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Proposed Rule2024-29125

Endangered and Threatened Wildlife and Plants; Endangered Species Status for Puerto Rican Skink, Lesser Virgin Islands Skink, and Virgin Islands Bronze Skink and Designation of Critical Habitat; Threatened Species Status With Section 4(d) Rule for Culebra Skink and Designation of Critical Habitat; Not Warranted Species Status for Mona Skink, Greater Virgin Islands Skink, Greater Saint Croix Skink, and Lesser Saint Croix Skink

Primary source

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Published

December 19, 2024

Issuing agencies

Interior DepartmentFish and Wildlife Service

Abstract

We, the U.S. Fish and Wildlife Service (Service), propose to list the Puerto Rican skink (Spondylurus nitidus), a skink species from Puerto Rico and Desecheo Island, and the Lesser Virgin Islands skink (S. semitaeniatus) and Virgin Islands bronze skink (S. sloanii), two skink species from the U.S. Virgin Islands and the British Virgin Islands, as endangered species. We propose to list the Culebra skink (S. culebrae), a skink species from Culebra Island and offshore cays of Puerto Rico, as a threatened species with protective regulations under section 4(d) of the Endangered Species Act of 1973, as amended (Act) ("4(d) rule"). After a review of the best available scientific and commercial information, we find that listing these species is warranted. If we finalize this rule as proposed, we will add these species to the List of Endangered and Threatened Wildlife and extend the Act's protections to these species. We also propose to designate critical habitat for the Puerto Rican skink, Culebra skink, Lesser Virgin Islands skink, and Virgin Islands bronze skink under the Act. We also announce the availability of an economic analysis of the proposed designation of critical habitat for the Puerto Rican skink, Culebra skink, Lesser Virgin Islands skink, and Virgin Islands bronze skink. We find that it is not warranted at this time to list the Mona skink (Spondylurus monae), the Greater Virgin Islands skink (S. spilonotus), the Greater Saint Croix skink (S. magnacruzae), and the Lesser Saint Croix skink (Capitellum parvicruzae). However, we ask the public to submit to us at any time any new information relevant to the status of any of the species mentioned above and their habitats.

Full Text

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[Federal Register Volume 89, Number 244 (Thursday, December 19, 2024)]
[Proposed Rules]
[Pages 103938-103989]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2024-29125]

[[Page 103937]]

Vol. 89

Thursday,

No. 244

December 19, 2024

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; Endangered Species
Status for Puerto Rican Skink, Lesser Virgin Islands Skink, and Virgin
Islands Bronze Skink and Designation of Critical Habitat; Threatened
Species Status With Section 4(d) Rule for Culebra Skink and Designation
of Critical Habitat; Not Warranted Species Status for Mona Skink,
Greater Virgin Islands Skink, Greater Saint Croix Skink, and Lesser
Saint Croix Skink; Proposed Rule

Federal Register / Vol. 89 , No. 244 / Thursday, December 19, 2024 /
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2024-0154; FXES1111090FEDR-256-FF09E21000]
RIN 1018-BH81

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule and notification of findings.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
list the Puerto Rican skink (Spondylurus nitidus), a skink species from
Puerto Rico and Desecheo Island, and the Lesser Virgin Islands skink
(S. semitaeniatus) and Virgin Islands bronze skink (S. sloanii), two
skink species from the U.S. Virgin Islands and the British Virgin
Islands, as endangered species. We propose to list the Culebra skink
(S. culebrae), a skink species from Culebra Island and offshore cays of
Puerto Rico, as a threatened species with protective regulations under
section 4(d) of the Endangered Species Act of 1973, as amended (Act)
(``4(d) rule''). After a review of the best available scientific and
commercial information, we find that listing these species is
warranted. If we finalize this rule as proposed, we will add these
species to the List of Endangered and Threatened Wildlife and extend
the Act's protections to these species. We also propose to designate
critical habitat for the Puerto Rican skink, Culebra skink, Lesser
Virgin Islands skink, and Virgin Islands bronze skink under the Act. We
also announce the availability of an economic analysis of the proposed
designation of critical habitat for the Puerto Rican skink, Culebra
skink, Lesser Virgin Islands skink, and Virgin Islands bronze skink. We
find that it is not warranted at this time to list the Mona skink
(Spondylurus monae), the Greater Virgin Islands skink (S. spilonotus),
the Greater Saint Croix skink (S. magnacruzae), and the Lesser Saint
Croix skink (Capitellum parvicruzae). However, we ask the public to
submit to us at any time any new information relevant to the status of
any of the species mentioned above and their habitats.

DATES: We will accept comments received or postmarked on or before
February 18, 2025. Comments submitted electronically using the Federal
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59
p.m. eastern time on the closing date. We must receive requests for a
public hearing, in writing, at the address shown in FOR FURTHER
INFORMATION CONTACT by February 3, 2025.

ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal:
<a href="https://www.regulations.gov">https://www.regulations.gov</a>. In the Search box, enter FWS-R4-ES-
2024-0154, which is the docket number for this rulemaking. Then, click
on the Search button. On the resulting page, in the panel on the left
side of the screen, under the Document Type heading, check the Proposed
Rule box to locate this document. You may submit a comment by clicking
on ``Comment.''
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: FWS-R4-ES-2024-0154, U.S. Fish and Wildlife Service,
MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on <a href="https://www.regulations.gov">https://www.regulations.gov</a>. This
generally means that we will post any personal information you provide
us (see Information Requested, below, for more information).
Availability of supporting materials: Supporting materials, such as
the species status assessment report, are available on the Service's
website at <a href="https://www.fws.gov/office/caribbean-ecological-services">https://www.fws.gov/office/caribbean-ecological-services</a>, at
<a href="https://www.regulations.gov">https://www.regulations.gov</a> at Docket No. FWS-R4-ES-2024-0154, or both.

FOR FURTHER INFORMATION CONTACT: Lourdes Mena, Field Supervisor, U.S.
Fish and Wildlife Service, Caribbean Ecological Services Field Office,
P.O. Box 491, Boquer[oacute]n, PR 00622; telephone 352-749-2462; email:
<a href="/cdn-cgi/l/email-protection#f69a998384929385a99b939897b6908185d8919980"><span class="__cf_email__" data-cfemail="98f4f7edeafcfdebc7f5fdf6f9d8feefebb6fff7ee">[email&#160;protected]</span></a>. 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. Please see Docket No. FWS-R4-ES-2024-
0154 on <a href="https://www.regulations.gov">https://www.regulations.gov</a> for a document that summarizes this
proposed rule.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule. Under the Act, a species warrants
listing if it meets the definition of an endangered species (in danger
of extinction throughout all or a significant portion of its range) or
a threatened species (likely to become an endangered species within the
foreseeable future throughout all or a significant portion of its
range). If we determine that a species warrants listing, we must list
the species promptly and designate the species' critical habitat to the
maximum extent prudent and determinable. We have determined that the
Puerto Rican skink, Lesser Virgin Islands skink, and Virgin Islands
bronze skink meet the Act's definition of endangered species and the
Culebra skink meets the definition of a threatened species; therefore,
we are proposing to list them as such and propose designation of
critical habitat for each species. Both listing a species as an
endangered or threatened species and making a critical habitat
designation can be completed only by issuing a rule through the
Administrative Procedure Act rulemaking process (5 U.S.C. 551 et seq.).
What this document does. We propose to add the Puerto Rican skink,
Lesser Virgin Islands skink, and Virgin Islands bronze skink as
endangered species to the List of Endangered and Threatened Wildlife
(List) in title 50 of the Code of Federal Regulations at 50 CFR 17.11.
We also propose adding the Culebra skink as a threatened species to the
List with a rule under section 4(d) of the Act, and we propose the
designation of critical habitat for all of these species. This document
serves as our 12-month petition findings for the Puerto Rican skink,
Lesser Virgin Islands skink, Virgin Islands bronze skink, and the
Culebra skink. We also announce 12-month petition findings that the
Mona skink, Greater Virgin Islands skink, Greater Saint Croix skink,
and Lesser Saint Croix skink are not warranted for listing as
endangered or threatened species under the Act.
The basis for our action. Under the Act, we may determine that a
species is an endangered or threatened species because of any of five
factors: (A) The present or threatened destruction, modification, or
curtailment of its habitat or range; (B) overutilization for
commercial, recreational, scientific, or

[[Page 103939]]

educational purposes; (C) disease or predation; (D) the inadequacy of
existing regulatory mechanisms; or (E) other natural or manmade factors
affecting its continued existence. We have determined that the Puerto
Rican skink, Lesser Virgin Islands skink, and Virgin Islands bronze
skink are endangered species due to the following threats: nonnative
predators (Factor C) and habitat loss and degradation from development
(Factor A). We have determined that the Culebra skink is a threatened
species due to the following threats: nonnative predators (Factor C),
habitat loss and degradation from development (Factor A), and sea level
rise and storm surge from a changing climate (Factor E).
Section 4(a)(3) of the Act requires the Secretary of the Interior
(Secretary), to the maximum extent prudent and determinable,
concurrently with listing designate critical habitat for the species.
Section 3(5)(A) of the Act defines critical habitat as (i) the specific
areas within the geographical area occupied by the species, at the time
it is listed, on which are found those physical or biological features
(I) essential to the conservation of the species and (II) which may
require special management considerations or protections; and (ii)
specific areas outside the geographical area occupied by the species at
the time it is listed, upon a determination by the Secretary that such
areas are essential for the conservation of the species. Section
4(b)(2) of the Act states that the Secretary must make the designation
on the basis of the best scientific data available and after taking
into consideration the economic impact, the impact on national
security, and any other relevant impacts of specifying any particular
area as critical habitat.

Information Requested

We intend that any final actions resulting from this proposed rule
will be based on the best scientific and commercial data available and
be as accurate and as effective as possible. Therefore, we request
comments or information from other governmental agencies, Native
American Tribes, the scientific community, industry, or any other
interested parties concerning this proposed rule. We particularly seek
comments concerning:
(1) Each skink species' biology, ranges, and population trends,
including:
(a) Biological or ecological requirements of the species, including
habitat requirements for feeding, breeding, and sheltering;
(b) Genetics and taxonomy;
(c) Historical and current ranges, including distribution patterns
and the locations of any additional populations of these species;
(d) Historical and current population levels, and current and
projected trends; and
(e) Past and ongoing conservation measures for these species and/or
their habitats.
(2) Threats and conservation actions affecting the species,
including:
(a) Factors that may be affecting the continued existence of the
species, which may include habitat modification or destruction,
overutilization, disease, predation, the inadequacy of existing
regulatory mechanisms, or other natural or manmade factors.
(b) Biological, commercial trade, or other relevant data concerning
any threats (or lack thereof) to these species.
(c) Existing regulations or conservation actions that may be
addressing threats to these species.
(3) Additional information concerning the historical and current
status of these species.
(4) Information to assist us with applying or issuing protective
regulations under section 4(d) of the Act that may be necessary and
advisable to provide for the conservation of the Culebra skink, in
particular, whether we should consider any additional or different
exceptions from the prohibitions in the 4(d) rule.
(5) Specific information related to critical habitat, such as:
(a) The amount and distribution of Puerto Rican skink, Culebra
skink, Lesser Virgin Islands skink, and Virgin Islands bronze skink
habitat;
(b) Any additional areas occurring within the range of each of the
species, including Puerto Rico and surrounding islands and cays as well
as the U.S. Virgin Islands and British Virgin Islands, that should be
included in the designation because they (i) are occupied at the time
of listing and contain the physical or biological features that are
essential to the conservation of the species and that may require
special management considerations or protection, or (ii) are unoccupied
at the time of listing and are essential for the conservation of the
species;
(c) Special management considerations or protection that may be
needed in critical habitat areas we are proposing, including managing
for the potential effects of predators and climate change; and
(d) Whether areas not occupied at the time of listing qualify as
habitat for the species and are essential for the conservation of the
species.
(6) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat.
(7) Any probable economic, national security, or other relevant
impacts of designating any area that may be included in the final
designation, and the related benefits of including or excluding
specific areas.
(8) Information on the extent to which the description of probable
economic impacts in the economic analyses is a reasonable estimate of
the likely economic impacts and any additional information regarding
probable economic impacts that we should consider.
(9) Whether any specific areas we are proposing for critical
habitat designation should be considered for exclusion under section
4(b)(2) of the Act, and whether the benefits of potentially excluding
any specific area outweigh the benefits of including that area under
section 4(b)(2) of the Act. If you think we should exclude any
additional areas, please provide information supporting a benefit of
exclusion.
(10) Whether we could improve or modify our approach to designating
critical habitat in any way to provide for greater public participation
and understanding, or to better accommodate public concerns and
comments.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include.
Please note that submissions merely stating support for, or
opposition to, the action under consideration without providing
supporting information, although noted, do not provide substantial
information necessary to support a determination. Section 4(b)(1)(A) of
the Act directs that determinations as to whether any species is an
endangered or a threatened species must be made solely on the basis of
the best scientific and commercial data available, and section 4(b)(2)
of the Act directs that the Secretary shall designate critical habitat
on the basis of the best scientific data available.
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
If you submit information via <a href="https://www.regulations.gov">https://www.regulations.gov</a>, your
entire submission--including any personal identifying information--will
be posted

[[Page 103940]]

on the website. If your submission is made via a hardcopy that includes
personal identifying information, you may request at the top of your
document that we withhold this information from public review. However,
we cannot guarantee that we will be able to do so. We will post all
hardcopy submissions on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.
Our final determination may differ from this proposal because we
will consider all comments that we receive during the comment period as
well as any information that may become available after this proposal.
Based on the new information that we receive (and, if relevant, any
comments on that new information), we may conclude that the Puerto
Rican skink, Lesser Virgin Islands skink, or Virgin Islands bronze
skink are threatened instead of endangered species, or that the Culebra
skink is an endangered species instead of a threatened species, or we
may conclude that these species do not warrant listing as either
endangered species or threatened species. For critical habitat, our
final designation may not include all areas proposed, may include some
additional areas that meet the definition of critical habitat, or may
exclude some areas if we find the benefits of exclusion outweigh the
benefits of inclusion and exclusion will not result in the extinction
of the species. In addition, we may change the parameters of the
prohibitions or the exceptions to those prohibitions in the protective
regulations issued or applied under section 4(d) of the Act for Culebra
skink if we conclude it is appropriate in light of comments and new
information received. For example, we may expand the prohibitions if we
conclude that the protective regulations as a whole, including those
additional prohibitions, are necessary and advisable to provide for the
conservation of the Culebra skink. Conversely, we may establish
additional exceptions to the prohibitions in the final rule if we
conclude that the activities would facilitate or are compatible with
the conservation and recovery of the Culebra skink. In our final rule,
we will clearly explain our rationale and the basis for our final
decision, including why we made changes, if any, that differ from this
proposal.

Public Hearing

Section 4(b)(5) of the Act provides for a public hearing on this
proposal, if requested. Requests must be received by the date specified
in DATES. Such requests must be sent to the address shown in FOR
FURTHER INFORMATION CONTACT. We will schedule a public hearing on this
proposal, if requested, and announce the date, time, and place of the
hearing, as well as how to obtain reasonable accommodations, in the
Federal Register and local newspapers at least 15 days before the
hearing. We may hold the public hearing in person or virtually via
webinar. We will announce any public hearing on our website, in
addition to the Federal Register. The use of virtual public hearings is
consistent with our regulations at 50 CFR 424.16(c)(3).

Previous Federal Actions

On February 11, 2014, we received a petition from the Center for
Biological Diversity (CBD) and Dr. Renata Platenberg (reptile
ecologist) requesting that nine Caribbean skink species be listed as
endangered or threatened and that critical habitat be designated for
these species under the Act. These nine species are: the Puerto Rican
skink, the Culebra skink, the Mona skink, the Monito skink, the Greater
and Lesser Virgin Islands skinks, the Virgin Islands bronze skink, and
the Greater and Lesser Saint Croix skinks. We acknowledged receipt of
this petition via email on February 12, 2014. On January 12, 2016, we
published a positive 90-day finding (81 FR 1368) indicating that the
petitioned action may be warranted and that the petition presented
substantial scientific or commercial information for seven of the skink
species. On March 16, 2016, we published a not-substantial 90-day
finding (81 FR 14058) for Monito skink. On September 14, 2016, we
published a substantial 90-day finding (81 FR 63160) for the Lesser
Virgin Islands skink.
On March 10, 2020, CBD issued a notice of intent to file suit to
compel the Service to issue 12-month findings for the eight skinks with
substantial 90-day findings. On September 22, 2020, CBD filed a
complaint for declaratory and injunctive relief, stating that the
Service had failed to make a timely determination for whether the eight
species of Caribbean skink warrant protection under the Act. On May 27,
2021, the Service agreed to a settlement to complete its review of the
status of the skinks and submit 12-month findings to the Federal
Register by December 12, 2024.

Peer Review

A species status assessment (SSA) team prepared an SSA report for
the Puerto Rican skink, Mona skink, Culebra skink, Greater Virgin
Islands skink, Lesser Virgin Islands skink, Virgin Islands bronze
skink, Greater Saint Croix skink, and Lesser Saint Croix skink (Service
2023, entire). The SSA team was composed of Service biologists and a
contractor from Texas A&M University, in consultation with other
species experts. The SSA report represents a compilation of the best
scientific and commercial data available concerning the status of each
of the species, including the impacts of past, present, and future
factors (both negative and beneficial) affecting each of the species.
In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), and our August 22,
2016, memorandum updating and clarifying the role of peer review in
listing actions under the Act (<a href="https://www.fws.gov/sites/default/files/documents/peer-review-policy-directors-memo-2016-08-22.pdf">https://www.fws.gov/sites/default/files/documents/peer-review-policy-directors-memo-2016-08-22.pdf</a>), we
solicited independent scientific review of the information contained in
the SSA report. We sent the SSA report to seven independent peer
reviewers and received three responses. Results of this structured peer
review process can be found at <a href="https://www.regulations.gov">https://www.regulations.gov</a>. In
preparing this proposed rule, we incorporated the results of these
reviews, as appropriate, into the SSA report, which is the foundation
for this proposed rule.

Summary of Peer Reviewer Comments

As discussed in Peer Review above, we received comments from three
peer reviewers on the draft SSA report. We reviewed all comments we
received from the peer reviewers for substantive issues and new
information regarding the contents of the SSA report. The peer
reviewers generally concurred with our methods and conclusions and
provided clarifications and editorial suggestions. One reviewer
indicated the Service was not justified in concluding that the Puerto
Rican skink does not inhabit Culebra, Cayo Norte, and Cayo Luis Pena.
The Service acknowledges it is possible that the Puerto Rican skink may
have been in these locations historically; however, we lack genetic
information that could confirm Puerto Rican skinks are sympatric with
Culebra skinks. The SSA report provides this background in the
historical distribution narrative (Service 2023, p. 33) but does not
include Puerto Rican skinks in the distribution maps for these areas.
We also received a comment disagreeing with information presented in
appendix B of the SSA report (Service 2023, pp. 146-169) summarizing
the likely extinct status of the Greater Virgin Islands skink, Greater
Saint Croix skink, and

[[Page 103941]]

Lesser Saint Croix skink, referencing the discrepancy with the
International Union for Conservation's (IUCN) criterion for possible
extinction. The Service does not use the IUCN criterion to determine
whether a species is extinct. The Service used the best available
information, as presented in the SSA report, to determine that these
species are extinct. Otherwise, no substantive changes to our analysis
and conclusions within the SSA report were deemed necessary, and peer
review comments are addressed in version 1.0 of the SSA report.

I. Proposed Listing Determination

Background

A thorough review of the taxonomy, genetics, life history, and
ecology of each of the skink species is presented in the SSA report
(Service 2023, pp. 17-43), and species-specific distribution
information follows the general overview below.
The eight Caribbean skink species--Puerto Rican skink, Mona skink,
Culebra skink, Greater Virgin Islands skink, Lesser Virgin Islands
skink, Virgin Islands bronze skink, Greater Saint Croix skink, and
Lesser Saint Croix skink--have similar patterns and coloration. All are
generally some shades of tans and browns, with a pair of dark lateral
stripes and limb pattern, if present, with spots or blotches (Hedges
and Conn 2012, pp. 14-15). Juveniles often have blue tails. Available
information suggests that females are slightly larger than males
(Hedges and Conn 2012, p. 10). Adult snout-vent length (SVL) will also
differ slightly between species, but in general ranges from
approximately 3 to 4 inches (in) (7.6 to 10 centimeters (cm)).
Caribbean skinks are ectothermic (cold-blooded) animals and
therefore highly dependent on the air and soil temperature to
thermoregulate (maintain body core temperature) (Noble et al. 2017, p.
72) and are often observed basking in the sun on rocks, leaf litter,
and fallen logs in forest habitat (Henderson and Powell 2009, p. 293;
Sanchez 2013, p. 1). Caribbean skinks have been observed on the ground,
shrubs, cacti, trees, boulder and limestone rocks, leaf litter, on and
under debris piles, under rocks and rock fissures, near human
habitation and houses, and are known to hide from perceived predators
under or within rocks, vegetation, and debris or when they are not
basking (Bullock and Evans 1990, p. 428; Henderson and Powell 2009, pp.
292-293, Hedges and Conn 2012, entire).
Very little information exists about the diet and foraging behavior
of Caribbean skinks. They appear to be diurnal and primarily hunt for
prey by actively foraging in dry coastal woodlands but are known to be
somewhat omnivorous including consumption of some plants (Platenberg
and Boulon 2006, p. 224; Daudin and de Silva 2011, p. 265; Henderson
and Powell 2009, pp. 292-293; Hedges and Conn 2012, p. 220). Some
information specifies that the skink diet is omnivorous, including
insects, fruits, and even a common coqui (Eleutherodactylus coqui) in
Puerto Rico (Henderson and Powell 2009, p. 293).
Caribbean skinks are viviparous (i.e., bearing live young). It is
theorized that the timing of birth in viviparous skinks is meant to
maximize food availability (Vrcibradic and Rocha 2011, p. 822; Hedges
and Conn 2012, p. 223) as well as maximize optimal conditions for
growth and survival of neonates (Abts 1988, p. 389; Olsson and Shine
1997, entire). Most skink species reproduce annually, but many skinks
have more than one brood; however, it is unknown which reproductive
strategy is exhibited in female Caribbean skinks. Collection of
specimens indicates Caribbean skinks are gravid during the dry season,
which is January through April, and birthing occurs primarily in
February through May (Hedges and Conn 2012, p. 223). Little information
is available about the influences on fecundity of Caribbean skinks.
Given that Spondylurus reproductive strategy is similar to other
viviparous skinks, maternal thermoregulation (i.e., basking behavior)
is likely used by female Caribbean skinks to keep developing embryos at
optimal temperatures for development of the young. Therefore,
influences on basking time of female skinks (e.g., the presence of
predators) could have the potential to decrease the fecundity of
Caribbean skinks or decrease the survival of young skinks.
No population estimates are available for the eight skink species.
During 2021-2022 skink surveys (Rivera et al. 2023, p. 9), there were
42 observations of Puerto Rican skinks, 8 of Mona skinks, 59 of Culebra
skinks, and 4 of Virgin Islands bronze skinks. In addition, on Desecheo
Island, five Puerto Rican skinks were encountered during a 6-day
herpetological survey (Herrera-Giraldo and Bermudez 2010, p. 22).
Current and historical distributions of the eight Caribbean skink
species encompass the islands of Puerto Rico, the U.S. Virgin Islands
(USVI), and the British Virgin Islands (BVI). The Puerto Rican skink,
the Mona skink, and the Culebra skink all fall within the U.S.
territory of Puerto Rico, which includes the main island of Puerto Rico
and surrounding islands (figure 1). The Puerto Rican skink's current
range includes the main island of Puerto Rico and Desecheo (figure 1).
BILLING CODE 4333-15-P

[[Page 103942]]

[GRAPHIC] [TIFF OMITTED] TP19DE24.000

The Mona skink occurs on only one island, Mona Island, off the west
coast of Puerto Rico (figure 1). The current range of the Culebra skink
encompasses the island of Culebra and its surrounding cays (Cayo Agua,
Cayo Botella, Cayo Lobito, and Cayo Yerba), all occurring to the east
of the main island of Puerto Rico (figure 1).

[[Page 103943]]

[GRAPHIC] [TIFF OMITTED] TP19DE24.001

Species that did occur entirely within the USVI include the Greater
Virgin Islands skink (figure 2), the Greater Saint Croix skink (figure
3), and the Lesser Saint Croix skink (figure 3), all of which are
considered likely extinct. The species that occur in both the USVI and
BVI include the Lesser Virgin Islands skink and the Virgin Islands
bronze skink (figure 2). The Lesser Virgin Islands skink has the
largest range of all the Caribbean skink species and still occurs in
both the USVI (Hans Lollik) and BVI (Guana Island, Mosquito Island,
Tortola) (figure 2). The Virgin Islands bronze skink also had a larger
range but is now confined to a few small to medium sized islands in the
USVI (Buck Island, Water Island, Turtledove Cay; figure 2).

[[Page 103944]]

[GRAPHIC] [TIFF OMITTED] TP19DE24.002

BILLING CODE 4333-15-C

Regulatory and Analytical Framework

Regulatory Framework

Section 4 of the Act (16 U.S.C. 1533) and the implementing
regulations in title 50 of the Code of Federal Regulations set forth
the procedures for determining whether a species is an endangered
species or a threatened species, issuing protective regulations for
threatened species, and designating critical habitat for endangered and
threatened species.
The Act defines an ``endangered species'' as a species that is in
danger of extinction throughout all or a significant portion of its
range and a ``threatened species'' as a species that is likely to
become an endangered species within the foreseeable future throughout
all or a significant portion of its range. The Act requires that we
determine whether any species is an endangered species or a threatened
species because of any of the following factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
These factors represent broad categories of natural or human-caused
actions or conditions that could have an effect on a species' continued
existence. In evaluating these actions and conditions, we look for
those that may have a negative effect on individuals of the species, as
well as other actions or conditions that may ameliorate any negative
effects or may have positive effects.
We use the term ``threat'' to refer in general to actions or
conditions that are known to or are reasonably likely to negatively
affect individuals of a species. The term ``threat'' includes actions
or conditions that have a direct impact on individuals (direct
impacts), as well as those that affect individuals through alteration
of their habitat or required resources (stressors). The term ``threat''
may encompass--either together or separately--the source of the action
or condition or the action or condition itself.
However, the mere identification of any threat(s) does not
necessarily mean that the species meets the statutory definition of an
``endangered species'' or a ``threatened species.'' In determining
whether a species meets either definition, we must evaluate all
identified threats by considering the species' expected response and
the effects of the threats--in light of those actions and conditions
that will ameliorate the threats--on an individual, population, and
species level. We evaluate each threat and its expected effects on the
species, then analyze the cumulative effect of all of the threats on
the species as a whole. We also consider the cumulative effect of the
threats in light of those actions and conditions that will have
positive effects on the species, such as any existing regulatory
mechanisms or conservation efforts. The Secretary determines whether
the species meets the definition of an ``endangered species'' or a
``threatened species'' only after conducting this cumulative analysis
and describing the expected effect on the species.
The Act does not define the term ``foreseeable future,'' which
appears in the statutory definition of ``threatened species.'' Our
implementing regulations at 50 CFR 424.11(d) set forth a framework for
evaluating the foreseeable future on a case-by-case basis, which is
further described in the 2009 Memorandum Opinion on the foreseeable
future from the Department

[[Page 103945]]

of the Interior, Office of the Solicitor (M-37021, January 16, 2009;
``M-Opinion,'' available online at <a href="https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf">https://www.doi.gov/sites/doi.opengov.ibmcloud.com/files/uploads/M-37021.pdf</a>). The foreseeable
future extends as far into the future as the U.S. Fish and Wildlife
Service and National Marine Fisheries Service (hereafter, the Services)
can make reasonably reliable predictions about the threats to the
species and the species' responses to those threats. We need not
identify the foreseeable future in terms of a specific period of time.
We will describe the foreseeable future on a case-by-case basis, using
the best available data and taking into account considerations such as
the species' life-history characteristics, threat projection
timeframes, and environmental variability. In other words, the
foreseeable future is the period of time over which we can make
reasonably reliable predictions. ``Reliable'' does not mean
``certain''; it means sufficient to provide a reasonable degree of
confidence in the prediction, in light of the conservation purposes of
the Act.

Analytical Framework

The SSA report documents the results of our comprehensive
biological review of the best scientific and commercial data regarding
the status of the species, including an assessment of the potential
threats to the species. The SSA report does not represent our decision
on whether the species should be proposed for listing as an endangered
or threatened species under the Act. However, it does provide the
scientific basis that informs our regulatory decisions, which involve
the further application of standards within the Act and its
implementing regulations and policies.
To assess Puerto Rican skink, Mona skink, Culebra skink, Greater
Virgin Islands skink, Lesser Virgin Islands skink, Virgin Islands
bronze skink, Greater Saint Croix skink, and Lesser Saint Croix skink
viability, we used the three conservation biology principles of
resiliency, redundancy, and representation (Shaffer and Stein 2000, pp.
306-310). Briefly, resiliency is the ability of the species to
withstand environmental and demographic stochasticity (for example, wet
or dry, warm or cold years); redundancy is the ability of the species
to withstand catastrophic events (for example, droughts, large
pollution events); and representation is the ability of the species to
adapt to both near-term and long-term changes in its physical and
biological environment (for example, climate conditions, pathogens). In
general, species viability will increase with increases in resiliency,
redundancy, and representation (Smith et al. 2018, p. 306). Using these
principles, we identified the species' ecological requirements for
survival and reproduction at the individual, population, and species
levels, and described the beneficial and risk factors influencing the
species' viability.
The SSA process can be categorized into three sequential stages.
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the historical
and current condition of the species' demographics and habitat
characteristics, including an explanation of how the species arrived at
its current condition. The final stage of the SSA involved making
predictions about the species' responses to positive and negative
environmental and anthropogenic influences. Throughout all of these
stages, we used the best available information to characterize
viability as the ability of a species to sustain populations in the
wild over time, which we then used to inform our regulatory decision.
The following is a summary of the key results and conclusions from
the SSA report; the full SSA report can be found at Docket No. FWS-R4-
ES-2024-0154 on <a href="https://www.regulations.gov">https://www.regulations.gov</a>.

Summary of Biological Status and Threats

In this discussion, we review the biological condition of each
species and their resources, and the threats that influence the
species' current and future conditions, in order to assess the species'
overall viability and the risks to that viability.

Individual, Population, and Species Needs

At the individual level, skinks require suitable foraging, basking,
and shelter habitat to survive during each life stage from birth to
adulthood, and to successfully reproduce. Individual needs of Caribbean
skink species are: (1) trees, shrubs, bushes ground cover/leaf litter,
cacti, debris, rocks, and crevices for shelter; (2) basking locations
for thermoregulation; and (3) arthropods as a food source (Service
2023, p. 44). Suitable habitat contains substrate that provides
refugia, presence of vegetation, vertical spaces, and areas that offer
both canopied and exposed sections for basking.
Skink populations are defined as single island units except for
mainland Puerto Rico (see Current Condition Methods, below). For
populations to demonstrate resiliency, the needs of individual skinks
must be met at a larger scale. Specific demographic information on
population carrying capacity, birth rates, and reproductive success is
lacking for these species. It can be inferred from individual needs
that an interbreeding population requires the elements needed by
individuals in sufficient quantities and configuration to support
multiple individuals and life stages. Given the small size of skink
species, patches that can support a population are expected to be
relatively small (~3 ac (1.2 ha)), based on the size of the smallest
occupied cays. In addition, while there are skink populations that have
persisted alongside nonnative predators like cats or rats, in general,
populations show higher resiliency where predators are few or absent.
Further, nonnative predators are currently absent from small cays where
skink populations have persisted (Service 2023, p. 45).
For species' viability, there must be adequate redundancy (number
of resilient populations with distribution and connectivity to allow
the species to withstand catastrophic events) and representation
(genetic and environmental diversity to allow the species to adapt to
changing environmental conditions). The minimum number of resilient
populations necessary to sustain each skink species is unknown, but we
assume that populations with low resiliency contribute negligibly to
overall species' viability. As island species, the relatively small,
patchily distributed, and isolated cays can each support only small
numbers of individuals (or separate populations). Redundancy improves
with increasing numbers of populations distributed across the species'
range, and connectivity allows connected populations to ``rescue'' each
other after catastrophes. The level of redundancy (distribution)
operating within a species is determined by the resiliency (abundance
and health) of its populations. Representation, or adaptive capacity,
improves with increased genetic and/or ecological diversity within and
among populations. Long-term viability requires resilient populations
in locations that are protected from the long-term catastrophic but
permanent effects of climate change (e.g., sea level rise and effects
from catastrophic hurricanes claiming low-lying habitat) and invasion
of nonnative predators.

Influences

Influences on the Caribbean skink species vary by location, but
threats include nonnative predators, habitat

[[Page 103946]]

loss and degradation from development, and sea level rise and storm
surge from a changing climate. Positive influences on the Caribbean
skink species viability are habitat protection and predator control.
Nonnative Predators
A primary threat to Caribbean skink populations is the presence of
nonnative predators including cats (Felis catus), rats (Rattus sp.),
and mongooses (Herpestes javanicus or Urva auropunctata).
Mongooses are implicated in the decline and loss of several
Caribbean skink species (Hedges and Conn 2012, pp. 224-229). Mongooses
were introduced to the Caribbean during the late 19th and early 20th
centuries with the goal of reducing rat populations. However, the
presence of mongooses did not decrease rat densities, and mongooses
have become a predator of many native vertebrate and invertebrate
species in the Caribbean, including lizards (Wolcott 1953, entire;
Witmer et al. 1998, p. 282; Henderson 1992, p. 3). Other reptile
species with similar life history traits that are also endemic in the
Caribbean have been shown to be vulnerable to mongoose depredation. For
example, the endangered St. Croix ground lizard was extirpated from the
main island of St. Croix in the 1900s, in part due to mongoose
predation (Angeli and Fitzgerald 2021, p. 345). Lizards from the genus
Ameiva (whiptail lizards) and snakes from the genera Alsophis (racers)
are also susceptible to mongoose predation because they are diurnal,
ground-dwelling, oviparous, active foragers, relatively small
(Henderson 1992, p. 7), and easily caught by mongooses. Other than
laying eggs (oviparity), these characteristics are shared by the
Caribbean skink species.
Feral cats have occurred for hundreds of years throughout the
Caribbean near human development and are known to be predators of
reptiles on numerous islands (Henderson 1992, p. 2; Service 2023, pp.
46-47). Cats are instinctively natural predators and have been
documented killing a variety of lizard species including five-lined
skinks (Plestiodon fasciatus), broad-headed skinks (P. laticeps), and
ground skinks (Scincella lateralis) (Mitchell and Beck 1992, p. 200).
Cats are documented to have preyed on the Mona skink (L[oacute]pez-
Torres and Garc[iacute]a 2013, entire) and the Puerto Rican skink
(Gonz[aacute]lez 2023, pers. comm.).
Rats are known to depredate small lizards on many islands,
including the St. Lucia whiptail lizard (Cnemidophorous vanzoi), the
Belize leaf-tailed gecko (Phyllodactylus insularis) on Half Moon Cay,
and blue-tailed skinks (Cryptoblepharus egeriae) on Christmas Island
(Harper and Bunbury 2015, p. 616). However, the influence of rats on
skink populations is unclear. Despite being omnivorous, rats' primary
food on islands is arthropods and plants, suggesting that rats may be
consuming the food sources of the skinks as well as depleting local
vegetation. This consumption would lower the suitability of the habitat
while also increasing depredation on the skinks themselves (Harper and
Bunbury 2015, pp. 614, 616). Rats have a much more profound effect on
skink populations that occur on very small islands and cays.
Furthermore, rats are consistently introduced to islands, as they are
easily transported by boats (Harper and Bunbury 2015, entire).
Besides direct predation, skinks (as prey) may respond to the
presence of predators by increasing their time seeking refuge at the
cost of foraging, thermoregulation, and mating (Sih 1994, entire).
Further, prey may be less adapted to changes in these pressures because
these are introduced species (Mart[iacute]n and L[oacute]pez 1999, p.
491). The impacts from nonnative predators are likely more severe on
smaller islands because there is often a lower diversity of prey items
for predators (Henderson 1992, p. 5).
Habitat Loss and Degradation
Caribbean skinks occur on both private and publicly owned land.
Where skinks occur in urban or rural areas, habitat loss and
degradation resulting from development is a threat to populations. This
is the case for Puerto Rico, Culebra, and the main developed islands in
USVI and BVI. For example, in Puerto Rico, human activity has been
described as ``intensive, pervasive, and fragments natural habitat''
(Lugo and Helmer 2004, p. 156). This is particularly true in the
northern and eastern portions of the main island of Puerto Rico;
however, the central and southern portions of the main island remain
largely undeveloped (Gould et al. 2008, p. 91; see figure 4.3 in SSA
report (Service 2023, p. 49)). Lands cleared for development would
essentially eliminate potential habitat for the skinks and may directly
kill individuals as well, particularly if development occurs in or
adjacent to suitable skink habitat. And although forest areas have
increased in Puerto Rico, unprotected forested areas are vulnerable to
urban development, particularly those near or within urban centers
(Kennaway and Helmer 2007, p. 376). In the USVI as well, human
population growth has resulted in habitat loss and degradation of
natural habitats, and most land is privately owned (Platenberg and
Boulon 2006, p. 217).
Skinks are now absent from completely developed urban landscapes
that are not adjacent to natural habitat; however, skinks have been
seen in and around rural residential areas in Puerto Rico within karst
habitat and in residential and developed areas in Culebra (Zegarra
2023, pers. comm.). This could be due to ``urban survival'' of the
skinks, which is the idea that mongooses are less abundant in areas
with larger human inhabitation because they are depredated by other
nonnatives (e.g., dogs; Hedges and Conn 2012, p. 228). Skinks have also
been observed using debris piles (i.e., vegetation and trash)
accumulated on the side of roads and trails adjacent to forested
habitat, and on human-made rock piles for road construction. As skink
habitat is developed and encroached upon, observations of skinks in
residential areas may become more common. However, skinks that occur
within these areas are more susceptible to impacts from habitat loss as
well as more susceptible to nonnative predators or competitors
introduced by humans. While deforestation and fragmentation result from
development, the extent of impacts to Caribbean skinks may range from
low to high depending on each landscape as well as potential increased
interactions with nonnative predators causing potential declines in
skinks.
Climate Change: Sea Level Rise and Storm Surge
One of the stressors affecting Caribbean skinks and their habitat
is the shift in climate impacts occurring because of increasing
greenhouse gas (GHG) emissions. The long-term persistence of several
small cays in the Caribbean is being challenged by rising sea levels
and the increased intensity of storm surges. The main stressors to the
skinks and their habitat resulting from climate change are sea level
rise (SLR) and increased storm surges.
Relative sea levels have risen approximately 2 mm (0.08 in) per
year in Puerto Rico and USVI since mid-20th century, and the rate or
rise has been accelerating since the early 2000s (PRCCC 2022, p. 27).
This recent acceleration suggests that, of the National Oceanic and
Atmospheric Administration (NOAA) SLR scenarios based on different GHG
emission scenarios (Sweet et al. 2017, pp. 21-22), the intermediate to
high SLR scenarios are more likely to occur than the low and
intermediate-low scenarios (Sweet et al. 2017, pp. 33-35; Sweet et al.
2022,

[[Page 103947]]

p. 12). For Puerto Rico, the near-term range at 2050 is 1 foot (ft)
(0.3 meter (m)) for the intermediate local SLR scenario and 1.6 ft (0.5
m) for the high SLR scenario, and by 2100, the range is projected to be
3.3 ft (1.0 m) for the intermediate SLR scenario and 6.6 ft (2.0 m) for
the high SLR scenario (NOAA 2023, entire). Most of the impacts of SLR
on Caribbean skinks will likely occur on low-lying cays in the region,
beginning with increased saltwater flooding events from more frequent
storms.
Most measures of Atlantic hurricane activity have increased
substantially since the early 1980s, the period during which high-
quality satellite data are available (Service 2023, p. 52). These
include measures of intensity, frequency, and duration as well as the
number of strongest (Category 4 and 5) storms (Walsh et.al. 2014, p.
20). In the future, there is high confidence that SLR will increase
storm inundation levels, and medium to high confidence that both
precipitation rates and storm intensity will increase in hurricanes
globally. In addition, there is medium to high confidence that the
proportion of very strong storms (Category 4 and 5) will increase, but
less confidence in increased frequency of storms overall (Knutson et
al. 2020, p. E303). Strong rainstorms, tropical storms, and hurricanes
are natural parts of a tropical ecosystem. However, with intensity,
inundation levels, and precipitation all likely to increase, small
patches and low-lying habitats are likely at risk. The resiliency of
Caribbean skink species will likely be affected in these areas when the
quantity and quality of their resources (food, cover) are compromised,
particularly if there is not time to recover from previous events or
areas are continually reduced over time.
Saltwater surges and short-term flooding of upland habitats from
strong storms and hurricanes on low-lying cays likely have and will
continue to influence Caribbean skink persistence (D[iacute]az et al.
2022, p. 66). The severity and duration of hurricane impacts to
Caribbean skinks and their habitat vary based on the intensity and
scale of these storm events. Localized impacts can vary greatly
depending upon not only the strength of the storm, but the direction of
its approach and how quickly it moves through the area. Storm surges
and their intensity can also vary depending on location. In 2017, nine
named storms impacted the Caribbean, including Hurricanes Irma and
Maria (both Category 5). Irma caused catastrophic storm surges in the
USVI although the peak water level is unknown because the tidal gauges
in the area went offline during the storm. Storm tides from Maria
measured between 6 ft to 9 ft (1.5 m to 2.7 m) above mean sea level in
southwestern Puerto Rico (FEMA 2018, p. i).
Impacts from heavy rainstorms, tropical storms, and hurricanes are
part of this tropical islands system. The heavy inundation and even
complete overwash of some islands during hurricanes may provide some
explanation for the lack of skinks being observed, even when the island
has recovered and again contains high-quality suitable skink habitat.
Thus, storm events are likely a contributing factor to the low
occurrence (historical and current) observed for several of the skink
species. Individual skinks may colonize and occupy smaller islands only
temporarily until storm events impact that island. Eventual
recolonization of impacted islands by skinks is uncertain. Over time,
storms could be a factor reducing the persistence of skink populations
and thereby reducing the redundancy of the species.

Conservation Efforts and Regulatory Mechanisms

We do not know of any skink-focused conservation actions or
efforts. However, any past, current, and future eradication or control
of nonnative species is beneficial for the skinks. For example, efforts
to control mongoose populations on St. Thomas, St. John, and St. Croix
have been attempted, and rats and mongooses were completely eradicated
on Buck Island, St. Thomas, USVI (Barun et al. 2011, p. 20). Rats were
also eradicated from Monito Island, eliminating that predation threat
for the Monito skink and other species on that island (Garc[iacute]a
et. al 2002, entire). Monkeys, goats, and rats were also eradicated
from Desecheo Island, a National Wildlife Refuge (Will et al. 2019,
entire). Eradication of pigs, cats, and possibly rats is being planned
for Mona Island (Service 2023, entire). Permanent eradication of
nonnatives is typically most effective on small islands that do not
have human development.
As skinks occur both on private and public lands, areas designated
as nature reserves or refuges provide high-quality skink habitat as
well as protection from development. For example, some of the most
consistent skink observations for the Puerto Rican skink are from the
Guajataca and Maricao Commonwealth Forests, two areas managed for
conservation by the Puerto Rico Department of Natural and Environmental
Resources (PRDNER). Skinks were also observed within the Montadero
Natural Protected Area (Quebradillas Municipality, Puerto Rico) managed
by the Puerto Rico Conservation Trust. Some of these karst forests are
contained within the larger Karst Conservation Zone, a large area in
Puerto Rico with stricter land regulations named the Karst Restricted
Zone designated by the Puerto Rico Planning Board (Ortiz-Maldonado et
al. 2019, entire). This Zone represents 7.2 percent (647 km\2\) of the
total area of Puerto Rico, includes both public and private lands, and
was designated as such for conservation purposes by prohibiting land
exploitation of any type (Castro-Prieto et al. 2019, p. 59).
The Mona skink has a wide distribution within the Mona Island
Nature Reserve, managed for conservation by the PRDNER. The Puerto
Rican skink has been reported from the Desecheo NWR, and the Culebra
skink occurs within the Culebra NWR specifically within the Monte
Resaca area and some of its offshore cays (i.e., Cayo Botella, Cayo
Agua, Cayo Lobito, Cayo Yerba).
However, protected habitat does not ensure persistence of skinks,
particularly if nonnative mammals are present. Rather, it suggests that
habitat destruction or modification in those areas is minimal and less
than for habitat that is not protected. For example, the Culebra skink
was historically reported from Culebrita Island (part of the Culebra
NWR) but is currently considered likely extirpated, most likely due to
presence of rats.

Cumulative Effects

We note that, by using the SSA framework to guide our analysis of
the scientific information documented in the SSA report, we have
analyzed the cumulative effects of identified threats and conservation
actions on the species. To assess the current and future condition of
the species, we evaluate the effects of all the relevant factors that
may be influencing the species, including threats and conservation
efforts. Because the SSA framework considers not just the presence of
the factors, but to what degree they collectively influence risk to the
entire species, our assessment integrates the cumulative effects of the
factors and replaces a standalone cumulative-effects analysis.

Current Condition Methods

We considered all skinks within each island or cay (i.e., outside
of mainland Puerto Rico) to be single populations. We assume that each
island is geographically isolated and the influences on and threats to
Caribbean skinks tend to occur to entire islands

[[Page 103948]]

(e.g., nonnative predators are either present or not present).
Geographic ranges (i.e., islands considered in these analyses outside
of the main island of Puerto Rico) are based on current and historical
records of each species.
As for the other Caribbean skink species, limited information is
available on the distribution of Puerto Rican skinks on the main island
of Puerto Rico. Therefore, we delineated the populations of the Puerto
Rican skink on the main island using the recently (2021-2023) collected
survey and genetic information to discern what areas could constitute
separate populations (Rivera et al 2023, pp. 15-16). Genetic
information was obtained via tail clips during surveys. We overlayed
populations with potential habitat identified by the Puerto Rico GAP
Analysis Project (PRGAP) for the species (Gould et al. 2008, p. 91).
Predicted habitat from the GAP model utilized landcover types (i.e.,
dry forest, woodland, and shrublands) in 2001 that were restricted to
at or below 300 m and the few point locations for skinks that were
available in 2006. The model is likely not comprehensive given the low
number of confirmed skink observations that were available in 2006 and
does not include the urban development that has occurred on the main
island of Puerto Rico since 2001; we modified the model to include
habitats below 500 m based on more recent survey locations and combined
it with more recent genetic information from 2021-2023.
Numerous islands with historical skink records have not been
surveyed recently, and it is possible that additional individuals and
populations are present on these islands or even other islands in the
Caribbean. Current data suggest that these species are habitat
generalists. Some areas are likely not suitable as habitat for skinks,
for example, entirely developed urban areas. However, skinks are also
known to occur within some developed and rural areas, particularly if
adjacent to suitable habitat. Thus, we considered an island with
documented occurrences as a single population, except for mainland
Puerto Rico, and we assessed habitat conditions based on
characteristics of the entire island. On mainland Puerto Rico, we
determined population status based on confirmed occurrence information
and amount of potential habitat as determined by the Puerto Rico GAP
analysis predicted habitat (Gould et al. 2008, p. 91); these
populations were confirmed using the survey and genetic information
(Rivera et al. 2023, pp. 15, 16). Survey methodology and reporting has
varied significantly from population to population. Even with the same
methodology and reporting, survey success can differ based on external
factors like weather conditions, surveyor experience, detection
probabilities, threats, or habitat conditions. All these factors
contribute to high levels of uncertainty in the presence or absence of
skinks within a population.
For each island population, we considered the population ``extant''
if skinks have been detected there since 2000. The threshold of
detection before and after 2000, along with a Bayesian estimate of
occurrence, which is a probabilistic model linking skink occurrence to
several variables, such as predator presence, island size, maximum
elevation, habitat class, human population size, and co-occurring
species (see section 5.1.1 of SSA report (Service 2023, pp. 57-59),
allows for a more conservative estimate of occurrence (i.e., avoidance
of classifying a population as extirpated when it is, in fact, extant).
Because extensive surveys have not occurred on islands within the
geographic ranges of many of the Caribbean skink species, we utilized
Bayesian analyses to assess likelihood of skink existence on individual
smaller islands (<5 square kilometers (km\2\) (500 ha)) with detections
pre-2000 to assess if a skink population likely currently occurs there.
If a smaller island was known to be occupied by skinks before 2000 and
had a Bayesian probability score of <=0.49, then we considered the
status of that island ``likely extirpated'' and if the score is >=0.50,
we considered the status ``unknown.'' The exception to this was when
islands had been extensively surveyed since 2000 and there have been no
detections. Caribbean skinks are cryptic and difficult to detect, and
the potential habitats on the larger islands are often difficult to
access or survey thoroughly, and predators on some larger islands have
seemingly already eliminated skinks (i.e., St. Thomas, St. John, and
St. Croix). Additionally, there are few case studies for larger islands
for the Bayesian analysis, and the resulting network (i.e., output from
analysis) linking variables did a poor job predicting probability of
existence on islands >5 km\2\ (500 ha); therefore, we did not try to
estimate status of populations on larger islands and considered all
islands >5 km\2\ with detections from between 1970 and 2000 to have an
``unknown'' status (see table 5.2 of the SSA report (Service 2023, p.
61)).
Resiliency is the ability of a species to withstand environmental
stochasticity which is normal, year-to-year variations in environmental
conditions, as well as demographic stochasticity; typically, the larger
a population and the more individuals present, the more resilient the
population. We assume that current threat levels influence the current
population size; in other words, threats acting negatively on a
population can reduce the overall size of the population, which can
then result in a lower ability to withstand environmental and/or
demographic stochasticity. Population size is typically used as a
reliable indicator of overall resiliency. Due to the cryptic nature of
Caribbean skinks and lack of research and survey data, demographic data
(i.e., presence/absence, abundance, population trends, population
structure) are lacking in most locations. Therefore, the resiliency of
the populations relies on habitat metrics such as level of habitat
protection, nonnative predator pressure, and risk from storm surge.
Resiliency scores were generated by combining scores for three
habitat metrics (Protection, Nonnative Predators, Storm Surge Risk).
Each island was assigned a level of habitat protection based on
ownership (public/private) and percentage area protected, which
represents development risk, and the size of the island. Protected area
percentages were assessed using the Protected Areas Database (PAD-US),
the Puerto Rico Protected Areas Database, and the World Database for
Protected Areas (WDPA) (UNEP-WCMC 2024, unpaginated; USGS 2022,
unpaginated; Caribbean Landscape Conservation Cooperative 2016,
unpaginated).
The presence of nonnative predators is an important influence on
Caribbean skinks, especially when islands are small. Mongooses are
known to be especially harmful to small reptiles, particularly in
island habitats. The larger the island, the more complex the ecosystem
due to a larger diversity of habitats, which can provide multiple patch
areas and refugia, more diverse prey items for nonnative predators, and
potentially a larger population of skinks (Simberloff 1974, entire;
Kohn and Walsh 1994, entire). It is difficult to know when an island is
``large enough'' so that skinks can persist alongside the presence of
nonnative predators, particularly mongooses. The smaller the island,
the greater the impact of nonnative predators, including rats. We
scored the level of predator pressure for each island based on the type
of nonnative predator present and the size of the island. Islands
smaller than 15 ha were considered likely extirpated due to a higher
risk of predator dispersal.
Finally, we determined the potential impact of storm surges on
skink populations. Storm surge heights were

[[Page 103949]]

estimated using the sea, lake, and overland surges from hurricanes
(SLOSH) model used by the National Weather Service (Jelesnianski et al.
1992, entire). All simulated hurricanes had a forward speed of 15 miles
per hour (the closest simulation option to the average hurricane speed
of 10.8 miles per hour at 15-20 degrees north latitude; NOAA 2014,
unpaginated) in a northwesterly direction, the primary direction of
hurricane movement in the skinks' range. The SLOSH model predicts
average storm surge heights for multiple trajectories of a hurricane of
the same strength, speed, direction, and tide to account for
uncertainty in the path of any one storm. To determine potential
maximum impact for storm surge on each island, we simulated Category 5
hurricanes at mean tide level. For each simulated storm surge, we
calculated the percent of each island or cay that lies below that
elevation and would thus be inundated (or potentially flooded in cases
where lower elevation areas are inland and surrounded by higher
elevation areas) (see appendix A of the SSA report (Service 2023, pp.
141-145)). Note that scoring for the island of Puerto Rico is
considered to be ``no effect'' because the skink populations on Puerto
Rico are inland at high elevations and therefore not prone to the same
effect from storm surges as other islands (and therefore skink
populations) in the Caribbean.
The best available information for each population was gathered
from the literature, data sources, and species experts. Each metric was
weighed equally. Ultimately, resiliency classifications relied on
habitat conditions, as affected by threats. For each metric,
populations were assigned a score of -1, 0, or 1, as described below in
table 1.

Table 1--Scoring of Habitat Factors To Determine Population Resiliency of Eight Caribbean Skink Species
----------------------------------------------------------------------------------------------------------------
Habitat metrics
----------------------------------------------------------------------------
Score Nonnative predator
Habitat protection pressure Storm surge risk
----------------------------------------------------------------------------------------------------------------
-1................................. Low................... High.................. High: >25% inundated from
category 5 hurricane.
0.................................. Moderate.............. Low................... Low: <25% inundated from
category 5 hurricane.
1.................................. High.................. No impact............. No effect for main island
Puerto Rico.
----------------------------------------------------------------------------------------------------------------

The scores for all habitat metrics were summed, and final relative
population resiliency categories were assigned to each population
(except those that are likely extirpated). The range of final scores
was evenly divided into the four possible categories: High, Moderate,
Low, and Likely Extirpated. Likely extirpated means that all the
habitat factors are unfavorable for skink viability and the population
is/would be likely extirpated. A low score means that multiple
resiliency factors are not favorable for skink viability. Moderate or
high scores indicate that multiple habitat factors are conducive to
skink population viability on a given island.
Redundancy reduces the species' extinction risk if a portion of the
species' range is negatively affected by a natural or anthropogenic
catastrophic disturbance. For a Caribbean skink species to withstand
catastrophic events such as hurricanes or the introduction of nonnative
predators, it needs to have multiple, sufficiently resilient
populations across its range. We used the Bayesian probability to
determine likelihood of existence for each of the islands with
historical or current populations to assess redundancy for each
species. As described above, the status of the species on each of the
islands (extant, likely extirpated, unknown) allowed the assessment of
redundancy for each species.
Most of the Caribbean skink species exhibit limited distribution
(except Puerto Rican skink) and relative geographic rarity (see
appendix E of the SSA report (Service 2023, pp. 174-196)). Despite
these circumstances, they appear to use a wide variety of habitat and
structure across islands. They also appear moderately tolerant of human
infrastructure and disturbance (e.g., removal of unexploded ordnance
(Puente-Rol[oacute]n and Vega-Castillo 2019, p. 12)), with the
exceptions of introduced nonnative predators and direct loss of
habitat. There also appear to be no known restrictions to movement
throughout the year.
In some cases, genetic representation is limited to a single or
very few small islands, while others are represented by multiple
populations on large islands and scattered outlying cays; thus, the
catastrophic loss of a single island might have substantially different
effects on genetic and geographic representation depending on the
species. For instance, the Puerto Rican skink has multiple populations,
some on a single large island and at least one on a smaller island;
therefore, risk associated with catastrophic events (e.g., particularly
strong hurricanes and associated storm surge) would likely be
distributed across more populations and complete loss of genetic
diversity is less likely. However, loss of some populations could
reduce genetic diversity of this species.
The Mona skink is distributed on a single large island with both
higher elevation and lower elevation sites closer to the coast, while
other species, such as Culebra skink, Lesser Virgin Islands skink, and
Virgin Islands bronze skink, have populations on several small, low-
elevation islands. In species where few, small islands contain all
known genetic diversity or where a substantial proportion of sites are
located on small islands, risk of losing existing representation and
redundancy is likely higher. For instance, catastrophic events (e.g.,
particularly strong hurricanes, storm surge, and overwash) could
eliminate a much higher percentage of the existing genetic diversity
within a species if localized skink populations are lost or are
represented by only a single location on a small cay or if sea level
rise acts with storm surge to remove several small islands over time.
Such events could reduce species-level adaptive potential, limiting
future ability to respond to changing environmental conditions (Service
2021, pp. 4-5). In addition, many of the traits are still unknown at
this time for these species (e.g., population size, competitive
ability, site fidelity, age structure, recruitment rate, etc. (Thurman
et al. 2020, entire)). Therefore, at present we have an incomplete
picture of adaptive capacity for each of the species, and additional
knowledge about these traits could further refine our understanding of
representation.

Future Conditions Methods

The primary threats to Caribbean skinks in the future are: (1)
habitat destruction and modification, (2) nonnative predators, and (3)
climate change, specifically SLR, and the increases in intensity,
frequency, and duration of hurricane activity. Due to a lack of survey
effort in many locations and the cryptic nature of these species,

[[Page 103950]]

we assessed the future condition of the habitat quality on islands that
have current or historical documentation of skink occurrences. We
predicted resiliency at three future time points: 2050, 2070, and 2100.
We considered the same metrics as current condition (habitat
protection, predator pressure, risk from storm surge) as well as
predicted SLR for each scenario.

Table 2--Scores of Habitat Metrics To Determine Future Resiliency of Eight Caribbean Skink Species
----------------------------------------------------------------------------------------------------------------
Habitat metrics
-------------------------------------------------------------------------------
Score Nonnative predator Sea level rise
Habitat protection pressure (SLR) Storm surge
----------------------------------------------------------------------------------------------------------------
-1.............................. Low............... High (extirpation High: >25% High: >25%
likely on islands inundated from inundated from
<15 ha). SLR or SLR + SLR + storm
storm surge. surge.
0............................... Moderate.......... Low............... Moderate or Low: Moderate or Low:
<25% inundated >10% but <25%
from SLR or SLR + inundated from
storm surge. SLR + storm
surge.
---------------------------------------
1............................... High.............. No impact......... No effect (Puerto Rico main island
only).
----------------------------------------------------------------------------------------------------------------

For each influence on future resiliency of each Caribbean skink
species (extant populations only), we scored each habitat factor (table
2), as previously described for current condition, and calculated final
scores to determine the future resiliency of each population, under
four possible scenarios (table 3).

Table 3--Future Scenarios To Determine the Resiliency of Populations of Eight Caribbean Skink Species
----------------------------------------------------------------------------------------------------------------
Nonnative predator Sea level rise (SLR) +
Scenario Habitat protection pressure storm surge risk
----------------------------------------------------------------------------------------------------------------
1A................................. same as current....... same as current....... Intermediate SLR + Cat3 *
(2050).
Intermediate SLR + Cat5 *
(2070 & 2100).
1B................................. same as current....... increased pressure.... Intermediate SLR + Cat3
(2050).
Intermediate SLR + Cat5
(2070 & 2100).
2A................................. same as current....... same as current....... High SLR + Cat5.
2B................................. same as current....... increased pressure.... High SLR + Cat5.
----------------------------------------------------------------------------------------------------------------
* Cat3 = Category 3 hurricane; Cat5 = Category 5 hurricane.

Scenario 1A

Under scenario 1A, conditions continue along their current
trajectory. The risk of human development (measured here as level of
habitat protection) remains the same as current, and populations that
are currently impacted by the associated stressors from development
remain negatively impacted by these threats. Under this scenario, we
calculated impacts under the Intermediate SLR scenario as well as the
additional storm surge risk from a Category 3 hurricane (2050 only) and
Category 5 hurricane (2070 and 2100), which are expected to represent a
higher proportion of hurricanes in the Caribbean into the future
(Service 2023, pp. 52-55).

Scenario 1B

Under Scenario 1B, there is an increase in predator pressure on
islands where nonnative predators do not currently occur. Impacts to
small islands not currently impacted by nonnative predators include the
theoretical introduction of nonnative mammalian predators, most likely
rats, which can have a profound negative effect on skinks on smaller
islands/cays. Because larger islands will continue to have nonnative
predators, the risk will remain unchanged on those islands. The risk of
human development (i.e., level of habitat protection) remains the same
as current because we do not have data to inform this metric in the
future (note, this metric is held constant for all future scenarios).
Under this scenario, we calculated impacts under the Intermediate SLR
scenario as well as the additional storm surge risk from a Category 3
hurricane (2050 only) and Category 5 (2070 and 2100), which are
expected represent a higher proportion of hurricanes in the Caribbean
into the future.

Scenario 2A

Under Scenario 2A, habitat protection and nonnative predator risk
remain status quo, and SLR and storm surge calculations are based on
the High SLR scenario and the storm surge risk from Category 5
hurricanes for all time iterations.

Scenario 2B

Under scenario 2B, impacts of nonnative predators, SLR, and storm
surge worsen. Impacts to small islands not currently impacted by
nonnative predators include the theoretical introduction of nonnative
mammalian predators. Because larger islands will continue to have
nonnative predators, the risk will remain unchanged on those islands,
but we expect the impacts to continue to increase since eradication is
not feasible and exacerbated as human population sizes increase;
therefore, this scenario includes the lowering of habitat protection
category by one level. For this scenario we calculated impacts using
the High SLR scenario as well as the additional storm surge risk from
Category 5 hurricanes.

Puerto Rican Skink

Here, we present both current and future condition analyses results
for the Puerto Rican skink. There are currently four known extant
Puerto Rican skink populations on the island of Puerto Rico and one on
the island of Desecheo. Historical records indicate that Puerto Rican
skinks likely occurred on Icacos (1932) and Vieques (1980; figure 2.16;
Hedges and Conn 2012, p. 186), and on the main island of Puerto Rico
skinks were historically collected in and around San Juan (in 1879,
1880) and Bayam[oacute]n (in 1919, 1931); the southern coastal areas
including Ensenada (in 1915, 1919), North Descalabrado (in 1967), and
Cerro del Muerto (in 1980); Cape San Juan (in 1931) which is in extreme
northeastern Puerto Rico; and Barrio Coto in the municipality of

[[Page 103951]]

Isabela (in 1966), which is near Quebradillas (Hedges and Conn 2012, p.
186). Skink populations in San Juan and Cape San Juan are considered
historical and are designated as likely extirpated in our analyses.
Three skink specimens, one from Culebra, another from Cayo Norte, and
one from Cayo Luis Pe[ntilde]a in Culebra, were also assigned to the
Puerto Rican skink species; however, there is no genetic information
for these three specimens to confirm if Puerto Rican skinks are
sympatric with Culebra skinks. Unlike other island populations of
skinks, which are much smaller than those on the main island of Puerto
Rico, we treat each skink population on the main island of Puerto Rico
separately regarding amount of predator pressure and level of
protection.

Habitat Protection

For level of protection, we describe the total percentage protected
and indicate the percentage that includes the Zona de
Conservaci[oacute]n del Carso (Karst Conservation Zone) due to
differences in protection levels as compared to other protected areas.
This zone includes both public and privately owned lands, and
conservation within this zone cannot be considered conclusive since
permits for certain activities within this zone are subject to PRDNER
evaluation and there is uncertainty if activities will be allowed or
not.
Most of the information for the Quebradillas population is from
near and in the Guajataca Commonwealth Forest, which is a subtropical
moist forest occurring within the karst landscape in the northwestern
municipality of Isabela, Puerto Rico. The Quebradillas population
encompasses almost ~42,000 ac (17,000 ha) of predicted habitat, with 73
percent of that area with varied protection designations (67 percent
Karst Conservation Zone, 6 percent other protected areas (Service 2023,
pp. 74-76)). The high habitat protection in this area is considered to
provide a lower development risk, primarily due to restricted
development within the Karst Conservation Zone.
The southwest population overlaps with several municipalities where
skinks have been documented, particularly within and around the
southern portions of the Maricao Commonwealth Forest (San Germ[aacute]n
and Sabana Grande within humid subtropical forests; Rivera et al. 2023,
p. 10). This large area of predicted habitat (92,986 ac (37,630 ha))
has 22 percent (6 percent within Karst Conservation Zone, 16 percent
other protected areas) of that area being protected.
The third population occurs in south central Puerto Rico in the
municipality of Ponce. Of the 6,155 ac (2,491 ha) of predicted habitat
in the area, very little is protected (approximately 1 percent);
therefore, development risk is high.
In 2022, a skink was collected inside a garage in north central
Puerto Rico in the municipality of Florida, an area where skinks had
not been detected in the past but includes 19,714 ac (7,978 ha) of
predicted skink habitat. A large percentage of this potential habitat
is currently protected (88 percent). Of the area protected, 78 percent
is within the Karst Conservation Zone and 10 percent is within other
protected areas.
Outside of the main island, the only other population known to be
extant is on the island of Desecheo off the west coast of Puerto Rico.
During surveys in 2010, 2012, and 2016, researchers observed skinks
that are presumed to be Puerto Rican skinks (Wolf et al. 2010, p. 5;
Herrera-Giraldo and Bermudez 2010, p. 22; Figuerola 2023, pers. comm.).
The entire island is a National Wildlife Refuge (NWR) with no
development risk.

Predator Pressure

Because the main island of Puerto Rico is occupied by nonnative
predators including mongooses, rats, cats, etc., the influence of
predator pressure on population resiliency is always present and
therefore considered high risk to skinks in all main island
populations. Nonnative predators have been eradicated from Desecheo;
therefore, there is currently no impact from predator pressure for this
population.

Storm Surge Risk

The populations on the main island of Puerto Rico occur inland and
are not influenced by storm surge. In addition, Desecheo is an island
with high elevation; therefore, skink populations there are not
impacted by the effects of storm surge.

Current Condition Summary

Currently, five of nine (56 percent) known populations are extant,
while four (44 percent) are considered likely extirpated (table 4). One
population (Desecheo) is in high resiliency condition, and two
(Quebradillas and Florida) are in moderate resiliency condition, and
these populations are distributed across the northern part of the
species' range on Puerto Rico and Desecheo Island; the remaining two
populations (Southwest and Ponce) have low resiliency (table 4).
Habitat for all populations is generally located at elevations that are
not at risk of storm surge or sea level rise. Development is a risk to
all populations. Because the main island of Puerto Rico is occupied by
nonnative predators including mongoose, rats, cats, and dogs, the
influence of predator pressure on population resiliency is always
present and therefore considered high risk to skinks. In addition, all
current populations are geographically isolated at considerable
distance from one another; therefore, it will be difficult for a high
or moderate condition population to supplement or rescue another
population affected by threats. Thus, current redundancy is low for the
Puerto Rican skink.
Given the reduction in historical range, representation has also
been reduced from historical condition. However, current populations
exist in multiple locations in several different habitat types across
Puerto Rico and on Desecheo Island. Based on the genetic analysis, the
populations on Puerto Rico may range from small to large effective
population sizes with potential for admixture, although there is some
evidence of inbreeding within the Florida population (Rivera et al.
2023, p. 20). This apparent genetic diversity across Puerto Rican skink
populations contributes to the species' overall adaptive capacity,
giving the species the potential to adapt when faced with changes in
its current or future environment.

Table 4--Puerto Rican Skink Current Resiliency Summary
[Numbers in parentheses are metric scores (see table 1), summed to provide overall resiliency. NA = not applicable, as likely extirpated populations do
not have resiliency.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population Habitat protection Predator pressure Risk from storm surge Status Resiliency
--------------------------------------------------------------------------------------------------------------------------------------------------------
Icacos............................. High (1).............. High (-1)............. High (-1)............ Likely extirpated.... NA.
Desecheo........................... High (1).............. No Impact (1)......... Low (0).............. Extant............... High (2).
Vieques............................ High (1).............. High (-1)............. Low (0).............. Likely extirpated.... NA.

[[Page 103952]]

Main Island, PR
San Juan....................... Low (-1).............. High (-1)............. Low (0).............. Likely extirpated.... NA.
Cape San Juan.................. Moderate (0).......... High (-1)............. Low (0).............. Likely extirpated.... NA.
Quebradillas................... High (1).............. High (-1)............. No effect (1)........ Extant............... Moderate (1).
Southwest...................... Low (-1).............. High (-1)............. No effect (1)........ Extant............... Low (-1).
Ponce.......................... Low (-1).............. High (-1)............. No effect (1)........ Extant............... Low (-1).
Florida........................ High (1).............. High (-1)............. No effect (1)........ Extant............... Moderate (1).
--------------------------------------------------------------------------------------------------------------------------------------------------------

As part of the SSA report, we also developed future-condition
scenarios to capture the range of uncertainties regarding future
threats and the projected responses by the Puerto Rican skink. Our
scenarios assumed nonnative predators and further fragmentation from
development are the main risks to populations on Puerto Rico and the
only future threat to the population on Desecheo would be if predators
are introduced, which would cause reduced resiliency (note: it is
highly unlikely that mongooses would ever be introduced). Because we
determined that the current condition of the Puerto Rican skink is
consistent with the Act's definition of an endangered species (see
Determination of Status--Puerto Rican Skink, below), we are not
presenting the results of the future scenarios in this proposed rule.
Please refer to the SSA report (Service 2023, pp. 79-82) for the full
analysis of future scenarios.

Mona Skink

The Mona skink is historically and currently known only from Mona
Island, a 13,838-ac (5,600-ha) island off the west coast of Puerto
Rico. The entire island is a designated nature preserve protected and
managed by the PRDNER. The Mona skink has been consistently detected on
the island over time, with the earliest known detection in 1894 to more
recent detections in 2021. The species is readily observed on Mona
Island, indicating this singular population has maintained a level of
resiliency to withstand stochastic events over time. Although the
species is limited to one island, there are multiple, interconnected
habitat patches occupied across the island (Rivera et al. 2023, p. 12).
The species occupies interior areas of the island, which are not
subject to storm surge or sea level rise. These habitat patches that do
not experience SLR and storm surge threats likely ensure that the
species is less susceptible to catastrophic events; however, the
species is still vulnerable to other unknown threats given that its
range is limited to one island. The one population on Mona Island
houses all known genetic diversity for the species; however, genetic
evidence is insufficient to determine the level of genetic diversity.
The primary threat driving species' viability is nonnative
predators. Mona Island is currently occupied by nonnative predators
(cats and rats). There are no mongooses or dog predators on the island.
Given the larger size of the island and the fact that mongooses are not
present, predator pressure was assessed as low for the species. Low
does not mean there is no predator pressure but a lower level of
predator pressure from cats and rats. Mona Island has a maximum
elevation of over 296 feet (ft) (90 meters (m)) and, therefore, most of
the island is not susceptible to impacts from storm surge or sea level
rise like other low-lying islands. Mona Island has high habitat
protection given it is protected and managed by PRDNER, and therefore
there are no current impacts from development pressure.
The current resiliency of the one Mona skink population is moderate
(table 5). Though the species is known only from Mona Island and is
considered a single population, habitat patches are occupied across the
island, and the species occupies interior as well as coastal areas of
the island. Although the species is impacted by some threats across the
range, the Mona skink exhibits sufficient resiliency, redundancy, and
representation to support the species' viability.

Table 5--Mona Skink Current Resiliency Summary
[Numbers in parentheses are metric scores (see table 1), summed to provide overall resiliency.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population Habitat protection Predator pressure Risk from storm surge Status Resiliency
--------------------------------------------------------------------------------------------------------------------------------------------------------
Mona Island........................ High (1).............. Low (0)............... Low (0).............. Extant............... Moderate (1)
--------------------------------------------------------------------------------------------------------------------------------------------------------

In considering future threats to the species, nonnative predators
are the primary driver to the species' viability in the future. Given
the larger size of the island, and that mongooses are not likely to be
introduced, predator pressure was assessed as low in the future for the
species. Nonnative predator introductions would be expected to reduce
skink numbers on the island, but there are a diversity of habitats and
patches, and it is a large island; therefore, predation risk is not
likely to eliminate the known population, nor do we expect it to reduce
to low resiliency condition in the future. Impacts from climate change
in the future were also assessed as low given the higher elevation of
the island. Further, impacts of development pressure to the species are
low as Mona Island has high habitat protection given it is protected
and managed by PRDNER.

[[Page 103953]]

Table 6--Mona Skink Future Resiliency Summary for Four Future Scenarios Under Three Time Steps
[M = moderate]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Current 2050 2070 2100
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Status Resiliency 1A 1B 2A 2B 1A 1B 2A 2B 1A 1B 2A 2B
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Extant.................................... M........................... M M M M M M M M M M M M
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

The projected future resiliency of skinks on Mona Island is
assessed as moderate (table 6), given the future level of threats to
the species. The future range of the Mona skink is limited to one
island; however, it is still expected to have moderate resiliency to
withstand stochastic events. Although the species is impacted by
several threats across the range, the Mona skink exhibits sufficient
resiliency, redundancy, and representation to support the species'
future viability.

Culebra Skink

The Culebra skink currently occupies five islands including Culebra
and several of the small cays surrounding Culebra Island. Culebra
skinks were historically found on Isla Culebrita, the largest cay near
Culebra, but they have not been seen there since 1936 likely because it
is a small to medium sized island with nonnative predators.
Observations on the cays surrounding Culebra Island, including Cayo
Agua, Cayo Botella, Cayo Lobito, and Cayo Yerba are recent (since
2017).
The small cays currently occupied by skinks are very small (<10 ac
(<4 ha)), are not currently occupied by any nonnative predators, and
are protected from development. Much of the land on each cay is low
elevation (i.e., less than 33 ft (10 m)) making them susceptible to
storm surge, with projected Category 3 storms at 5 ft (1.52 m) and
Category 5 storms at 6 ft (1.83 m) (see table 8.3 and appendix A of the
SSA report; Service 2023, pp. 92, 142). Culebra Island is inhabited by
people, and there is development on parts of the island, except in
areas that are protected, primarily within the Culebra NWR. Although
mongooses have not been observed, other nonnative predators including
cats and rats occur there. Culebra Island has a higher average
elevation (~646 ft (197 m)) than the smaller cays and is less
susceptible to storm surge risk currently.
Each of the small cays currently occupied by Culebra skinks is
relatively similar; each cay is protected and not currently occupied by
nonnative mammalian predators. However, because they each have low
elevations and are small in size, the risk of impacts from storm surge
is high, and therefore they currently have moderate resiliency (table
7). Even though the Culebra skink on Culebra Island is less impacted by
storm surge and has large tracts of protected areas, it has moderate
current resiliency because several nonnative predators occupy the
island. In addition, skinks occur partially on unprotected lands, which
are vulnerable to development.

Table 7--Culebra Skink Current Resiliency Summary
[Numbers in parentheses are metric scores (see table 1), summed to provide overall resiliency. NA = not applicable, as likely extirpated populations do
not have resiliency.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population Habitat protection Predator pressure Risk from storm surge Status Resiliency
--------------------------------------------------------------------------------------------------------------------------------------------------------
Isla Culebrita..................... High (1).............. Low (0)............... Low (1).............. Likely extirpated.... NA
Cayo Botella....................... High (1).............. No impact (1)......... High (-1)............ Extant............... Moderate (1)
Cayo Agua.......................... High (1).............. No impact (1)......... High (-1)............ Extant............... Moderate (1)
Cayo Lobito........................ High (1).............. No impact (1)......... High (-1)............ Extant............... Moderate (1)
Cayo Yerba......................... High (1).............. No impact (1)......... High (-1)............ Extant............... Moderate (1)
Culebra............................ Moderate (0).......... Low (0)............... Low (0).............. Extant............... Moderate (0)
--------------------------------------------------------------------------------------------------------------------------------------------------------

Currently, the Culebra skink has multiple populations in moderate
resiliency condition across its known range (table 7). The number and
distribution of these sufficiently resilient populations enable the
species to withstand both stochastic and catastrophic events. The range
is not large, and many of the islands are small, but the species
currently has substantial genetic representation in the form of
separate islands.

Table 8--Culebra Skink Current and Future Resiliency Summary
[NA = not applicable, as likely extirpated populations do not have resiliency; M = moderate; X = extirpated.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Current 2050 2070 2100
Population -------------------------------------------------------------------------------------------------------------------------
Status Resiliency 1A 1B 2A 2B 1A 1B 2A 2B 1A 1B 2A 2B
--------------------------------------------------------------------------------------------------------------------------------------------------------
Isla Culebrita................ Likely extirpated NA............... ..... ...... ..... ...... ..... ...... .... ..... .... ..... .... .....
Cayo Botella.................. Extant........... Moderate......... M X M X M X X X X X X X
Cayo Agua..................... Extant........... Moderate......... M X M X M X M X M X X X
Cayo Lobito................... Extant........... Moderate......... M X M X M X M X M X M X
Cayo Yerba.................... Extant........... Moderate......... M X M X M X M X M X X X
Culebra....................... Extant........... Moderate......... M Low M Low M Low M Low M Low M Low
--------------------------------------------------------------------------------------------------------------------------------------------------------

By 2050, resiliency of each of the populations will change only if
predator pressure is increased (see ``B'' scenarios in table 8). Since
most of the populations are on small cays, the addition of a predator
will almost certainly mean the extirpation of skinks within a short
time. Results are similar for 2070 except Cayo Botella will

[[Page 103954]]

become too small to support a population of skinks under the High SLR
scenario (Scenario 2A, table 8). By 2100, nearly all the small cays
(except for Cayo Lobito) will be classified as extirpated under the
High SLR scenario (Scenario 2A) and skinks on Cayo Botella will likely
be extirpated under both Intermediate and High SLR scenarios (table 8).
The main risk on the main island of Culebra is the increased predator
pressure and continued habitat modification. The addition of any
predator to the small cays would likely lead to the skinks being
quickly extirpated.
Future redundancy and representation of Culebra skink is expected
to be reduced by 2100 under most scenarios, ultimately with the loss of
smaller cays due to a combination of predator introduction and SLR/
storm surge. Only two populations are expected to remain (Culebra and
possibly Cayo Lobito) by 2100 if predators are not introduced to the
small cays; therefore, redundancy at 2100 would be limited. There is
evidence of genetic clustering (i.e., grouping of similar genes)
between populations on Culebra, but the actual genetic structure of
skinks on Culebra is still largely unknown (Rivera et al. 2023, p. 15).
Culebra has some diverse habitats, and skinks have been seen in both
the coast and upland forests. Coastal areas will likely be impacted by
sea level rise. Therefore, representation is expected to be
substantially reduced across the range by 2100 under three of four
future scenarios.

Greater Virgin Islands Skink

The Greater Virgin Islands skink is believed to be historically
distributed in the USVI on St. John and St. Thomas (Hedges and Conn
2012, p. 210). It is possible that the Greater Virgin Islands skink
occurred in the BVI as well. The species likely had patchy distribution
across its range, and its small size, cryptic coloration, and secretive
behavior could account for its lack of detection. If observed, it could
be misidentified as the sympatric Lesser Virgin Islands skink or Virgin
Islands bronze skink, but lack of observations of any skinks on St.
John or St. Thomas make misidentification less probable.
The Greater Virgin Islands skink has not been seen in nearly 150
years since the last specimen was cataloged in 1877, despite
considerable herpetological survey work through the Virgin Islands
(Hedges and Conn 2012, p. 210). There are six known museum specimens,
collected in 1779-1799, 1834, 1845-1846, and 1877 (Hedges and Conn
2012, p. 207). Because the species has long been believed to be
extirpated from the main islands of St. John and St. Thomas, not many
targeted surveys have been undertaken to look for skinks on either
island. From 1986 to 2023, qualified researchers and wildlife agency
staff invested considerable efforts in looking for other herpetofauna
that would almost certainly document opportunistic encounters of any
herp species, and no known documentation of skinks exist (Service 2023,
pp. 150-151). Herp survey efforts on St. Thomas do not appear to be as
extensive as those on St. John, but optimal habitat on St. Thomas is
known to be fragmented by extensive human development (Platenberg and
Harvey 2010, p. 548), and the consensus from the herpetology community
is that there are no known skinks on the island of St. Thomas. Given
what is known about the life history and habitat associations of
Spondylurus skinks, it is reasonable to assume that skinks would have
been detected given the extent of survey efforts in optimal habitats on
both islands of St. Thomas and St. John (see chapter 9 and appendix B-I
of the SSA report (Service 2023, pp. 100, 146-152)).
Skinks that once occurred on the islands of St. Thomas and St. John
faced a primary threat from the introduced mongoose, a predator that
has been implicated in the extinction of the Greater Virgin Islands
skink (Hedges and Conn 2012, p. 210; Hedges 2013, p. 1). The invasive
predator was introduced as a biological control of rats in sugar cane
fields in the late nineteenth century, immediately resulting in a mass
extinction of skinks and other reptiles (Hedges and Conn 2012, p. 4).
The ground-dwelling and diurnal habits of skinks make them particularly
susceptible to mongoose predation.
Based on the best scientific and commercial information available,
it is highly unlikely that an individual of Greater Virgin Islands
skink could be extant but undetected; therefore, we presume that the
species is likely extinct.

Lesser Virgin Islands Skink

Lesser Virgin Islands skink was historically known to occur on 15
islands within the USVI and BVI. The populations on three historically
occupied islands, making up approximately 43 percent of the species'
historical range, are considered likely extirpated, including St.
Thomas, the largest island in the USVI, and two islands in BVI (Necker
Island and Great Camanoe Island). The status of seven populations
(Capella Island, Buck Island (St. Thomas), Little Thatch Island, Fallen
Jerusalem, Salt Island, Round Rock Island, and Ginger Island) are
currently unknown, primarily because recent surveys have not been
conducted, and very little information is known about these islands.
However, there is a high likelihood that skinks could be extirpated on
these islands given the nonnative predator threat on surrounding
islands and the short distance of the seven islands to those with known
predator presence. Given the potential for these threats and likely
extirpation of skinks, we assumed that these seven unknown populations
do not contribute to the resiliency, redundancy, and representation for
the species and thus were not considered as contributing to overall
species viability.

Table 9--Lesser Virgin Islands Skink Current Resiliency Summary
[Numbers in parentheses are metric scores (see table 1), summed to provide overall resiliency. NA = not applicable, as likely extirpated and unknown
populations do not have resiliency.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population Habitat protection Predator pressure Risk from storm surge Status Resiliency
--------------------------------------------------------------------------------------------------------------------------------------------------------
USVI
Capella Island................. High (1).............. No impact (1)......... Low (0).............. Unknown.............. NA
Buck Island.................... High (1).............. No impact (1)......... Low (0).............. Unknown.............. NA
Hans Lollik.................... Low (-1).............. Low (0)............... Low (0).............. Extant............... Low (-1)
St. Thomas..................... Moderate (0).......... High (-1)............. Low (0).............. Likely extirpated.... NA
BVI
Little Thatch Island........... Low (-1).............. Low (0)............... Low (0).............. Unknown.............. NA
Fallen Jerusalem............... High (1).............. Unknown............... Low (0).............. Unknown.............. NA

[[Page 103955]]

Salt Island.................... Moderate (0).......... Low (0)............... Low (0).............. Unknown.............. NA
Round Rock Island.............. High (1).............. Unknown............... High (-1)............ Unknown.............. NA
Ginger Island.................. Low (-1).............. Unknown............... Low (0).............. Unknown.............. NA
Guana Island................... Low (-1).............. Low (0)............... Low (0).............. Extant............... Low (-1)
Necker Island.................. Low (-1).............. Low (0)............... Low (0).............. Likely extirpated.... NA
Great Camanoe Island........... Moderate (0).......... Low (0)............... Low (0).............. Likely extirpated.... NA
Mosquito Island................ Low (-1).............. No impact (1)......... Low (0).............. Extant............... Moderate (0)
Virgin Gorda................... Moderate (0).......... High (-1)............. Low (0).............. Extant............... Low (-1)
Tortola........................ Moderate (0).......... High (-1)............. Low (0).............. Extant............... Low (-1)
--------------------------------------------------------------------------------------------------------------------------------------------------------

Currently, the species is considered extant on 5 of the 15 islands:
1 in USVI (Hans Lollik) and 4 in BVI (Guana, Mosquito, Virgin Gorda,
and Tortola) (table 9). Of the five, four have low resiliency, and one
has moderate resiliency. Hans Lollik, the one extant population in the
USVI, currently has low resiliency due to lack of habitat protection
(privately owned) and predator pressure (rats present). In the BVI, one
population is currently moderate, and three are low resiliency. There
are mixed levels of habitat protection for the islands in the BVI;
thus, development pressure is a risk to the species. In addition, each
island has variable impacts from nonnative predators, and the two
larger islands (Tortola and Virgin Gorda) have mongooses present. All
islands have low impacts from storm surge due to the average height of
these islands all being above 60 m (197 ft).
Together, the extirpated and low-resiliency populations represent
94 percent of the range of the Lesser Virgin Islands skink. Given the
reduction in historical range, the species' redundancy and
representation (adaptive capacity) have been greatly reduced from
historical condition. Current redundancy, or distribution of
populations with sufficient resiliency to withstand catastrophic
events, is very low for this species as there is only one moderate-
resiliency population remaining. Given the limited range, any
catastrophic event would likely negatively impact all existing
populations, thus the species is unlikely to withstand catastrophic
events.
As part of the SSA report, we also developed future-condition
scenarios to capture the range of uncertainties regarding future
threats and the projected responses by the Lesser Virgin Islands skink.
Our scenarios assumed nonnative predators are the main risk to
populations which would cause reduced resiliency (note: it is highly
unlikely that mongooses would ever be introduced). Because we
determined that the current condition of the Lesser Virgin Islands
skink is consistent with the Act's definition of an endangered species
(see Determination of Status--Lesser Virgin Islands Skink, below), we
are not presenting the results of the future scenarios in this proposed
rule. Please refer to the SSA report (Service 2023, pp. 108-117) for
the full analysis of future scenarios.

Virgin Islands Bronze Skink

Virgin Islands bronze skink was historically known to occur on nine
islands within the USVI and BVI. Four populations, making up
approximately 96 percent of the species' historical range, are
considered likely extirpated, including St. Thomas, the largest island
in the USVI, and three islands in BVI (Little Tobago Island, Norman
Island, and Peter Island). Currently, three of the nine islands are
extant, all within the USVI (Buck Island, Turtledove Cay, and Water
Island); there are no known extant populations occurring in BVI. The
status of two populations (Capella Island and Salt Island) are
currently unknown, primarily because recent surveys have not been
conducted and very little information is known about these islands.
Thus, we assumed that these two populations do not contribute to the
resiliency, redundancy, and representation for the species and thus
were not considered as contributing to overall species viability.

Table 10--Virgin Islands Bronze Skink Current Resiliency Summary
[Numbers in parentheses are metric scores (see table 1), summed to provide overall resiliency. NA = not applicable, as likely extirpated and unknown
populations do not have resiliency.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Population Habitat protection Predator pressure Risk from storm surge Status Resiliency
--------------------------------------------------------------------------------------------------------------------------------------------------------
USVI
Buck Island.................... High (1).............. No impact (1)......... Low (0).............. Extant............... High (2)
Capella Island................. High (1).............. No impact (1)......... Low (0).............. Unknown.............. NA
Turtledove Cay................. High (1).............. No impact (1)......... Low (0).............. Extant............... High (2)
Water Island................... Low (-1).............. Low (0)............... Low (0).............. Extant............... Low (-1)
St. Thomas..................... High (1).............. High (-1)............. Low (0).............. Likely extirpated.... NA
BVI
Little Tobago Island........... High (1).............. Low (0)............... Low (0).............. Likely extirpated.... NA
Salt Island.................... Moderate (0).......... Low (0)............... Low (0).............. Unknown.............. NA
Norman Island.................. Low (-1).............. Low (0)............... Low (0).............. Likely extirpated.... NA
Peter Island................... Low (-1).............. Low (0)............... Low (0).............. Likely extirpated.... NA
--------------------------------------------------------------------------------------------------------------------------------------------------------

[[Page 103956]]

Of the three extant populations, two were assessed to have high
resiliency while one was assessed to have low resiliency (table
10).Water Island, the largest island (489 ac (198 ha)) with an extant
population, is currently occupied by nonnative predators (rats) and
privately owned, and therefore has low resiliency. Buck Island and
Turtledove Cay have high resiliency due to high levels of habitat
protection and no current predator pressure, as nonnative predators
were eradicated previously, and the islands' elevations are not at risk
from storm surge. Despite having two populations with high resiliency,
the Virgin Islands bronze skink is vulnerable to catastrophic events
such as the introduction of nonnative predators, primarily due to the
extremely small size of the remaining extant islands (i.e., Buck Island
and Turtledove Cay are 22 and 32 ac (9 and 13 ha) in size,
respectively). Representation (and adaptive capacity) has been greatly
reduced due to the loss of historical range and remaining islands
making up 4 percent of the species' current range.
As part of the SSA report, we also developed future-condition
scenarios to capture the range of uncertainties regarding future
threats and the projected responses by the Virgin Islands bronze skink.
Our scenarios assumed nonnative predators and SLR are the main risks to
populations in the future, which would cause reduced resiliency and
eventual extirpation (note: it is highly unlikely that mongooses would
ever be introduced). Because we determined that the current condition
of the Virgin Islands bronze skink is consistent with the Act's
definition of an endangered species (see Determination of Status--
Virgin Islands Bronze Skink, below), we are not presenting the results
of the future scenarios in this proposed rule. Please refer to the SSA
report (Service 2023, pp. 122-129) for the full analysis of future
scenarios.

Greater St. Croix Skink

The Greater St. Croix skink has been recorded from St. Croix and
its satellite island Green Cay, both in the USVI; this is also presumed
to be the provenance of several historical specimens with the locality
data ``West Indies,'' suggesting that the skink was endemic to this
large island and its satellite (Hedges and Conn 2012, p. 173). No more
specific locality data are available, and the species was last recorded
from St. Croix in the late 19th century, but this species has a well-
documented collection history, and it is consequently ``without
dispute'' that the species historically occurred on the island (Hedges
and Conn 2012, p. 174).
Because the species has long been believed to be extirpated from
St. Croix, not many targeted surveys to look for skinks on the island
have occurred. Qualified researchers and wildlife agency staff have
made several efforts to look for other herpetofauna on both St. Croix
and Green Cay that would almost certainly document opportunistic
encounters of any herp species, and since 2000, no known documentation
of skinks exists (see appendix B-II of SSA report (Service 2023, pp.
154-160)). Given what is known about the life history and habitat
associations of Spondylurus skinks, it is reasonable to assume that
skinks would have been detected given the extent of survey efforts in
optimal habitats on St. Croix and Green Cay.
Skinks that once occurred on St. Croix faced a primary threat from
the introduced mongoose, a predator that has been implicated in the
extinction of the Greater St. Croix skink (Hedges and Conn 2012, p.
174; Hedges 2013, p. 4). The invasive predator was introduced as a
biological control of rats in sugar cane fields in the late nineteenth
century, immediately resulting in a mass extinction of skinks and other
reptiles (Hedges and Conn 2012, p. 4). The ground-dwelling and diurnal
habits of skinks have made them particularly susceptible to mongoose
predation.
Based on the best scientific and commercial information available,
it is highly unlikely that an individual of Greater St. Croix skink
could be extant but undetected; therefore, we presume that the species
is likely extinct.

Lesser St. Croix Skink

The Lesser St. Croix skink is believed to be endemic to the large
island of St. Croix in the USVI, which has an area of 230 km\2\ (Hedges
and Conn 2012, p. 69). The only known specimen from 1875 was reported
with no precise locality data (Hedges and Conn 2012, p. 68). The
introduction of mongooses to this island in the late 19th century, and
the seeming disappearance of the Greater St. Croix skink at the same
time, suggests that the Lesser St. Croix skink is probably now extinct
(Hedges and Conn 2012, p. 69).
Because the species has long been believed to be extirpated from
St. Croix, not many targeted surveys to look for skinks on the island
have occurred. Qualified researchers and wildlife agency staff have
made several efforts to look for other herpetofauna that would almost
certainly document opportunistic encounters of any herp species (see
appendix B-III of SSA report (Service 2023, pp. 162-168)). Given what
is known about the life history and habitat associations of Capitellum
skinks, it is reasonable to assume that skinks would have been detected
given the extent of survey efforts in optimal habitats on St. Croix.
Skinks that once occurred on St. Croix faced threats from habitat
loss and predation from the introduced mongoose, a predator that has
been implicated in the extinction of the Lesser St. Croix skink (Hedges
and Conn 2012, p. 69; Hedges 2013, p. 1) and other lizards. For
example, the mongoose is also partly implicated for the extirpation of
the endangered St. Croix ground lizard, last seen on the main island of
St. Croix in 1964 (Service 1984, entire). The mongoose was introduced
as a biological control of rats in sugar cane fields in the late
nineteenth century, immediately resulting in a mass extinction of
skinks and other reptiles (Hedges and Conn 2012, p. 4). The ground-
dwelling and diurnal habits of skinks have made them particularly
susceptible to predation by mongooses and cats.
Based on the best scientific and commercial information available,
it is highly unlikely that an individual of Lesser St. Croix skink
could be extant but undetected; therefore, we presume that the species
is likely extinct.

Determination of Status for Eight Caribbean Skink Species

Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for determining
whether a species meets the definition of an endangered species or a
threatened species. The Act defines an ``endangered species'' as a
species in danger of extinction throughout all or a significant portion
of its range and a ``threatened species'' as a species likely to become
an endangered species within the foreseeable future throughout all or a
significant portion of its range. The Act requires that we determine
whether a species meets the definition of an endangered species or a
threatened species because of any of the following factors: (A) The
present or threatened destruction, modification, or curtailment of its
habitat or range; (B) overutilization for commercial, recreational,
scientific, or educational purposes; (C) disease or predation; (D) the
inadequacy of existing regulatory mechanisms; or (E) other natural or
manmade factors affecting its continued existence.

[[Page 103957]]

Status Throughout All of Its Range--Puerto Rican Skink

After evaluating threats to the species and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we assessed the status of the Puerto Rican skink to determine
if it meets the Act's definition of an endangered species. The Puerto
Rican skink was historically known from three island populations and
six populations on the main island of Puerto Rico. Four historical
populations, approximately 35 percent of the species' historical range,
are considered likely extirpated, including two of the smaller islands
within the range.
Of the five extant populations, one of the smaller islands,
Desecheo, is currently occupied and has high resiliency based on
habitat metrics, including no predators, and the island is protected as
an NWR. Predators were previously present on Desecheo and success of
eradication efforts was confirmed in 2017. Of note, the last detection
record for the Puerto Rican skink on Desecheo Island was in 2016,
although there were no surveys conducted on the island during 2021-2023
survey efforts. This population represents 0.19 percent of the extant
range.
The remaining four populations occur on the main island of Puerto
Rico; two populations currently have moderate resiliency, and two have
low resiliency. Habitat for all populations is generally located at
elevations that are not at risk of storm surge or sea level rise.
Development (Factor A) is a risk to all populations. Because the main
island of Puerto Rico is occupied by nonnative predators (Factor C)
including mongooses, rats, cats, and dogs, the influence of predator
pressure on population resiliency is always present and therefore
considered high risk to skinks.
The five extant populations are geographically isolated at
considerable distance from one another, and, therefore, it will be
difficult for a higher resiliency population to supplement or rescue
another population affected by potential catastrophic events. Together,
the extirpated and low-resiliency populations represent 75 percent of
the range. Given the reduction in historical range, the species'
redundancy has been reduced from historical condition, and
representation (and adaptive capacity) has also been reduced. The
current resiliency, redundancy, and representation indicate that the
magnitude and scale of threats are currently impacting the Puerto Rican
skink such that it meets the Act's definition of an endangered
species.Thus, after assessing the best available information, we
determine that Puerto Rican skink is in danger of extinction throughout
all of its range. Because the threats are currently impacting the
species such that it is in danger of extinction currently throughout
all of its range, it does not meet the Act's definition of a threatened
species.

Status Throughout a Significant Portion of Its Range--Puerto Rican
Skink

Determination of Status--Puerto Rican Skink

Based on the best scientific and commercial data available, we
determine that the Puerto Rican skink meets the Act's definition of an
endangered species. Therefore, we propose to list the Puerto Rican
skink as an endangered species in accordance with sections 3(6) and
4(a)(1) of the Act.

Status Throughout All of Its Range--Mona Skink

After evaluating threats to the species and assessing the
cumulative effect of the threats under the section 4(a)(1) factors, we
evaluated the status of the Mona skink to determine if it meets the
Act's definition of an endangered species. The Mona skink is
historically and currently known only from Mona Island, a 13,838-ac
(5,600-ha) island off the west coast of Puerto Rico. The entire island
is a designated nature preserve protected and managed by the PRDNER.
The Mona skink has been consistently detected on the island over time
with the earliest known detection in 1894 to more recent detections in
2021. The species continues to be observed on Mona Island, indicating
that the population has maintained a level of resiliency to withstand
stochastic events over time.
The primary threat driving the species' viability is nonnative
predators (Factor C). Mona Island is currently occupied by nonnative
predators (cats and rats) and also goats and pigs. There are no
mongooses or dog predators on the island. Given the larger size of the
island and that mongooses are not present, predator pressure was
assessed as low for the species. Low does not mean there is no predator
pressure but a lower level of predator pressure from cats and rats.
Mona Island has a maximum elevation of over 296 ft (90 m) and,
therefore, most of the island is not susceptible to impacts from storm
surge or sea level rise (Factor E) like other low-lying islands. Mona
Island has high habitat protection given it is protected and managed by
PRDNER, and therefore there are no current impacts from development
pressure (Factor A).
The current resiliency of the one Mona skink population is
moderate. Though the species is known only from Mona Island and likely
consists of a single population, there are multiple habitat patches
occupied across the island and the species occupies interior as well as
coastal areas of the island. Although the species is impacted by some
threats across the range, the Mona skink exhibits sufficient
resiliency, redundancy, and representation to support the species'
viability. Overall, no current threat is acting at an extent or
severity such that the species is at risk of extinction throughout all
of its range. Thus, after assessing the best available information, we
conclude that the Mona skink is not in danger of extinction throughout
all of its range. Therefore, we proceed with determining whether the
Mona skink is likely to become endangered within the foreseeable future
throughout all of its range.
In considering future threats to the species, we examined habitat
destruction and modification from development risk (Factor A);
nonnative predators (Factor C); climate change, specifically SLR
(Factor E); and increases in intensity, frequency, and duration of
hurricane activity (Factor E) out to the end of the century, or 2100.
For the Mona skink, nonnative predators are the primary driver to the
species' viability in the future. There is a chance of introduction of
additional nonnative predators from tourism, and thus increased
predator pressure to the Mona skink in the future. However, ongoing and
future funded eradication efforts of nonnative predators is likely to
occur. Given the larger size of the

[[Page 103958]]

island, and that mongooses are not likely to be introduced, predator
pressure was assessed as low in the future for the species. Nonnative
predator introductions would be expected to reduce skink numbers on the
island, but the island is large and includes a diversity of habitats
and patches: therefore, predation risk is not likely to eliminate the
known population, nor do we expect it to reduce to low-resiliency
condition in the future. Impacts from climate change in the future were
also assessed as low for similar reasons as current impacts because
most of the island is not susceptible to impacts from SLR or increased
hurricane activity. Further, impacts of development pressure to the
species are low as Mona Island has high habitat protection given it is
protected and managed by PRDNER.
The projected future resiliency of skinks on Mona Island is
assessed as moderate, given the future level of threats to the species.
The future range of the Mona skink is limited to one island; however,
it is still expected to have moderate resiliency to withstand
stochastic events. Although the species is impacted by some level of
threats across the range, the Mona skink exhibits sufficient
resiliency, redundancy, and representation to support the species'
future viability. Overall, no projected future threat is acting at an
extent or severity such that the species is at risk of extinction
throughout all of its range within the foreseeable future. Thus, after
assessing the best available information, we conclude that the Mona
skink is not likely to become endangered within the foreseeable future
throughout all of its range.

Status Throughout a Significant Portion of Its Range--Mona Skink

Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
within the foreseeable future throughout all or a significant portion
of its range. Having determined that the Mona skink is not in danger of
extinction or likely to become so within the foreseeable future
throughout all of its range, we now consider whether it may be in
danger of extinction or likely to become so within the foreseeable
future in a significant portion of its range--that is, whether there is
any portion of the species' range for which it is true that both (1)
the portion is significant; and (2) the species is in danger of
extinction now or likely to become so within the foreseeable future in
that portion. Depending on the case, it might be more efficient for us
to address the ``significance'' question or the ``status'' question
first. We can choose to address either question first. Regardless of
which question we address first, if we reach a negative answer with
respect to the first question that we address, we do not need to
evaluate the other question for that portion of the species' range.
In undertaking this analysis for the Mona skink, we chose to
address the status question first. We began by identifying portions of
the range where the biological status of the species may be different
from its biological status elsewhere in its range. For this purpose, we
considered information pertaining to the geographic distribution of (a)
individuals of the species, (b) the threats that the species faces, and
(c) the resiliency condition of populations.
We evaluated the range of the Mona skink to determine if the
species is in danger of extinction now or likely to become so within
the foreseeable future in any portion of its range. The Mona skink is a
narrow endemic that functions as a single, contiguous population and
occurs on one 13,838-ac (5,600-ha) island (Mona Island). Thus, there is
no biologically meaningful way to break this limited range into
portions, and the threats that the species faces affect the species
comparably throughout its entire range. As a result, there are no
portions of the species' range where the species has a different
biological status from its rangewide biological status. Therefore, we
conclude that there are no portions of the species' range that warrant
further consideration, and the species is not in danger of extinction
or likely to become so within the foreseeable future in any significant
portion of its range. This does not conflict with the courts' holdings
in Desert Survivors v. U.S. Department of the Interior, 321 F. Supp. 3d
1011, 1070-74 (N.D. Cal. 2018) and Center for Biological Diversity v.
Jewell, 248 F. Supp. 3d. 946, 959 (D. Ariz. 2017) because, in reaching
this conclusion, we did not apply the aspects of the Final Policy on
Interpretation of the Phrase ``Significant Portion of Its Range'' in
the Endangered Species Act's Definitions of ``Endangered Species'' and
``Threatened Species'' (79 FR 37578; July 1, 2014), including the
definition of ``significant'' that those court decisions held to be
invalid.

Determination of Status--Mona Skink

Based on the best scientific and commercial data available, we
determine that the Mona skink does not meet the Act's definition of an
endangered species or a threatened species in accordance with sections
3(6) and 3(20) of the Act. Therefore, we find that listing the Mona
skink is not warranted at this time.

Status Throughout All of Its Range--Culebra Skink

After evaluating threats to the species and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we evaluated the status of the Culebra skink to determine if
it meets the Act's definition of an endangered species. The Culebra
skink historically occupied six islands across the species' known
range. Currently, it occupies five islands, including Culebra and four
small cays surrounding Culebra. The skink is likely extirpated from
Isla Culebrita, as it has not been observed there since 1936. Of the
five currently known extant populations, the smaller cays have no
predator pressure and are all protected from development. However,
because each cay has low elevation and is small in size, it is at high
risk of impacts from storm surge (Factor E). Culebra currently has
predators (Factor C) present (cats, rats) and a mix of land uses, with
expanding developed lands (Factor A) and some protected lands.
The Culebra skink currently has five extant populations with
moderate resiliency. The current number and distribution of these
sufficiently resilient populations enables the species to withstand
both stochastic and catastrophic events. While the range is relatively
small and many of the cays are small, the species currently has
substantial genetic representation in the form of separate islands.The
Culebra skink currently exhibits sufficient resiliency, redundancy, and
representation to support viability. Overall, no current threat is
acting at an extent or severity such that the species is at risk of
extinction throughout all of its range. Thus, after assessing the best
available information, we conclude that the Culebra skink is not in
danger of extinction throughout all of its range and does not meet the
definition of an endangered species.
In the future, sea level rise (Factor E) and storm impacts (Factor
E) will be realized, along with increased development pressure (Factor
A) on Culebra and increased predator risk (Factor C) across the range.
When predators reach the small cays, skink extirpation is imminent.
Further, three of the four cays have low elevations such that storm
surge risk and sea level rise will result in extirpation of the
population on one cay by 2070, and the remaining cays' populations by
2100. Given the future projections, the

[[Page 103959]]

number and distribution of skink populations impacted in the future
will affect the species' ability to withstand both stochastic and
catastrophic events. Therefore, the Culebra skink is projected not to
have sufficient resiliency, redundancy, and representation to support
the species' viability within the foreseeable future. Thus, after
assessing the best available information, we conclude that the Culebra
skink is likely to become in danger of extinction throughout all of its
range within the foreseeable future.

Status Throughout a Significant Portion of Its Range--Culebra Skink

Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
in the foreseeable future throughout all or a significant portion of
its range. The court in Center for Biological Diversity v. Everson, 435
F. Supp. 3d 69 (D.D.C. 2020) (Everson), vacated the provision of the
Final Policy on Interpretation of the Phrase ``Significant Portion of
Its Range'' in the Endangered Species Act's Definitions of ``Endangered
Species'' and ``Threatened Species'' (hereafter ``Final Policy''; 79 FR
37578, July 1, 2014) that provided if the Services determine that a
species is threatened throughout all of its range, the Services will
not analyze whether the species is endangered in a significant portion
of its range.
Therefore, we proceed to evaluating whether the species is
endangered in a significant portion of its range--that is, whether
there is any portion of the species' range for which both (1) the
portion is significant; and (2) the species is in danger of extinction
in that portion. Depending on the case, it might be more efficient for
us to address the ``significance'' question or the ``status'' question
first. We can choose to address either question first. Regardless of
which question we address first, if we reach a negative answer with
respect to the first question that we address, we do not need to
evaluate the other question for that portion of the species' range.
Following the court's holding in Everson, we now consider whether
the species is in danger of extinction (i.e., endangered) in a
significant portion of its range. In undertaking this analysis for
Culebra skink, we choose to address the status question first.
We evaluated the range of the Culebra skink to determine if the
species is in danger of extinction now in any portion of its range. The
range of a species can theoretically be divided into portions in an
infinite number of ways. We focused our analysis on portions of the
species' range that may meet the definition of an endangered species.
For the Culebra skink, we considered whether the threats or their
effects on the species are greater in any biologically meaningful
portion of the species' range than in other portions such that the
species is in danger of extinction now in that portion.
The statutory difference between an endangered species and a
threatened species is the timeframe in which the species becomes in
danger of extinction; an endangered species is in danger of extinction
now while a threatened species is not in danger of extinction now but
is likely to become so within the foreseeable future. Thus, we
considered the time horizon for the threats that are driving the
Culebra skink to warrant listing as a threatened species throughout all
of its range. We then considered whether these threats or their effects
are occurring in any portion of the species' range such that the
species is in danger of extinction now in that portion of its range. We
examined the following threats: habitat destruction or modification
through development risk, nonnative predators, and storm surge,
including cumulative effects. Current population resiliency is moderate
across the Culebra skink's range. The small cays currently occupied by
skinks are small (<10 ac (4 ha)) but are not currently occupied by any
nonnative predators and are protected from development. Much of the
land on each cay is low elevation (i.e., less than 33 ft (10 m)),
making them susceptible to storm surge. The island of Culebra is
inhabited by people and there is development throughout the island,
except in areas that are protected, primarily the Culebra NWR in the
north. Because of the development, there are many nonnative predators
including cats and rats, but no mongooses are currently found on the
island. The island of Culebra has a higher average elevation (~646 ft
(197 m)) than the smaller cays and is less susceptible to storm surge
risk currently. Despite differences in impacts of threats, all
populations currently have moderate resiliency and have sufficient
redundancy such that no portions would meet the Act's definition of an
endangered species.
The best scientific and commercial data available indicate that the
time horizon on which those threats to the species and the species'
response to those threats are likely to occur is the foreseeable
future. In addition, the best scientific and commercial data available
do not indicate that any of the threats to the species and the species'
response to those threats are more immediate in any portions of the
species' range. Therefore, we determine that the Culebra skink is not
in danger of extinction now in any portion of its range, but that the
species is likely to become in danger of extinction within the
foreseeable future throughout all of its range. This does not conflict
with the courts' holdings in Desert Survivors v. U.S. Department of the
Interior, 321 F. Supp. 3d 1011, 1070-74 (N.D. Cal. 2018) and Center for
Biological Diversity v. Jewell, 248 F. Supp. 3d 946, 959 (D. Ariz.
2017) because, in reaching this conclusion, we did not apply the
aspects of the Final Policy, including the definition of
``significant'' that those court decisions held to be invalid.

Determination of Status--Culebra Skink

Based on the best scientific and commercial data available, we
determine that the Culebra skink meets the Act's definition of a
threatened species. Therefore, we propose to list the Culebra skink as
a threatened species in accordance with sections 3(20) and 4(a)(1) of
the Act.

Status Throughout All of Its Range--Greater Virgin Islands Skink

[[Page 103960]]

herpetofauna by qualified researchers has been invested across several
decades on both St. Thomas and St. John, where the species once
occurred. These multiple survey efforts, while not targeted at skinks,
did overlap with potential skink habitat, and would most likely have
encountered skinks if they were still extant. The loss of the Greater
Virgin Islands skink can be attributed to predation by the mongoose. No
skinks have been observed on St. Thomas or St. John for over a century.
Based on the best scientific and commercial information available, it
is highly unlikely that an individual could be extant but undetected;
therefore, we conclude that the Greater Virgin Islands skink is
extinct. A detailed discussion of the basis for this finding can be
found in appendix B-I of the SSA report (Service 2023, pp. 146-154) and
other supporting documents (see ADDRESSES, above).

Determination of Status--Greater Virgin Islands Skink

Based on the best scientific and commercial data available, we
determine that the Greater Virgin Islands skink is extinct and is
therefore not warranted for listing at this time.

Status Throughout All of Its Range--Lesser Virgin Island Skink

After evaluating threats to the species and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we assessed the status of the Lesser Virgin Islands skink to
determine if it meets the Act's definition of an endangered species.
The Lesser Virgin Islands skink was historically known to occur on 15
islands within the USVI and BVI. Three historically occupied islands,
making up approximately 43 percent of the species' historical range,
are considered likely extirpated, including St. Thomas, the largest
island in the USVI. The status of seven populations (Capella Island,
Buck Island, Little Thatch Island, Fallen Jerusalem, Salt Island, Round
Rock Island, and Ginger Island) is currently unknown, primarily because
recent surveys have not been conducted and very little information is
known about these islands. The best available science indicates that
likely threats exist such that these seven populations do not
contribute to the resiliency, redundancy, and representation for the
species, and thus were not considered as contributing to overall
species viability.
Currently, the Lesser Virgin Islands skink is considered extant on
5 of the 15 islands: 1 in USVI (Hans Lollik) and 4 in BVI (Guana,
Mosquito, Virgin Gorda and Tortola). Of the five, four have low
resiliency and one has moderate resiliency. Hans Lollik, the one extant
population in the USVI, currently has low resiliency due to a lack of
habitat protection (privately owned land) (Factor A) and having
predator pressure (rats present) (Factor C). In the BVI, one population
is currently moderate, and three are low resiliency. The islands in the
BVI provide mixed levels of habitat protection; thus, development
pressure is a risk. In addition, each island has variable impacts from
nonnative predators, and the two larger islands (Tortola and Virgin
Gorda) have mongooses present. All islands have low impacts from storm
surge due to the average elevation of these islands.
Together, the extirpated and low-resiliency populations represent
94 percent of the range. Given the reduction in historical range, the
species' redundancy has been reduced from historical condition, and
representation (and adaptive capacity) has also been reduced. The
current resiliency, redundancy, and representation indicate that the
magnitude and scale of threats are currently impacting the Lesser
Virgin Islands skink such that it meets the Act's definition of an
endangered species. Thus, after assessing the best available
information, we determine that the Lesser Virgin Islands skink is in
danger of extinction throughout all of its range. Because the threats
are currently impacting the species such that it is in danger of
extinction currently throughout all of its range, it does not meet the
Act's definition of a threatened species.

Status Throughout a Significant Portion of Its Range--Lesser Virgin
Islands Skink

Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
within the foreseeable future throughout all or a significant portion
of its range. We have determined that the Lesser Virgin Islands skink
is in danger of extinction throughout all of its range and accordingly
did not undertake an analysis of any significant portion of its range.
Because the Lesser Virgin Islands skink warrants listing as endangered
throughout all of its range, our determination does not conflict with
the decision in Center for Biological Diversity v. Everson, 435 F.
Supp. 3d 69 (D.D.C. 2020), because that decision related to significant
portion of the range analyses for species that warrant listing as
threatened, not endangered, throughout all of their range.

Determination of Status--Lesser Virgin Islands Skink

Based on the best scientific and commercial data available, we
determine that the Lesser Virgin Islands skink meets the Act's
definition of an endangered species. Therefore, we propose to list the
Lesser Virgin Islands skink as an endangered species in accordance with
sections 3(6) and 4(a)(1) of the Act.

Status Throughout All of Its Range--Virgin Islands Bronze Skink

After evaluating threats to the species and assessing the
cumulative effect of the threats under the Act's section 4(a)(1)
factors, we assessed the status of the Virgin Islands bronze skink to
determine if it meets the Act's definition of an endangered species.
The Virgin Islands bronze skink was historically known to occur on nine
islands within the USVI and BVI. Four populations, making up
approximately 96 percent of the species' historical range, are
considered likely extirpated, including St. Thomas, the largest island
in the USVI. Currently, three of the nine islands are extant, all
within the USVI; there are no known extant populations occurring in
BVI. The status of two populations (Capella Island and Salt Island) are
currently unknown, primarily because recent surveys have not been
conducted and very little information is known about these islands.
Of the three extant populations, two were assessed to have high
resiliency while one was assessed to have low resiliency.Water Island,
the largest island (489 ac (198 ha)) with an extant population, is
currently occupied by nonnative predators (rats) and privately owned,
and therefore has low resiliency. Buck Island and Turtledove Cay have
high resiliency due to high levels of habitat protection and no current
predator pressure, as nonnative predators were eradicated previously.
Despite having two populations with high resiliency, the Virgin Islands
bronze skink is vulnerable to catastrophic events, primarily due to the
small size of the remaining extant islands (i.e., Buck Island and
Turtledove Cay being 22 and 32 ac (9 and 13 ha) in size, respectively).
Representation (and adaptive capacity) has been greatly reduced due to
the loss of historical range and remaining islands making up 4 percent
of the current range.
Given the current resiliency, redundancy, and representation of the
Virgin Islands bronze skink, the

[[Page 103961]]

magnitude and scale of threats are impacting the species such that it
meets the Act's definition of an endangered species.Thus, after
assessing the best available information, we determine that the Virgin
Islands bronze skink is in danger of extinction throughout all of its
range. Because the threats are currently impacting the species such
that it is in danger of extinction currently throughout all of its
range, it does not meet the Act's definition of a threatened species.

Status Throughout a Significant Portion of Its Range--Virgin Islands
Bronze Skink

Under the Act and our implementing regulations, a species may
warrant listing if it is in danger of extinction or likely to become so
within the foreseeable future throughout all or a significant portion
of its range. We have determined that the Virgin Islands bronze skink
is in danger of extinction throughout all of its range and accordingly
did not undertake an analysis of any significant portion of its range.
Because the Virgin Islands bronze skink warrants listing as endangered
throughout all of its range, our determination does not conflict with
the decision in Center for Biological Diversity v. Everson, 435 F.
Supp. 3d 69 (D.D.C. 2020), because that decision related to significant
portion of the range analyses for species that warrant listing as
threatened, not endangered, throughout all of their range.

Determination of Status--Virgin Islands Bronze Skink

Based on the best scientific and commercial data available, we
determine that the Virgin Islands bronze skink meets the Act's
definition of an endangered species. Therefore, we propose to list the
Virgin Islands bronze skink as an endangered species in accordance with
sections 3(6) and 4(a)(1) of the Act.

Status Throughout All of Its Range--Greater St. Croix Skink

When evaluating the possibility of extinction, we attempted to
minimize the possibility of either (1) prematurely determining that the
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 scientific and
commercial data available indicate 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 the species'
life history. Other lines of evidence may also support the
determination and be included in our analysis.
In conducting our analyses of whether the Greater St. Croix skink
is 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 include information from recognized experts, Federal
and State governments, academic institutions, and private entities.
The Greater St. Croix skink was a small lizard known to occur in
St. Croix and Green Cay. The skink's small size, cryptic coloration,
and secretive behavior could prevent detection; however, considerable
effort to observe other herpetofauna by qualified researchers has been
invested across several decades on St. Croix and Green Cay, where the
species once occurred. These multiple survey efforts, while not
targeted at skinks, did overlap with potential skink habitat, and would
most likely have encountered skinks if they were still extant. The loss
of the Greater St. Croix skink can be attributed to predation by the
mongoose. No skinks have been observed on St. Croix for over a century,
and none have been observed on Green Cay for nearly a quarter of a
century. Based on the best scientific and commercial information
available, it is highly unlikely that an individual could be extant but
undetected. Therefore, we conclude that the Greater St. Croix skink is
extinct. A detailed discussion of the basis for this finding can be
found in appendix B-II of the SSA report (Service 2023, pp. 154-162)
and other supporting documents (see ADDRESSES, above).

Determination of Status--Greater St. Croix Skink

Based on the best scientific and commercial data available, we
determine that the Greater St. Croix skink is extinct and is therefore
not warranted for listing at this time.

Status Throughout All of Its Range--Lesser St. Croix Skink

When evaluating the possibility of extinction, we attempted to
minimize the possibility of either (1) prematurely determining that the
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 scientific and
commercial data available indicate 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 the species'
life history. Other lines of evidence may also support the
determination and be included in our analysis.
In conducting our analyses of whether the Lesser St. Croix skink is
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 include information from recognized experts, Federal and
State governments, academic institutions, and private entities.
The Lesser St. Croix skink was a small lizard known from only one
specimen collected in 1875. The skink's small size, cryptic coloration,
and secretive behavior could lower detection probabilities; however,
considerable effort to observe other herpetofauna by qualified
researchers has been invested across several decades on St. Croix,
where the species once occurred. These multiple survey efforts, while
not targeted at skinks, did overlap with potential skink habitat, and
would most likely have detected skinks if they were still extant. The
loss of the Lesser St. Croix skink is mainly attributed to predation by
the mongoose in addition to habitat loss. No skinks have been observed
on St. Croix for over a century. Based on the best scientific and
commercial information available, it is highly unlikely that an
individual would be extant but undetected. Therefore, we conclude that
the Lesser St. Croix skink is extinct. A detailed discussion of the
basis for this finding can be found in appendix B-III of the SSA report
(Service 2023, pp. 162-169) and other supporting documents (see
ADDRESSES, above).

Determination of Status--Lesser St. Croix Skink

Based on the best scientific and commercial data available, we
determine that the Lesser St. Croix skink is extinct and is therefore
not warranted for listing at this time.

Available Conservation Measures

Conservation measures provided to species listed as endangered or
threatened species under the Act include recognition as a listed
species, planning and implementation of recovery actions, requirements
for Federal protection, and prohibitions against certain practices.
Recognition through listing results in public

[[Page 103962]]

awareness, and conservation by Federal, State, Tribal, and local
agencies, private organizations, and individuals. The Act encourages
cooperation with the States and other countries and calls for recovery
actions to be carried out for listed species. The protection required
by Federal agencies, including the Service, and the prohibitions
against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered
and threatened species and the ecosystems upon which they depend. The
ultimate goal of such conservation efforts is the recovery of these
listed species, so that they no longer need the protective measures of
the Act. Section 4(f) of the Act calls for the Service to develop and
implement recovery plans for the conservation of endangered and
threatened species. The goal of this process is to restore listed
species to a point where they are secure, self-sustaining, and
functioning components of their ecosystems.
The recovery planning process begins with development of a recovery
outline made available to the public soon after a final listing
determination. The recovery outline guides the immediate implementation
of urgent recovery actions while a recovery plan is being developed.
Recovery teams (composed of species experts, Federal and State
agencies, nongovernmental organizations, and stakeholders) may be
established to develop and implement recovery plans. The recovery
planning process involves the identification of actions that are
necessary to halt and reverse the species' decline by addressing the
threats to its survival and recovery. The recovery plan identifies
recovery criteria for review of when a species may be ready for
reclassification from endangered to threatened (``downlisting'') or
removal from protected status (``delisting''), and methods for
monitoring recovery progress. Recovery plans also establish a framework
for agencies to coordinate their recovery efforts and provide estimates
of the cost of implementing recovery tasks. Revisions of the plan may
be done to address continuing or new threats to the species, as new
substantive information becomes available. The recovery outline, draft
recovery plan, final recovery plan, and any revisions will be available
on our website as they are completed (<a href="https://www.fws.gov/program/endangered-species">https://www.fws.gov/program/endangered-species</a>) or from our Caribbean Ecological Services Field
Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the
participation of a broad range of partners, including other Federal
agencies, States, Tribes, nongovernmental organizations, businesses,
and private landowners. Examples of recovery actions include habitat
restoration (e.g., restoration of native vegetation), research, captive
propagation and reintroduction, and outreach and education. The
recovery of many listed species cannot be accomplished solely on
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires
cooperative conservation efforts on private, State, and Tribal lands.
If these species are listed, funding for recovery actions will be
available from a variety of sources, including Federal budgets, State
programs, and cost-share grants for non-Federal landowners, the
academic community, and nongovernmental organizations. In addition,
pursuant to section 6 of the Act, the Commonwealth of Puerto Rico and
Territory of the USVI would be eligible for Federal funds to implement
management actions that promote the protection or recovery of the
Puerto Rican skink, Culebra skink, Lesser Virgin Islands skink, and
Virgin Islands bronze skink. Information on our grant programs that are
available to aid species recovery can be found at: <a href="https://www.fws.gov/service/financial-assistance">https://www.fws.gov/service/financial-assistance</a>.
Although the Puerto Rican skink, Culebra skink, Lesser Virgin
Islands skink, and Virgin Islands bronze skink are only proposed for
listing under the Act at this time, please let us know if you are
interested in participating in recovery efforts for this species.
Additionally, we invite you to submit any new information on these
species whenever it becomes available and any information you may have
for recovery planning purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7 of the Act is titled, ``Interagency Cooperation,'' and it
mandates all Federal action agencies to use their existing authorities
to further the conservation purposes of the Act and to ensure that
their actions are not likely to jeopardize the continued existence of
listed species or adversely modify critical habitat. Regulations
implementing section 7 are codified at 50 CFR part 402.
Section 7(a)(2) states that each Federal action agency shall, in
consultation with the Secretary, ensure that any action they authorize,
fund, or carry out is not likely to jeopardize the continued existence
of a listed species or result in the destruction or adverse
modification of designated critical habitat. Each Federal agency shall
review its action at the earliest possible time to determine whether it
may affect listed species or critical habitat. If a determination is
made that the action may affect listed species or critical habitat,
formal consultation is required (50 CFR 402.14(a)), unless the Service
concurs in writing that the action is not likely to adversely affect
listed species or critical habitat. At the end of a formal
consultation, the Service issues a biological opinion, containing its
determination of whether the Federal action is likely to result in
jeopardy or adverse modification.
In contrast, section 7(a)(4) of the Act requires Federal agencies
to confer with the Service on any action which is likely to jeopardize
the continued existence of any species proposed to be listed under the
Act or result in the destruction or adverse modification of critical
habitat proposed to be designated for such species. Although the
conference procedures are required only when an action is likely to
result in jeopardy or adverse modification, action agencies may
voluntarily confer with the Service on actions that may affect species
proposed for listing or critical habitat proposed to be designated. In
the event that the subject species are listed, or the relevant critical
habitats are designated, a conference opinion may be adopted as a
biological opinion and serve as compliance with section 7(a)(2).
Examples of discretionary actions for the Puerto Rican skink,
Culebra skink, Lesser Virgin Islands skink, and Virgin Islands bronze
skink that may be subject to conference and consultation procedures
under section 7 of the Act are management of Federal lands administered
by the National Park Service and the U.S. Forest Service, as well as
actions that require a Federal permit (such as a permit from the U.S.
Army Corps of Engineers under section 404 of the Clean Water Act (33
U.S.C. 1251 et seq.)) or actions funded by Federal agencies such as the
Federal Highway Administration, Federal Aviation Administration, or the
Federal Emergency Management Agency. Federal actions not affecting
listed species or critical habitat--and actions on State, Tribal,
local, or private lands that are not federally funded, authorized, or
carried out by a Federal agency--do not require section 7 consultation.
Federal agencies should coordinate with the local Service Field Office
(see FOR FURTHER INFORMATION CONTACT) with any specific questions on
section 7 consultation and conference requirements.
The Act and its implementing regulations set forth a series of
general prohibitions and exceptions that apply

[[Page 103963]]

to endangered wildlife. The prohibitions of section 9(a)(1) of the Act,
codified at 50 CFR 17.21, make it illegal for any person subject to the
jurisdiction of the United States to commit, to attempt to commit, to
solicit another to commit or to cause to be committed any of the
following acts with regard to endangered wildlife: (1) import into, or
export from, the United States; (2) take (which includes harass, harm,
pursue, hunt, shoot, wound, kill, trap, capture, or collect, or to
attempt to engage in any such conduct) within the United States, within
the territorial sea of the United States, or on the high seas; (3)
possess, sell, deliver, carry, transport, or ship, by any means
whatsoever, any such wildlife that has been taken illegally; (4)
deliver, receive, carry, transport, or ship in interstate or foreign
commerce, by any means whatsoever and in the course of commercial
activity; or (5) sell or offer for sale in interstate or foreign
commerce. Certain exceptions to these prohibitions apply to employees
or agents of the Service, the National Marine Fisheries Service, other
Federal land management agencies, and State conservation agencies.
We may issue permits to carry out otherwise prohibited activities
involving endangered wildlife under certain circumstances. Regulations
governing permits for endangered wildlife are codified at 50 CFR 17.22,
and general Service permitting regulations are codified at 50 CFR part
13. With regard to endangered wildlife, a permit may be issued: for
scientific purposes, for enhancing the propagation or survival of the
species, or for take incidental to otherwise lawful activities. The
statute also contains certain exemptions from the prohibitions, which
are found in sections 9 and 10 of the Act.

II. Protective Regulations Under Section 4(d) of the Act

Background

As discussed in Available Conservation Measures, section 9 of the
Act provides a specific list of prohibitions for endangered species but
does not provide these same prohibitions for threatened species.
Instead, pursuant to section 4(d) of the Act, for any species listed as
a threatened species, the Secretary must issue protective regulations
that are ``necessary and advisable to provide for the conservation of
such species'' (these are referred to as ``4(d) rules''). Section 4(d)
of the Act contains two sentences. The first sentence states that the
Secretary shall issue such regulations as she deems necessary and
advisable to provide for the conservation of species listed as
threatened species. Conservation is defined in the Act to mean the use
of all methods and procedures which are necessary to bring any
endangered species or threatened species to the point at which the
measures provided pursuant to the Act are no longer necessary.
Additionally, the second sentence of section 4(d) of the Act states
that the Secretary may by regulation prohibit with respect to any
threatened species any act prohibited under section 9(a)(1), in the
case of fish or wildlife, or section 9(a)(2), in the case of plants.
With these two sentences in section 4(d), Congress delegated broad
authority to the Secretary to determine what protections would be
necessary and advisable to provide for the conservation of threatened
species, and even broader authority to put in place any of the section
9 prohibitions, for a given species.
Courts have recognized the extent of the Secretary's discretion
under section 4(d) to develop regulations that are appropriate for the
conservation of threatened species. For example, courts have upheld, as
a valid exercise of agency authority, rules developed under section
4(d) that included limited prohibitions against takings (see Alsea
Valley Alliance v. Lautenbacher, 2007 WL 2344927 (D. Or. 2007);
Washington Environmental Council v. National Marine Fisheries Service,
2002 WL 511479 (W.D. Wash. 2002)). Courts have also upheld 4(d) rules
that do not address all of the threats a species faces (see State of
Louisiana v. Verity, 853 F.2d 322 (5th Cir. 1988)). As noted in the
legislative history when the Act was initially enacted, ``once an
animal is on the threatened list, the Secretary has an almost infinite
number of options available to [her] with regard to the permitted
activities for those species. [She] may, for example, permit taking,
but not importation of such species, or [she] may choose to forbid both
taking and importation but allow the transportation of such species''
(H.R. Rep. No. 412, 93rd Cong., 1st Sess. 1973).
Under our 4(d) authorities, we put in place protections intended to
both prevent a threatened species from becoming an endangered species
and to promote its recovery. We have two ways to put in place these
protections for a threatened species: (1) we can issue a species-
specific 4(d) rule (at 50 CFR 17.40-17.47 or 17.73-17.74), which would
contain all of the protective regulations for that species; or (2) we
can apply a ``blanket rule'' (for more information, see 89 FR 23919,
April 5, 2024), which extends to threatened species without a species-
specific rule all of the prohibitions that apply to endangered species
under section 9 (with certain exceptions applicable to threatened
species).
Both ``blanket rules'' and species-specific 4(d) rules explain what
is prohibited for a threatened species, thus making the activity
unlawful without a permit or authorization under the Act for the
prohibited activity unless otherwise excepted in the 4(d) rule
(species-specific 4(d) rules may also include affirmative
requirements). Section 4(d) rules are therefore directly related to
what actions may require permits in the future. As discussed in
Available Conservation Measures, permits may be issued for purposes
described in our threatened species permitting regulations at 50 CFR
17.32 and 17.72, including for recovery actions, conservation benefit
agreements (previously referred to as candidate conservation agreements
with assurances and safe harbor agreements), or habitat conservation
plans. We may also except otherwise prohibited activities through a
4(d) rule itself, in which case threatened species permits would not be
required for those activities. For example, there are two categories of
exceptions that we frequently include in 4(d) rules, and these are for
otherwise prohibited acts or forms or amounts of ``take'' that are: (1)
unavoidable while conducting beneficial actions for the species, or (2)
considered inconsequential (de minimis) to the conservation of the
species. For otherwise prohibited take activities that require section
10 permits, programmatic approaches--such as general conservation plans
and template habitat conservation plans--may be available as another
way for project proponents to comply with take prohibitions or
requirements applicable to one or more species while reducing the time
that would otherwise be associated with developing individual permit
applications. In addition, the Service and project proponents can
reduce the need for such permits by developing standardized
conservation measures that avoid the risk of ``take.''
The provisions of the Culebra skink's proposed protective
regulations under section 4(d) of the Act are one of many tools that we
would use to promote the conservation of the Culebra skink. The
proposed protective regulations would apply only if and when we make
final the listing of the Culebra skink as a threatened species. Nothing
in 4(d) rules changes in any way the recovery planning provisions of
section 4(f) of the Act, the consultation requirements under section 7
of the Act, or the ability

[[Page 103964]]

of the Service to enter into partnerships for the management and
protection of the Culebra skink.
As mentioned previously in Available Conservation Measures, section
7(a)(2) of the Act requires Federal agencies, including the Service, to
ensure that any action they authorize, fund, or carry out is not likely
to jeopardize the continued existence of any endangered species or
threatened species or result in the destruction or adverse modification
of designated critical habitat of such species. In addition, even
before the listing of any species or the designation of its critical
habitat is finalized, section 7(a)(4) of the Act requires Federal
agencies to confer with the Service on any agency action which is
likely to jeopardize the continued existence of any species proposed to
be listed under the Act or result in the destruction or adverse
modification of critical habitat proposed to be designated for such
species. These requirements are the same for a threatened species
regardless of what is included in its 4(d) rule.
Section 7 consultation is required for Federal actions that ``may
affect'' a listed species regardless of whether take caused by the
activity is prohibited or excepted by a 4(d) rule (under application of
a ``blanket rule'' or a species-specific 4(d) rule). For example, as
with an endangered species, a Federal agency's determination that an
action is ``not likely to adversely affect'' a threatened species
requires the Service's written concurrence (50 CFR 402.13(c)).
Similarly, if a Federal agency determines that an action is ``likely to
adversely affect'' a threatened species, the action will require formal
consultation with the Service and the formulation of a biological
opinion (50 CFR 402.14(a)). Because consultation obligations and
processes are unaffected by 4(d) rules, we may consider developing
tools to streamline future intra-Service and inter-agency consultations
for actions that result in forms of take that are not prohibited by the
4(d) rule (but that still require consultation). These tools may
include consultation guidance, online consultation processes via the
Service's digital project planning tool (Information for Planning and
Consultation; <a href="https://ipac.ecosphere.fws.gov/">https://ipac.ecosphere.fws.gov/</a>), template language for
biological opinions, or programmatic consultations.

Provisions of the Proposed 4(d) Rule

Exercising the Secretary's authority under section 4(d) of the Act,
we have developed a proposed rule that is designed to address the
Culebra skink's conservation needs. As discussed previously in Summary
of Biological Status and Threats, we have concluded that the Culebra
skink is likely to become in danger of extinction within the
foreseeable future primarily due to nonnative predators and sea level
rise. Section 4(d) requires the Secretary to issue such regulations as
she deems necessary and advisable to provide for the conservation of
each threatened species and authorizes the Secretary to include among
those protective regulations any of the prohibitions that section
9(a)(1) of the Act prescribes for endangered species. We are not
required to make a ``necessary and advisable'' determination when we
apply or do not apply specific section 9 prohibitions to a threatened
species (In re: Polar Bear Endangered Species Act Listing and 4(d) Rule
Litigation, 818 F. Supp. 2d 214, 228 (D.D.C. 2011) (citing Sweet Home
Chapter of Communities for a Great Oregon v. Babbitt, 1 F.3d 1, 8 (D.C.
Cir. 1993), rev'd on other grounds, 515 U.S. 687 (1995))).
Nevertheless, even though we are not required to make such a
determination, we have chosen to be as transparent as possible and
explain below why we find that, if finalized, the protections,
prohibitions, and exceptions in this proposed rule as a whole satisfy
the requirement in section 4(d) of the Act to issue regulations deemed
necessary and advisable to provide for the conservation of the Culebra
skink.
The protective regulations we are proposing for the Culebra skink
incorporate prohibitions from section 9(a)(1) to address the threats to
the species. The prohibitions of section 9(a)(1) of the Act, and
implementing regulations codified at 50 CFR 17.21, make it illegal for
any person subject to the jurisdiction of the United States to commit,
to attempt to commit, to solicit another to commit or to cause to be
committed any of the following acts with regard to any endangered
wildlife: (1) import into, or export from, the United States; (2) take
(which includes harass, harm, pursue, hunt, shoot, wound, kill, trap,
capture, or collect, or to attempt to engage in any such conduct)
within the United States, within the territorial sea of the United
States, or on the high seas; (3) possess, sell, deliver, carry,
transport, or ship, by any means whatsoever, any such wildlife that has
been taken illegally; (4) deliver, receive, carry, transport, or ship
in interstate or foreign commerce, by any means whatsoever and in the
course of commercial activity; or (5) sell or offer for sale in
interstate or foreign commerce. This protective regulation includes all
of these prohibitions for the Culebra skink because the Culebra skink
is at risk of extinction within the foreseeable future, and putting
these prohibitions in place will help to prevent further declines,
preserve the species' remaining populations, and decrease potential
synergistic, negative effects from other ongoing or future threats.
In particular, this proposed 4(d) rule would provide for the
conservation of the Culebra skink by prohibiting the following
activities, unless they fall within specific exceptions or are
otherwise authorized or permitted: importing or exporting; take;
possession and other acts with unlawfully taken specimens; delivering,
receiving, carrying, transporting, or shipping in interstate or foreign
commerce in the course of commercial activity; or selling or offering
for sale in interstate or foreign commerce.
Under the Act, ``take'' means to harass, harm, pursue, hunt, shoot,
wound, kill, trap, capture, or collect, or to attempt to engage in any
such conduct. Some of these provisions have been further defined in
regulations at 50 CFR 17.3. Take can result knowingly or otherwise, by
direct and indirect impacts, intentionally or incidentally. Regulating
take would help preserve the species' remaining populations, slow their
rate of decline, and decrease cumulative effects from other ongoing or
future threats. Therefore, we propose to prohibit take of the Culebra
skink, except for take resulting from those actions and activities
specifically excepted by the 4(d) rule.
Exceptions to the prohibition on take would include all of the
general exceptions to the prohibition on take of endangered wildlife as
set forth in 50 CFR 17.21 and additional exceptions, as described
below.
Despite these prohibitions regarding threatened species, we may
under certain circumstances issue permits to carry out one or more
otherwise-prohibited activities, including those described above. The
regulations that govern permits for threatened wildlife state that the
Director may issue a permit authorizing any activity otherwise
prohibited with regard to threatened species. These include permits
issued for the following purposes: for scientific purposes, to enhance
propagation or survival, for economic hardship, for zoological
exhibition, for educational purposes, for incidental taking, or for
special purposes consistent with the purposes of the Act (50 CFR
17.32). The statute also contains certain exemptions from the
prohibitions, which are found in sections 9 and 10 of the Act.

[[Page 103965]]

In addition, to further the conservation of the species, any
employee or agent of the Service, any other Federal land management
agency, the National Marine Fisheries Service, a State conservation
agency, or a federally recognized Tribe, who is designated by their
agency or Tribe for such purposes, may, when acting in the course of
their official duties, take threatened wildlife without a permit if
such action is necessary to: (i) Aid a sick, injured, or orphaned
specimen; or (ii) dispose of a dead specimen; or (iii) salvage a dead
specimen that may be useful for scientific study; or (iv) remove
specimens that constitute a demonstrable but nonimmediate threat to
human safety, provided that the taking is done in a humane manner; the
taking may involve killing or injuring only if it has not been
reasonably possible to eliminate such threat by live-capturing and
releasing the specimen unharmed, in an appropriate area.
We recognize the special and unique relationship with our State
natural resource agency partners in contributing to conservation of
listed species. State agencies often possess scientific data and
valuable expertise on the status and distribution of endangered,
threatened, and candidate species of wildlife and plants. State
agencies, because of their authorities and their close working
relationships with local governments and landowners, are in a unique
position to assist us in implementing all aspects of the Act. In this
regard, section 6 of the Act provides that we must cooperate to the
maximum extent practicable with the States in carrying out programs
authorized by the Act. Therefore, any qualified employee or agent of a
State conservation agency that is a party to a cooperative agreement
with us in accordance with section 6(c) of the Act, who is designated
by their agency for such purposes, would be able to conduct activities
designed to conserve the Culebra skink that may result in otherwise
prohibited take without additional authorization.
The proposed 4(d) rule would also provide for the conservation of
the species by allowing exceptions that incentivize conservation
actions or that, while they may have some minimal level of take of the
Culebra skink, are not expected to rise to the level that would have a
negative impact (i.e., would have only de minimis impacts) on the
species' conservation. The proposed exceptions to these prohibitions
include predator control or eradication efforts and habitat restoration
efforts (described below) that are expected to have negligible impacts
to the Culebra skink and its habitat:
(1) Eradication or control of nonnative species such as mongooses,
rats, cats, pigs, goats, etc., is beneficial for skinks. Permanent
eradication of nonnative species is typically most effective on small
islands that do not have human development, as introductions (whether
passive or intentional) happen often in the presence of humans.
However, any activities intended to reduce or eliminate nonnative
species will benefit the Culebra skink.
(2) Habitat management or restoration activities expected to
provide a benefit to the Culebra skink and other sensitive species,
including removal of nonnative, invasive plants. These activities must
be coordinated with and reported to the Service in writing and approved
the first time an individual or agency undertakes them or if there are
planned changes to the activities.
We ask the public, particularly State agencies and other interested
stakeholders that may be affected by the proposed 4(d) rule, to provide
comments and suggestions regarding additional guidance and methods that
we could provide or use, respectively, to streamline the implementation
of this proposed 4(d) rule (see Information Requested, above).

III. Critical Habitat

Background

Section 4(a)(3) of the Act requires that, to the maximum extent
prudent and determinable, we designate a species' critical habitat
concurrently with listing the species. Critical habitat is defined in
section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features
(a) Essential to the conservation of the species, and
(b) Which may require special management considerations or
protection; and
(2) Specific areas outside the geographical area occupied by the
species at the time it is listed, upon a determination that such areas
are essential for the conservation of the species.
Our regulations at 50 CFR 424.02 define the geographical area
occupied by the species as an area that may generally be delineated
around species' occurrences, as determined by the Secretary (i.e.,
range). Such areas may include those areas used throughout all or part
of the species' life cycle, even if not used on a regular basis (e.g.,
migratory corridors, seasonal habitats, and habitats used periodically,
but not solely by vagrant individuals).
Conservation, as defined under section 3(3) of the Act, means to
use and the use of all methods and procedures that are necessary to
bring an endangered or threatened species to the point at which the
measures provided pursuant to the Act are no longer necessary. Such
methods and procedures include, but are not limited to, all activities
associated with scientific resources management such as research,
census, law enforcement, habitat acquisition and maintenance,
propagation, live-trapping, and transplantation, and, in the
extraordinary case where population pressures within a given ecosystem
cannot be otherwise relieved, may include regulated taking.
Critical habitat receives protection under section 7 of the Act
through the requirement that each Federal action agency ensure, in
consultation with the Service, that any action they authorize, fund, or
carry out is not likely to result in the destruction or adverse
modification of designated critical habitat. The designation of
critical habitat does not affect land ownership or establish a refuge,
wilderness, reserve, preserve, or other conservation area. Such
designation also does not allow the government or public to access
private lands. Such designation does not require implementation of
restoration, recovery, or enhancement measures by non-Federal
landowners. Rather, designation requires that, where a landowner
requests Federal agency funding or authorization for an action that may
affect an area designated as critical habitat, the Federal agency
consult with the Service under section 7(a)(2) of the Act. If the
action may affect the listed species itself (such as for occupied
critical habitat), the Federal agency would have already been required
to consult with the Service even absent the designation because of the
requirement to ensure that the action is not likely to jeopardize the
continued existence of the species. Even if the Service were to
conclude after consultation that the proposed activity is likely to
result in destruction or adverse modification of the critical habitat,
the Federal action agency and the landowner are not required to abandon
the proposed activity, or to restore or recover the species; instead,
they must implement ``reasonable and prudent alternatives'' to avoid
destruction or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat,
areas within the geographical area occupied

[[Page 103966]]

by the species at the time it was listed are included in a critical
habitat designation if they contain physical or biological features (1)
which are essential to the conservation of the species and (2) which
may require special management considerations or protection. For these
areas, critical habitat designations identify, to the extent known
using the best scientific data available, those physical or biological
features that are essential to the conservation of the species (such as
space, food, cover, and protected habitat).
Under the second prong of the Act's definition of critical habitat,
we can designate critical habitat in areas outside the geographical
area occupied by the species at the time it is listed, upon a
determination that such areas are essential for the conservation of the
species.
Section 4(b)(2) of the Act requires that we designate critical
habitat on the basis of the best scientific data available. Further,
our Policy on Information Standards Under the Endangered Species Act
(published in the Federal Register on July 1, 1994 (59 FR 34271)), the
Information Quality Act (section 515 of the Treasury and General
Government Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554;
H.R. 5658)), and our associated Information Quality Guidelines provide
criteria, establish procedures, and provide guidance to ensure that our
decisions are based on the best scientific data available. They require
our biologists, to the extent consistent with the Act and with the use
of the best scientific data available, to use primary and original
sources of information as the basis for recommendations to designate
critical habitat.
When we are determining which areas should be designated as
critical habitat, our primary source of information is generally the
information from the SSA report and information developed during the
listing process for the species. Additional information sources may
include any generalized conservation strategy, criteria, or outline
that may have been developed for the species; the recovery plan for the
species; articles in peer-reviewed journals; conservation plans
developed by States and counties; scientific status surveys and
studies; biological assessments; other unpublished materials; or
experts' opinions or personal knowledge.
Habitat is dynamic, and species may move from one area to another
over time. We recognize that critical habitat designated at a
particular point in time may not include all of the habitat areas that
we may later determine are necessary for the recovery of the species.
For these reasons, a critical habitat designation does not signal that
habitat outside the designated area is unimportant or may not be needed
for recovery of the species. Areas that are important to the
conservation of the species, both inside and outside the critical
habitat designation, will continue to be subject to: (1) Conservation
actions implemented under section 7(a)(1) of the Act; (2) regulatory
protections afforded by the requirement in section 7(a)(2) of the Act
for Federal agencies to ensure their actions are not likely to
jeopardize the continued existence of any endangered or threatened
species; and (3) the prohibitions found in section 9 of the Act for the
Puerto Rican skink, Lesser Virgin Islands skink, and Virgin Islands
bronze skink, or the proposed 4(d) rule for the Culebra skink.
Federally funded or permitted projects affecting listed species outside
their designated critical habitat areas may still result in jeopardy
findings in some cases. These protections and conservation tools will
continue to contribute to recovery of the species. Similarly, critical
habitat designations made on the basis of the best available
information at the time of designation will not control the direction
and substance of future recovery plans, habitat conservation plans
(HCPs), or other species conservation planning efforts if new
information available at the time of those planning efforts calls for a
different outcome.

Physical or Biological Features Essential to the Conservation of the
Species

In accordance with section 3(5)(A)(i) of the Act and regulations at
50 CFR 424.12(b), in determining which areas we will designate as
critical habitat from within the geographical area occupied by the
species at the time of listing, we consider the physical or biological
features that are essential to the conservation of the species and
which may require special management considerations or protection. The
regulations at 50 CFR 424.02 define ``physical or biological features
essential to the conservation of the species'' as the features that
occur in specific areas and that are essential to support the life-
history needs of the species, including, but not limited to, water
characteristics, soil type, geological features, sites, prey,
vegetation, symbiotic species, or other features. A feature may be a
single habitat characteristic or a more complex combination of habitat
characteristics. Features may include habitat characteristics that
support ephemeral or dynamic habitat conditions. Features may also be
expressed in terms relating to principles of conservation biology, such
as patch size, distribution distances, and connectivity. For example,
physical features essential to the conservation of the species might
include gravel of a particular size required for spawning, alkaline
soil

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