institutions; foreign
governments; private entities; and other members of the public.
The 5-year reviews of these species contain more detailed
biological information on each species. This supporting information can
be found on the internet at https://www.regulations.gov under the
appropriate docket number (see table under ADDRESSES, above). The
following information summarizes the analyses for each of the species
delisted by this rule.
Summary of Biological Status and Threats
Mammals
Little Mariana Fruit Bat (Pteropus Tokudae)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On August 27, 1984, we listed the little Mariana fruit bat as
endangered (49 FR 33881). The most recent 5-year status review
completed in 2019 (initiated on May 7, 2018; see 83 FR 20088)
recommended delisting due to extinction likely resulting from habitat
loss, poaching, and predation by the brown tree snake (Boiga
irregularis) (USFWS 2019, entire). This recommendation was based on an
assessment of all available
[[Page 71649]]
information for the species, coupled with an evaluation of population
trends and threats affecting the larger, extant Mariana fruit bat,
which likely shares similar behavioral and biological traits and
provides important context for the historical decline of the little
Mariana fruit bat.
The little Mariana fruit bat was first described from a male type
specimen collected in August 1931 (Tate 1934, p. 1). Its original
scientific name, Pteropus tokudae, remains current. Only three
confirmed observations of the little Mariana fruit bat existed in the
literature based on collections of three specimens: two males in 1931
(Tate 1934, p. 3), and a female in 1968 (Perez 1972, p. 146), all on
the island of Guam where it was presumably endemic. Despite the dearth
of confirmed collections and observations, two relatively recent
studies have confirmed the taxonomic validity of the little Mariana
fruit bat, via morphology (Buden et al. 2013, entire) and genetics
(Almeida et al. 2014, entire).
The little Mariana fruit bat was always likely rare, as suggested
by written accounts of the species first recorded in the early 1900s
(Baker 1948, p. 54; Perez 1972, pp. 145-146; Wiles 1987, p. 154). In
addition to possibly having been inherently rare, as indicated by the
literature, a concurrent decline in the little Mariana fruit bat
population likely occurred during the well-documented decrease in
Mariana fruit bat abundance on Guam in the 1900s. In 1920, it was ``not
an uncommon sight'' to see fruit bats flying over the forest during the
daytime in Guam (Wiles 1987, p. 150). Just 10 years later (when the
first two little Mariana fruit bat specimens were collected), fruit
bats were uncommon on the island (Wiles 1987, p. 150), and were found
mostly in northern Guam; introduced firearms may have been a
contributing factor in their decline because they increased the
efficiency of hunting (Wiles 1987, p. 150).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The little Mariana fruit bat was much smaller than the related
Mariana fruit bat (Tate 1934, p. 2; Perez 1972, p. 146; Buden et al.
2013, pp. 109-110). Adult bats measured approximately 5.5 to 5.9 inches
(in) (14 to 15.1 centimeters (cm)) in head-body length, with a wingspan
of approximately 25.6 to 27.9 in (650 to 709 millimeters (mm)). The
adults weighed approximately 5.36 ounces (152 grams). Although
primarily dark brown in color, the little Mariana fruit bat showed some
variation on the neck and head, which could appear pale gold and
grayish or yellowish-brown in color. Because of their small size
(O'Shea and Bogan 2003, pp. 49, 254; USFWS 2009, p. 55), it is possible
that adult little Mariana fruit bats were historically confused with
juvenile Mariana fruit bats. Therefore, historical accounts of the
species may have been underrepresented (Perez 1972, p. 143; Wiles 1987,
p. 15).
The challenges of surveying for the Mariana fruit bat and most
Pteropus spp. (including, in theory, the little Mariana fruit bat) are
numerous. Mariana fruit bats sleep during the day in canopy emergent
trees, either solitarily or within colonial aggregations that may occur
across several acres (O'Shea and Bogan 2003, p. 254; Utzurrum et al.
2003, p. 49; USFWS 2009, p. 269). The tropical islands where many
tropical fruit bats (Pteropus spp.) are located have widely diverse and
steeply topographical habitat, making surveys difficult. Additionally,
most Pteropus spp. choose roost sites (both colonial and individual)
that occur in locations difficult for people to reach, such as adjacent
to steep cliffsides in remote forest areas (Wilson and Graham 1992, p.
65). The selection of roost sites in these areas is likely both a
result of their evolved biology (for example, to take advantage of
updrafts for flight) (Wilson and Graham 1992, p. 4) and possible
learned behavior to avoid poachers (USFWS 2009, pp. 24-25; Mildenstein
and Johnson 2017, p. 36). To avoid triggering this avoidance behavior,
surveyors must generally keep a distance of 164 feet (50 meters) and
survey only downwind of roost sites (Mildenstein and Boland 2010, pp.
12-13; Mildenstein and Johnson 2017, pp. 55, 86). Additionally,
Pteropus spp. typically sleep during the day and do not vocalize, and
flying individuals may be easily counted twice due to their foraging
patterns (Utzurrum et al. 2003, p. 54).
Survey Effort
By 1945, fruit bats were difficult to locate even in the northern
half of Guam, where they were largely confined to forested cliff lines
along the coasts (Baker 1948, p. 54). During surveys conducted between
1963 and 1968, the Guam Division of Aquatic and Wildlife Resources
(DAWR) confirmed that bats were declining across much of Guam and were
absent in the south. It was also during these same field studies that
the third and last little Mariana fruit bat was collected in northern
Guam in 1968 (Baker 1948, p. 146).
Increased survey efforts during the late 1970s and early 1980s
reported no confirmed sightings of the little Mariana fruit bat
(Wheeler and Aguon 1978, entire; Wheeler 1979, entire; Wiles 1987,
entire; Wiles 1987, pp. 153-154). In the final rule listing the little
Mariana fruit bat as endangered (49 FR 33881; August 27, 1984), we
noted that the species was on the verge of extinction and had not been
verifiably observed after 1968. When we published a joint recovery plan
for the little Mariana fruit bat and the Mariana fruit bat in 1990, we
considered the little Mariana fruit bat already extinct based upon the
available literature (USFWS 1990, p. 7).
During the 1990s, Mariana fruit bat numbers on Guam decreased and
fatalities of immature bats increased, hypothesized to be a result of
predation by the brown tree snake (Wiles et al. 1995, pp. 33-34, 39-
42). With bat abundance continuing to decline in the 2000s, the
island's Mariana fruit bat population currently fluctuates between 15
and 45 individuals (Mildenstein and Johnson 2017, p. 24; USFWS 2017, p.
54). Even if the little Mariana fruit bat persisted at undetectable
numbers for some time after its last confirmed collection in 1968, it
is highly likely the little Mariana fruit bat experienced the same
pattern of decline that we are now seeing in the Mariana fruit bat.
Time Since Last Detection
As stated above, the little Mariana fruit bat was last collected in
northern Guam in 1968 (Baker 1948, p. 146). Intensive survey efforts
conducted by Guam DAWR and other researchers in subsequent decades have
failed to locate the species. Decades of monthly (and, later, annual)
surveys for the related Mariana fruit bat by qualified personnel in
northern Guam have failed to detect the little Mariana fruit bat
(Wheeler and Aguon 1978, entire; Wheeler 1979, entire; Wiles 1987,
entire; Wiles 1987, pp. 153-154; USFWS 1990, p. 7).
III. Analysis
Like the majority of bat species in the genus Pteropus, specific
biological traits likely exacerbated the little Mariana fruit bat's
susceptibility to human activities and natural events (Wilson and
Graham 1992, pp. 1-8). For example, low fecundity in the genus due to
late reproductive age and small broods (1 to 2 young annually) inhibits
population rebound from catastrophic events such as typhoons, and from
slow progression of habitat loss and hunting pressure that we know
occurred over time. The tendency of Pteropus bats to roost together in
sizeable groups or colonies in large trees rising above the
[[Page 71650]]
surrounding canopy makes them easily detected by hunters (Wilson and
Graham 1992, p. 4). Additionally, Pteropus bats show a strong tendency
for roost site fidelity, often returning to the same roost tree year
after year to raise their young (Wilson and Graham 1992, p. 4;
Mildenstein and Johnson 2017, pp. 54, 68). This behavior likely allowed
hunters and (later) poachers to easily locate and kill the little
Mariana fruit bat and, with the introduction of firearms, kill them
more efficiently (Wiles 1987, pp. 151, 154; USFWS 2009, pp. 24-25;
Mildenstein and Johnston 2017, pp. 41-42). The vulnerability of the
entire genus Pteropus is evidenced by the fact that 6 of the 62 species
in this genus have become extinct in the last 150 years (including the
little Mariana fruit bat). The International Union for Conservation of
Nature (IUCN) categorizes an additional 37 species in this genus at
risk of extinction (Almeida et al. 2014, p. 84).
In discussing survey results for the Mariana fruit bat in the late
1980s, experts wrote that the level of illegal poaching of bats on Guam
remained extremely high, despite the establishment of several legal
measures to protect the species beginning in 1966 (Wiles 1987, p. 154).
They also wrote about the effects of brown tree snake predation on
various fruit bat species (Savidge 1987, entire; Wiles 1987, pp. 155-
156). To date, there is only one documented instance of the brown tree
snake preying upon the Mariana fruit bat; in that case, three young
bats were found within the stomach of a snake (Wiles 1987, p. 155).
However, immature Pteropus pups are particularly vulnerable to
predators between approximately 3 weeks and 3 months of age. During
this timeframe, the mother bats stop taking their young with them while
they forage in the evenings, leaving them alone to wait at their roost
tree (Wiles 1987, p. 155).
Only three specimens of little Mariana fruit bat have ever been
collected, all on the island of Guam, and no other confirmed captures
or observations of this species exist. Based on the earliest records,
the species was already rare in the early 1900s. Therefore, since its
discovery, the little Mariana fruit bat likely experienced greater
susceptibility to a variety of factors because of its small population
size. Predation by the brown tree snake, alteration and loss of
habitat, increased hunting pressure, and possibly competition with the
related Mariana fruit bat for the same resources under the increasingly
challenging conditions contributed to the species' decreased ability to
persist.
It is highly likely the brown tree snake, the primary threat
thought to be the driver of multiple bird and reptile species
extirpations and extinctions on Guam, has been present throughout the
little Mariana fruit bat's range for at least the last half-century,
and within the last northern refuge in northern Guam since at least the
1980s. Because of its life history and the challenges presented by its
small population size, we conclude that the little Mariana fruit bat
was extremely susceptible to predation by the brown tree snake.
IV. Conclusion
At the time of listing in 1984, hunting and loss of habitat were
considered the primary threats to the little Mariana fruit bat. The
best available information now indicates that the little Mariana fruit
bat is extinct. The species appears to have been vulnerable to
pervasive, rangewide threats including habitat loss, poaching, and
predation by the brown tree snake. Since its last detection in 1968,
qualified observers have conducted surveys and searches throughout the
range of the little Mariana fruit bat but have not detected the
species. Available information indicates that the species was not able
to persist in the face of anthropogenic and environmental stressors,
and we conclude that the best available scientific and commercial
information indicates that the species is extinct.
Birds
Bachman's Warbler (Vermivora Bachmanii)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On March 11, 1967, we listed the Bachman's warbler as endangered under
the Endangered Species Preservation Act of 1966 (32 FR 4001), as a
result of the loss of breeding and wintering habitat. Two 5-year
reviews were completed for the species on February 9, 2007 (initiated
on July 26, 2005; see 70 FR 43171), and May 6, 2015 (initiated on
September 23, 2014; see 79 FR 56821). Both 5-year reviews recommended
that if the species was not detected within the following 5 years, it
would be appropriate to delist due to extinction.
The Bachman's warbler was first named in 1833 as Sylvia bachmanii
based on a bird observed in a swamp near Charleston, South Carolina
(American Ornithologists' Union (AOU) 1983, pp. 601-602). The species
was found in the southeastern portions of the United States from the
south Atlantic and Gulf Coastal Plains. Historically, the bulk of the
species' population left the North American mainland each fall for Cuba
and Isle of Pines (Dingle 1953, pp. 67-68, 72-73).
Migratory habitat preferences appear to have differed from winter
and breeding habitat preferences in that the bird used or tolerated a
wider range of conditions and vegetative associations during migration.
Bachman's warbler typically nested in low, wet, forested areas
containing variable amounts of water, but usually with some permanent
water. Nests were typically found in shrubs low to the ground from late
March through June, and average known clutch size was 4.2 (with a range
of 3 to 5) (Hamel 2018, pp. 14-15). During the winter in Cuba, it was
found in a wider variety of habitats across the island including
forests, ranging from dry, semi-deciduous forests to wetlands, and even
in forested urban spaces (Hamel 1995, p. 5). Life expectancy is unknown
but was likely 7 years, which is the documented lifespan of the two
species most closely related to Bachman's warbler, blue-winged warbler
(V. cyanoptera) and golden-winged warbler (V. chrysoptera) (Gill et al.
2020 and Confer et al. 2020, respectively).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Bachman's warbler was one of the smallest warblers, with a
total length of 11.0 to 11.5 cm. Males were easy to distinguish from
other warblers. However, the drab coloration of the females and
immature birds made positive identification difficult (Hamel and
Gauthreaux 1982, p. 235). Additionally, females were much more
difficult to identify because variability in plumage was greater.
Immature females were also most likely to be confused with other
similarly drab warblers.
The song of the Bachman's warbler was a fast series of buzzy
``zeeps'' usually ending with a short, downward whistled note given by
both sexes (Hamel 2020, Sounds and Vocal Behavior). This species may
have been difficult to differentiate by call alone, as its call was
somewhat reminiscent of the pulsating trill of the northern parula
(Parula americana) (Curson et al. 1994, p. 95), and only four
recordings exist, all from the 1950s (two cited in Hamel 2018, p. 32,
and all four in Cornell Lab of Ornithology, Macaulay Library), to guide
ornithologists on distinguishing it by sound.
[[Page 71651]]
Despite the fact that it could be mistaken for the northern parula,
Bachman's warbler was of high interest to birders, and guides have been
published specifically to aid in field identification (Hamel and
Gauthreaux 1982, entire). As a result, substantial informal and formal
effort has been expended searching for the bird and verifying potential
sightings as outlined below (see ``Survey Effort'').
Survey Effort
Although Bachman's warbler was first described in 1833, it remained
relatively unnoticed for roughly the next 50 years. Population
estimates are qualitative in nature and range from rare to abundant
(Service 1999, pp. 4-448). Populations were probably never large and
were found in ``some numbers'' between 1890 and 1920, but afterwards
populations appeared to be very low (Hamel 2018, pp. 16-18). For
instance, several singing males were reported in Missouri and Arkansas
in 1897 (Widmann 1897, p. 39), and Bachman's warbler was seen as a
migrant along the lower Suwannee River in flocks of several species
(Brewster and Chapman 1891, p. 127). The last confirmed nest was
documented in 1937 (Curson et al. 1994, p. 96). A dramatic decline
occurred sometime between the early 1900s and 1940 or 1950. Recognition
of this decline resulted in the 1967 listing of the species (see 32 FR
4001; March 11, 1967) under the Endangered Species Preservation Act of
1966.
Between 1975 and 1979, an exhaustive search was conducted in South
Carolina, Missouri, and Arkansas. No Bachman's warblers were located
(Hamel 1995, p. 10). The last (though unconfirmed) sighting in Florida
was from a single bird observed near Melbourne in 1977. In 1989, an
extensive breeding season search was conducted on Tensas National
Wildlife Refuge in Louisiana. Six possible Bachman's warbler
observations occurred but could not be documented sufficiently to meet
acceptability criteria established for the study (Hamilton 1989, as
cited in Service 2015, p. 4).
An experienced birder reported multiple, possible sightings of
Bachman's warbler at Congaree National Park, South Carolina, in 2000
and 2001. These included hearing a male and seeing a female. In 2002,
the National Park Service partnered with the Service and the Atlantic
Coast Joint Venture to investigate these reports. Researchers searched
over 3,900 acres of forest during 166 hours of observation in March and
April; however, no Bachman's warbler sightings or vocalizations were
confirmed. As noted previously, females and immature birds are
difficult to positively identify. Males (when seen) are more easily
distinguishable from other species. Researchers trying to verify the
sightings traced several promising calls back to northern parulas and
finally noted that they were confident the species would have been
detected had it been present (Congaree National Park 2020, p. 3).
In several parts of the Bachman's warbler's range, relatively
recent searches (since 2006) for ivory-billed woodpecker also prompted
more activity in appropriate habitat for the Bachman's warbler. Much of
the search period for ivory-billed woodpecker is during the winter, and
the searches usually continued until the end of April, when the
Bachman's warbler would be expected in its breeding range. Because the
Bachman's warbler was a very early migrant, many knowledgeable
searchers looking for ivory-billed woodpeckers would have had
opportunities to encounter this warbler as early as February across the
southeastern United States, yet no putative encounters were reported.
Given that Bachman's warbler habitat overlaps with ivory-billed
woodpecker habitat, the probability that the Bachman's warbler would be
detected, if present, has recently increased (Service 2015, pp. 5-6).
Further, in general, substantial informal effort has been expended
searching for the Bachman's warbler because of its high interest among
birders (Service 2015, p. 5). Despite these efforts, the Bachman's
warbler has not been observed in the United States in more than three
decades. With a likely maximum lifespan of 7 years, the time period
through which this species has not been seen constitutes at least 7
generations, and the time period since its last confirmed breeding
constitutes more than 10 generations.
In Cuba, the species' historical wintering range, the last
ornithologist to see the species noted that the species was observed
twice in the 1960s in the Zapata Swamp: one sighting in the area of a
modern-day hotel in Laguna del Tesoro and the other one in the Santo
Tomas, Zanja de la Cocodrila area. Some later potential observations
(i.e., 1988) in the same areas were thought to be a female common
yellowthroat (Geothlypis trichas) (Navarro 2020, pers. comm.). A single
bird was reported in Cuba in 1981 at Zapata Swamp (Garrido 1985, p.
997; Hamel 2018, p. 20). However, additional surveys in Cuba by Hamel
and Garrido in 1987 through 1989 did not confirm additional birds
(Navarro 2020, pers. comm.). There have been no sightings or bird
surveys in recent years in Cuba, and all claimed sightings of Bachman's
warbler from 1988 onwards have been rejected by the ornithological
community (Navarro 2020, pers. comm.). Curson et al. (1994, p. 96)
considers all sightings from 1978 through 1988 in Cuba as unconfirmed.
Time Since Last Detection
After 1962, reports of the Bachman's warbler in the United States
have not been officially accepted, documented observations (Chamberlain
2003, p. 5). Researchers have been thorough and cautious in
verification of potential sightings, and many of the more recent ones
could not be definitively verified. Bachman's warbler records from
1877-2001 in North America are characterized as either relying on
physical evidence or on independent expert opinion, or as controversial
sightings (Elphick et al. 2010, pp. 8, 10). In Cuba, no records have
been verified since the 1980s (Navarro 2020, pers. comm.).
Other Considerations Applicable to the Species' Status
At breeding grounds, the loss of habitat from clearing of large
tracts of palustrine (i.e., having trees, shrubs, or emergent
vegetation) wetland beginning in the 1800s was a major factor in the
decline of the Bachman's warbler. Most of the palustrine habitat in the
Mississippi Valley (and large proportions in Florida) was historically
converted to agriculture or affected by other human activities
(Fretwell et al. 1996, pp. 8, 10, 124, 246). Often the higher, drier
portions of land that the Bachman's warbler required for breeding were
the first to be cleared because they were more accessible and least
prone to flooding (Hamel 1995, pp. 5, 11; Service 2015, p. 4).
During World Wars I and II, many of the remaining large tracts of
old growth bottomland forest were cut, and the timber was used to
support the war effort (Jackson 2020, Conservation and Management, p.
2). At the wintering grounds of Cuba, extensive loss of primary forest
wintering habitat occurred due to the clearing of large areas of the
lowlands for sugarcane production (Hamel 2018, p. 24). Hurricanes also
may have caused extensive damage to habitat and direct loss of
overwintering Bachman's warblers. Five hurricanes occurred between
November 1932 and October 1935. Two storms struck western Cuba in
October 1933, and the November 1932 hurricane is considered one of the
most destructive ever recorded. These hurricanes, occurring when
Bachman's warblers would have been present at their wintering grounds
in Cuba, may
[[Page 71652]]
have resulted in large losses of the birds (Hamel 2018, p. 19). The
dramatic reduction in encounter frequency, beginning in the late 1930s
following the string of hurricanes in Cuba, never reversed, strongly
suggesting that these storms, combined with accumulated habitat loss in
breeding grounds, diminished viability of the Bachman's warbler as it
approached extinction.
III. Analysis
As early as 1953, Bachman's warbler was reported as one of the
rarest songbirds in North America (Dingle 1953, p. 67). The species may
have gone extinct in North America by 1967 (Elphick et al. 2010, p.
619). Despite extensive efforts to document presence of the species, no
new observations of the species have been verified in the United States
or Cuba in several decades (Elphick et al. 2010, supplement; Navarro
2020, pers. comm.). Given the likely lifespan of the species, it has
not been observed in several generations.
IV. Conclusion
As far back as 1977, Bachman's warbler has been described as being
on the verge of extinction (Hooper and Hamel 1977, p. 373) and the
rarest songbird native to the United States (Service 1999, pp. 4-445).
The species has not been seen in the United States or Cuba since the
1980s, despite extensive efforts to locate it and verify potential
sightings. Therefore, we conclude that the best available scientific
and commercial information indicates that the species is extinct.
Bridled White-Eye (Zosterops Conspicillatus Conspicillatus)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On August 27, 1984, we listed the bridled white-eye (Nossa in the
Chamorro language) as endangered (49 FR 33881). The species was last
observed in 1983, and the 1984 final listing rule for the bridled
white-eye noted that the species ``may be the most critically
endangered bird under U.S. jurisdiction'' (49 FR 33881, August 27,
1984, p. 49 FR 33883), citing disease and predation by nonnative
predators, including the brown tree snake, as the likely factors
contributing to its rarity (49 FR 33881, August 27, 1984, p. 49 FR
33884). The most recent 5-year status review, completed in 2019
(initiated on May 7, 2018; see 83 FR 20088), recommended delisting due
to extinction, based on continued lack of detections and the pervasive
rangewide threat posed by the brown tree snake (USFWS 2019, p. 10).
At the time of listing, the bridled white-eye on Guam was
classified as one subspecies within a complex of bridled white-eye
populations found in the Mariana Islands. The most recent taxonomic
work (Slikas et al. 2000, p. 360) continued to classify the Guam
subspecies within the same species as the bridled white-eye populations
currently found on Saipan, Tinian, and Aguiguan in the Commonwealth of
the Northern Mariana Islands (Z. c. saypani) but considered the Rota
population (Z. rotensis; now separately listed as endangered under the
Act) to be a distinct species.
Endemic only to Guam, within the Mariana Islands, the bridled
white-eye was a small (0.33 ounce or 9.3 grams), green and yellow,
warbler-like forest bird with a characteristic white orbital ring
around each eye (Jenkins 1983, p. 48). The available information about
the life history of the species is sparse, based on a few early
accounts in the literature (Seale 1901, pp. 58-59; Stophlet 1946, p.
540; Marshall 1949, p. 219; Baker 1951, pp. 317-318; Jenkins 1983, pp.
48-49). Nonterritorial and often observed in small flocks, the species
was a canopy-feeding insectivore that gleaned small insects from the
twigs and branches of trees and shrubs (Jenkins 1983, p. 49). Although
only minimal information exists about the bridled white-eye's nesting
habits and young, observations of nests during several different months
suggests the species bred year-round (Marshall 1949, p. 219; Jenkins
1983, p. 49). No information is available regarding longevity of the
bridled white-eye, but lifespans in the wild for other white-eyes in
the same genus range between 5 and 13 years (Animal Diversity Web 2020;
The Animal Aging and Longevity Database 2020; WorldLifeExpectancy.com
2020).
The bridled white-eye was reported to be one of the more common
Guam bird species between the early 1900s and the 1930s (Jenkins 1983,
p. 5). However, reports from the mid- to late-1940s indicated the
species had perhaps become restricted to certain areas on Guam (Baker
1951, p. 319; Jenkins 1983, p. 50). By the early- to mid-1970s, the
bridled white-eye was found only in the forests in the very northern
portion of Guam (Wiles et al. 2003, p. 1353). It was considered rare by
1979, causing experts to conclude that the species was nearing
extinction (Jenkins 1983, p. 50).
By 1981, the bridled white-eye was known to inhabit only a single
395-acre (160-hectare) limestone bench known as Pajon Basin in a
limestone forest at Ritidian Point, an area that later became the Guam
National Wildlife Refuge. Nestled at the base of towering limestone
cliffs of about 426 feet (130 meters), the site was bordered by
adjoining tracts of forest on three sides, and ocean on the northern
side (Wiles et al. 2003, p. 1353). Pajon Basin was also the final
refuge for many of Guam's native forest bird species and was the last
place where 10 of Guam's forest bird species were still observed
together in one locality at historical densities (Savidge 1987, p. 661;
Wiles et al. 2003, p. 1353).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The bridled white-eye was described as active and occurred in small
flocks of 3 to 12 individuals (Jenkins 1983, p. 48). Although
apparently not as vocal as its related subspecies on the other Mariana
Islands, the bridled white-eye was observed singing and typically
vocalized with ``chipping calls'' while flocking, less so during
foraging (Jenkins 1983, p. 48). Although perhaps not correctly
identified as a ``secretive'' or ``cryptic'' species (Amidon 2000, pp.
14-15), the detectability of the related Rota bridled white-eye is
greatest during surveys when it is close to the observer, relative to
other species of birds that are detected at further distances. While we
are unaware of surveys for the bridled white-eye using alternative
methodologies specific for rare or secretive bird species, we conclude
there is still sufficient evidence of extinction based upon the large
body of literature confirming the impacts of the brown tree snake on
Guam (see discussion below under ``III. Analysis'').
Survey Effort
During a multi-year VCP study at Pajon Basin consisting of annual
surveys between 1981 and 1987, observations of the bridled white-eye
drastically declined in just the first 3 years of the study. In 1981,
54 birds were observed, and in 1982, 49 birds were documented,
including the last observation of a family group (with a fledging) of
the species. One year later, during the 1983 survey, only a single
individual bridled white-eye was sighted. Between 1984 and 1987,
researchers failed to detect the species within this same 300-acre
(121-hectare) site (Beck 1984, pp. 148-149).
Between the mid- and late-1980s, experts had already begun to
hypothesize that the bridled white-eye had become extinct (Jenkins
1983, p. 50;
[[Page 71653]]
Savidge 1987, p. 661). Although human access has become more restricted
within portions of Andersen Air Force Base since 1983, the Guam DAWR
has, to date, continued annual roadside counts across the island as
well as formal transect surveys in northern Guam in areas previously
inhabited by the bridled white-eye.
Time Since Last Detection
The species remains undetected since the last observation in Pajon
Basin in 1983 (Wiles 2018, pers. comm.; Quitugua 2018, pers. comm.;
Aguon 2018, pers. comm.). Researchers failed to observe the species at
the Pajon Basin during the annual surveys between 1984 and 1987, and
during subsequent intermittent avian surveys in northern Guam in areas
where this species would likely occur (Savidge 1987, p. 661; Wiles et
al. 1995, p. 38; Wiles et al. 2003, entire).
III. Analysis
The brown tree snake is estimated to be responsible for the
extinction, extirpation, or decline of 2 bat species, 4 reptiles, and
17 of Guam's 22 (77 percent) native bird species, including all of the
native forest bird species (Wiles et al. 2003, p. 1358; Rodda and
Savidge 2007, p. 307). The most comprehensive study of the decline
(Wiles et al. 2003, entire) indicated that 22 bird species were
severely impacted by the brown tree snake. Observed bird species
declines of greater than or equal to 90 percent occurred rapidly,
averaging 8.9 years from invasion by the snake. Additionally, birds
that nested and roosted in locations where the brown tree snake was
uncommon had a greater likelihood of coexisting with the snake. Bird
species with large clutch sizes and large body sizes also exhibited
longer persistence, although large body size delayed but did not
prevent extirpation. Measuring a mere 0.33 ounces (9.3 grams), the
bridled white-eye was relatively small, and its nests occurred in areas
accessible to brown tree snakes (Baker 1951, pp. 316-317; Jenkins 1983,
pp. 49-50).
We used a recent analytical tool that assesses information on
threats to infer species extinction based on an evaluation of whether
identified threats are sufficiently severe and prolonged to cause local
extinction, as well as sufficiently extensive in geographic scope to
eliminate all occurrences (Keith et al. 2017, p. 320). Applying this
analytical approach to the bridled white-eye, we examined years of
research and dozens of scientific publications and reports that
indicate that the effects of predation by the brown tree snake have
been sufficiently severe, prolonged, and extensive in geographic scope
to cause widespread range contraction, extirpation, and extinction for
several birds and other species. Based on this analysis, we conclude
that the bridled white-eye is extinct and brown tree snake predation
was the primary causal agent.
IV. Conclusion
At the time of its listing in 1984, disease and predation by
nonnative predators, including the brown tree snake, were considered
the primary threats to the bridled white-eye. The best available
information now indicates that the bridled white-eye is extinct. The
species appears to have been vulnerable to the pervasive, rangewide
threat of predation from the brown tree snake. Since its last detection
in 1983, qualified observers have conducted surveys and searches
throughout the range of the bridled white-eye and have not detected the
species. Available information indicates that the species was not able
to persist in the face of environmental stressors, and we conclude that
the best available scientific and commercial information indicates that
the species is extinct.
Kauai Akialoa (Akialoa Stejnegeri)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On March 11, 1967, we listed the Kauai akialoa (listed as Hemignathus
stejnegeri), a Hawaiian honeycreeper, as endangered (32 FR 4001). This
bird was included in the Kauai Forest Birds Recovery Plan (USFWS 1983,
p. 1), and the Revised Recovery Plan for Hawaiian Forest Birds (USFWS
2006, p. 2-86). At the time of listing, we considered Kauai akialoa to
have very low population numbers and to be threatened by habitat loss,
avian disease, and predation by rats (Rattus spp.). The last confirmed
observation of the species was in 1965, although there was an
unconfirmed sighting in 1969 (Reynolds and Snetsinger 2001, p. 142).
The most recent 5-year status review, completed in 2019, recommended
delisting due to extinction based on consideration of additional
information about the biological status of the species, as discussed
below (USFWS 2019, pp. 5, 10).
The life history of Kauai akialoa is poorly known and based mainly
on observations from the end of the 19th century (USFWS 2006, p. 2-86).
There is no information on the lifespan of the Kauai akialoa nor its
threats when it was extant. The species was widespread on Kauai and
occupied all forest types above 656 feet (200 meters) elevation
(Perkins 1903, pp. 369, 422, 426). Its historical range included nearly
all Kauai forests visited by naturalists at the end of the 19th
century. After a gap of many decades, the species was seen again in the
1960s, when one specimen was collected (Richardson and Bowles 1964, p.
30).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Kauai akialoa was a large (6.7 to 7.5 inches, or 17 to 19
centimeters, total length), short-tailed Hawaiian honeycreeper with a
very long, thin, curved bill, the longest bill of any historically
known Hawaiian passerine. The plumage of both sexes was olive-green;
males were more brightly colored, were slightly larger, and had a
somewhat longer bill (USFWS 2006, p. 2-86). The Kauai akialoa's
relatively large size and distinctive bill suggest that if it were
extant, it would be detectable by sight and recognized.
Survey Effort
A comprehensive survey of Hawaiian forest birds was initiated in
the 1970s using the VCP method (Scott et al. 1986, entire). Please
refer to the ``Summary of Comments and Recommendations'' for a
description of the VCP method. VCP surveys have been the primary method
used to count birds in Hawaii; however, it is not appropriate for all
species and provides poor estimates for extremely rare birds (Camp et
al. 2009, p. 92). In recognition of this issue, the RBS was undertaken
from 1994 to 1996, to update the status and distribution of 13
``missing'' Hawaiian forest birds (Reynolds and Snetsinger 2001, pp.
134-137). The RBS was designed to improve efficiency in the search for
extremely rare species, using the method of continuous observation
during 20- to 30-minute timed searches in areas where target species
were known to have occurred historically, in conjunction with audio
playback of species vocalizations (when available). Several recent
surveys and searches, including the RBS, have been unsuccessful in
detecting Kauai akialoa despite intensive survey efforts by wildlife
biologists from 1968 to 1973, and in 1981, 1989, 1993, 1994, 2000,
2005, and 2011 to 2018 (Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
[[Page 71654]]
2017, entire; Crampton 2018, pers. comm.). An unconfirmed 1969 report
may have been the last sighting of Kauai akialoa (Conant et al. 1998,
p. 15). Kauai akialoa has been presumed likely extinct for some time
(Reynolds and Snetsinger 2001, p. 142).
In addition, extensive time has been spent by qualified observers
in the historical range of the Kauai akialoa searching for the small
Kauai thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and
akikiki (or Kauai creeper) (Oreomystis bairdi). HFBSs were conducted in
1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al.
2016, entire; Paxton et al. 2020, entire). The Kauai Forest Bird
Recovery Project (KFBRP) conducted occupancy surveys for the small
Kauai thrush in Kokee State Park, Hono O NaPali NAR, Na Pali Kona
Forest Reserve, and Alakai Wilderness Preserve, from 2011 to 2013
(Crampton et al. 2017, entire), and spent over 1,500 person-hours per
year from 2015 to 2018 searching for akikiki and akekee nests. During
the HFBS in 2012 and 2018, occupancy surveys and nest searches did not
yield any new detections of Kauai akialoa. The KFBRP conducted mist-
netting in various locations within the historical range of Kauai
akialoa from 2006 through 2009, and from 2011 through 2018, and no
Kauai akialoa were caught or encountered (Crampton 2018, pers. comm.).
Time Since Last Detection
The Kauai akialoa has not been seen since the 1960s, despite
efforts by ornithologists (Conant et al. 1998, p. 15) and birders, and
intensive survey efforts by wildlife biologists spanning 1968 to 2018
(USFWS 1983, p. 2; Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018, pers. comm.). Another approach used to
determine whether extremely rare species are likely extinct or
potentially still extant is to calculate the probability of a species'
extinction based on time (years) since the species was last observed
(Elphick et al. 2010, p. 620). This approach, when applied to extremely
rare species, has the drawback that an incorrect assignment of species
extinction may occur due to inadequate survey effort and/or
insufficient time by qualified observers spent in the area where the
species could still potentially exist. Using 1969 as the last credible
sighting of Kauai akialoa, the authors' estimated date for the species'
extinction is 1973, with 95 percent confidence that the species was
extinct by 1984.
III. Analysis
The various bird species in the subfamily Drepanidinae (also known
as the Hawaiian honeycreepers), which includes Kauai akialoa, are
highly susceptible to introduced avian disease. They are particularly
susceptible to avian malaria (Plasmodium relictum), which results in
high rates of mortality. At elevations below approximately 4,500 feet
(1,372 meters) in Hawaii, the key factor driving disease epizootics
(outbreaks) of pox virus (Avipoxvirus) and avian malaria is the
seasonal and altitudinal distribution and density of the primary vector
of these diseases, the mosquito Culex quinquefasciatus (Atkinson and
Lapointe 2009a, pp. 237-238, 245-246).
We relied on a recently developed analytic tool that uses
information on threats to infer species extinction based on an
evaluation of whether identified threats are sufficiently severe and
prolonged to cause local extinction, and sufficiently extensive in
geographic scope to eliminate all occurrences (Keith et al. 2017, p.
320). The disappearance of many Hawaiian honeycreeper species over the
last century from areas below approximately 4,500 feet elevation points
to effects of avian disease having been sufficiently severe and
prolonged, and extensive in geographic scope, to cause widespread
species' range contraction and possible extinction. It is highly likely
avian disease is the primary causal factor for the disappearance of
many species of Hawaiian honeycreepers from forested areas below 4,500
feet on the islands of Kauai, Oahu, Molokai, and Lanai (Scott et al.
1986, p. 148; Banko and Banko 2009, pp. 52-53; Atkinson and Lapointe
2009a, pp. 237-238).
It is widely established that small populations of animals are
inherently more vulnerable to extinction because of random demographic
fluctuations and stochastic environmental events (Mangel and Tier 1994,
p. 607; Gilpin and Soul[eacute] 1986, pp. 24-34). Formerly widespread
populations that become small and isolated often exhibit reduced levels
of genetic variability, which diminishes the species' capacity to adapt
and respond to environmental changes, thereby lessening the probability
of long-term persistence (e.g., Barrett and Kohn 1991, p. 4; Keller and
Waller 2002, p. 240; Newman and Pilson 1997, p. 361). As populations
are lost or decrease in size, genetic variability is reduced, resulting
in increased vulnerability to disease and restricted potential
evolutionary capacity to respond to novel stressors (Spielman et al.
2004, p. 15261; Whiteman et al. 2006, p. 797). As numbers decreased
historically, effects of small population size were very likely to have
negatively impacted Kauai akialoa, reducing its potential for long-term
persistence. Surveys and searches have been unsuccessful in detecting
Kauai akialoa (refer to ``Survey Effort'' discussion, above).
IV. Conclusion
At the time of listing in 1967, the Kauai akialoa faced threats
from habitat loss, avian disease, and predation by introduced mammals.
The best available information now indicates that the Kauai akialoa is
extinct. The species appears to have been vulnerable to introduced
avian disease. In addition, the effects of small population size likely
limited the species' genetic variation and adaptive capacity, thereby
increasing the vulnerability of the species to environmental stressors
including habitat loss and degradation. Since its last detection in
1969, qualified observers have conducted extensive surveys, and
searches but have not detected the species. Available information
indicates that the species was not able to persist in the face of
environmental stressors, and we conclude that the best available
scientific and commercial information indicates that the species is
extinct.
Kauai Nukupuu (Hemignathus Hanapepe)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On March 11, 1967, we listed the Kauai nukupuu as endangered (32 FR
4001). This bird was included in the Kauai Forest Birds Recovery Plan
(USFWS 1983, p. 1), as well as the Revised Recovery Plan for Hawaiian
Forest Birds (USFWS 2006, p. viii). At the time of listing,
observations of only two individuals had been reported during that
century (USFWS 1983, p. 3). The last confirmed observation (based on
independent expert opinion and physical evidence) of the species was in
1899 (Eliphick et al. 2010, p. 620). The latest 5-year status review
completed in 2019 recommended delisting due to extinction based on
consideration of additional information about the biological status of
the species, as discussed below (USFWS 2019, pp. 4-5, 10).
The historical record provides little information on the life
history of Kauai
[[Page 71655]]
nukupuu (USFWS 2006, p. 2-89). There is no specific information on the
lifespan or breeding biology of Kauai nukupuu, although it is presumed
to be similar to its closest relative, akiapolaau (Hemignathus munroi,
listed as H. wilsoni), a honeycreeper from the island of Hawaii. The
last confirmed observation (based on independent expert opinion and
physical evidence) of Kauai nukupuu was in 1899 (Eliphick et al. 2010,
p. 620); however, there was an unconfirmed observation in 1995 (Conant
et al. 1998, p. 14).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Kauai nukupuu was a medium-sized, approximately 23-gram (0.78-
ounce), Hawaiian honeycreeper (family Fringillidae, subfamily
Drepanidinae) with an extraordinarily thin, curved bill, slightly
longer than the bird's head. The lower mandible was half the length of
the upper mandible. Adult male plumage was olive-green with a yellow
head, throat, and breast, whereas adult female and immature plumage
consisted of an olive-green head and yellow or yellowish gray under-
parts (USFWS 2006, p. 2-89). The long, curved, and extremely thin bill
of Kauai nukupuu, in combination with its brightly colored plumage,
would have made this bird highly detectable to ornithologists and
birders had it persisted (USFWS 2006, p. 2-89). No subsequent sightings
or vocalizations have been documented since the unconfirmed sighting in
1995, despite extensive survey efforts.
Survey Effort
In the absence of early historical surveys, the extent of the
geographical range of the Kauai nukupuu is unknown. Several recent
surveys and searches, including the RBS, have been unsuccessful in
detecting Kauai nukupuu despite intensive survey efforts by wildlife
biologists from 1968 to 1973, and in 1981, 1989 1993, 1994, 2000, 2005,
and 2011 to 2018 (Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018 pers. comm.). During the RBS, Kauai nukupuu
was not detected. The lack of detections combined with analysis of
detection probability (P >= 0.95) suggested that the possible
population count was fewer than 10 birds in 1996 (Reynolds and
Snetsinger 2001, p. 142).
Extensive time has been spent by qualified observers in the
historical range of the Kauai nukupuu searching for the small Kauai
thrush, akekee, and akikiki. HFBSs were conducted in 1981, 1989, 1994,
2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 2016, entire;
Paxton et al. 2020, entire). During the HFBSs in 2012 and 2018,
occupancy surveys and nest searches did not yield any new detections of
the Kauai nukupuu. The KFBRP conducted mist-netting in various
locations within the historical range of the Kauai nukupuu from 2006
through 2009, and from 2011 through 2018, and no Kauai nukupuu were
caught or encountered (Crampton 2018, pers. comm.). Despite
contemporary search efforts, the last credible sighting of Kauai
nukupuu occurred in 1899.
Time Since Last Detection
Using 1899 as the last credible sighting of Kauai nukupuu based on
independent expert opinion and physical evidence, the estimated date
for the species' extinction was 1901, with 95 percent confidence that
the species was extinct by 1906 (Elphick et al. 2010, p. 620).
III. Analysis
Some of the reported descriptions of this species better match the
Kauai amakihi (Chlorodrepanis stejnegeri) (USFWS 2006, p. 2-90).
Although skilled observers reported three unconfirmed sightings of
Kauai nukupuu in 1995 (Reynolds and Snetsinger 2001, p. 142), extensive
hours of searching within the historical range failed to detect any
individuals. The last credible sightings of Kauai nukupuu was in 1899,
based on independent expert opinion and physical evidence (Elphick et
al. 2010, p. 620). It was estimated that 1901 was the year of
extinction, with 95 percent confidence that the species was extinct by
1906. The species was likely vulnerable to the persistent threats of
avian disease combined with habitat loss and degradation, which remain
drivers of extinction for Hawaiian forest birds.
IV. Conclusion
At the time of listing in 1967, the Kauai nukupuu had not been
detected for almost 70 years. Since its last detection in 1899,
qualified observers have conducted extensive surveys and searches
throughout the range of the Kauai nukupuu and have not detected the
species. Available information indicates that the species was not able
to persist in the face of environmental stressors, and we conclude that
the best available scientific and commercial information indicates that
the species is extinct.
Kauai [revaps]o[revaps]o (Moho Braccatus)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On March 11, 1967, we listed the Kauai [revaps]o[revaps]o (Moho
braccatus) as endangered (32 FR 4001). This bird was included in the
Kauai Forest Birds Recovery Plan (USFWS 1983, p. 1), as well as the
Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006, p. viii).
At the time of listing, the population size was estimated at 36
individuals (USFWS 1983, p. 3). Threats to the species included the
effects of low population numbers, habitat loss, avian disease, and
predation by introduced mammals. The last plausible record of a Kauai
[revaps]o[revaps]o was a vocal response to a recorded vocalization
played by a field biologist on April 28, 1987, in the locality of
Halepaakai Stream. The latest 5-year status review completed in 2019
recommended delisting due to extinction based on consideration of new
information about the biological status of the species, as discussed
below (USFWS 2019, pp. 5, 10).
The Kauai [revaps]o[revaps]o measured 7.7 inches (19.5 centimeters)
and was somewhat smaller than the Moho species on the other islands. It
was glossy black on the head, wings, and tail; smoky brown on the lower
back, rump, and abdomen; and rufous-brown on the upper tail coverts. It
had a prominent white patch at the bend of the wing. The thigh feathers
were golden yellow in adults and black in immature birds (Berger 1972,
p. 107). The Kauai [revaps]o[revaps]o is one of four known Hawaiian
species of the genus Moho and one of five known Hawaiian bird species
within the family Mohoidae (Fleischer et al. 2008, entire). Its last
known habitat was the dense ohia (Metrosideros polymorpha) forest in
the valleys of Alakai Wilderness Preserve. It reportedly fed on various
invertebrates and the fruits and nectar from ohia, lobelia, and other
flowering plants. There is no information on the lifespan of the Kauai
[revaps]o[revaps]o.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The vocalizations of this species were loud, distinctive, and
unlikely to be overlooked. The song consisted of loud whistles that
have been described as flute-like, echoing, and haunting, suggesting
that detectability would be high in remaining suitable habitat if the
[[Page 71656]]
Kauai [revaps]o[revaps]o still existed (USFWS 2006, p. 2-47).
Survey Effort
In the absence of early historical surveys, the extent of the
geographical range of the Kauai [revaps]o[revaps]o cannot be
reconstructed. The comprehensive surveys of Hawaiian forest birds are
described above under ``Survey Effort'' for the Kauai akialoa. Several
recent surveys and searches, including the VCP and RBS, have been
unsuccessful in detecting Kauai [revaps]o[revaps]o despite intensive
survey efforts by wildlife biologists from 1968 to 1973, and in 1981,
1989 1993, 1994, 2000, 2005, and 2011 to 2018 (Hawaii Department of
Land and Natural Resources unpubl. data; Reynolds and Snetsinger 2001,
entire; Crampton et al. 2017, entire; Crampton 2018 pers. comm.).
During the RBS, coverage of the search area was extensive; therefore,
there was a high probability of detecting a Kauai [revaps]o[revaps]o.
None were detected, and it was concluded the Kauai [revaps]o[revaps]o
was likely extinct (P >= 0.95) (Reynolds and Snetsinger 2001, p. 142).
Extensive time has been spent by qualified observers in the
historical range of the Kauai [revaps]o[revaps]o searching for the
small Kauai thrush, akekee, and akikiki. HFBSs were conducted in 1981,
1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 2016,
entire; Paxton et al. 2020, entire). During the HFBSs in 2012 and 2018,
occupancy surveys and nest searches did not yield any new detections of
Kauai [revaps]o[revaps]o. The KFBRP conducted mist-netting in various
locations within the historical range for Kauai [revaps]o[revaps]o from
2006 through 2009 and 2011 through 2018, and no Kauai
[revaps]o[revaps]o were caught or encountered (Crampton 2018, pers.
comm.). The last credible sighting was in 1987.
Time Since Last Detection
Using 1987 as the last credible sighting of the Kauai
[revaps]o[revaps]o based on independent expert opinion, the estimated
date for the species' extinction was 1991, with 95 percent confidence
that the species was extinct by 2000 (Elphick et al. 2010, p. 620).
III. Analysis
The various bird species in the subfamily Drepanidinae (also known
as the Hawaiian honeycreepers), which includes Kauai
[revaps]o[revaps]o, are highly susceptible to introduced avian disease,
particularly avian malaria. At elevations below approximately 4,500
feet (1,372 meters) in Hawaii, the key factor driving disease
epizootics of pox virus (Avipoxvirus) and avian malaria is the seasonal
and altitudinal distribution and density of the primary vector of these
diseases, the mosquito Culex quinquefasciatus (Atkinson and Lapointe
2009a, pp. 237-238, 245-246). Because they occur at similar altitudes
and face similar threats, please refer to ``III. Analysis'' for the
Kauai akialoa, above, for more information.
IV. Conclusion
At the time of listing in 1967, the Kauai [revaps]o[revaps]o faced
threats from effects of low population numbers, habitat loss, avian
disease, and predation by introduced mammals. The best available
information now indicates that the Kauai [revaps]o[revaps]o is extinct.
The species appears to have been vulnerable to introduced avian
disease. In addition, the effects of small population size likely
limited the species' genetic variation and adaptive capacity, thereby
increasing the vulnerability of the species to environmental stressors
including habitat loss and degradation. Since its last detection in
1987, qualified observers have conducted extensive surveys and searches
and have not detected the species. Available information indicates that
the species was not able to persist in the face of environmental
stressors, and we conclude that the best available scientific and
commercial information indicates that the species is extinct.
Large Kauai Thrush (Myadestes Myadestinus)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On October 13, 1970, we listed the large Kauai thrush (kama[revaps]o in
the Hawaiian language) as endangered (35 FR 16047). This bird was
included in the Kauai Forest Birds Recovery Plan (USFWS 1983, p. 1), as
well as the Revised Recovery Plan for Hawaiian Forest Birds (USFWS
2006, p. viii). At the time of listing, the population size was
estimated at 337 individuals (USFWS 1983, p. 3). Threats to the species
included effects of low population numbers, habitat loss, avian
disease, and predation by introduced mammals. The latest 5-year status
review completed in 2019 recommended delisting due to extinction based
on consideration of additional information about the biological status
of the species, as discussed below (USFWS 2019, pp. 5, 10).
The large Kauai thrush was a medium-sized (7.9 inches, or 20
centimeters, total length) solitaire. Its plumage was gray-brown above,
tinged with olive especially on the back, and light gray below with a
whitish belly and undertail coverts. The large Kauai thrush lacked the
white eye-ring and pinkish legs of the smaller puaiohi (small Kauai
thrush) (USFWS 2006, p. 2-19). The last (unconfirmed) observation of
the large Kauai thrush was made during the February 1989 Kauai Forest
Bird Survey (Hawaii Department of Land and Natural Resources unpubl.
data). However, the last credible sighting of the large Kauai thrush
occurred in 1987.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The large Kauai thrush was often described for its habit of rising
into the air, singing a few vigorous notes and then suddenly dropping
down into the underbrush. The vocalizations of this species varied
between sweet and melodic to lavish and flute-like, often given just
before dawn and after dusk (USFWS 2006, p. 2-19). These behaviors
indicate that detectability would be high in remaining suitable habitat
if the large Kauai thrush still existed. No subsequent sightings or
vocalizations have been documented despite extensive survey efforts by
biologists and birders.
Survey Effort
Several recent surveys and searches, including the VCP and RBS,
have been unsuccessful in detecting the large Kauai thrush despite
intensive survey efforts by wildlife biologists from 1968 to 1973, and
in 1981, 1989, 1993, 1994, 2000, 2005, and 2011 to 2018 (Hawaii
Department of Land and Natural Resources unpubl. data; Scott et al.
1986, entire; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018, pers. comm.). During the RBS in 2001,
coverage of the search area was extensive; therefore, they had a high
probability of detecting the large Kauai thrush. None were detected,
and it was concluded that the large Kauai thrush was likely extinct (P
>= 0.95) (Reynolds and Snetsinger 2001, p. 142).
Extensive time has been spent by qualified observers in the
historical range of the large Kauai thrush searching for the small
Kauai thrush, akekee, and akikiki. HFBSs were conducted in 1981, 1989,
1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et al. 2016,
entire; Paxton et al. 2020, entire). During the HFBS in 2012 and 2018,
occupancy surveys and nest
[[Page 71657]]
searches did not yield any new detections of the large Kauai thrush.
The KFBRP conducted mist-netting in various locations within the
historical range for the large Kauai thrush from 2006 through 2009, and
from 2011 through 2018, and no large Kauai thrush were caught or
encountered (Crampton 2018, pers. comm.). The last credible sighting of
the large Kauai thrush occurred in 1987.
Time Since Last Detection
Using 1987 as the last credible sighting of the large Kauai thrush
based on independent expert opinion, the estimated date for the
species' extinction was 1991, with 95 percent confidence that the
species was extinct by 1999 (Elphick et al. 2010, p. 620).
III. Analysis
Several recent surveys and searches, including the RBS and HFBS,
have been unsuccessful in detecting the large Kauai thrush despite
intensive survey efforts by wildlife biologists in 1993, 1994, 2000,
2005, and 2011 to 2018 (Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018, pers. comm.). Using 1987 as the last
credible sighting based on independent expert opinion and the species'
observational record, the estimated date for the species' extinction
was 1991, with 95 percent confidence the species was extinct by 1999
(Elphick et al. 2010, p. 620). Another analysis determined that the
large Kauai thrush was probably extinct at the time of the RBS in 1994
(P >= 0.95) (Reynolds and Snetsinger 2001, p. 142).
IV. Conclusion
At the time of listing in 1970, the large Kauai thrush faced
threats from low population numbers, habitat loss, avian disease, and
predation by introduced mammals. The best available information now
indicates that the large Kauai thrush is extinct. The species appears
to have been vulnerable to the effects of small population size, which
likely limited its genetic variation, disease resistance, and adaptive
capacity, thereby increasing the vulnerability of the species to the
environmental stressors of habitat degradation and predation by
nonnative mammals. Since its last credible detection in 1987, qualified
observers have conducted extensive surveys and searches throughout the
range of the species but have not detected the species. Available
information indicates that the species was not able to persist in the
face of environmental stressors, and we conclude that the best
available scientific and commercial information indicates that the
species is extinct.
Maui Akepa (Loxops Coccineus Ochraceus)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On October 13, 1970, we listed the Maui akepa (originally listed as
Loxops ochraceus) as endangered (35 FR 16047). This bird was included
in the Maui-Molokai Forest Birds Recovery Plan (USFWS 1984, pp. 12-13),
and the Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006,
pp. 2-94, 2-134-2-137). At the time of listing, we considered Maui
akepa to have very low population numbers, and to face threats from
habitat loss, avian disease, and predation by introduced mammals. The
latest 5-year status review completed in 2018 (initiated on February
12, 2016; see 81 FR 7571) recommended delisting due to extinction,
based in part on continued lack of detections and consideration of
extinction probability (USFWS 2018, pp. 5, 10).
The Maui akepa was known only from the island of Maui in the
Hawaiian Islands. Maui akepa were found in small groups with young in
the month of June when the birds were molting (Henshaw 1902, p. 62).
The species appeared to also use the ohia tree for nesting, as a pair
of Maui akepa was observed building a nest in the terminal foliage of a
tall ohia tree (Perkins 1903, p. 420).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Maui akepa adult males varied from dull brownish orange to light
brownish yellow, while females were duller and less yellowish (USFWS
2006, p. 2-134). Although the species was easily identifiable by sight,
its small body size (less than 5 inches (13 centimeters) long) and
habitat type (dense rainforest) made visual detection difficult. Songs
and calls of Maui akepa could be confused with those of other Maui
forest bird species; therefore, detection of the species requires
visual confirmation of the individual producing the songs and calls
(USFWS 2006, p. 2-135).
Survey Effort
In the absence of early historical surveys, the extent of the
geographical range of the Maui akepa is unknown. Because the species
occupied Maui Island, one might expect that it also inhabited Molokai
and Lanai Islands like other forest birds in the Maui Nui group, but
there are no fossil records of Maui akepa from either of these islands
(USFWS 2006, p. 2-135). All historical records of the Maui akepa in the
late 19th and early 20th centuries were from high-elevation forests
most accessible to naturalists, near Olinda and Ukulele Camp on the
northwest rift of Haleakala, and from mid-elevation forests in Kipahulu
Valley (USFWS 2006, p. 2-134). This range suggests that the birds were
missing from forests at lower elevations, perhaps due to the
introduction of disease-transmitting mosquitoes to Lahaina in 1826
(USFWS 2006, p. 2-135). From 1970 to 1995, there were few credible
sightings of Maui akepa (USFWS 2006, p. 2-136).
The population of Maui akepa was estimated at 230 individuals, with
a 95 percent confidence interval of plus or minus 290 individuals
(Scott et al. 1986, pp. 37, 154) during VCP surveys in 1980. In other
words, the estimate projects a maximum population of 520 individuals
and a minimum population of 0. However, confidence intervals were
large, and this estimate was based on potentially confusing auditory
detections, and not on visual observation (USFWS 2006, p. 2-136). On
Maui, given the density of VCP survey stations, it is estimated that
5,865 point counts would be needed to determine with 95 percent
confidence the absence of Maui akepa on Maui (Scott et al. 2008, p. 7).
In 2008, only 84 VCP counts had been conducted on Maui in areas where
this species was known to have occurred historically. Although the
results of the 1980 VCP surveys find Maui akepa extant at that time,
tremendous effort is required using the VCP method to confirm this
species' extinction (Scott et al. 2008, pp. 6-8). For Maui akepa,
nearly 70 times more VCP counts than conducted up to 2008 would be
needed to confirm the species' extinction with 95 percent confidence.
Songs identified as Maui akepa were heard on October 25, 1994,
during the RBS in Hanawi NAR and on November 28, 1995, from Kipahulu
Valley at 6,142 feet (1,872 meters) elevation, but the species was not
confirmed visually. Auditory detections of Maui akepa require visual
confirmation because of possible confusion or mimicry with similar
songs of Maui parrotbill (Reynolds and Snetsinger 2001, p. 140).
Qualified observers spent extensive time searching for Maui akepa,
po[revaps]ouli (Melamprosops phaeosoma), and Maui nukupuu in the 1990s.
Between September 1995 and October 1996,
[[Page 71658]]
1,730 acres (700 hectares) in Hanawi NAR were searched during 318
person-days (Baker 2001, p. 147), including the area with the most
recent confirmed sightings of Maui akepa. During favorable weather
conditions (good visibility and no wind or rain), teams would stop when
``chewee'' calls given by Maui parrotbill, or when po[revaps]ouli and
Maui nukupuu were heard, and would play either Maui parrotbill or
akiapolaau calls and songs to attract the bird for identification. Six
po[revaps]ouli were found, but no Maui akepa were detected (Baker 2001,
p. 147). The MFBRP conducted searches from 1997 through 1999 from
Hanawi NAR to Koolau Gap (west of Hanawi NAR), for a total of 355 hours
at three sites with no detections of Maui akepa (Vetter 2018, pers.
comm.). The MFBRP also searched Kipahulu Valley on northern Haleakala
from 1997 to 1999, for a total of 320 hours with no detections of Maui
akepa. However, the Kipahulu searches were hampered by bad weather, and
playback was not used (Vetter 2018, pers. comm.). Despite over 10,000
person-hours of searches in the Hanawi NAR and nearby areas from
October 1995 through June 1999, searches failed to confirm earlier
detections of Maui akepa (Pratt and Pyle 2000, p. 37). While working on
Maui parrotbill recovery from 2006 to 2011, the MFBRP spent extensive
time in the area of the last Maui akepa sighting. The most recent
survey in 2017 across much of east and west Maui did not find Maui
akepa (Judge et al. 2019, entire). The MFBRP project coordinator
concluded that if Maui akepa were present, they would have been
detected (Mounce 2018, pers. comm.).
Time Since Last Detection
The last confirmed sighting (as defined for the RBS) of the Maui
akepa was in 1988 (Engilis 1990, p. 69). Surveys conducted during the
late 1980s to the 2000s failed to locate the species (Pratt and Pyle
2000, p. 37; Baker 2001, p. 147). Using 1980 as the last documented
observation record for Maui akepa (the 1988 sighting did not meet the
author's criteria for a ``documented'' sighting), 1987 was estimated to
be the year of extinction of Maui akepa, with 2004 as the upper 95
percent confidence bound on that estimate (Elphick et al. 2010, p.
620).
III. Analysis
Reasons for decline presumably are similar to threats faced by
other endangered forest birds on Maui, including small populations,
habitat degradation by feral ungulates and introduced invasive plants,
and predation by introduced mammalian predators, including rats, cats
(Felis catus), and mongoose (Herpestes auropunctatus) (USFWS 2006, p.
2-136). Rats may have played an especially important role as nest
predators of Maui akepa. While the only nest of Maui akepa ever
reported was built in tree foliage, the birds may also have selected
tree cavities as does the very similar Hawaii akepa (L. c. coccineus).
In Maui forests, nest trees are of shorter stature than where akepa
survive on Hawaii Island. Suitable cavity sites on Maui are low in the
vegetation, some near or at ground level, and thus are more accessible
to rats. High densities of both black and Polynesian rats (R. rattus
and R. exulans) are present in akepa habitat on Maui (USFWS 2006, p. 2-
136).
The population of Maui akepa was estimated at 230 birds in 1980
(Scott et al. 1986, p. 154); however, confidence intervals on this
estimate were large. In addition, this may have been an overestimate
because it was based on audio detections that can be confused with
similar songs of Maui parrotbill. The last confirmed sighting of Maui
akepa was in 1988, from Hanawi NAR (Engilis 1990, p. 69). Over 10,000
search hours in Hanawi NAR and nearby areas including Kipahulu Valley
from October 1995 through June 1999 failed to confirm presence of Maui
akepa (Pratt and Pyle 2000, p. 37). Field presence by qualified
observers from 2006 to 2011 in the area Maui akepa was last known
failed to detect this species, and the MFBRP project coordinator
concluded that if Maui akepa were present they would have been detected
(Mounce 2018, pers. comm.). Further, using the method to determine
probability of species extinction based on time (years) since the
species was last observed (using 1980 as the last documented
observation record, as described above), the estimated year the Maui
akepa became extinct is 1987, with 2004 as the upper 95 percent
confidence bound on that estimate (Elphick et al. 2010, p. 620).
IV. Conclusion
At the time of listing in 1970, we considered the Maui akepa to be
facing threats from habitat loss, avian disease, and predation by
introduced mammals. The best available information now indicates that
the Maui akepa is extinct. The species appears to have been vulnerable
to the effects of small population size, which likely limited its
genetic variation, disease resistance, and adaptive capacity, thereby
increasing the vulnerability of the species to the environmental
stressors of habitat degradation and predation by nonnative mammals.
Since the last detection in 1988, qualified observers have conducted
extensive surveys in that same area with no additional detections of
the species. Available information indicates that the species was not
able to persist in the face of environmental stressors, and we conclude
that best available scientific and commercial information indicates
that the species is extinct.
Maui Nukupuu (Hemignathus Lucidus Affinis)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On October 13, 1970, we listed the Maui nukupuu (originally listed as
Hemignathus affinis) as endangered (35 FR 16047). This bird was
included in the Maui-Molokai Forest Birds Recovery Plan (USFWS 1984,
pp. 8, 10-12), and the Revised Recovery Plan for Hawaiian Forest Birds
(USFWS 2006, pp. 2-92-2-96). At the time of listing, we considered Maui
nukupuu to have very low population numbers and to be threatened by
habitat loss, avian disease, and predation by introduced mammals. The
5-year status review completed in 2018 (initiated on February 12, 2016;
see 81 FR 7571) recommended delisting due to extinction (USFWS 2018, p.
11).
The Maui nukupuu was known only from the island of Maui in the
Hawaiian Islands. The historical record provides little information on
the life history of the Maui nukupuu (Rothschild 1893 to 1900, pp. 103-
104; Perkins 1903, pp. 426-430). Nothing is known of its breeding
biology, which likely was similar to its closest relative, the
akiapolaau on Hawaii Island. Maui nukupuu often joined mixed-species
foraging flocks (Perkins 1903, p. 429).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection Species Detectability
The Maui nukupuu was a medium-sized (approximately 0.78 ounce, or
23 gram) Hawaiian honeycreeper with an extraordinarily thin, curved
bill that was slightly longer than the bird's head. The lower mandible
was half the length of the upper mandible and followed its curvature
rather than being straight (as in the related akiapolaau) (USFWS 2006,
p. 2-92). Adult males were olive green with a yellow head, throat, and
breast, whereas adult females and juveniles had an olive-green head and
[[Page 71659]]
yellow or yellowish gray under-parts. The species' coloration and bill
shape were quite distinctive, making visual identification of Maui
nukupuu relatively easy. The Maui nukupuu's song resembled the warble
of a house finch (Haemorhous mexicanus) but was lower in pitch. Both
the song and the ``kee-wit'' call resembled those of Maui parrotbill,
and audio detection required visual confirmation (USFWS 2006, p. 2-92).
Survey Effort
Historically, the Maui nukupuu was known only from Maui, but
subfossil bones of a probable Maui nukupuu from Molokai show that the
species likely formerly inhabited that island (USFWS 2006, p. 2-92).
All records from late 19th and early 20th centuries were from locations
most accessible to naturalists, above Olinda on the northwest rift of
Haleakala, and from mid-elevation forests in Kipahulu Valley (USFWS
2006, pp. 2-134). Observers at the time noted the restricted
distribution and low population density of Maui nukupuu. As on Kauai,
introduced mosquitoes and avian diseases may have already limited these
birds to forests at higher elevations, and we can presume that the Maui
nukupuu once had a much wider geographic range (USFWS 2006, pp. 2-92).
In 1967, Maui nukupuu were rediscovered in the upper reaches of
Kipahulu Valley on the eastern slope of Haleakala, east Maui (Banko
1968, pp. 65-66; USFWS 2006, pp. 2-95). Since then, isolated sightings
have been reported on the northern and eastern slopes of Haleakala, but
these reports are uncorroborated by behavioral information or follow-up
sightings (USFWS 2006, pp. 2-95).
Based on a single sighting of an immature bird during VCP surveys
in 1980, the population of Maui nukupuu was estimated to be 28
individuals, with a 95 percent confidence interval of plus or minus 56
individuals (Scott et al. 1986, pp. 37, 131). On Maui, given the
density of VCP survey stations, it was estimated that 1,357 point
counts would be needed to determine with 95 percent confidence the
absence of Maui nukupuu on Maui (Scott et al. 2008, p. 7). In 2008,
only 35 VCP counts had been conducted on Maui in areas where Maui
nukupuu could still potentially exist. Although the results of VCP
surveys in 1980 find Maui nukupuu extant at that time, a tremendous
effort is required to confirm this species' extinction using VCP method
(Scott et al. 2008, pp. 6-8). For Maui nukupuu, nearly 39 times more
VCP counts than conducted up to 2008 would be needed to confirm this
species' extinction with 95 percent confidence. The RBS reported an
adult male Maui nukupuu with bright yellow plumage at 6,021 feet (1,890
meters) elevation in 1996 from Hanawi NAR (Reynolds and Snetsinger
2001, p. 140). Surveys and searches have been unsuccessful in finding
Maui nukupuu since the last confirmed sighting by RBS. Based on these
results, the last reliable record of Maui nukupuu was from Hanawi NAR
in 1996 (24 years ago).
Qualified observers spent extensive time searching for Maui
nukupuu, po[revaps]ouli, and Maui akepa in the 1990s. Between September
1995 and October 1996, 1,730 acres (700 hectares) of Hanawi NAR were
searched during 318 person-days (Baker 2001, p. 147). Please refer to
``Survey Effort'' for the Maui akepa, above, for the method used in
this survey. The MFBRP conducted searches from 1997 to 1999, from
Hanawi NAR to Koolau Gap (west of the last sighting of Maui nukupuu)
for a total of 355 hours of searches at three sites with no detections
of Maui nukupuu (Vetter 2018, pers. comm.). The MFBRP also searched
Kipahulu Valley on northern Haleakala from 1997 to 1999, for a total of
320 hours, with no detections of Maui nukupuu. The Kipahulu searches
were hampered, however, by bad weather, and playback was not used
(Vetter 2018, pers. comm.). Despite over 10,000 person-hours of
searching in the Hanawi NAR and nearby areas from October 1995 through
June 1999, searches failed to confirm the 1996 detection of Maui
nukupuu, or produce other sightings (Pratt and Pyle 2000, p. 37). While
working on Maui parrotbill recovery from 2006 to 2011, the MFBRP spent
extensive time in the area of the last Maui nukupuu sighting. The most
recent survey in 2017 across much of east and west Maui did not find
Maui nukupuu (Judge et al. 2019, entire). The MFBRP project coordinator
concluded that if Maui nukupuu were still present they would have been
detected (Mounce 2018, pers. comm.).
Time Since Last Detection
The Maui nukupuu was last sighted in the Hanawi NAR in 1996
(Reynolds and Snetsinger 2001, p. 140). Surveys conducted during the
late 1990s and early 2000s were unable to locate the species (Pratt and
Pyle 2000, p. 37; Baker 2001, p. 147).
Elphick et al. 2010 (p. 630) attempted to apply their method to
predict the probability of species extinction for the Maui nukupuu
based on time (years) since the species was last observed (see ``Time
Since Last Detection'' for Kauai akialoa, above). However, observations
in 1967, 1980, and 1996 were not considered for this analysis because
they did not meet the researchers' criteria for a confirmed sighting.
Therefore, using 1896 as the last observation of Maui nukupuu, under
their stringent criteria, the authors were unable to determine an
estimated date for species extinction.
III. Analysis
The Maui nukupuu is also affected by small population sizes and
other threats, as discussed above under ``III. Analysis'' for the Maui
akepa. The population of Maui nukupuu was estimated to be 28 birds in
1980 (Scott et al. 1986, pp. 37, 131); however, confidence intervals on
this estimate were large. This population was vulnerable to negative
effects of small population size, including stochastic effects and
genetic drift that can accelerate the decline of small populations.
However, even rare species can persist despite having low numbers. The
last confirmed sighting of Maui nukupuu was in 1996, from Hanawi NAR
(Reynolds and Snetsinger 2001, p. 140). Over 10,000 person-search hours
in Hanawi NAR and nearby areas, including Kipahulu Valley, from October
1995 through June 1999 failed to confirm this sighting or to detect
other individuals (Pratt and Pyle 2000, p. 37). While working on Maui
parrotbill recovery from 2006 to 2011, the MFBRP spent extensive time
in the area of the last Maui nukupuu sighting; however, no Maui nukupuu
were observed, and the MFBRP project coordinator concluded that if Maui
nukupuu were still present they would have been detected (Mounce 2018,
pers. comm.).
IV. Conclusion
At the time of listing in 1970, Maui nukupuu had very low
population numbers and faced threats from habitat loss, avian disease,
and predation by introduced mammals. The species appears to have been
vulnerable to avian disease and the effects of small population size.
The latter likely limited the species' genetic variation and adaptive
capacity, thereby increasing the vulnerability of the species to the
environmental stressors of habitat degradation and predation by
nonnative mammals. Since its last detection in 1996, qualified
observers have conducted extensive searches in the area where the
species was last sighted and other native forest habitat where the
species occurred historically, but they have not detected the species.
Available information indicates that the species was not able to
persist in the face of environmental stressors, and we conclude that
the best available
[[Page 71660]]
scientific and commercial data indicate that the species is extinct.
Molokai Creeper (Paroreomyza Flammea)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On October 13, 1970, we listed the Molokai creeper
(k[amacr]k[amacr]wahie in the Hawaiian language) as endangered (35 FR
16047). This bird was included in the Maui-Molokai Forest Birds
Recovery Plan (USFWS 1984, pp. 18-20) and the Revised Recovery Plan for
Hawaiian Forest Birds (USFWS 2006, pp. 2-121-2-123). At the time of
listing, the Molokai creeper was considered extremely rare and faced
threats from habitat loss, avian disease, and predation by introduced
mammals. The latest 5-year status review completed in 2018 (initiated
on February 12, 2016; see 81 FR 7571) recommended delisting due to
extinction based in part on continued lack of detections and
consideration of extinction probability (USFWS 2018, p. 9).
The Molokai creeper was known only from Molokai in the Hawaiian
Islands. Only fragmentary information is available about the life
history of the species from the writings of early naturalists (Perkins
1903, pp. 413-417; Pekelo 1963, p. 64; USFWS 2006, p. 2-122). This
species was an insectivore that gleaned vegetation and bark in wet ohia
forests and was known almost solely from boggy areas of Molokai (Pekelo
1963, p. 64.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Adult males were mostly scarlet in various shades, while adult
females were brown with scarlet washes and markings, and juvenile males
ranged from brown to scarlet with many gradations. The bill was short
and straight. Its calls were described as chip or chirping notes
similar to other creeper calls (USFWS 2006, p. 2-122). Its closest
relatives are the Maui creeper (Paroreomyza montana) and the Oahu
creeper (P. maculata). The species' coloration and bill shape were
distinctive, and Molokai creeper was identified visually with
confidence.
Survey Effort
Molokai creeper was common in 1907, but by the 1930s they were
considered in danger of extinction (Scott et al. 1986, p. 148). The
species was last detected in 1963, on the west rim of Pelekunu Valley
(Pekelo 1963, p. 64). Surveys and searches have been unsuccessful in
finding the Molokai creeper since the last sighting, including VCP
surveys on the Olokui Plateau in 1980 and 1988, and the RBS of the
Kamakou-Pelekunu Plateau in 1995 (Reynolds and Snetsinger 2001, p.
141). Following up on a purported sighting in 2005 of a Molokai thrush
(Myadestes lanaiensis rutha), a survey was conducted over 2 to 3 days
in Puu Alii NAR, the last place the Molokai creeper was sighted in the
1960s (Pekelo 1963, p. 64; USFWS 2006, pp. 2-29). Using playback
recordings for Molokai thrush, searchers covered the reserve area
fairly well, but no Molokai creepers or Molokai thrush were detected
(Vetter 2018, pers. comm.).
No Molokai creepers were detected during VCP surveys beginning in
the late 1970s to the most recent Hawaiian forest bird survey on
Molokai in 2010 (Scott et al. 1986, p. 37; Camp 2015, pers. comm.). On
Molokai, given the density of VCP survey stations, it was estimated
that 215,427 point counts would be needed to determine with 95 percent
confidence the absence of Molokai creeper on Maui (Scott et al. 2008,
p. 7). In 2008, only 131 VCP counts had been conducted on Molokai in
areas where Molokai creeper could still potentially exist. For the
Molokai creeper, nearly 1,650 times more VCP counts than conducted up
to 2008 would be needed to confirm the species' extinction with 95
percent confidence. Based on species detection probability, the RBS
determined the likelihood of the Molokai creeper being extirpated from
the Kamakou-Pelekunu plateau was greater than 95 percent. Additional
VCP surveys were conducted on Molokai in 2010 and 2021, but no Molokai
creepers were detected (Camp 2015, pers. comm., p. 2; Berry 2021, pers.
comm., p. 1). The RBS estimated the Molokai creeper to be extinct over
the entirety of its range, but because not all potential suitable
habitat was searched, extinction probability was not determined
(Reynolds and Snetsinger 2001, p. 141).
Time Since Last Detection
The last reliable record (based on independent expert opinion and
physical evidence) of Molokai creeper was from Pelekunu Valley in 1963
(Pekelo 1963, p. 64). Using 1963 as the last reliable observation
record for Molokai creeper, 1969 is estimated to be year of extinction
of the Molokai creeper with 1985 as the upper 95 percent confidence
bound (Elphick et al. 2010, p. 620).
III. Analysis
The Molokai creeper faced similar threats to the other Maui bird
species (see ``III. Analysis'' for the Maui akepa, above). The last
confirmed detection of the Molokai creeper was in 1963 (Pekelo 1963, p.
64). Forest bird surveys in 1980, 1988, and 2010, and the RBS in 1994-
1996 (although not including the Olokui Plateau), failed to detect this
species. A 2- to 3-day search by qualified personnel for the Molokai
thrush in Puu Alii NAR in 2005, the last location where Molokai creeper
was sighted, also failed to detect the Molokai creeper. The estimated
year of extinction is 1969, with 1985 as the 95 percent confidence
upper bound (Elphick et al. 2010, p. 620). It is highly likely that
avian disease, thought to be the driver of range contraction and
disappearance of many Hawaiian honeycreeper species, was present
periodically throughout nearly all of the Molokai creeper's range over
the last half-century.
IV. Conclusion
At the time of listing in 1970, the Molokai creeper was considered
to be facing threats from habitat loss, avian disease, and predation by
introduced mammals. The best information now indicates that the Molokai
creeper is extinct. The species appears to have been vulnerable to
avian disease, as well as the effects of small population size. The
latter likely limited the species' genetic variation and adaptive
capacity, thereby increasing the vulnerability of the species to the
environmental stressors of habitat degradation and predation by
nonnative mammals. Since its last detection in 1963, qualified
observers have conducted extensive searches for the Molokai creeper but
have not detected the species. Available information indicates that the
species was not able to persist in the face of environmental stressors,
and we conclude that the best available scientific and commercial
information indicates that the species is extinct.
Po[revaps]ouli (Melamprosops Phaeosoma)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On September 25, 1975, we listed the po[revaps]ouli (Melamprosops
phaeosoma) as endangered (40 FR 44149), and the species was included in
the Maui-
[[Page 71661]]
Molokai Forest Birds Recovery Plan (USFWS 1984, pp. 16-17) and the
Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006, pp. 2-144-
2-154). At the time of listing, we considered the po[revaps]ouli to
have very low abundance and likely to be threatened by habitat loss,
avian disease, and predation by introduced mammals. The latest 5-year
status review completed in 2018 (initiated on February 12, 2016; see 81
FR 7571) recommended delisting due to extinction, based in part on
continued lack of detections and consideration of extinction
probability (USFWS 2018, pp. 4-5, 10).
The po[revaps]ouli was known only from the island of Maui in the
Hawaiian Islands and was first discovered in 1973, in high-elevation
rainforest on the east slope of Haleakala (USFWS 2006, p. 2-146).
Fossil evidence shows that the po[revaps]ouli once inhabited drier
forests at lower elevation on the leeward slope of Haleakala,
indicating it once had a much broader geographic and habitat range
(USFWS 2006, p. 2-147). Po[revaps]ouli were observed singly, in pairs,
and in family groups consisting of both parents and a single offspring
(Pratt et al. 1997, p. 1). Po[revaps]ouli foraged primarily on tree
branches, making extensive use of the subcanopy and understory. They
seemed to have preferred the native hydrangea (kanawao [Broussaisia
arguta]), the native holly (kawau [Ilex anomala]), and ohia (Pratt et
al. 1997, p. 4). Po[revaps]ouli were unusually quiet. Males rarely sang
and did so mostly as part of courtship prior to egg-laying. The maximum
lifespan of this species is estimated to be 9 years (The Animal Aging
and Longevity Database 2020, unpaginated).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The po[revaps]ouli was a medium-sized, 0.9 ounce (26 gram), stocky
Hawaiian honeycreeper, easily recognized by its brown plumage and
characteristic black mask framed by a gray crown and white cheek patch.
However, po[revaps]ouli were unusually quiet. Although distinctive
visually, because the species rarely vocalized, it was difficult to
survey by audio detections.
Survey Effort
The po[revaps]ouli was first discovered in 1973 (USFWS 2006, p. 2-
146). Total population was estimated at 140 individuals, with a 95
percent confidence interval of plus or minus 280 individuals, during
VCP surveys in 1980 (Scott et al. 1986, pp. 37, 183), but estimates of
population size and density were likely inaccurate and considered
imprecise due to the species' low density and cryptic behavior (USFWS
2006, p. 2-147). In 1994, after nearly 2 years without a sighting, the
continued existence and successful breeding of five to six
po[revaps]ouli in the Kuhiwa drainage of Hanawi NAR was confirmed
(Reynolds and Snetsinger 2001, p. 141). Thorough surveys of the
historical range between 1997 and 2000, the MFBRP located only three
birds, all in separate territories in Hanawi NAR. These three
po[revaps]ouli were color-banded in 1996 and 1997, and subsequently
observed (see below), but no other individuals have been observed since
then (Baker 2001, p. 144; USFWS 2006, pp. 2-147-2-148). The MFBRP
searched Kipahulu Valley on northern Haleakala from 1997 to 2000, for a
total of 320 hours, but failed to detect po[revaps]ouli. These searches
were hampered by bad weather, however, and playback was not used
(Vetter 2018, pers. comm.). The most recent survey in 2017 across much
of east and west Maui did not find po[revaps]ouli (Judge et al. 2019,
entire).
Time Since Last Detection
In 2002, what was thought to be the only female po[revaps]ouli of
the three in Hanawi NAR was captured and released into one of the
male's territories, but she returned to her home range the following
day (USFWS 2006, p. 2-151). In 2004, an effort was initiated to capture
the three remaining po[revaps]ouli to breed them in captivity. One
individual was captured and successfully maintained in captivity for 78
days, but died on November 26, 2004, before a potential mate could be
obtained. The remaining two birds were last seen in December 2003 and
January 2004 (USFWS 2006, pp. 2-153-2-154). While working on Maui
parrotbill recovery from 2006 to 2011, the MFBRP spent extensive time
in the area of the last po[revaps]ouli sightings. No po[revaps]ouli
were seen or heard. The MFBRP project coordinator concluded that if
po[revaps]ouli were present, they would have been detected (Mounce
2018, pers. comm.).
Using 2004 as the last reliable observation record for
po[revaps]ouli, 2005 is estimated to be the year of extinction, with
2008 as the upper 95 percent confidence bound on that estimate (Elphick
et al. 2010, p. 620).
III. Analysis
The po[revaps]ouli faced threats similar to other bird species
occurring on Maui (see ``III. Analysis'' for the Maui akepa, above).
The last confirmed sighting of po[revaps]ouli was in 2004 from Hanawi
NAR (USFWS 2006, p. 2-154). Extensive field presence by qualified
individuals from 2006 to 2011 in Hanawi NAR, where po[revaps]ouli was
last observed, failed to detect this species, as did searches of
Kipahulu Valley near Hanawi NAR from 1997 to 1999 (USFWS 2006, p. 2-
94). Using 2004 as the last reliable observation record for
po[revaps]ouli, the estimated year the species went extinct is 2005,
with 2008 the upper 95 percent confidence bound on that estimate
(Elphick et al. 2010, p. 620).
IV. Conclusion
At the time of its listing in 1975, we considered po[revaps]ouli to
have very low population abundance, and to face threats from habitat
loss, avian disease, and predation by introduced mammals. The best
available information now indicates that the po[revaps]ouli is extinct.
Although the po[revaps]ouli was last detected as recently as early
2004, the species appears to have been vulnerable to the effects of
small population size since it was first discovered in 1973. The small
population size likely limited its genetic variation, disease
resistance, and adaptive capacity over time, thereby increasing the
vulnerability of the species to the environmental stressors of habitat
degradation and predation by nonnative mammals. Experienced staff with
MFBRP conducted extensive recovery work in po[revaps]ouli habitat
between 2006 and 2011, and had no detections of the species. Available
information indicates that the species was not able to persist in the
face of environmental stressors, and we conclude that the species is
extinct.
Fishes
San Marcos Gambusia (Gambusia Georgei)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On July 14, 1980, we listed the San Marcos gambusia, a small fish, as
endangered (45 FR 47355). We concurrently designated approximately 0.5
miles of the San Marcos River as critical habitat for the species (45
FR 47355, July 14, 1980, p. 47364). The San Marcos gambusia was endemic
to the San Marcos River in San Marcos, Texas. The San Marcos gambusia
has historically only been found in a section of the upper San Marcos
River approximately from Rio Vista Dam to a point near the U.S.
Geological Survey gaging station immediately downstream from Thompson's
Island. Only a limited number of species of Gambusia are
[[Page 71662]]
native to the United States; of this subset, the San Marcos gambusia
had one of the most restricted ranges.
We listed the species as endangered due to decline in population
size, low population numbers, and possibility of lowered water tables,
pollution, bottom plowing (a farming method that brings subsoil to the
top and buries the previous top layer), and cutting of vegetation (43
FR 30316; July 14, 1978). We identified groundwater depletion, reduced
spring flows, contamination, habitat impacts resulting from severe
drought conditions, and cumulative effects of human activities as
threats to the species (43 FR 30316; July 14, 1978). At the time of
listing, this species was extremely rare.
There has also been evidence of hybridization between G. georgei
and G. affinis (western mosquitofish) in the wild. Hybridization
between G. georgei and G. affinis continued for many years without
documented transfer of genes between the species that would have
resulted in the establishment of a new species (Hubbs and Peden 1969,
p. 357). Based on collections in the 1920s, a study in the late 1960s
surmised that limited hybridization with G. affinis did not seem to
have reduced the specific integrity of either species. However, as
fewer G. georgei individuals existed in the wild and therefore
encountered each other, the chances of hybridization with the much more
common G. affinis increased.
On May 31, 2018, we initiated a 5-year review of the species (83 FR
25034). The review relied on available information, including survey
results, fish collection records, peer-reviewed literature, various
agency records, and correspondences with leading Gambusia species
experts in Texas. That 5-year review recommended delisting the San
Marcos gambusia due to extinction.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Historically, the San Marcos gambusia had small populations, and
the pattern of abundance strongly suggests a decrease beginning prior
to the mid-1970s. Historical records indicate that San Marcos gambusia
was likely collected from the headwaters of the San Marcos River (Hubbs
and Peden 1969, p. 28). The highest number of San Marcos gambusia ever
collected was 119 in 1968. Because this species preferred sections of
slow-moving waters and had a limited historical range of a small
section of the San Marcos River, potential detection was not expected
to be difficult.
Survey Effort
In 1976, we contracted a status survey to improve our understanding
of the species and its habitat needs. We facilitated bringing
individuals into captivity for breeding and study. Many researchers
have been involved and have devoted considerable effort to attempts to
locate and preserve populations. Intensive collections during 1978 and
1979 yielded only 18 San Marcos gambusia from 20,199 Gambusia total,
which means San Marcos gambusia amounted to only 0.09 percent of those
collections (Edwards et al. 1980, p. 20). Captive populations were
established at the University of Texas at Austin in 1979, and fish from
that captive population were used to establish a captive population at
our Dexter National Fish Hatchery in 1980. Both captive populations
later became contaminated with another Gambusia species. The fish
hybridized, and the pure stocks were lost.
Following the failed attempt at maintaining captive populations at
Dexter National Fish Hatchery and the subsequent listing of the species
in 1980, we contracted for research to examine known localities and
collect fish to establish captive refugia. Collections made in 1981 and
1982 within the range of San Marcos gambusia indicated a slight
decrease in relative abundance of this species (0.06 percent of all
Gambusia). From 1981 to 1984, efforts were made to relocate populations
and reestablish a culture of individuals for captive refugia. Too few
pure San Marcos gambusia and hybrids were found to establish a culture,
although attempts were made with the few fish available (Edwards et al.
1980, p. 24). In the mid-1980s, staff from the San Marcos National Fish
Hatchery and Technology Center also searched unsuccessfully for the
species in attempts to locate individuals to bring into captivity.
Intensive searches for San Marcos gambusia were conducted in May,
July, and September of 1990, but were unsuccessful in locating any pure
San Marcos gambusia. The searches consisted of more than 180 people-
hours of effort over the course of 3 separate days and covered the area
from the headwaters at Spring Lake to the San Marcos wastewater
treatment plant outfall. Over 15,450 Gambusia were identified during
the searches. One individual collected during the search was visually
identified as a possible backcross of G. georgei and G. affinis
(Service 1990 permit report). This individual was an immature fish with
plain coloration. Additional sampling near the Interstate Highway 35
type locality has occurred at approximately yearly intervals since
1990, and no San Marcos gambusia have been found. No San Marcos
gambusia were found in the 32,811 Gambusia collected in the upper San
Marcos River by the Service from 1994 to 1996 (Edwards 1999, pp. 6-13).
Time Since Last Detection
Academic researchers, Texas Parks and Wildlife Department
scientists, and the Service have continued to search for the San Marcos
gambusia during all collection and research with fishes on the San
Marcos River. San Marcos gambusia have not been found in the wild since
1983, even with intensive searches, including the ones conducted in
May, July, and September of 1990, covering the species' known range and
designated critical habitat. Since 1996, all attempts to locate and
collect San Marcos gambusia have failed (Edwards 1999, p. 3; Edwards et
al. 2002, p. 358; Hendrickson and Cohen 2015, unpaginated; Bio-West
2016, p. 43; Bonner 2018, pers. comm.). More recent surveys and
analyses of fish species already consider the San Marcos gambusia
extinct (Edwards et al. 2002, p. 358; Hubbs et al. 2008, p. 3).
Additionally, hybridized individuals have not been documented since
1990.
III. Analysis
Although the population of San Marcos gambusia was historically
small, it also had one of the most restricted ranges of Gambusia
species. San Marcos gambusia have not been found in the wild since
1983, even with intensive searches, including the ones conducted in
May, July, and September of 1990, covering the species' known range and
designated critical habitat. Additionally, no detections of hybridized
San Marcos gambusia with G. affinis is further evidence that extinction
has occurred.
In addition to the San Marcos gambusia not being found in the wild,
all attempts at captive breeding have failed. This is largely due to
unsuccessful searches for the species in attempts to locate individuals
to bring into captivity.
Due to the narrow habitat preference and limited range of the San
Marcos gambusia, and the exhaustive survey and collection efforts that
have failed to detect the species, we conclude there is a very low
possibility of an individual or population remaining extant but
undetected. Therefore, the decrease in San Marcos gambusia abundance,
and the lack of hybridized individuals in
[[Page 71663]]
any recent samples, indicates that the species is extinct.
IV. Conclusion
The San Marcos gambusia was federally listed as endangered in 1980.
At the time of listing, this species was rare. The last known
collections of San Marcos gambusia from the wild were in the early
1980s (Edwards 1999, p. 2; Edwards 2002, p. 358), and the last known
sighting in the wild occurred in 1983. In 1985, after unsuccessful
breeding attempts with G. affinis from the upper San Marcos River, the
last captive female San Marcos gambusia died. All available information
and field survey data support a determination that the San Marcos
gambusia has been extinct in the wild for more than 35 years. We have
reviewed the best scientific and commercial data available to conclude
that the species is extinct.
Scioto Madtom (Noturus Trautmani)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On September 25, 1975, we listed the Scioto madtom (Noturus trautmani)
as endangered (40 FR 44149), due to the pollution and siltation of its
habitat and the proposal to construct two impoundments within its
range. Two 5-year reviews were initiated in 2009 (74 FR 11600; March
18, 2009) and 2014 (79 FR 38560; July 8, 2014). The recommendations
from both the 2009 and 2014 reviews were to delist the species due to
extinction (Service 2009, p. 7; Service 2014, p. 6).
The Scioto madtom was a small, nocturnal species of catfish in the
family Ictaluridae. The Scioto madtom has been found only in a small
section of Big Darby Creek, a major tributary to the Scioto River, and
was believed to be endemic to the Scioto River basin in central Ohio
(40 FR 44149, September 25, 1975; Service 1985, p. 10; Service 1988, p.
1).
The species was first collected in 1943 (Trautman 1981, p. 504),
and was first described as a species in 1969 (Taylor 1969, pp. 156-
160). Only 18 individuals of the Scioto madtom were ever collected. All
were found along one stretch of Big Darby Creek, and all but one were
found within the same riffle known as Trautman's riffle. The riffle
habitat was comprised of glacial cobble, gravel, sand, and silt
substrate, with some large boulders (Trautman 1981, p. 505) with
moderate current and high-quality water free of suspended sediments.
The exact cause of the Scioto madtom's decline is unknown, but was
likely due to modification of its habitat from siltation, suspended
industrial effluents, and agricultural runoff (40 FR 44149, September
25, 1975; Service 1988, p. 2). At the time of listing, two dams were
proposed for Big Darby Creek, although ultimately they were never
constructed. It should also be noted that the northern madtom (N.
stigmosus) was first observed in Big Darby Creek in 1957, the same year
the last Scioto madtom was collected (Service 1982, p. 3; Kibbey 2009,
pers. comm.). Given the apparent small population size and highly
restricted range of the Scioto madtom in the 1940s and 1950s, it is
possible that the species was unable to successfully compete with the
northern madtom for the same food and shelter resources (Kibbey 2009,
pers. comm.).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Scioto madtom looked similar to other madtom species but could
be distinguished by characteristics such as the number of pectoral and
anal rays (Taylor 1969, p. 156). The species, like other madtom
species, was relatively cryptic as they hid during the daylight hours
under rocks or in vegetation and emerged after dark to forage along the
bottom of the stream (Tetzloff 2003, p. 1). Despite these detection
challenges, many surveys by experienced biologists have been undertaken
to try to locate extant populations of Scioto madtom (USFWS 1977,
entire; USFWS 1982, entire; USFWS 1985, entire; USFWS 1997, entire;
Kibbey 2009, pers. comm.).
Survey Effort
No Scioto madtoms have been observed since 1957, despite intensive
fish surveys throughout Big Darby Creek in 1976-1977 (Service 1977, p.
15), 1981-1985 (Service 1982, p. 1; Service 1985, p. 1), 2014-2015
(Ohio Environmental Protection Agency (OEPA) 2018, p. 48), and 2001-
2019 (Kibbey 2009, pers. comm.; Zimmerman 2014, 2020, pers. comm.).
The fish surveys conducted in Big Darby Creek in 1976-1977 and
1981-1985 specifically targeted the Scioto madtom. The 1976-1977 survey
found 41 madtoms of 3 species and 34 species of fish in riffles at and
near the Scioto madtom type locality (Service 1977, pp. 13-15). The
1981-1985 survey occurred throughout Big Darby Creek and found a total
of 2,417 madtoms of 5 species (Service 1985, pp. 1, 5, 19-23). Twenty-
two percent (542 individuals) of the total madtoms were riffle madtoms
of the subgenus Rabida, which also includes the Scioto madtom (Service
1985, p. 1). None of the species identified were the Scioto madtom.
The 2014-2015 fish surveys occurred throughout the Big Darby Creek
watershed as part of the Ohio Environmental Protection Agency's
(OEPA's) water-quality monitoring program. A total of 96,471 fish
representing 85 different species and 6 hybrids, were collected at 93
sampling locations throughout the Big Darby Creek study area during the
2014 sampling season. Fish surveys were conducted at numerous sites in
Big Darby Creek between 2001 and 2019, using a variety of survey
techniques, including seining, boat electrofishing, backpack
electrofishing, and dip netting (Zimmerman 2020, pers. comm.). Another
survey was also conducted annually in the Big Darby Creek from 1970 to
2005 (Cavender 1999, pers. comm.; Kibbey 2016, pers. comm.).
These surveys also included extensive searches for populations of
Scioto madtoms outside of the type locality in Big Darby Creek (Kibbey
2016, pers. comm.). In addition to fish surveys in the Big Darby Creek
watershed, the OEPA has conducted a number of fish studies throughout
the Upper, Middle, and Lower Scioto River watershed as part of the
agency's Statewide Water Quality Monitoring Program (OEPA 1993a, 1993b,
1999, 2002, 2004, 2006, 2008, 2012, 2019, entire). These surveys have
never detected a Scioto madtom.
Time Since Last Detection
No collections of the Scioto madtom have been made since 1957.
Given that the extensive fish surveys conducted since 1970 within the
species' historical location, as well as along the entire length of Big
Darby Creek and in the greater Scioto River watershed, have recorded
three other species of madtom but not the Scioto madtom, it is highly
unlikely that the Scioto madtom has persisted without detection.
Other Considerations Applicable to the Species' Status
The habitat that once supported the Scioto madtom has been
drastically altered, primarily via strong episodic flooding. Although
periodic flooding has historically been a part of Big Darby Creek's
hydrological regime, many of the original riffles where Scioto madtoms
were collected from just downstream of the U.S. Route 104 Bridge to
approximately one-half mile upstream have been washed out to the
[[Page 71664]]
point where they are nearly gone (Kibbey 2009, pers. comm.).
Furthermore, pollution sources throughout the Scioto River watershed,
including row crop agriculture, development, and urban runoff, have
reduced the water quality and suitability of habitat for madtoms (OEPA
2012, pp. 1-2).
III. Analysis
There has been no evidence of the continued existence of the Scioto
madtom since 1957. Surveys for the species were conducted annually
between 1970 and 2005, at the only known location for the species.
Additional surveys in the Big Darby Creek watershed have never found
other locations of Scioto madtom. After decades of survey work with no
individuals being detected, it is extremely unlikely that the species
is extant. Further, available habitat for the species in the only
location where it has been documented is now much reduced, which
supports the conclusion that the species is likely extinct.
IV. Conclusion
We conclude that the Scioto madtom is extinct and, therefore,
should be delisted. This conclusion is based on a lack of detections
during numerous surveys conducted for the species and significant
alteration of habitat at its known historical location.
Mussels
Flat Pigtoe (Pleurobema Marshalli)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On April 7, 1987, we listed the flat pigtoe (formerly known as
Marshall's mussel), as endangered, primarily due to habitat alteration
from a free-flowing riverine system to an impounded system (52 FR
11162). Two 5-year reviews were completed in 2009 (initiated on
September 8, 2006; see 71 FR 53127) and 2015 (initiated on March 25,
2014; see 79 FR 16366); both recommended delisting the flat pigtoe due
to extinction. The Service solicited peer review from six experts for
both 5-year reviews from State, Federal, university, and museum
biologists with known expertise and interest in Mobile River Basin
mussels (USFWS 2009, pp. 23-24; USFWS 2015, pp. 15-16); we received
responses from three of the peer reviewers, and they concurred with the
content and conclusion that the species is extinct.
The flat pigtoe was described in 1927, from specimens collected in
the Tombigbee River (USFWS 1989, p. 2). The shell of the flat pigtoe
had pustules or welts on the postventral surface, and the adults were
subovate in shape and approximately 2.4 inches long and 2 inches wide
(USFWS 1989, p. 2). Freshwater mussels of the Mobile River Basin, such
as the flat pigtoe, are most often found in clean, fast-flowing water
in stable sand, gravel, and cobble/gravel substrates that are free of
silt (USFWS 2000, p. 81). They are typically found buried in the
substrate in shoals and runs (USFWS 2000, p. 81). This type of habitat
has been nearly eliminated within the historical range of the species
because of the construction of the Tennessee-Tombigbee Waterway in
1984, which created a dredged, straightened navigation channel and a
series of impoundments that inundated nearly all riverine mussel
habitat (USFWS 1989, p. 1).
The flat pigtoe was historically known from the Tombigbee River
from just above Tibbee Creek near Columbus, Mississippi, downstream to
Epes, Alabama (USFWS 1989, p. 3). Surveys in historical habitat over
the past three decades have failed to locate the species, and all
historical habitat is impounded or modified by channelization and
impoundments (USFWS 2015, p. 5). No live or freshly dead shells have
been observed since the species was listed in 1987 (USFWS 2009, p. 4;
USFWS 2015, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging and can be affected by a variety of
factors, including:
Size of the mussel (smaller mussels, including juvenile
mussels, can be more difficult to find in complex substrates than
larger mussels, and survey efforts must be thorough enough to try to
detect smaller mussels);
Behavior of the mussel (some are found subsurface, some at
the surface, and some above the surface, and position can vary
seasonally [some are more visible during the reproductive phase when
they need to come into contact with host fish; therefore, surveys
likely need to be conducted during different times of the year to
improve detection]);
Substrate composition (it can be easier to see/feel
mussels in sand and clay than in gravel or cobble; therefore, surveys
need to include all substrate types because mussels can fall off host
fish into a variety of substrates);
Size of river (larger rivers usually have more expansive
habitat areas to search and are sometimes deep, requiring specialized
survey techniques such as self-contained underwater breathing apparatus
[SCUBA]);
Flow conditions (visibility can be affected in very fast-
flowing, very shallow, or turbid conditions; therefore, surveys need to
use tactile or excavation methods, or delay until turbidity conditions
improve);
Surveyor experience (finding mussels requires a well-
developed search image, knowledge of instream habitat dynamics, and
ability to identify and distinguish species); and
Survey methodology and effort (excavation and sifting of
stream bottom can detect more mussels than visual or tactile surveys).
All of these challenges are taken into account when developing
survey protocols for any species of freshwater mussel, including the
flat pigtoe. The flat pigtoe was medium-sized (but juveniles were very
small) and most often found buried in sand, gravel, or cobble in fast-
flowing runs. However, mussels can be found in suboptimal conditions,
depending on where they dropped off of the host fish. Therefore, all of
the above-mentioned considerations need to be accounted for when trying
to detect this mussel species. Despite detection challenges, many well-
planned, comprehensive surveys by experienced State and Federal
biologists have been carried out, and those surveys have not been able
to locate extant populations of flat pigtoe in the Tombigbee River
(USFWS 2000, p. 81; USFWS 2015, p. 5).
Survey Effort
Prior to listing, freshly dead shells of flat pigtoe were collected
in 1980, from the Tombigbee River, Lowndes County, Mississippi (USFWS
2009, pp. 4-5), and a 1984 survey of the Gainesville Bendway of
Tombigbee River also found shells of the flat pigtoe (USFWS 1989, p.
4). After listing in 1987, surveys in 1988 and 1990 only found
weathered, relict shells of the flat pigtoe below Heflin Dam, thus
casting doubt on the continued existence of the species in the
Gainesville Bendway (USFWS 1989, p. 4; USFWS 2009, p. 5). Over the past
three decades, surveys between 1990-2001, and in 2002, 2003, 2009,
2011, and 2015, of potential habitat throughout the historical range,
including intensive surveys of the Gainesville Bendway, where adequate
[[Page 71665]]
habitat and flows may still occur below the Gainesville Dam on the
Tombigbee River in Alabama, have failed to find any live or dead flat
pigtoes (USFWS 2000, p. 81).
Time Since Last Detection
The flat pigtoe has not been collected alive since completion of
the Tennessee-Tombigbee Waterway in 1984 (USFWS 2000, p. 81; USFWS
2015, p. 5). Mussel surveys within the Tombigbee River drainage during
1984-2015 failed to document the presence of the flat pigtoe (USFWS
2015, p. 8).
Other Considerations Applicable to the Species' Status
Habitat modification is the major cause of decline of the flat
pigtoe (USFWS 2000, p. 81). Construction of the Tennessee-Tombigbee
Waterway for navigation adversely impacted mussels and their habitat by
physical destruction during dredging, increasing sedimentation,
reducing water flow, and suffocating juveniles with sediment (USFWS
1989, p. 6). Other threats include channel improvements such as
clearing and snagging, as well as sand and gravel mining, diversion of
flood flows, and water removal for municipal use. These activities
impact mussels by altering the river substrate, increasing
sedimentation, changing water flows, and killing individuals via
dredging and snagging (USFWS 1989, pp. 6-7). Runoff from fertilizers
and pesticides results in algal blooms and excessive growth of other
aquatic vegetation, resulting in eutrophication and death of mussels
due to lack of oxygen (USFWS 1989, p. 7). The cumulative impacts of
habitat degradation due to these factors likely led to flat pigtoe
populations becoming scattered and isolated over time. Low population
levels increased the difficulty of successful reproduction (USFWS 1989,
p. 7). When individuals become scattered, the opportunity for egg
fertilization is diminished. Coupled with habitat changes that result
in reduced host fish interactions, the spiral of failed reproduction
leads to local extirpation and eventual extinction of the species
(USFWS 1989, p. 7).
III. Analysis
There has been no evidence of the continued existence of the flat
pigtoe for more than three decades. Mussel surveys within the Tombigbee
River drainage from 1984-2015 have failed to document the presence of
the species (USFWS 2015, p. 8). All known historical habitat has been
altered or degraded by impoundments, and the species is presumed
extinct by most authorities.
IV. Conclusion
We conclude that the flat pigtoe is extinct and, therefore, should
be delisted. This conclusion is based on significant alteration of all
known historical habitat and lack of detections during numerous surveys
conducted throughout the species' range.
Southern Acornshell (Epioblasma Othcaloogensis)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On March 17, 1993, we listed the southern acornshell as endangered,
primarily due to habitat modification, sedimentation, and water-quality
degradation (58 FR 14330). We designated critical habitat on July 1,
2004 (69 FR 40084). Two 5-year reviews were completed in 2008
(initiated on June 14, 2005; see 70 FR 34492) and 2018 (initiated on
September 23, 2014; see 79 FR 56821), both recommending delisting the
southern acornshell due to extinction. We solicited peer review from
eight experts for both 5-year reviews from State, Federal, university,
nongovernmental, and museum biologists with known expertise and
interest in Mobile River Basin mussels (Service 2008, pp. 36-37;
Service 2018, p. 15); we received responses from five of the peer
reviewers, who all concurred with the content and conclusion that the
species is extinct.
The southern acornshell was described in 1857 from Othcalooga Creek
in Gordon County, Georgia (58 FR 14330 at 14331, March 17, 1993). Adult
southern acornshells were round to oval in shape and approximately 1.2
inches in length (Service 2000, p. 57). Epioblasma othcaloogensis was
included as a synonym of E. penita and was considered to be an
ectomorph of the latter (58 FR 14330 at 14331, March 17, 1993). The
Service recognizes Unio othcaloogensis (Lea) and U. modicellus (Lea) as
synonyms of Epioblasma othcaloogensis.
The southern acornshell was historically found in shoals in small
rivers to small streams in the Coosa and Cahaba River systems (Service
2000, p. 57). As with many of the freshwater mussels in the Mobile
River Basin, it was found in stable sand, gravel, cobble substrate in
moderate to swift currents. The species had a sexual reproduction
strategy and required a host fish to complete the life cycle.
Historically, the species occurred in upper Coosa River tributaries and
the Cahaba River in Alabama, Georgia, and Tennessee (Service 2000, p.
57). In the upper Coosa River system, the southern acornshell occurred
in the Conasauga River, Cowan's Creek, and Othcalooga Creek (58 FR
14330 at 14331, March 17, 1993). At the time of listing in 1993, the
species was estimated to persist in low numbers in streams in the upper
Coosa River drainage in Alabama and Georgia, and possibly in the Cahaba
River (58 FR 14330 at 14331, March 17, 1993; Service 2018, p. 6). The
southern acornshell was last collected in 1973, from the Conasauga
River in Georgia and from Little Canoe Creek, near the Etowah and St.
Clair County line, Alabama. It has not been collected from the Cahaba
River since the 1930s (Service 2018, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The southern acornshell
was small-sized (with very small juveniles) and most often found buried
in sand, gravel, or cobble in fast flowing runs. However, mussels can
be found in sub-optimal conditions, depending on where they dropped off
of the host fish. Therefore, all of the detection considerations need
to be accounted for when trying to detect this mussel species. Despite
detection challenges, many well-planned, comprehensive surveys by
experienced State and Federal biologists have been carried out, and
those surveys have not been able to locate extant populations of
southern acornshell (Service 2000, p. 57; Service 2008, p. 20; Service
2018, p. 7).
Survey Effort
Prior to listing, southern acornshell was observed during surveys
in the upper Coosa River drainage in Alabama and Georgia in 1966-1968
and in 1971-1973, by Hurd (58 FR 14330 at 14331, March 17, 1993).
Records of the species in the Cahaba River are from surveys at Lily
Shoals in Bibb County, Alabama, in 1938, and from Buck Creek (Cahaba
River tributary), Shelby County, Alabama, in the early 1900s (58 FR
14330 at 14331, March 17, 1993). Both the 2008 and 2018 5-year reviews
reference multiple surveys by experienced Federal, State, and private
biologists--17 survey reports from 1993-2006 and 6 survey reports from
2008-2017--and despite these repeated
[[Page 71666]]
surveys of historical habitat in both the Coosa and Cahaba River
drainages, no living animals or fresh or weathered shells of the
southern acornshell have been located (Service 2008, p. 19; Service
2018, p. 6).
Time Since Last Detection
The most recent records for the southern acornshell were from
tributaries of the Coosa River in 1966-1968 and 1974, and the Cahaba
River in 1938 (58 FR 14330 at 14331, March 17, 1993; Service 2008, p.
19; Service 2018, p. 5). No living populations of the southern
acornshell have been located since the 1970s (Service 2000, p. 57;
Service 2008, p. 20; Service 2018, p. 7).
Other Considerations Applicable to the Species' Status
Habitat modification was the major cause of decline of the southern
acornshell (Service 2000, p. 57). Other threats included channel
improvements such as clearing and snagging, as well as sand and gravel
mining, diversion of flood flows, and water removal for municipal use;
these activities impacted mussels by alteration of the river substrate,
increasing sedimentation, alteration of water flows, and direct
mortality from dredging and snagging (Service 2000, pp. 6-13). Runoff
from fertilizers and pesticides results in algal blooms and excessive
growth of other aquatic vegetation, resulting in eutrophication and
death of mussels due to lack of oxygen (Service 2000, p.13). The
cumulative impacts of habitat degradation likely led to southern
acornshell populations becoming scattered and isolated over time. Low
population levels mean increased difficulty for successful reproduction
(Service 2000, p.14). When individuals become scattered, the
opportunity for a female southern acornshell to successfully fertilize
eggs is diminished, and the spiral of failed reproduction leads to
local extirpation and eventual extinction of the species (Service 2000,
p. 14).
III. Analysis
There has been no evidence of the continued existence of the
southern acornshell for over five decades; the last known specimens
were collected in the early 1970s. When listed in 1993, it was thought
that the southern acornshell was likely to persist in low numbers in
the upper Coosa River drainage and, possibly, in the Cahaba River.
Numerous mussel surveys have been completed within these areas, as well
as other areas within the historical range of the species since the
listing, with no success. Although other federally listed mussels have
been found by mussel experts during these surveys, no live or freshly
dead specimens of the southern acornshell have been found (Service
2018, p. 7). The species is extinct.
IV. Conclusion
We conclude that the southern acornshell is extinct and, therefore,
should be delisted. This conclusion is based on significant alteration
of known historical habitat and lack of detections during numerous
surveys conducted throughout the species' range.
Stirrupshell (Quadrula Stapes)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On April 7, 1987, we listed the stirrupshell as endangered, primarily
due to habitat alteration from a free-flowing riverine system to an
impounded system (52 FR 11162). Two 5-year reviews were completed in
2009 (initiated on September 8, 2006; see 71 FR 53127) and 2015
(initiated on March 25, 2014; see 79 FR 16366); both recommended
delisting the stirrupshell due to extinction. We solicited peer review
from six experts for both 5-year reviews from State, Federal,
university, and museum biologists with known expertise and interest in
Mobile River Basin mussels (Service 2009, pp. 23-24; Service 2015, pp.
15-16); we received responses from three of the peer reviewers, and
they concurred with the content and conclusion that the species is
extinct.
The stirrupshell was described as Unio stapes in 1831, from the
Alabama River (Stansbery 1981, entire). Other synonyms are Margarita
(Unio) stapes in 1836, Margaron (Unio) stapes in 1852, Quadrula stapes
in 1900, and Orthonymus stapes in 1969 (Service 1989, pp. 2-3). Adult
stirrupshells were quadrate in shape and reached a size of
approximately 2 inches long and 2 inches wide. The stirrupshell
differed from other closely related species by the presence of a sharp
posterior ridge and truncated narrow rounded point posteriorly on its
shell, and it had a tubercled posterior surface (Service 1989, p. 3;
Service 2000, p. 85). Freshwater mussels of the Mobile River Basin,
such as the stirrupshell, are most often found in clean, fast-flowing
water in stable sand, gravel, and cobble gravel substrates that are
free of silt (Service 2000, p. 85). They are typically found buried in
the substrate in runs (Service 2000, p. 85). This type of habitat has
been nearly eliminated in the Tombigbee River because of the
construction of the Tennessee-Tombigbee Waterway, which created a
dredged, straightened navigation channel and series of impoundments
that inundated much of the riverine mussel habitat (Service 1989, p.
1).
The stirrupshell was historically found in the Tombigbee River from
Columbus, Mississippi, downstream to Epes, Alabama; the Sipsey River, a
tributary to the Tombigbee River in Alabama; the Black Warrior River in
Alabama; and the Alabama River (Service 1989, p. 3). Surveys in
historical habitat over the past three decades have failed to locate
the species, as all historical habitat is impounded or modified by
channelization and impoundments (Tombigbee and Alabama Rivers) or
impacted by sediment and nonpoint pollution (Sipsey and Black Warrior
Rivers) (Service 1989, p. 6; Service 2000, p. 85; Service 2015, p. 5).
No live or freshly dead shells have been observed since the species was
listed in 1987 (Service 2009, p. 6; Service 2015, p. 7). A freshly dead
shell was last collected from the lower Sipsey River in 1986 (Service
2000, p. 85).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The stirrupshell was
medium-sized (with very small juveniles) and most often found buried in
sand, gravel, or cobble in fast flowing runs. However, mussels can be
found in sub-optimal conditions, depending on where they dropped off of
the host fish. Therefore, all of the detection considerations need to
be accounted for when trying to detect this mussel species. Despite
detection challenges, many well-planned, comprehensive surveys by
experienced State and Federal biologists have been carried out, and
those surveys have not been able to locate extant populations of
stirrupshell (Service 1989, pp. 3-4; Service 2000, p. 85; Service 2015,
pp. 7-8).
Survey Effort
Prior to listing in 1987, stirrupshell was collected in 1978, from
the Sipsey River, and a 1984 and 1986 survey of the Sipsey River found
freshly dead shells; a 1984 survey of the Gainsesville Bendway of
Tombigbee River found
[[Page 71667]]
freshly dead shells of the stirrupshell (Service 1989, p. 4; Service
2000, p. 85). After listing, surveys in 1988 and 1990 only found
weathered, relict shells of the stirrupshell from the Tombigbee River
at the Gainesville Bendway and below Heflin Dam, which cast doubt on
the continued existence of the species in the mainstem Tombigbee River
(Service 1989, p. 4; Service 2009, p. 6). Over the past three decades,
repeated surveys (circa 1988, 1998, 2001, 2002, 2003, 2006, 2011) of
unimpounded habitat in the Sipsey and Tombigbee Rivers, including
intensive surveys of the Gainesville Bendway, have failed to find any
evidence of stirrupshell (Service 2009, p. 6; Service 2015, p. 7).
The stirrupshell was also known from the Alabama River; however,
over 92 hours of dive bottom time were expended searching appropriate
habitats for imperiled mussel species between 1997-2007 without
encountering the species (Service 2009, p. 6), and a survey of the
Alabama River in 2011 also did not find stirrupshell (Service 2015, p.
5). Surveys of the Black Warrior River in 1993 and from 2009-2012 (16
sites) focused on finding federally listed and State conservation
concern priority mussel species but did not find any stirrupshells
(Miller 1994, pp. 9, 42; McGregor et al. 2009, p. 1; McGregor et al.
2013, p. 1).
Time Since Last Detection
The stirrupshell has not been collected alive since the Sipsey
River was surveyed in 1978 (Service 1989, p. 4); one freshly dead shell
was last collected from the Sipsey River in 1986 (Service 2000, p. 85).
In the Tombigbee River, the stirrupshell has not been collected alive
since completion of the Tennessee-Tombigbee Waterway in 1984 (Service
2015, p. 7). Mussel surveys within the Tombigbee River drainage during
1984-2015 failed to document the presence of the stirrupshell (Service
2015, p. 8). The stirrupshell has not been found alive in the Black
Warrior River or the Alabama River since the early 1980s (Service 1989,
p. 3).
Other Considerations Applicable to the Species' Status
Because the stirrupshell occurred in similar habitat type and area
as the flat pigtoe, it faced similar threats. Please refer to the
discussion for the flat pigtoe for more information.
III. Analysis
There has been no evidence of the continued existence of the
stirrupshell for nearly four decades; the last live individual was
observed in 1978 and the last freshly dead specimen was from 1986.
Mussel surveys within the Tombigbee River drainage (including the
Sipsey and Black Warrior tributaries) from 1984-2015, and the Alabama
River from 1997-2007 and in 2011, have failed to document the presence
of the species (Service 2015, pp. 5, 8). All known historical habitat
has been altered or degraded by impoundments and nonpoint source
pollution, and the species is presumed extinct by most authorities.
IV. Conclusion
We conclude that the stirrupshell is extinct and, therefore, should
be delisted. This conclusion is based on significant alteration of all
known historical habitat and lack of detections during numerous surveys
conducted throughout the species' range.
Upland Combshell (Epioblasma Metastriata)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On March 17, 1993, we listed the upland combshell as endangered,
primarily due to habitat modification, sedimentation, and water-quality
degradation (58 FR 14330). We designated critical habitat on July 1,
2004 (69 FR 40084). Two 5-year reviews were completed in 2008
(initiated on June 14, 2005; see 70 FR 34492) and 2018 (initiated on
September 23, 2014; see 79 FR 56821), both recommending delisting the
upland combshell due to extinction. We solicited peer review from eight
experts for both 5-year reviews from State, Federal, university,
nongovernmental, and museum biologists with known expertise and
interest in Mobile River Basin mussels (Service 2008, pp. 36-37;
Service 2018, p. 15); we received responses from five of the peer
reviewers, who concurred with our conclusion that the species is
extinct.
The upland combshell was described in 1838, from the Mulberry Fork
of the Black Warrior River near Blount Springs, Alabama (58 FR 14330 at
14331, March 17, 1993). Adult upland combshells were rhomboidal to
quadrate in shape and were approximately 2.4 inches in length (58 FR
14330-14331, March 17, 1993).
The upland combshell was historically found in shoals in rivers and
large streams in the Black Warrior, Cahaba, and Coosa River systems
above the Fall Line in Alabama, Georgia, and Tennessee (Service 2000,
p. 61). As with many of the freshwater mussels in the Mobile River
Basin, it was found in stable sand, gravel, and cobble in moderate to
swift currents. The historical range included the Black Warrior River
and tributaries (Mulberry Fork and Valley Creek); Cahaba River and
tributaries (Little Cahaba River and Buck Creek); and the Coosa River
and tributaries (Choccolocco Creek and Etowah, Conasauga, and Chatooga
Rivers) (58 FR 14330 at 14331, March 17, 1993). At the time of listing
in 1993, the species was estimated to be restricted to the Conasauga
River in Georgia, and possibly portions of the upper Black Warrior and
Cahaba River drainages (58 FR 14330 at 14331, March 17, 1993; Service
2008, p. 19). The upland combshell was last collected in the Black
Warrior River drainage in the early 1900s; in the Coosa River drainage
in 1986, from the Conasauga River near the Georgia/Tennessee State
line; and the Cahaba River drainage in the early 1970s (58 FR 14330 at
14331, March 17, 1993; Service 2000, p. 61; Service 2018, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The upland combshell was
small-sized (with very small juveniles) and most often found buried in
sand, gravel, or cobble in fast flowing runs. However, mussels can be
found in sub-optimal conditions, depending on where they dropped off of
the host fish. Therefore, all of the detection considerations need to
be accounted for when trying to detect this mussel species. Despite
detection challenges, many well-planned, comprehensive surveys by
experienced State and Federal biologists have been carried out, and
those surveys have not been able to locate extant populations of upland
combshell (Service 2008, p. 19; Service 2018, p. 5).
Survey Effort
Prior to listing in 1993, upland combshell was observed during
surveys in the Black Warrior River drainage in the early 1900s;
repeated surveys in this drainage in 1974, 1980-1982, 1985, and 1990
did not encounter the species (58 FR 14330 at 14331, March 17, 1993).
The upland combshell was observed in the Cahaba River drainage in 1938
and
[[Page 71668]]
in 1973, but a 1990 survey failed to find the species in the Cahaba
River drainage (58 FR 14330 at 14331, March 17, 1993). The species was
observed in the upper Coosa River drainage in Alabama and Georgia in
1966-1968, but not during 1971-1973 surveys; a single specimen was
collected in 1988 from the Conasauga River (58 FR 14330 at 14331, March
17, 1993). Both the 2008 and 2018 5-year reviews reference multiple
surveys by experienced Federal, State, and private biologists--18
survey reports from 1993-2006 and 10 survey reports from 2008-2017--and
despite these repeated surveys of historical habitat in the Black
Warrior, Cahaba, and Coosa River drainages, no living animals or fresh
or weathered shells of the upland combshell have been located (Service
2008, p. 19; Service 2018, p. 5).
Time Since Last Detection
The most records for the upland combshell are many decades old:
from tributaries of the Black Warrior in early 1900s, from the Cahaba
River drainage in the early 1970s, and from the Coosa River drainage in
the mid-1980s (58 FR 14330 at 14331, March 17, 1993; Service 2008, p.
19; Service 2018, p. 5). No living populations of the upland combshell
have been located since the mid-1980s (Service 2000, p. 61; Service
2008, p. 20; Service 2018, p. 7).
Other Considerations Applicable to the Species' Status
Because the upland combshell occurred in similar habitat type and
area as the southern acornshell, it faced similar threats. Please refer
to the discussion of the southern acornshell, above, for more
information on any other overarching consideration.
III. Analysis
There has been no evidence of the continued existence of the upland
combshell for over three decades; the last known specimens were
collected in the late-1980s. When listed, it was thought that the
upland combshell was likely restricted to the Conasauga River in
Georgia, and possibly portions of the upper Black Warrior and Cahaba
River drainages. Numerous mussel surveys have been completed within
these areas, as well as other areas within the historical range of the
species since the late 1980s, with no success. Although other federally
listed mussels have been found by mussel experts during these surveys,
no live or freshly dead specimens of the upland combshell have been
found (Service 2018, p. 7). The species is extinct.
IV. Conclusion
We conclude that the upland combshell is extinct and, therefore,
should be delisted. This conclusion is based on significant alteration
of known historical habitat and lack of detections during numerous
surveys conducted throughout the species' range.
Green Blossom (Epioblasma Torulosa Gubernaculum)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On June 14, 1976, we listed the green blossom as endangered (41 FR
24062). At the time of listing, the single greatest factor contributing
to the species' decline was the alteration and destruction of stream
habitat due to impoundments. Two 5-year reviews were completed in 2007
(initiated on September 20, 2005; see 70 FR 55157) and 2017 (initiated
on March 25, 2014; see 79 FR 16366); both reviews recommended delisting
due to extinction. For the 2017 5-year review, the Service solicited
peer review from eight peer reviewers including Federal and State
biologists with known expertise and interest in blossom pearly mussels.
All eight peer reviewers indicated there was no new information on the
species, or that the species was presumed extirpated or extinct from
their respective State(s) (USFWS 2017, pp. 8-9).
The green blossom was described in 1865, with no type locality
given for the species. However, all historical records indicate the
species was restricted to the upper headwater tributary streams of the
Tennessee River above Knoxville (USFWS 1984, pp. 1-2). A comprehensive
description of shell anatomy is provided in our 5-year review and
supporting documents (Parmalee and Bogan 1998, pp. 104-107).
The green blossom was always extremely rare and never had a wide
distribution (USFWS 1984, p. 9). Freshwater mussels found within the
Cumberland rivers and tributary streams, such as the green blossom, are
most often observed in clean, fast-flowing water in substrates that
contain relatively firm rubble, gravel, and sand substrates swept free
from siltation (USFWS 1984, p. 5). They are typically found buried in
substrate in shallow riffle and shoal areas. This type of habitat has
been nearly eliminated by impoundment of the Tennessee and Cumberland
Rivers and their headwater tributary streams (USFWS 1984, p. 9).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are riverine, typically found only in streams
that are shallow with sandy-gravel substrate and rapid currents
(Stansbery 1972, pp. 45-46). Eight species of Epioblasma were extinct
at the time of the recovery plan, primarily due to impoundments,
siltation, and pollution (USFWS 1984, p. 6).
Stream impoundment affects species composition by eliminating those
species not capable of adapting to reduced flows and altered
temperatures. Tributary dams typically have storage impoundments with
cold water discharges and sufficient storage volume to cause the stream
below the dam to differ significantly from pre-impoundment conditions.
These hypolimnial discharges result in altered temperature regimes,
extreme water-level fluctuations, reduced turbidity, seasonal oxygen
deficits, and high concentrations of certain heavy metals (Tennessee
Valley Authority (TVA) 1980, entire).
Siltation within the range of the green blossom, resulting from
strip mining, coal washing, dredging, farming, and road construction,
also likely severely affected the species. Since most freshwater
mussels are riverine species that require clean, flowing water over
stable, silt-free rubble, gravel, or sand shoals, smothering caused by
siltation can be detrimental. Pollution, primarily from wood pulp,
paper mills, and other industries, has also severely impacted many
streams within the historical range of the species.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The green blossom was a
medium-sized mussel most often found buried in substrate in shallow
riffle and shoal areas. However, mussels can be found in sub-optimal
conditions, depending on where they dropped off of the host fish.
Survey Effort
As of 1984, freshwater mussel surveys by numerous individuals had
failed to document any living populations of green blossom in any
Tennessee River tributary other than the Clinch River.
[[Page 71669]]
The recovery plan cites several freshwater mussel surveys (which took
place between 1972 and 2005) of the Powell River; North, South, and
Middle Forks of the Holston River; Big Moccasin Creek; Copper Creek;
Nolichucky River; and French Broad River, all of which failed to find
living or freshly dead green blossom specimens (USFWS 1984, p. 5).
Annual surveys continue to be conducted in the Clinch River since 1972.
Biologists conducting those surveys have not reported live or freshly
dead individuals of the green blossom (Ahlstedt et al. 2016, entire;
Ahlstedt et al. 2017, entire; Jones et al. 2014, entire; Jones et al.
2018, entire).
Time Since Last Detection
The last known record for the green blossom was a live individual
collected in 1982, in the Clinch River at Pendleton Island, Virginia.
III. Analysis
Habitat within the historical range of the green blossom has been
significantly altered by water impoundments, siltation, and pollution,
including at Pendleton Island on the Clinch River, the site of the last
known occurrence of the species (Jones et al. 2018, pp. 36-56). The
last known collection of the species was 41 years ago, and numerous
surveys have been completed within the known range of the species over
these 41 years. Although other federally listed mussels have been found
by these experts during these surveys, no live or freshly dead
specimens of the green blossom have been found (Ahlstedt et al. 2016,
pp. 1-18; Ahlstedt et al. 2017, pp. 213-225). Mussel experts conclude
that the species is extinct.
IV. Conclusion
We conclude the green blossom is extinct and, therefore, should be
delisted. This conclusion is based on lack of detections during surveys
and searches conducted throughout the species' range since the green
blossom was last observed in 1982, and the amount of significant
habitat alteration that has occurred within the range of the species,
rendering most of the species' historical habitat unlikely to support
the species.
Tubercled Blossom (Epioblasma Torulosa Torulosa)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On June 14, 1976, we listed the tubercled blossom as endangered (41 FR
24062). At the time of listing, the greatest factor contributing to the
species' decline was the alteration and destruction of stream habitat
due to impoundments. The most recent 5-year review, completed in 2017
(initiated on March 25, 2014; see 79 FR 16366), indicated that the
species was extinct, and recommended delisting. The Service solicited
peer review from three peer reviewers for the 2017 5-year review from
Federal and State biologists with known expertise and interest in
blossom pearly mussels. All three peer reviewers indicated there was no
new information on the species, all populations of the species were
extirpated from their respective States, and the species was presumed
extinct.
The tubercled blossom was described as Amblema torulosa from the
Ohio and Kentucky Rivers (Rafinesque 1820; referenced in USFWS 1985, p.
2). All records for this species indicate it was widespread in the
larger rivers of the eastern United States and southern Ontario, Canada
(USFWS 1985, p. 2). Records for this species included the Ohio,
Kanawha, Scioto, Kentucky, Cumberland, Tennessee, Nolichucky, Elk, and
Duck Rivers (USFWS 1985, pp. 3-6). Historical museum records gathered
subsequently add the Muskingum, Olentangy, Salt, Green, Barren, Wabash,
White, East Fork White, and Hiwassee Rivers to its range (Service 2011,
p. 5). The total historical range includes the States of Alabama,
Illinois, Indiana, Kentucky, Ohio, Tennessee, and West Virginia. This
species was abundant in archaeological sites along the Tennessee River
in extreme northwestern Alabama, making it likely that the species also
occurred in adjacent northeastern Mississippi where the Tennessee River
borders that State (Service 2011, p. 5).
The tubercled blossom was medium-sized, reaching about 3.6 inches
(9.1 centimeters) in shell length, and could live 50 years or more. The
shell was irregularly egg-shaped or elliptical, slightly sculptured,
and corrugated with distinct growth lines. The outer surface was smooth
and shiny; was tawny, yellowish-green, or straw-colored; and usually
had numerous green rays (Parmalee and Bogan 1980, pp. 22-23).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are characteristic riffle or shoal species,
typically found only in streams that are shallow with sandy-gravel
substrate and rapid currents (Parmalee and Bogan 1980, pp. 22-23).
Eight species of Epioblasma were extinct at the time of the 1985
recovery plan. The elimination of these species has been attributed to
impoundments, barge canals, and other flow alteration structures that
have eliminated riffle and shoal areas (USFWS 1985, p. 1).
The single greatest factor contributing to the decline of the
tubercled blossom is the alteration and destruction of stream habitat
due to impoundments for flood control, navigation, hydroelectric power
production, and recreation. Siltation is another factor that has
severely affected the tubercled blossom. Increased silt transport into
waterways due to strip mining, coal washing, dredging, farming,
logging, and road construction increased turbidity and consequently
reduced the depth of light penetration and created a blanketing effect
on the substrate. A third factor is the impact caused by various
pollutants. An increasing number of streams throughout the tubercled
blossom's range receive municipal, agricultural, and industrial waste
discharges.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The tubercled blossom was
a large-river species most often found inhabiting parts of those rivers
that are shallow with sandy-gravel substrate and rapid currents.
However, mussels can be found in sub-optimal conditions, depending on
where they dropped off of the host fish.
Survey Effort
All three rivers where the species was last located have been
extensively sampled in the intervening years without further evidence
of this species' occurrence, including Kanawha River, Nolichucky River,
and Green River (Service 2011, p. 5).
Based on this body of survey information in large rivers in the
Ohio River system, investigators have been considering this species as
possibly extinct since the mid-1970s. The best reach of potential
habitat remaining may be in the lowermost 50 miles of the free-flowing
portion of the Ohio River, in Illinois and Kentucky. This reach is one
of the last remnants of large-river habitat remaining in the entire
historical range of the tubercled blossom. In our 2011 5-year review
for the tubercled blossom, we hypothesized that this mussel might be
found in this stretch of the Ohio River. Unfortunately, mussel experts
have not reported any new collections
[[Page 71670]]
of the species (USFWS 2017, p. 8). Additionally, State biologists have
conducted extensive surveys within the Kanawha Falls area of the
Kanawha River since 2005 and have found no evidence that the tubercled
blossom still occurs there (USFWS 2017, p 4). This species is extinct.
Time Since Last Detection
The last individuals were collected live or freshly dead in 1969,
in the Kanawha River, West Virginia, below Kanawha Falls; in 1968, in
the Nolichucky River, Tennessee; and in 1963, in the Green River,
Kentucky.
III. Analysis
The tubercled blossom has not been seen since 1969, despite
extensive survey work in nearly all of the rivers of historical
occurrence, prompting many investigators to consider this species as
possibly extinct. According to the last two 5-year reviews, experts
indicate that the species is presumed extinct throughout its range.
IV. Conclusion
We conclude the tubercled blossom is extinct and, therefore, should
be delisted. This conclusion is based on the lack of detections during
surveys and searches conducted throughout the species' range since the
tubercled blossom was last sighted in 1969, and the significant habitat
alteration that has occurred within the range of the species, rendering
most of the species' habitat unable to support the life-history needs
of the species.
Turgid Blossom (Epioblasma Turgidula)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the species background and
legal history. Here, we will briefly summarize the species background.
On June 14, 1976, we listed the turgid blossom as endangered (41 FR
24062). At the time of listing, the single greatest factor contributing
to the species' decline was the alteration and destruction of stream
habitat due to impoundments. Two 5-year reviews were completed in 2007
(initiated on September 20, 2005; see 70 FR 55157) and 2017 (initiated
on August 30, 2016; see 81 FR 59650); both reviews recommended
delisting due to extinction. The Service solicited peer review from
eight peer reviewers for the 2017 5-year review from Federal and State
biologists with known expertise and interest in blossom pearly mussels
(the turgid blossom was one of four species assessed in this 5-year
review). All eight peer reviewers indicated there was no new
information on the species, all populations of the species were
extirpated from their respective States, and the species was presumed
extinct.
The turgid blossom was described (Lea 1858; referenced in USFWS
1985, p. 2) as Unio turgidulus from the Cumberland River, Tennessee,
and the Tennessee River, Florence, Alabama. It has been reported from
the Tennessee River and tributary streams, including Shoal and Bear
Creeks, and Elk, Duck, Holston, Clinch, and Emory Rivers (USFWS 2017,
p. 4). Additional records are reported from the Cumberland River (USFWS
2017, p. 4) and from the Ozark Mountain Region, including Spring Creek,
and Black and White Rivers (USFWS 2017, p. 6).
The turgid blossom was a medium-river, Cumberlandian-type mussel
that was also reported from the Ozarks. These mussels could live 50
years or more. The genus Epioblasma as a whole has suffered extensively
because members of this genus are characteristic riffle or shoal
species, typically found only in streams that are shallow with sandy-
gravel substrate and rapid currents (Parmalee et al. 1980, pp. 93-105).
Eight species of Epioblasma were extinct at the time of the 1985
recovery plan. The elimination of these species has been attributed to
impoundments, barge canals, and other flow alteration structures that
have eliminated riffle and shoal areas (USFWS 1985, p. 1). The last
known population of the turgid blossom occurred in the Duck River and
was collected in 1972, at Normandy (Ahlstedt 1980, pp. 21-23). Field
notes associated with this collection indicate that it was river-
collected 100 yards above an old iron bridge. Water at the bridge one
mile upstream was very muddy, presumably from dam construction above
the site (Ahlstedt et al. 2017, entire). Additionally, surveys in the
1960s of the upper Cumberland Basin indicated an almost total
elimination of the genus Epioblasma, presumably due to mine wastes
(Neel and Allen 1964, as cited in USFWS 1985, p. 10).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The turgid blossom was a
small-sized mussel most often found buried in substrate in shallow
riffle and shoal areas. However, mussels can be found in sub-optimal
conditions, depending on where they dropped off of the host fish.
Survey Effort
This species has not been found in freshwater mussel surveys
conducted on the Duck River since the time of the Normandy Dam
construction (Ahlstedt 1980, pp. 21-23), nor has it been reported from
any other stream or river system. The most recent 5-year review notes
that the Tennessee Wildlife Resources Agency had completed or funded
surveys (1972-2005) for blossom pearly mussels in the Cumberland,
Tennessee, Clinch, Duck, Elk, Emory, Hiwassee, Little, and Powell
Rivers, yet there were no recent records of turgid blossom (USFWS 2017,
p. 4). Surveys in the Ozarks have not observed the species since the
early 1900s (USFWS 1985, p. 7).
Time Since Last Detection
The last known collection of the turgid blossom was a freshly dead
specimen found in the Duck River, Tennessee, in 1972 by a biologist
with the TVA. The species has not been seen in the Ozarks since the
early 1900s (USFWS 1985, p. 7).
III. Analysis
Habitat within the historical range of the turgid blossom has been
significantly altered by water impoundments, siltation, and pollution.
The last known collection of the species was more than 45 years ago.
Mussel experts conclude that the species is likely to be extinct.
Numerous surveys have been completed within the known range of the
species over the years. Although other federally listed mussels have
been found by experts during these surveys, no live or freshly dead
specimens of the turgid blossom have been found.
IV. Conclusion
We conclude the turgid blossom is extinct and, therefore, should be
delisted. This conclusion is based on the lack of detections during
surveys and searches conducted throughout the species' range since the
turgid blossom was last sighted in 1972, and the significant habitat
alteration that occurred within the range of the species, rendering
most of the species' habitat unlikely to support the species.
Yellow Blossom (Epioblasma Florentina Florentina)
I. Background
Please refer to our proposed rule, published on September 30, 2021
(86 FR 54298), for a thorough review of the
[[Page 71671]]
species background and legal history. Here, we will briefly summarize
the species background. On June 14, 1976, listed the yellow blossom as
endangered (41 FR 24062). At the time of listing, the single greatest
factor contributing to the species' decline was the alteration and
destruction of stream habitat due to impoundments. Two 5-year reviews
were completed in 2007 (initiated on September 20, 2005; see 70 FR
55157) and 2017 (initiated on March 25, 2014; see 79 FR 16366); both
reviews recommended delisting due to extinction. The Service solicited
peer review from eight peer reviewers for the 2017 5-year review from
Federal and State biologists with known expertise and interest in
blossom pearly mussels (the yellow blossom was one of four species
assessed in this 5-year review). All eight peer reviewers indicated
there was no new information on the species, all populations of the
species were extirpated from their respective States, and the species
was presumed extinct.
The yellow blossom was described (Lea 1857; referenced in USFWS
1985, pp. 2-3) as Unio florentinus from the Tennessee River, Florence
and Lauderdale Counties, Alabama, and the Cumberland River, Tennessee.
The yellow blossom was reported from Hurricane, Limestone, Bear, and
Cypress Creeks, all tributary streams to the Tennessee River in
northern Alabama (Ortmann 1925 p. 362; Bogan and Parmalee 1983, p. 23).
This species was also reported from larger tributary streams of the
lower and upper Tennessee River, including the Flint, Elk, and Duck
Rivers (Isom et al. 1973, p. 439; Bogan and Parmalee 1983, pp. 22-23)
and the Holston, Clinch, and Little Tennessee Rivers (Ortmann 1918, pp.
614-616). Yellow blossoms apparently occurred throughout the Cumberland
River (Wilson and Clark 1914, p. 46; Ortmann 1918, p. 592; Neel and
Allen 1964, p. 448).
The yellow blossom seldom achieved more than 2.4 inches (6
centimeters) in length. The slightly inflated valves were of unequal
length, and the shell surface was marked by uneven growth lines. The
shell was a shiny honey-yellow or tan with numerous green rays
uniformly distributed over the surface. The inner shell surface was
bluish-white (Bogan and Parmalee 1983, pp. 22-23).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are characteristic riffle or shoal species,
typically found only in streams that are shallow with sandy-gravel
substrate and rapid currents (Bogan and Parmalee 1983, pp. 22-23).
Eight species of Epioblasma were extinct at the time of the 1985
recovery plan. The elimination of these species has been attributed to
impoundments, barge canals, and other flow alteration structures that
have eliminated riffle and shoal areas (USFWS 1985, p. 1).
The single greatest factor contributing to the decline of the
yellow blossom, not only in the Tennessee Valley but in other regions
as well, is the alteration and destruction of stream habitat due to
impoundments for flood control, navigation, hydroelectric power
production, and recreation. Siltation is another factor that has
severely affected the yellow blossom. Increased silt transport into
waterways due to strip mining, coal washing, dredging, farming,
logging, and road construction increased turbidity and consequently
reduced light penetration, creating a blanketing effect on the
substrate. A third factor is the impact caused by various pollutants.
An increasing number of streams throughout the mussel's range receive
municipal, agricultural, and industrial waste discharges (USFWS 2017,
p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to ``Species Detectability'' for the flat pigtoe,
above, for the descriptions of these factors. The yellow blossom was a
small-sized mussel most often found buried in substrate in shallow
riffle and shoal areas. However, mussels can be found in sub-optimal
conditions, depending on where they dropped off of the host fish.
Survey Effort
Since the last recorded collections in the mid-1960s, numerous
mussel surveys (1872-2005) have been done by mussel biologists from the
TVA, Virginia Tech, U.S. Geological Survey, and others in rivers
historically containing the species. Biologists conducting those
surveys have not reported live or freshly dead individuals of the
yellow blossom.
Time Since Last Detection
This species was last collected live from Citico Creek in 1957, and
the Little Tennessee River in the 1966 (Bogan and Parmalee, 1983, p.
23), and archeological shell specimens were collected from the
Tennessee and Cumberland Rivers between 1976 and 1979 (Parmalee et al.
1980, entire).
III. Analysis
Habitat within the historical range of the yellow blossom has been
significantly altered by water impoundments, siltation, and pollution.
The last known collection of the species was over 50 years ago. Mussel
experts conclude that the species is likely to be extinct. Numerous
surveys have been completed within the known range of the species over
the years. Although other federally listed mussels have been found by
these experts during these surveys, no live or freshly dead specimens
of the yellow blossom have been found.
IV. Conclusion
We conclude the yellow blossom is extinct and, therefore, should be
delisted. This conclusion is based on lack of detections during surveys
conducted throughout the species' range since the yellow blossom was
last sighted in the mid-1960s and on the significant habitat alteration
that occurred within the range of the species, rendering most of the
species' habitat unlikely to support the species.
Required Determinations
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
We do not need to prepare environmental analyses pursuant to the
National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.) in
connection with regulations adopted pursuant to section 4(a) of the
Act. We published a notice outlining our reasons for this determination
in the Federal Register on October 25, 1983 (48 FR 49244). Further,
NEPA analyses are not applicable for the removal of any associated
rules (e.g., critical habitat) as the removal of those rules are
required with the delisting of a species.
Government-to-Government Relationship With Tribes
In accordance with the President's memorandum of April 29, 1994
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with recognized Federal
Tribes on a government-to-government basis. In accordance with
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights,
Federal-Tribal Trust Responsibilities, and the Endangered Species Act),
we readily acknowledge
[[Page 71672]]
our responsibilities to work directly with Tribes in developing
programs for healthy ecosystems, to acknowledge that Tribal lands are
not subject to the same controls as Federal public lands, to remain
sensitive to Indian culture, and to make information available to
Tribes. The Seminole Tribe of Florida and the Miccousukee Tribe have
expressed interest in the Bachman's warbler. We reached out to these
Tribes by providing an advance notification prior to the publication of
the September 30, 2021, proposed rule (86 FR 54298). We received no
comments from any Tribes during the public comment period on the
proposed rule.
References Cited
Lists of the references cited in in this document are available on
the internet at https://www.regulations.gov in the dockets provided
above under ADDRESSES and upon request from the appropriate person, as
specified under FOR FURTHER INFORMATION CONTACT.
Authors
The primary authors of this document are the staff members of the
Branch of Delisting and Foreign Species, Ecological Services Program,
as well as the staff of the Ecological Services Field Offices as
specified under FOR FURTHER INFORMATION CONTACT.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Plants,
Reporting and recordkeeping requirements, Transportation, Wildlife.
Regulation Promulgation
Accordingly, we hereby amend part 17, subchapter B of chapter I,
title 50 of the Code of Federal Regulations as set forth below:
PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, unless
otherwise noted.
Sec. 17.11 [Amended]
0
2. Amend Sec. 17.11 in paragraph (h), the List of Endangered and
Threatened Wildlife, by:
0
a. Under MAMMALS, removing the entry for ``Bat, little Mariana fruit'';
0
b. Under BIRDS, removing the entries for ``Akepa, Maui'', ``Akialoa,
Kauai'', ``Creeper, Molokai'', ``Nukupuu, Kauai'', ``Nukupuu, Maui'',
``[revaps]O[revaps]o, Kauai (honeyeater)'', ``Po[revaps]ouli
(honeycreeper)'', ``Thrush, large Kauai'', ``Warbler (wood),
Bachman's'', and ``White-eye, bridled'';
0
c. Under FISHES, removing the entries for ``Gambusia, San Marcos'' and
``Madtom, Scioto''; and
0
d. Under CLAMS, removing the entries for ``Acornshell, southern'' and
``Blossom, green''; both entries for ``Blossom, tubercled'', ``Blossom,
turgid'', and ``Blossom, yellow''; and the entries for ``Combshell,
upland'', ``Pigtoe, flat'', and ``Stirrupshell''.
Sec. 17.85 [Amended]
0
3. Amend Sec. 17.85 by:
0
a. In paragraph (a) introductory text:
0
i. In the heading, removing the word ``Seventeen'' and adding in its
place the word ``Fourteen''; and
0
ii. In the table, removing the entries for ``tubercled blossom
(pearlymussel)'', ``turgid blossom (pearlymussel)'', and ``yellow
blossom (pearlymussel)'';
0
b. In paragraph (a)(1)(i), removing the number ``17'' and adding in its
place the number ``14'';
0
c. In paragraph (a)(1)(ii), removing the number ``17'' and adding in
its place the number ``14''; and
0
d. In paragraph (a)(2)(iii), by removing the number ``17'' and adding
in its place the number ``14''.
0
4. Amend Sec. 17.95 by:
0
a. In paragraph (e), removing the entry for ``San Marcos Gambusia
(Gambusia georgei)''; and
0
b. In paragraph (f), in the entry for ``Eleven Mobile River Basin
Mussel Species: Southern acornshell (Epioblasma othcaloogensis), ovate
clubshell (Pleurobema perovatum), southern clubshell (Pleurobema
decisum), upland combshell (Epioblasma metastriata), triangular
kidneyshell (Ptychobranchus greenii), Alabama moccasinshell (Medionidus
acutissimus), Coosa moccasinshell (Medionidus parvulus), orangenacre
mucket (Hamiota perovalis), dark pigtoe (Pleurobema furvum), southern
pigtoe (Pleurobema georgianum), and finelined pocketbook (Hamiota
altilis)'', revising the entry's heading, the first sentence of
paragraph (1) introductory text, the introductory text of paragraph
(2)(i), the table in paragraph (2)(ii), the introductory text of
paragraph (2)(xiv), paragraph (2)(xiv)(B), the introductory text of
paragraph (2)(xv), paragraph (2)(xv)(B), the introductory text of
paragraph (2)(xx), paragraph (2)(xx)(B), the introductory text of
paragraph (2)(xxi), paragraph (2)(xxi)(B), the introductory text of
paragraph (2)(xxiii), paragraph (2)(xxiii)(B), the introductory text of
paragraph (2)(xxvi), paragraph (2)(xxvi)(B), the introductory text of
paragraph (2)(xxvii), paragraph (2)(xxvii)(B), the introductory text of
paragraph (2)(xxviii), and paragraph (2)(xxviii)(B).
The revisions read as follows:
Sec. 17.95 Critical habitat--fish and wildlife.
* * * * *
(f) Clams and Snails.
* * * * *
Nine Mobile River Basin Mussel Species: Ovate Clubshell (Pleurobema
Perovatum), Southern Clubshell (Pleurobema Decisum), Triangular
Kidneyshell (Ptychobranchus Greenii), Alabama Moccasinshell (Medionidus
Acutissimus), Coosa Moccasinshell (Medionidus Parvulus), Orange-Nacre
Mucket (Hamiota Perovalis), Dark Pigtoe (Pleurobema Furvum), Southern
Pigtoe (Pleurobema Georgianum), and Fine-Lined Pocketbook (Hamiota
Altilis)
(1) The primary constituent elements essential for the conservation
of the ovate clubshell (Pleurobema perovatum), southern clubshell
(Pleurobema decisum), triangular kidneyshell (Ptychobranchus greenii),
Alabama moccasinshell (Medionidus acutissimus), Coosa moccasinshell
(Medionidus parvulus), orange-nacre mucket (Hamiota perovalis), dark
pigtoe (Pleurobema furvum), southern pigtoe (Pleurobema georgianum),
and fine-lined pocketbook (Hamiota altilis) are those habitat
components that support feeding, sheltering, reproduction, and physical
features for maintaining the natural processes that support these
habitat components. * * *
(2) * * *
(i) Index map. The index map showing critical habitat units in the
States of Mississippi, Alabama, Georgia, and Tennessee for the nine
Mobile River Basin mussel species follows:
* * * * *
(ii) * * *
Table 1 to Nine Mobile River Basin Mussel Species Paragraph (2)(ii)
----------------------------------------------------------------------------------------------------------------
Species Critical habitat units States
----------------------------------------------------------------------------------------------------------------
Ovate clubshell (Pleurobema perovatum).. Units 1, 2, 3, 4, 5, 6, 7, 8, 9, AL, GA, MS, TN.
10, 11, 12, 13, 17, 18, 19, 21,
24, 25, 26.
[[Page 71673]]
Southern clubshell (Pleurobema decisum). Units 1, 2, 3, 4, 5, 6, 7, 8, 9, AL, GA, MS, TN.
13, 14, 15, 17, 18, 19, 21, 24,
25, 26.
Triangular kidneyshell (Ptychobranchus Units 10, 11, 12, 13, 18, 19, AL, GA, TN.
greenii). 20, 21, 22, 23, 24, 25, 26.
Alabama moccasinshell (Medionidus Units 1, 2, 3, 4, 5, 6, 7, 8, 9, AL, GA, MS, TN.
acutissimus). 10, 11, 12, 13, 15, 25, 26.
Coosa moccasinshell (Medionidus Units 18, 19, 20, 21, 22, 23, AL, GA, TN.
parvulus). 24, 25, 26.
Orange-nacre mucket (Hamiota perovalis). Units 1, 2, 3, 4, 5, 6, 7, 8, 9, AL, MS.
10, 11, 12, 13, 14, 15.
Dark pigtoe (Pleurobema furvum)......... Units 10, 11, 12................ AL.
Southern pigtoe (Pleurobema georgianum). Units 18, 19, 20, 21, 22, 23, AL, GA, TN.
24, 25, 26.
Fine-lined pocketbook (Hamiota altilis). Units 13, 16, 17, 18, 19, 20, AL, GA, TN.
21, 22, 23, 24, 25, 26.
----------------------------------------------------------------------------------------------------------------
* * * * *
(xiv) Unit 12. Locust Fork and Little Warrior Rivers, Jefferson,
Blount Counties, Alabama. This is a critical habitat unit for the ovate
clubshell, triangular kidneyshell, Alabama moccasinshell, orange-nacre
mucket, and dark pigtoe.
* * * * *
(B) Map of Unit 12 follows:
BILLING CODE 4333-15-P
[[Page 71674]]
Figure 14 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xiv)(B)
Unit 12: Ovate Clubshell, Triangular Kidneyshell, Alabama
Moccasinshell, Orange-Nacre Mucket, Dark Pigtoe
[GRAPHIC] [TIFF OMITTED] TR17OC23.000
(xv) Unit 13. Cahaba River and Little Cahaba River, Jefferson,
Shelby, Bibb Counties, Alabama. This is a critical habitat unit for the
ovate clubshell, southern clubshell, triangular kidneyshell, Alabama
moccasinshell, orange-nacre mucket, and fine-lined pocketbook.
* * * * *
[[Page 71675]]
(B) Map of Unit 13 follows:
Figure 15 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xv)(B)
Unit 13: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Alabama Moccasinshell, Orange-Nacre Mucket, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.001
* * * * *
(xx) Unit 18. Coosa River (Old River Channel) and Terrapin Creek,
Cherokee, Calhoun, Cleburne Counties, Alabama. This is a critical
habitat unit for the ovate clubshell, southern clubshell, triangular
kidneyshell, Coosa
[[Page 71676]]
moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 18 follows:
Figure 20 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xx)(B)
Unit 18: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.002
(xxi) Unit 19. Hatchet Creek, Coosa, Clay Counties, Alabama. This
is a critical habitat unit for the ovate clubshell, southern clubshell,
triangular kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
[[Page 71677]]
(B) Map of Unit 19 follows:
Figure 21 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xxi)(B)
Unit 19: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.003
* * * * *
(xxiii) Unit 21. Kelly Creek and Shoal Creek, Shelby, St. Clair
Counties, Alabama. This is a critical habitat unit for the ovate
clubshell, southern clubshell, triangular kidneyshell, Coosa
moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 21 follows:
[[Page 71678]]
Figure 23 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xxiii)(B)
Unit 21: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.004
* * * * *
(xxvi) Unit 24. Big Canoe Creek, St. Clair County, Alabama. This is
a critical habitat unit for the ovate clubshell, southern clubshell,
triangular kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
[[Page 71679]]
(B) Map of Unit 24 follows:
Figure 26 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xxvi)(B)
Unit 24: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Coosa Moccasinshell, Southern Pigtoe, Fine-Lined Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.005
(xxvii) Unit 25. Oostanaula, Coosawattee, and Conasauga Rivers, and
Holly Creek, Floyd, Gordon, Whitfield, Murray Counties, Georgia;
Bradley, Polk Counties, Tennessee. This is a critical habitat unit for
the ovate clubshell, southern clubshell, triangular kidneyshell,
Alabama moccasinshell,
[[Page 71680]]
Coosa moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 25 follows:
Figure 27 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xxvii)(B)
Unit 25: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Alabama Moccasinshell, Coosa Moccasinshell, Southern Pigtoe, Fine-Lined
Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.006
(xxviii) Unit 26. Lower Coosa River, Elmore County, Alabama. This
is a critical habitat unit for the ovate clubshell, southern clubshell,
triangular kidneyshell, Alabama moccasinshell,
[[Page 71681]]
Coosa moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 26 follows:
Figure 28 to Nine Mobile River Basin Mussel Species Paragraph
(2)(xxviii)(B)
Unit 26: Ovate Clubshell, Southern Clubshell, Triangular Kidneyshell,
Alabama Moccasinshell, Coosa Moccasinshell, Southern Pigtoe, Fine-Lined
Pocketbook
[GRAPHIC] [TIFF OMITTED] TR17OC23.007
[[Page 71682]]
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Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023-22377 Filed 10-16-23; 8:45 am]
BILLING CODE 4333-15-C