Endangered and Threatened Wildlife and Plants; Reclassifying the Virgin Islands Tree Boa From Endangered to Threatened With a Section 4(d) Rule, 66351-66360 [2023-20946]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 88, Number 186 (Wednesday, September 27, 2023)]
[Proposed Rules]
[Pages 66351-66360]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-20946]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2019-0069; FF09E21000 FXES11110900000 234]
RIN 1018-BE14


Endangered and Threatened Wildlife and Plants; Reclassifying the 
Virgin Islands Tree Boa From Endangered to Threatened With a Section 
4(d) Rule

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; withdrawal.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), withdraw the 
proposed rule to reclassify the Virgin Islands tree boa (listed as 
Epicrates monensis granti) from endangered to threatened under the 
Endangered Species Act of 1973 (Act), as amended. This withdrawal is 
based on new information we received during the proposed rule's public 
comment periods, specifically new survey results that indicate that the 
Virgin Islands tree boa is likely extirpated from Cayo Ratones. We also 
realized an error in calculations that reduced the resiliency of the 
Cayo Diablo population. After evaluating the status of the species 
following these changes, we find that the species still meets the Act's 
definition of an endangered species. We have, therefore, determined 
that reclassification of this species is not appropriate at this time. 
Accordingly, we also withdraw the proposed 4(d) rule for the Virgin 
Islands tree boa.

DATES: The proposed rule that published on September 30, 2020 (85 FR 
61700), to reclassify the Virgin Islands tree boa as threatened with a 
rule issued under section 4(d) of the Act is withdrawn on September 27, 
2023.

ADDRESSES: This withdrawal, comments on our September 30, 2020, 
proposed rule, and supplementary documents are available for public 
inspection on the internet at https://www.regulations.gov at Docket No. 
FWS-R4-ES-2019-0069 and on the Service's website at https://www.fws.gov/office/caribbean-ecological-services/library.

FOR FURTHER INFORMATION CONTACT: Edwin E. Mu[ntilde]iz, Field 
Supervisor, U.S. Fish and Wildlife Service, Caribbean Ecological 
Services Field Office, P.O. Box 491, Boquer[oacute]n, PR 00622; 
telephone 787-405-3641; email: [email protected]. Individuals in the 
United States who are deaf, deafblind, hard of hearing, or have a 
speech disability may dial 711 (TTY,

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TDD, or TeleBraille) to access telecommunications relay services. 
Individuals outside the United States should use the relay services 
offered within their country to make international calls to the point-
of-contact in the United States.

SUPPLEMENTARY INFORMATION:

Previous Federal Actions

    Please refer to the September 30, 2020, proposed rule (85 FR 61700) 
to reclassify the Virgin Islands tree boa (which we refer to below as 
``Virgin Islands boa'') for a detailed description of previous Federal 
actions concerning this species. The September 30, 2020, proposed rule 
opened a 60-day public comment period, ending November 30, 2020. We 
then reopened the public comment period for an additional 30 days, from 
April 26 to May 26, 2021, and held a public hearing on May 12, 2021 
(see 86 FR 22005; April 26, 2021). During both comment periods and at 
the public hearing, we accepted submission of new information and 
comments on the proposed reclassification.

Summary of Justification for Withdrawal

    Based on the comments we received during both of the September 30, 
2020, proposed rule's public comment periods and at the May 12, 2021, 
public hearing, we made several changes and corrections throughout the 
species status assessment (SSA) report for the Virgin Islands boa 
(Service 2022, entire). We received substantive comments regarding the 
probable extirpation of Virgin Islands boas due to colonization of rats 
on Cayo Ratones, and we have included that information in all 
descriptions of that population and addressed it in our analysis. 
Results from a survey effort in September 2021 by Puerto Rico 
Department of Natural and Environmental Resources (DNER) and other boa 
experts were provided to the Service; no boas or indirect evidence of 
boas were observed (Puente-Rol[oacute]n et al. 2021, p. 1) and the DNER 
affirms that the Cayo Ratones population is most likely extirpated 
(DNER 2019, p. 3). We also received comments on the characterization of 
the resiliency of the Cayo Diablo population, and upon reexamination of 
the current resiliency score, we realized we made an error in our 
calculations and subsequently have changed the resiliency of that 
population from moderately high resiliency to moderate resiliency. Upon 
incorporating these changes, we have determined that there are not 
sufficient data to support reclassifying the Virgin Islands boa from an 
endangered species to a threatened species. Accordingly, we are 
withdrawing our proposed rule to reclassify the Virgin Islands boa as a 
threatened species with a rule issued under section 4(d) of the Act (16 
U.S.C. 1531 et seq.).

Proposal to Update the Scientific Name of the Virgin Islands Tree Boa

    In the September 30, 2020, proposed rule (85 FR 61700), we proposed 
to correct the Federal List of Endangered and Threatened Wildlife 
(List) to change the scientific name of the Virgin Islands tree boa 
from Epicrates monensis granti to Chilabothrus granti to reflect the 
currently accepted taxonomy. Virgin Islands boa is a distinct species, 
not a subspecies, and Epicrates is no longer the scientifically 
accepted genus for this species. However, because we are withdrawing 
the September 30, 2020, proposed rule (85 FR 61700), the Virgin Islands 
boa's scientific name will remain Epicrates monensis granti in the List 
until we, in the future, publish a final rule recognizing the new 
taxonomy.

Background

    A thorough review of the taxonomy, life history, ecology, and 
overall viability of the Virgin Islands boa is presented in the SSA 
report (Service 2022, entire; available at https://www.regulations.gov 
under Docket No. FWS-R4-ES-2019-0069). A summary of this information 
follows.
    The Virgin Islands boa is endemic to Puerto Rico and the Virgin 
Islands (U.S. and British). The Virgin Islands boa is a medium-length, 
slender, nonvenomous snake. The largest snout-vent lengths (SVL) 
recorded for the species were 1,066 millimeters (mm; 42 inches (in)) 
for females and 1,112 mm (44 in) for males (total body lengths 1,203 mm 
(47 in) and 1,349 mm (53 in), respectively; Tolson 2005, entire), 
although most specimens range between 600 and 800 mm (24 and 31 in) 
SVL, with an average mass of 165 grams (6 ounces) (USVI Division of 
Wildlife, unpublished data). Adults are gray-brown with dark-brown 
blotches that are partially edged with black, and feature a blue-purple 
iridescence on their dorsal surface; the ventral surface is creamy 
white or yellowish white. Newborns, on the other hand, have an almost 
grayish-white body color with black blotches and weigh 2.0-7.2 grams 
(0.07-0.25 ounces) with SVLs of 200-350 mm (approx. 8-14 in) (Tolson 
1992, entire; Tolson 2018, pers. comm.).
    The Virgin Islands boa occurs in subtropical dry forest and 
subtropical moist forest (Service 2009, p. 11). Subtropical dry forest 
covers approximately 14 percent (128,420 hectares (ha); 317,332 acres 
(ac)) of Puerto Rico and the U.S. Virgin Islands (USVI), typically 
receives less than 750 mm (29 in) rainfall annually (Ewel and Whitmore 
1973, pp. 9-20), and is characterized by small (less than 5 meter (m; 
16 feet (ft)) deciduous trees with high densities of interlocking 
branches and vines connecting adjacent tree canopies (Ewel and Whitmore 
1973, p. 10). Subtropical moist forest covers approximately 58 percent 
(538,130 ha; 1,329,750 ac) of Puerto Rico and USVI and typically 
receives more than 1,100 mm (43 in) of annual rainfall. It is dominated 
by semi-evergreen and evergreen deciduous trees up to 20 m (66 ft) tall 
with rounded crowns. The Virgin Islands boa has also been reported to 
occur in mangrove forest, thicket/scrub, disturbed lower vegetation, 
and artificial structures (Harvey and Platenberg 2009, p. 114; Tolson 
2003, entire).
    Habitat needs for Virgin Islands boa can be divided into those for 
foraging and those for resting. Factors contributing to foraging 
habitat quality are tree density and connectivity, presence of arboreal 
and ground-level refugia, prey density, and rat presence/density 
(Tolson 1988, pp. 234-235). Tree density is more important than tree 
species or diversity; Virgin Islands boas do not appear to prefer a 
particular tree species after accounting for availability and structure 
(Platenberg 2006, pers. comm.). The highest densities of Virgin Islands 
boas are found where there are few or no exotic predators and high 
densities of lizard prey (Tolson 1988, p. 233). Resting habitat 
includes refugia for inactive boas to use during the day. Refugia can 
be the axils (angles between trunk and branches) of Cocos or Sabal 
species, tree holes, termite nests, or under rocks and debris (Tolson 
1988, p. 233).
    The Virgin Islands boa forages at night by gliding slowly along 
small branches in search of sleeping lizards (Service 1986, p. 6). The 
primary prey for the Virgin Islands boa is the Puerto Rican crested 
anole (Anolis cristatellus), and the greatest concentrations of Virgin 
Islands boa are found where Anolis densities exceed 60 individuals/100 
m\2\ (1,076 ft\2\; Tolson 1988, p. 233). Other prey species include 
ground lizard (Ameiva exsul), house mouse (Mus musculus), small birds, 
iguana (Iguana iguana) hatchlings, and likely other small animals 
encountered (MacLean 1982, pp. 30-31, 37; Tolson 1989, p. 165; Tolson 
2005, p. 9; Platenberg 2011, p. 3). The Virgin Islands boa may also 
compete for prey and other niche components with the green iguana 
(Iguana iguana) and the Puerto Rican

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racer (Borikenophis portoricensis), a snake native to Puerto Rico, 
USVI, the British Virgin Islands, and surrounding cays (small, low 
islands).
    Much of what is known about the Virgin Islands boa's life history 
comes from studies in captivity. Lifespans in captivity often exceed 20 
years, and sometimes exceed 30 years (7 percent of captive Virgin 
Islands boas exceeded 30 years of age; Smith 2018c, pers. comm.), but 
typical lifespans in the wild are not known. Sexual maturity is reached 
at 2 to 3 years of age (Tolson 1989, pp. 165-166; Tolson and 
Pi[ntilde]ero 1985, pp. 5-6), and boas are still reproductive at up to 
20 years of age (Tolson 2018, pers. comm.). Females breed biennially, 
but studies have suggested that annual breeding may occur in some 
conditions (Tolson and Pi[ntilde]ero 1985, pp. 6-7). Courtship 
behaviors and copulation occur from February through May, and 
interaction with conspecifics of the opposite sex appears to be 
necessary for reproductive cycling (Tolson 1989, p. 165). The gestation 
period, observed from a single known copulation between two 
individuals, is about 132 days (Tolson 1989, p. 165). Virgin Islands 
boas give birth to live young from late August through October to 
litters of 2 to 10 young, and litter size increases with female body 
size (Tolson 2018, pers. comm.).
    The exact historical distribution of the Virgin Islands boa is 
unknown, but its present disjointed distribution suggests that it was 
once more widely distributed across small islands within its range. In 
the 1970s, when the Virgin Islands boa was listed under the Endangered 
Species Conservation Act of 1969, its range was identified as three 
islands: Puerto Rico (no specific site); St. Thomas, USVI (from a 
single record); and Tortola in the British Virgin Islands (BVI) (from 
one report) (44 FR 70677; December 7, 1979). When the recovery plan was 
written (1986), 71 individuals were reported in two populations: one on 
the eastern side of St. Thomas in the USVI, and one at Cayo Diablo, an 
offshore islet in Puerto Rico (Service 2009, p. 6).
    Currently, the Virgin Islands boa occurs on six islands between 
Puerto Rico, USVI, and BVI: the eastern Puerto Rican islands of Cayo 
Diablo and Culebra; R[iacute]o Grande on the Puerto Rican main island; 
eastern St. Thomas and an offshore cay in USVI (USVI Cay; an introduced 
population); and Tortola. The occurrence of a seventh population (also 
an introduced population) on the Puerto Rican cay of Cayo Ratones is 
considered uncertain after the reestablishment of rats on this island 
possibly sometime after 2004 (Service 2022, p. 24). Surveys in April 
2018 and September 2021 did not find Virgin Islands boas on Cayo 
Ratones (Island Conservation 2018, pp. 5, 17; DNER 2021, unpublished 
data; Puente-Rol[oacute]n et al. 2021, entire), indicating this 
population is likely extirpated. Lastly, there is also one report from 
2004 that the species occurs on Greater St. James Island in St. Thomas, 
but nothing is known about that potential population (Dempsey 2019, 
pers. comm.). In 2009, based on all known populations in Puerto Rico 
and the USVI, an estimated 1,300-1,500 Virgin Islands boas were thought 
to occur (Service 2009, p. 8). However, some population numbers used 
for that estimate are speculative. The current overall estimate of the 
species is unknown, particularly with the likely extirpation of the 
Cayo Ratones population. Based on the 2022 SSA report (Service 2022, 
entire), current population trend estimates for Puerto Rico and USVI 
are either declining, potentially declining, considered rare, or 
unknown, and most populations are small or considered rare (Service 
2022, p. 30).
    The population on Tortola Island, BVI, was confirmed in 2018, but 
there are no specific data regarding the status of that population 
(McGowan 2018, pers. comm.). In addition, according to anecdotal 
reports, the species is thought to occur on Jost Van Dyke, Guana 
Island, Necker Cay, Great Camanoe, and Virgin Gorda of the BVI (Mayer 
and Lazell 1988, entire), but data and confirmed observations are 
limited. There is not enough information to reliably assess the status 
of Virgin Islands boa populations on those islands, and they are not 
included in our analysis.

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations in title 50 of the Code of Federal Regulations set forth 
the procedures for determining whether a species is an endangered 
species or a threatened species, issuing protective regulations for 
threatened species, and designating critical habitat for endangered and 
threatened species. In 2019, jointly with the National Marine Fisheries 
Service, the Service issued a final rule that revised the regulations 
in 50 CFR part 424 regarding how we add, remove, and reclassify 
endangered and threatened species and the criteria for designating 
listed species' critical habitat (84 FR 45020; August 27, 2019). On the 
same day, the Service also issued final regulations that, for species 
listed as threatened species after September 26, 2019, eliminated the 
Service's general protective regulations automatically applying to 
threatened species the prohibitions that section 9 of the Act applies 
to endangered species (84 FR 44753; August 27, 2019).
    The Act defines an ``endangered species'' as a species that is in 
danger of extinction throughout all or a significant portion of its 
range, and a ``threatened species'' as a species that is likely to 
become an endangered species within the foreseeable future throughout 
all or a significant portion of its range. The Act requires that we 
determine whether any species is an ``endangered species'' or a 
``threatened species'' because of any of the following factors:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects.
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the species' expected response and 
the effects of the threats--in light of those actions and conditions 
that will ameliorate the threats--on an individual, population, and 
species level. We evaluate each threat and its

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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 Act's definition of an 
``endangered species'' or a ``threatened species'' only after 
conducting this cumulative analysis and describing the expected effect 
on the species now and in the foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
``foreseeable future'' extends only so far into the future as we can 
reasonably determine that both the future threats and the species' 
responses to those threats are likely. In other words, the foreseeable 
future is the period of time in which we can make reliable predictions. 
``Reliable'' does not mean ``certain''; it means sufficient to provide 
a reasonable degree of confidence in the prediction. Thus, a prediction 
is reliable if it is reasonable to depend on it when making decisions.
    It is not always possible or necessary to define foreseeable future 
as a particular number of years. Analysis of the foreseeable future 
uses the best scientific and commercial data available and should 
consider the timeframes applicable to the relevant threats and to the 
species' likely responses to those threats in view of its life-history 
characteristics. Data that are typically relevant to assessing the 
species' biological response include species-specific factors such as 
lifespan, reproductive rates or productivity, certain behaviors, and 
other demographic factors.

Analytical Framework

    The SSA report (Service 2022, entire) documents the results of our 
comprehensive biological review of the best scientific and commercial 
data regarding the status of the species, including an assessment of 
the potential threats to the species. The SSA report does not represent 
a decision by the Service on whether the species should be listed as an 
endangered or threatened species under the Act. It does, however, 
provide the scientific basis that informs our regulatory decisions, 
which involve the further application of standards within the Act and 
its implementing regulations and policies. The following is a summary 
of the key results and conclusions from the SSA report; the full SSA 
report can be found at Docket FWS-R4-ES-2019-0069 on https://www.regulations.gov.
    To assess Virgin Islands boa's viability, we used the three 
conservation biology principles of resiliency, redundancy, and 
representation (Shaffer and Stein 2000, pp. 306-310). Briefly, 
resiliency supports the ability of the species to withstand 
environmental and demographic stochasticity (for example, wet or dry, 
warm or cold years), redundancy supports 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. We use this information to inform our regulatory 
decision. Our SSA was revised to reflect the comments and new 
information we received during both of the September 30, 2020, proposed 
rule's public comment periods and at the May 12, 2021, public hearing.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
species and its resources, and the threats that influence the species' 
current and future condition, in order to assess the species' overall 
viability and the risks to that viability. In the SSA report (Service 
2022, pp. 12-18), we reviewed all factors (i.e., threats, stressors) 
that could be affecting the Virgin Islands boa now or in the future. 
However, in this document, we will focus our discussion only on those 
factors that could meaningfully impact the status of the species. The 
risk factors affecting the status of the Virgin Islands boa vary from 
location to location, but generally include habitat loss and 
degradation from development, introduced predators, sea level rise 
(SLR) and a changing climate, and public attitudes towards snakes. 
Where habitat is available but the species is not present (i.e., most 
of the small islands in the eastern Puerto Rico bank and USVI), it is 
believed that absences are due to local extirpation resulting from 
habitat degradation and colonization of exotic species (Service 2009, 
p. 11). We discuss each of the risk factors below.

Habitat Loss and Degradation--Development

    Virgin Islands boas occur on both privately and publicly owned 
land. Virgin Islands boas have been observed living in developed areas 
around residences and can persist within developed areas if habitat 
patches are available, but only if no cats or rats are around 
(Platenberg and Harvey 2010, p. 552; Platenberg 2011, p. 11). 
Development continues to impact populations via habitat destruction, 
especially in St. Thomas, R[iacute]o Grande (Puerto Rico), and Culebra 
Island where habitat has declined over decades. In St. Thomas, 
available habitat has declined due to development for resorts, condos, 
and related infrastructure, and habitat has become more constricted and 
isolated (Platenberg and Harvey 2010, p. 552). In Puerto Rico, human 
populations are decreasing, but residential development continues to 
increase island-wide, including around protected areas (Castro-Prieto 
et al. 2017, entire). Consequences of human development on the boa and 
its habitat not only include habitat loss and fragmentation due to 
deforestation, but also mortality from vehicular strikes, an increase 
in predators such as cats and rats, and an increase in human-boa 
conflicts that results in snakes being killed because of fear of snakes 
(Service 2022, pp. 13-14).

Predation and Competition

    One of the primary threats to Virgin Islands boa populations is 
predation by exotic mammalian predators, mainly cats and rats, and 
possibly, to a lesser degree, mongoose. Mongoose are not likely a major 
predator of Virgin Islands boa because mongoose are terrestrial and 
active during the day, while Virgin

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Islands boas are arboreal and active primarily at night, although not 
exclusively (Service 2022, p. 14). Feral cats are known to prey upon 
boas (Tolson 1996b, p. 409), and cat populations around human 
development are further bolstered by cat feeding stations set up by 
residents. There has not been direct evidence of rats preying upon 
Virgin Islands boas, but boas are not present on islands with high 
densities of rats (Tolson 1986ab, unpaginated; Tolson 1988, p. 235). 
Rats likely negatively impact Virgin Islands boas by competing for 
prey, or by inducing behavioral changes in Anolis prey that make them 
less likely to be encountered by boas (Tolson 1988, p. 235). However, 
rats may also predate on neonate boas (Service 1986, p. 12). Complete 
predator removal on large, developed islands is challenging, but is 
feasible on smaller cays. Prior to reintroduction of the boas, rats 
were eliminated from Cayo Ratones and the USVI Cay using anticoagulant 
poison (Tolson 1996b, p. 410), although Cayo Ratones was recolonized by 
rats sometime after August 2004, highlighting the importance of ongoing 
monitoring for rat presence after a removal project. Cayo Ratones was 
thought to harbor one of the most robust Virgin Islands boa 
populations, but during the April 2018 survey (Island Conservation 
2018, p. 20) and more recent September 2021 survey (DNER 2021, 
unpublished data; Puente-Rol[oacute]n et al. 2021, entire), no boas 
were found.

Effects of Climate Change, Including Sea Level Rise

    Climate change will continue to influence the Virgin Islands boa's 
viability into the future. Species such as the Virgin Islands boa, that 
are dependent on specialized habitat types or limited in distribution, 
are the most susceptible to the impacts of climate change (Byers and 
Norris 2011, p. 22).
    The climate in the southeastern United States and Caribbean has 
warmed about 2 degrees Fahrenheit ([deg]F) from a cool period in the 
1960s and 1970s, and temperatures are expected to continue to rise 
(Carter et al. 2014, pp. 398-399). Projections for future precipitation 
trends in this area are less certain than those for temperature, but 
they suggest that overall annual precipitation will decrease and 
tropical storms will occur less frequently but with more force (i.e., 
more category 4 and 5 hurricanes) than historical averages (Carter et 
al. 2014, pp. 398-399; Knutson et al. 2010, pp. 161-162). With 
increasing temperatures and decreasing precipitation, drought could 
negatively influence Virgin Islands boa populations. After a severe 
drought in eastern Puerto Rico, Anolis populations crashed on Cayo 
Diablo, and body condition indices of the boas plummeted (Tolson 2018, 
pers. comm.).
    Sea levels are expected to rise globally, ranging from 0.2 m (7.9 
in) to over 1 m (3 ft) of SLR by the end of the century (Reynolds et 
al. 2012, p. 3; Service 2022, p. 38). Local SLR impacts in the 
Caribbean will depend on how much the ocean level itself rises, and on 
land subsidence or changes in offshore currents, but are predicted to 
range from 0.17 m (6.7 in) to 0.38 m (15.0 in) by 2065 (Carter et al. 
2014, p. 400; Service 2022, p. 38). Impacts on terrestrial ecosystems 
can be temporary, via submergence of habitat during storm surges, or 
permanent, via saltwater intrusion into the water table, inundation of 
habitat, and erosion. SLR and hurricane storm surges in the Caribbean 
are predicted to inundate low-lying islands and parts of larger islands 
(Bellard et al. 2014, pp. 203-204). The low-lying islands of Cayo 
Diablo and the USVI Cay, which support Virgin Islands boa populations, 
and the island of Cayo Ratones, where we are uncertain if the island 
still supports a population, are all vulnerable to SLR and storm surges 
in the future. Boa populations on R[iacute]o Grande, Culebra, and St. 
Thomas are not considered at risk from SLR; however, the three cays 
(Cayo Diablo, Cayo Ratones, and USVI Cay) could see 10-23 percent loss 
of low-lying habitat due to SLR over the next 30 years (Service 2022, 
pp. 38-46). Past and current observations suggest that the species can 
survive major hurricane events, although lasting impacts to habitat, 
particularly die-off of vegetation inundated by storm surges, have been 
observed (Platenberg 2018, pers. comm.; Smith 2018c, pers. comm.; 
Tolson 1991, pp. 12, 16; Yrigoyen 2018, pers. comm.). Loss of habitat 
due to storm surge impacts is similar to loss of habitat due to 
development; loss of low-lying forest habitat could result in decreased 
habitat availability for the Virgin Islands boas and their prey.

Persecution by Residents

    Intentional killing of the more common and larger sized Puerto 
Rican boa (Chilabothrus inornatus) due to fear or superstitious beliefs 
has been well documented (Bird-Pic[oacute] 1994, p. 35; Puente-
Rol[oacute]n and Bird-Pic[oacute] 2004, p. 343; Joglar 2005, p. 146). 
Thus, Virgin Islands boas in proximity to developed areas where people 
fear snakes are susceptible to intentional killings. Public encounters 
with Virgin Islands boas in the more populated R[iacute]o Grande and 
Culebra locations are considered questionable because of the rarity of 
boas in those populations, and there are only a couple of anecdotal 
records of intentional killings in those areas (Service 2009, pp. 15-
16). In the highly developed east side of St. Thomas, about 10 percent 
of the Virgin Islands boa records in St. Thomas are from boas killed by 
humans on private property (Platenberg 2006, unpublished data). We have 
no further information to assess the magnitude of this threat, but it 
is likely that intentional killings of Virgin Islands boas still occur, 
are not being documented, and would be particularly detrimental to rare 
populations such as in R[iacute]o Grande. The Service is not aware of a 
law enforcement case related to the boa in Puerto Rico or the USVI. 
Populations that occur within protected areas are not expected to be 
exposed to this threat.

Conservation Measures and Regulatory Mechanisms That Affect the Species

    Positive influences on the Virgin Islands boa's viability have been 
habitat protection, predator control, and captive breeding and 
reintroduction. Two populations of Virgin Islands boa were reintroduced 
to protected cays after predators had been removed, one on Cayo Ratones 
(Puerto Rico) in 1993, and another on USVI Cay in 2002. Founders for 
these reintroductions came largely from a cooperative captive-breeding 
program initiated in 1985 between the Service, Puerto Rico DNER, U.S. 
Virgin Islands Department of Planning and Natural Resources (VIDPNR), 
and Toledo Zoological Garden. Cayo Diablo provided the founding 
individuals for the captive population that was reintroduced to Cayo 
Ratones (6 kilometers (3.5 miles) away from Cayo Diablo), and St. 
Thomas provided the founding individuals for the captive population 
that was reintroduced to the USVI Cay (4 kilometers (2.5 miles) away 
from St. Thomas).
    The Cayo Ratones population originated from 41 captive-born boas 
(offspring of Cayo Diablo boas) released between 1993 and 1995. Post-
release survival was high: 82.6 percent of individuals and 89 percent 
of neonates survived at least 1 year (Tolson 1996a, unpaginated). By 
2004, the population had grown to an estimated 500 boas (Tolson et al. 
2008, p. 68). Unfortunately, since 2004, Cayo Ratones has been 
recolonized by rats, and no boas were found during surveys in April 
2018 (Island Conservation 2018, pp. 5, 20) and September 2021 (DNER 
2021, unpublished data; Puente-Rol[oacute]n et al. 2021, entire). 
However, because Virgin Islands boas are difficult to find,

[[Page 66356]]

additional surveys are needed to confirm whether a few individuals 
still persist or to conclude that the population is extirpated.
    The USVI Cay reintroduction was initiated with the release of 42 
Virgin Islands boas in 2002 and 2003, 11 from captivity and 31 from St. 
Thomas. Follow-up surveys in 2003-2004 provided an estimate of 168 boas 
(202 boas per hectare), which researchers suspected was near carrying 
capacity for the island (Tolson 2005, p. 9). More recent surveys in 
March 2018 detected 20 boas over 2 nights and 44 boas over 3 nights in 
November and December 2018 (Smith 2018ab, entire). These recent surveys 
revealed a potential decline in abundance and the loss of two prey 
species (Smith 2018ab, entire), possibly as a result of density 
dependence as the population approached carrying capacity after 
reintroduction. Differences in survey and analysis methodologies 
complicate direct comparisons of population size between the surveys. 
Recent surveys also indicate that there are no rats on the island. 
Additional surveys are being conducted by the VIDPNR that will help 
continue to monitor this population and refine current estimates. 
Factors for consideration for future reintroduction sites include the 
presence and amount of suitable habitat (e.g., appropriate forest 
structure, adequate prey base, available refugia), protection status or 
threat of development, the presence/absence/eradication of exotic 
predators, and geomorphology that provides protection from SLR and 
hurricane storm surges that are likely to affect the persistence of 
low-lying habitat. Potential sites for new introductions have been 
suggested (Reynolds et al. 2015, p. 499) and need to be further 
assessed, with one offshore island in St. Thomas as one of the primary 
sites. Some areas may require that predators be removed before boas are 
reintroduced and future monitoring is ensured to prevent recolonization 
by predators. In addition to reintroductions to new sites, augmentation 
of existing populations may prove beneficial or necessary for the 
persistence of existing populations, particularly on developed islands 
and cays where predators have become reestablished.
    Both Puerto Rico and the USVI have regulatory mechanisms 
established to protect the species and its habitat through consultation 
processes for the authorization of development projects. Presently, the 
Virgin Islands boa is legally protected under Puerto Rico's 
Commonwealth Law No. 241-1999 (see title 12 of the Laws of Puerto Rico 
at section 107 et seq. (12 L.P.R.A. sec. 107 et seq.)), known as Nueva 
Ley de Vida Silvestre de Puerto Rico (New Wildlife Law of Puerto Rico). 
This law has provisions to protect habitat for all wildlife species, 
including plants and animals. In addition, the species is protected by 
Puerto Rico DNER's Regulation 6766 (Reglamento para Regir el Manejo de 
las Especies Vulnerables y en Peligro de Extincio[acute]n en el Estado 
Libre Asociado de Puerto Rico (Regulation 6766: To govern the 
management of threatened and endangered species in the Commonwealth of 
Puerto Rico)). Article 2.06 of Regulation 6766 prohibits collecting, 
cutting, and removing, among other activities, listed plant and animal 
individuals within the jurisdiction of Puerto Rico (DRNA 2004, entire). 
In the USVI, Act No. 5665, known as the Virgin Islands' Indigenous and 
Endangered Species Act, which is enforced by the VIDPNR, protects the 
species.
    Despite these regulations being in place, including the requirement 
for developers to conduct environmental assessments and mitigate damage 
to the species and habitat, the regulations have proved difficult to 
enforce, they are often ignored by developers, and they do not cover 
all development activities in all Virgin Islands boa habitat 
(Platenberg 2011, pp. 11-13). For example, in St. Thomas, major permit 
applications submitted for projects in the coastal zone require an 
environmental impact assessment that addresses endangered species and 
protected habitat, but these requirements do not apply to smaller 
projects or those outside of the coastal zone. Furthermore, as noted in 
one study, even though a protocol was developed and applied to 
delineate habitat on protected sites and identify mitigation 
strategies, the absence of a legal mechanism to enforce mitigation has 
led to varying success as developers are slow to accept, and often 
ignore, the mitigation process (Platenberg and Harvey 2010, pp. 551-
552).
    Most offshore cays within the species' range are part of the 
Territorial Government or protected as wildlife refuges, thus formally 
protecting Virgin Islands boa habitat for three of the six populations 
(i.e., Cayo Diablo, Cayo Ratones, and USVI Cay). Cayo Ratones and Cayo 
Diablo are included in La Cordillera Natural Reserve managed by the 
Puerto Rico DNER, and the offshore cay in USVI is managed and protected 
by the VIDPNR. Furthermore, even though Virgin Islands boa habitat on 
privately owned land on Culebra Island is currently under pressure from 
urban and tourism development and deforestation, more than 1,000 acres 
of suitable habitat on the island are protected within the Service's 
Culebra National Wildlife Refuge.
    In conclusion, the Virgin Islands boa still faces the threat of 
development on St. Thomas, R[iacute]o Grande, and Culebra Island, and 
regulatory mechanisms addressing this threat are difficult to enforce 
or do not cover all development actions affecting the species. Human 
development results in habitat loss from deforestation and 
fragmentation, mortality from vehicular strikes, and increased 
predation by cats and rats. In addition, impacts from changes in 
climate could affect habitat. Drought could negatively influence Virgin 
Islands boa populations through loss of prey. SLR and storm surges are 
expected to inundate low-lying islands, such as Cayo Diablo, Cayo 
Ratones, and the USVI Cay, which currently support Virgin Islands boa 
populations. Finally, persecution of boas by citizens, due to fear or 
superstition, can affect individual boas, although there has never been 
a systematic study of the impact of these events on the overall 
population.
    When considering conservation actions and how they influence the 
viability of Virgin Islands boa, about half of known localities where 
Virgin Islands boas occur are on small offshore islets managed for 
conservation. In addition, predator removal has been successful at 
smaller cays, such as USVI Cay, although the reestablishment of rats on 
Cayo Ratones illustrates the need for continued monitoring and removal 
efforts. Lastly, successful reintroductions of Virgin Islands boas 
occurred on these islands after the eradication of predators.

Current Condition

    For the Virgin Islands boa to maintain viability, its populations, 
or some portion thereof, must be resilient. For the SSA report (Service 
2022, entire), our classification of resiliency relied heavily on 
habitat characteristics in the absence of a certain population size for 
most populations or trend estimates. The habitat characteristics we 
assessed were degree of habitat protection (or, conversely, development 
risk), presence of introduced predators, and vulnerability to storm 
surges (Service 2022, p. 31).
    Representation can be measured by the breadth of genetic or 
environmental diversity within and among populations and gauges the 
probability that a species is capable of adapting to environmental 
changes. A rangewide genetic analysis of the Virgin Islands boa showed 
there was little genetic variation; however, the

[[Page 66357]]

same study found that each sampled locality had unique mtDNA 
haplotypes, indicating a lack of gene flow between islands 
(Rodr[iacute]guez-Robles et al. 2015, entire). Therefore, in the SSA 
report we used genetics to delineate representative units.
    The species also needs to exhibit some degree of redundancy in 
order to maintain viability. Catastrophic events that could affect both 
single and multiple populations of the Virgin Islands boa include 
drought, hurricanes, and colonization or recolonization of exotic 
predators. This species occurs in geographically isolated groups and 
does not disperse from island to island to interact and interbreed; 
therefore, for purposes of analyzing redundancy, all boas within each 
island were considered to be individual populations.

Resiliency

    Because resiliency is a population-level attribute, the key to 
assessing it is the ability to delineate populations. As discussed 
above, we considered all boas within each island to be single 
populations. On small offshore cays, what we define as a population 
might consist of a single interbreeding deme (or subdivision) of Virgin 
Islands boas. On larger islands, what we define as a population 
functions more as a metapopulation, with multiple interbreeding groups 
in isolated habitat patches that may interact weakly via dispersal and 
recolonization of extirpated patches. Alternately, multiple occupied 
patches on large islands may be completely isolated from one another 
(Service 2022, p. 20).
    Six island populations were considered: Cayo Diablo, Cayo Ratones, 
Culebra Island, R[iacute]o Grande (Puerto Rico), St. Thomas, and USVI 
Cay (USVI). Further, one or more populations exist in the BVI (e.g., 
Tortola), but data are severely limited, and for the SSA report, we 
lacked sufficient data from these islands to incorporate them into our 
viability analysis. In addition, other populations may occur on other 
offshore islands in Puerto Rico and USVI, but most have not been 
searched for Virgin Islands boas and we could not confirm any to be 
extant at the time we completed our analysis.
    Resiliency scores for each population were generated by combining 
scores for three habitat metrics ((1) protection/development risk, (2) 
exotic mammals, and (3) storm surge risk) and one population metric 
(population size and/or trend, dependent on availability). Each metric 
was weighted equally, with the overall effect that habitat (three 
metrics) was weighted three times higher than population size/trend 
(one metric). For each metric, populations were assigned a score of -1, 
0, or 1, as described below in table 1.
    The scores were based on the best available information for each 
population, gathered from the literature and species experts. 
Monitoring data are scarce. The Virgin Islands boa recovery plan 
(Service 1986, pp. 16-19) called for periodic monitoring to estimate 
population sizes and trends, but surveys since then have been few and 
far between. Survey methodology and reporting have varied from 
population to population, with survey results given as estimated 
abundances, estimated densities, or encounter rates per person-hour of 
searching. The above-described factors in combination contribute to 
high levels of uncertainty in current and past population sizes, and 
how they have changed over time. Accordingly, resiliency 
classifications relied more heavily on habitat conditions than 
population size and trend estimates.

  Table 1--Description of Habitat and Population Factor Scores To Determine the Virgin Islands Boa's Population
                                                   Resiliency
----------------------------------------------------------------------------------------------------------------
                                                   Habitat metrics                            Population metric
                         ---------------------------------------------------------------------------------------
          Score            Habitat protection/                                                Population Size/
                            development risk       Exotic mammals       Storm surge risk           Trend *
----------------------------------------------------------------------------------------------------------------
-1......................  Habitat not           Exotic mammals        Topography and        Relatively low
                           protected, at risk    present.              elevation leaves      population size and/
                           of being developed.                         population            or declining trend.
                                                                       vulnerable to storm
                                                                       surges.
0.......................  Some habitat          Not applicable (not   Not applicable (not    Relatively
                           protected, some at    present).             an issue).            moderate population
                           risk of being                                                     size and stable
                           developed.                                                        trend, or
                                                                                             High degree
                                                                                             of uncertainty in
                                                                                             population size/
                                                                                             trends.
1.......................  Habitat protected in  Exotic mammals        Protected by          Relatively high
                           identified            absent.               topography and        population size and/
                           protected area.                             elevation.            or growth.
----------------------------------------------------------------------------------------------------------------
* Population size/trend scores are relative and were based on the best available information for each
  population, gathered from the literature and species experts.

    The scores for each population across all metrics were summed, and 
final population resiliency categories were assigned as follows:

Low Resiliency: -4 to -2
Moderately Low Resiliency: -1
Moderate Resiliency: 0
Moderately High Resiliency: 1
High Resiliency: 2 to 4

    Applying these resiliency categories to the six populations of 
Virgin Islands boa, we determined that two populations have moderate 
resiliency (Cayo Diablo and USVI Cay), one has moderately low 
resiliency (Culebra), two have low resiliency (R[iacute]o Grande and 
St. Thomas), and one has no resiliency because it is presumed to be 
extirpated (Cayo Ratones).
    One of the populations classified as having moderate resiliency 
(Cayo Diablo) occurs on a small offshore island that is free of exotic 
rats and cats and is protected for conservation. Boas have been 
consistently found on Cayo Diablo, with an April 2018 survey detecting 
10 boas (Island Conservation 2018, entire), one in November 2018 that 
detected 14 boas (DNER 2018, unpublished data), and one in April 2022 
that detected 2 boas (Smith 2022, unpublished data). Using the April 
2018 data, extrapolating the density within the transect area (2.9 boas 
per hectare) to the entire island, the model provides an estimate of 20 
boas on the island (95 percent confidence interval 13-39). This number 
is lower than earlier unpublished survey results; however, direct 
comparisons cannot be made with past surveys because of different 
survey and analytical methodologies (Service 2022, p. 23). The previous 
efforts in 1993 had marked over 250 snakes in Cayo Diablo (Tolson 
1996b, p. 411),

[[Page 66358]]

with an estimate of approximately 500 boas in the cay. Because of the 
protected and exotic-mammal-free state of the habitat, but with 
potentially declining numbers, this Cayo Diablo population is 
considered to have moderate resiliency to demographic and environmental 
stochastic events and disturbances (e.g., fluctuations in demographic 
rates, variation in climatic conditions, illegal human activities).
    The USVI Cay population, also on a protected offshore island with 
no exotic mammals, was also determined to have moderate resiliency. 
Previous survey efforts from 2004 resulted in a population estimate of 
168 snakes (Tolson 2005, p. 9). Recent surveys have revealed a 
potential decline in abundance and the loss of two prey species (Smith 
2018ab, entire), possibly as a result of density dependence as the 
population approached carrying capacity after reintroduction. Over two 
separate survey efforts in 2018, researchers found a total of 64 boas, 
including 10 recaptures (Smith 2018ab, entire). Additional surveys are 
being conducted by the VIDPNR, and although we do not have the results, 
additional boas have been detected (VIDPNR 2022, unpublished data).
    The Culebra population, with some portions of habitat protected as 
part of Culebra National Wildlife Refuge, was determined to have 
moderately low resiliency. Surveys in 2018 found no boas (Island 
Conservation 2018, p. 20); however, two individuals were documented in 
February 2019 within the Culebra National Wildlife Refuge (Puente-
Rol[oacute]n and Vega-Castillo 2019, p. 18). In October 2019, another 
individual was confirmed in an area outside of the refuge (Rom[aacute]n 
2019, pers. comm.).
    Three of the populations (R[iacute]o Grande, Culebra, and St. 
Thomas) with moderately low or low resiliency occur on larger and 
higher elevation islands, which provide more protection from storm 
surges, but have more human-boa interactions, habitat loss and 
fragmentation from development, and exotic cats and rats. Recent 
surveys in 2018 on R[iacute]o Grande found three boas (three survey 
nights) (Island Conservation 2018, p. 20). For St. Thomas, there have 
been no recent systematic surveys for the species as much of eastern 
St. Thomas is inaccessible due to private ownership or impenetrable 
habitat. Previous uncertain conservative estimates for this population 
ranged from 300 to 400 individuals (Tolson 1991, p. 12) to fewer than 
100 individuals based on effective population size estimates (Reynolds 
et al. 2015, p. 498).
    The remaining Cayo Ratones population is classified as not having 
resiliency because of the recolonization of rats on the island and 
subsequent declining trend of boas, which we presume to be extirpated, 
as no boas were detected during recent survey efforts conducted in 
April 2018 and September 2021.

Representation

    A rangewide genetic analysis of Virgin Islands boa showed that 
there was little genetic variation within the species 
(Rodr[iacute]guez-Robles et al. 2015, p. 150), supporting the idea that 
there is only one representative unit of Virgin Islands boa. However, 
each sampled island, and each sampled locality within the same island, 
had unique mtDNA haplotypes, indicating a lack of gene flow between 
islands/populations (Rodr[iacute]guez-Robles et al. 2015, p. 150). 
These results suggest that each population has a different genetic 
signature, perhaps as a result of genetic adaptations to their local 
environment, or genetic drift with increasing isolation of small 
populations. The reintroduction program took this view, and managed 
captive populations sourced from Cayo Diablo and St. Thomas separately 
(Tolson 1996b, p. 412). To minimize the chances of introducing 
individuals poorly suited to their new environment, the captive 
population sourced from Cayo Diablo founded the reintroduced population 
on nearby Cayo Ratones, and the captive St. Thomas population founded 
the reintroduced population on the nearby USVI Cay (Tolson 1996b, p. 
412).
    In addition to genetic differences, the six populations also have 
noticeable phenotypic differences. These are not just limited to 
coloration differences between USVI and Puerto Rican populations 
(Tolson 1996b, p. 412); Cayo Diablo reportedly has lighter coloration 
than the R[iacute]o Grande and Culebra populations (Tolson 2018, pers. 
comm.). The R[iacute]o Grande population also occurs in a different 
habitat type (subtropical moist forest) than the others (subtropical 
dry or littoral forest; Tolson 1996b, p. 410).
    In light of this information, we considered each of the four 
natural populations in Puerto Rico and USVI as a representative unit 
(see table 2, below). The Cayo Diablo population is considered to have 
moderate resiliency. As this was the source for the now presumed 
extirpated Cayo Ratones population, there is only one population 
representing the Cayo Diablo genetic signature. The USVI Cay population 
was sourced from St. Thomas, so there are two populations with St. 
Thomas representation, with neither considered to have high resiliency. 
The other two natural populations, Culebra and R[iacute]o Grande, both 
characterized as having moderately low or low resiliency, have not been 
used for captive breeding and reintroduction, and so have no additional 
populations on other islands with the same genetic characteristics. 
Overall, two of four representative units have at least one moderately 
resilient population.

       Table 2--Representation: Number of Virgin Islands Boa Populations of Each Resiliency Class in Each
   Representative Unit, Corresponding to Natural (Not Introduced) Populations, Which Themselves Correspond to
                                            Unique Genetic Signatures
----------------------------------------------------------------------------------------------------------------
                                                                      High or                         Low or
                                                                    moderately       Moderate       moderately
             Natural population  (genetic signature)                   high         resilience    low resilience
                                                                    resilience      populations     populations
                                                                    populations                    or extirpated
----------------------------------------------------------------------------------------------------------------
Cayo Diablo.....................................................               0               1               1
Culebra.........................................................               0               0               1
R[iacute]o Grande...............................................               0               0               1
St. Thomas......................................................               0               1               1
----------------------------------------------------------------------------------------------------------------

    While currently we could consider the USVI Cay reintroduced 
population (currently with moderate resiliency) to be a redundant 
population sharing the same genetic signature and adaptive potential as 
its source population, all

[[Page 66359]]

islands occupied by Virgin Islands boa are isolated from each other. 
Without human-mediated movement of boas between islands, reintroduced 
populations are expected to diverge genetically from their source 
populations over time, and may at some point in the future (decades to 
centuries; Reynolds et al. 2015, entire) be different enough to be 
considered their own unique representative unit.

Redundancy

    Redundancy describes the ability of a species to withstand 
catastrophic events. Measured by the number of populations, their 
resiliency (ability of a species to withstand environmental and 
demographic stochasticity (e.g., wet or dry years)) and their 
distribution (and connectivity), redundancy gauges the probability that 
the species has a margin of safety to withstand or return from 
catastrophic events (such as a rare destructive natural event or 
episode involving many populations).
    The exact historical distribution of the Virgin Islands boa is 
unknown, but its present disjointed distribution suggests that it was 
once more widely distributed across small islands within its range, 
which have been subject to local extirpations from habitat degradation, 
invasive species, and historical climate and sea level changes. 
However, for current redundancy, we identified the five populations in 
Puerto Rico and USVI. As discussed above, two of these populations are 
considered to have a moderate level of resiliency, which provides some 
ability to withstand the effects of catastrophic events. However, these 
populations are considered small and potentially declining or trend 
unknown. Therefore, overall redundancy for the species is low.

Current Condition Summary

    Of the six assessed populations, the Cayo Diablo population and the 
USVI Cay population have moderate resiliency and the Culebra population 
has moderately low resiliency. The other three assessed populations 
currently have low resiliency or are likely extirpated (Cayo Ratones). 
Redundancy for the species includes populations on five islands in 
Puerto Rico and USVI, and possibly more in the BVI, although islands in 
the BVI are not part of this assessment. Representation consists of 
four representative units, one of which has two populations 
representing its genetic signature, and two of the four units have 
populations with moderate levels of resiliency.
    The Virgin Islands boa has demonstrated some ability to adapt to 
changing environmental conditions over time from both anthropogenic 
threats (e.g., habitat disturbance due to development) and natural 
disturbances (e.g., predation and hurricanes). Compared to the species' 
distribution at the time of listing (see 35 FR 16047; October 13, 
1970), which included three locations (Puerto Rico, St. Thomas, and 
Tortola), the species currently has five populations (potentially more 
if others are eventually confirmed). Two of the five current 
populations exhibit moderate levels of resiliency, whereas three 
exhibit moderately low to low resiliency. One other assessed population 
is presumed extirpated (Cayo Ratones).
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. Our assessment of the 
current and future conditions encompasses and incorporates the threats 
individually and cumulatively. Our current and future condition 
assessment is iterative because it accumulates and evaluates the 
effects of all the 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.

Future Conditions

    Because we determined that the current condition of the Virgin 
Islands boa is consistent with an endangered species (see Determination 
of Status, below), we are not presenting the results of the future 
scenarios in this withdrawal. For more information on the future 
condition, future threats, and future scenarios for the Virgin Islands 
boa, see the SSA report (Service 2022, pp. 36-60).

Determination of Virgin Islands Boa's Status

    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 ``endangered species'' or 
``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 a species meets the definition of 
``endangered species'' or ``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.

Status Throughout All of Its Range

    Compared to the species' distribution at the time of listing (see 
35 FR 16047; October 13, 1970), which included three locations (Puerto 
Rico, St. Thomas, and Tortola), Virgin Islands boa currently has five 
extant populations (potentially more if others are eventually 
confirmed), and one presumed extirpated population. None of the 
populations exhibit high resiliency; only two of the six current 
populations exhibit moderate level of resiliency (Cayo Diablo and USVI 
Cay), one has moderately low resiliency (Culebra), two exhibit low 
resiliency (Rio Grande and St. Thomas), and one is considered presumed 
extirpated (Cayo Ratones). Recent surveys indicate that current 
population trend estimates are either declining, potentially declining, 
considered rare, or unknown and most populations are small or 
considered rare (Service 2022, p. 30). Three of the populations are 
currently impacted by habitat loss and degradation by development, 
three populations are at high risk from storm surges, and three of five 
populations are under imminent threat by exotic mammal predation. The 
species does not have enough current redundancy, lacking highly 
resilient populations and having only two moderately resilient 
populations; thus, the species is at risk from catastrophic events. In 
addition, as the species lacks multiple resilient populations that 
contribute to the genetic diversity of the species, thus limiting 
species representation or overall future adaptive capacity.
    In summary, due to the new information we received during both of 
the September 30, 2020, proposed rule's public comment periods and at 
the May 12, 2021, public hearing, we find that there is no longer 
sufficient evidence to justify reclassifying the Virgin Islands boa as 
a threatened species, and the

[[Page 66360]]

species still meets the Act's definition of an endangered species. The 
new information included the probable extirpation of Virgin Islands 
boas due to colonization of rats on Cayo Ratones, and an error in 
calculations affecting the current resiliency score for the Cayo Diablo 
population. Based on our revised SSA report (Service 2022, entire) 
incorporating this new information, estimates of current resiliency for 
the Virgin Islands boa are low, as are estimates for representation and 
redundancy. The Virgin Islands boa faces a variety of ongoing threats 
from habitat loss and degradation from development, introduced 
predators, SLR and a changing climate, and public attitudes towards 
snakes. Given current rates of resiliency, populations are vulnerable 
to extirpation from stochastic events, in turn, resulting in concurrent 
losses in representation and redundancy. For these reasons, the Virgin 
Islands boa is in danger of extinction throughout its range.

Status Throughout a Significant Portion of Its Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. We have determined that the Virgin Islands boa 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 boa 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) (Everson), which 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'' (79 FR 37578; July 1, 2014) providing that if 
the Service determines that a species is threatened throughout all of 
its range, the Service will not analyze whether the species is 
endangered in a significant portion of its range.

Determination of Status

    Our review of the best available scientific and commercial 
information indicates that the Virgin Islands boa continues to meet the 
Act's definition of an endangered species. Therefore, in accordance 
with section 4(b)(6)(A)(i)(IV) of the Act, we withdraw our proposed 
rule to reclassify the Virgin Islands boa as a threatened species with 
a rule issued under section 4(d) of the Act.

References Cited

    A complete list of references cited in this document is available 
on the internet at https://www.regulations.gov and upon request from 
the Caribbean Ecological Services Field Office (see FOR FURTHER 
INFORMATION CONTACT).

Authors

    The primary authors of this document are the staff members of the 
Fish and Wildlife Service's Species Assessment Team and the Caribbean 
Ecological Services Field Office.

Authority

    The authority for this action is the Endangered Species Act of 
1973, as amended (16 U.S.C. 1531 et seq.).

Martha Williams,
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023-20946 Filed 9-26-23; 8:45 am]
BILLING CODE 4333-15-P