Proposed Rule2026-05678
Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for 22 Species in the Commonwealth of the Northern Mariana Islands and the Territory of Guam
Primary source
Metadata and text below are from the Federal Register, a public-domain U.S. government work. Always verify the official published version before relying on it for any legal matter.
Published
March 24, 2026
Issuing agencies
Interior DepartmentFish and Wildlife Service
Abstract
We, the U.S. Fish and Wildlife Service (Service), propose to designate critical habitat for 9 animal species and 13 plant species from the Mariana Islands (the U.S. Territory of Guam and the Commonwealth of Northern Mariana Islands) under the Endangered Species Act (Act). In total across both the Territory and Commonwealth, approximately 59,886 acres (24,235 hectares) on the islands of Aguiguan, Alamagan, Asunci[oacute]n, Guam (including the island of Cocos), Pagan, Rota, Saipan, Sarigan, and Tinian fall within the boundaries of the proposed critical habitat designation. We also announce the availability of an economic analysis of the proposed designation of critical habitat for these species.
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[Federal Register Volume 91, Number 56 (Tuesday, March 24, 2026)]
[Proposed Rules]
[Pages 14074-14303]
From the Federal Register Online via the Government Publishing Office [<a href="http://www.gpo.gov">www.gpo.gov</a>]
[FR Doc No: 2026-05678]
[[Page 14073]]
Vol. 91
Tuesday,
No. 56
March 24, 2026
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; Designation of Critical
Habitat for 22 Species in the Commonwealth of the Northern Mariana
Islands and the Territory of Guam; Proposed Rule
Federal Register / Vol. 91 , No. 56 / Tuesday, March 24, 2026 /
Proposed Rules
[[Page 14074]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R1-ES-2024-0194; FXES1111090FEDR-267-FF09E21000]
RIN 1018-BI17
Endangered and Threatened Wildlife and Plants; Designation of
Critical Habitat for 22 Species in the Commonwealth of the Northern
Mariana Islands and the Territory of Guam
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
designate critical habitat for 9 animal species and 13 plant species
from the Mariana Islands (the U.S. Territory of Guam and the
Commonwealth of Northern Mariana Islands) under the Endangered Species
Act (Act). In total across both the Territory and Commonwealth,
approximately 59,886 acres (24,235 hectares) on the islands of
Aguiguan, Alamagan, Asunci[oacute]n, Guam (including the island of
Cocos), Pagan, Rota, Saipan, Sarigan, and Tinian fall within the
boundaries of the proposed critical habitat designation. We also
announce the availability of an economic analysis of the proposed
designation of critical habitat for these species.
DATES: We will accept comments received or postmarked on or before June
22, 2026. 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 May 8, 2026.
ADDRESSES:
Comment Submission: 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-R1-ES-2024-0194,
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-R1-ES-2024-0194, 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 economic analysis, are available on the Service's website at
<a href="https://www.fws.gov/project/critical-habitat-mariana-islands">https://www.fws.gov/project/critical-habitat-mariana-islands</a>, at
<a href="https://www.regulations.gov">https://www.regulations.gov</a> at Docket No. FWS-R1-ES-2024-0194, or both.
If we finalize the critical habitat designation, we will make the
coordinates or plot points or both from which the maps are generated
available at <a href="https://www.regulations.gov">https://www.regulations.gov</a> at Docket No. FWS-R1-ES-2024-
0194 and on the Service's website at <a href="https://www.fws.gov/project/critical-habitat-mariana-islands">https://www.fws.gov/project/critical-habitat-mariana-islands</a>.
FOR FURTHER INFORMATION CONTACT: Earl W. Campbell, Project Leader, U.S.
Fish and Wildlife Service, Pacific Islands Fish and Wildlife Office,
300 Ala Moana Boulevard, Room 3-122, Honolulu, HI 96850; by telephone
808-792-9400. 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-R1-ES-2024-0194 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 (16 U.S.C. 1531 et
seq.), when we determine that any species is an endangered or
threatened species, we are required to designate critical habitat, to
the maximum extent prudent and determinable. Designations and revisions
of critical habitat can be completed only by issuing a rule through the
Administrative Procedure Act rulemaking process (5 U.S.C. 551 et seq.).
We are proposing a designation of critical habitat for 22 Mariana
Islands species, totaling 59,886 acres (ac) (24,235 hectares (ha)). We
have also identified lands that meet the definition of critical habitat
for another Mariana Island species, an endangered plant species,
Solanum guamense (birenghenas h[aring]lom t[aring]no', biringhenas
halumt[aring]nu', birengenas h[aring]lomt[aring]no'), but that does not
have a proposed critical habitat designation in this proposed rule
because the identified lands are exempt from being designated as
critical habitat in accordance with section 4(a)(3)(B)(i) of the Act.
For the sake of brevity, throughout this document we collectively
refer to these species as the ``Mariana Islands species, also
including/noting reference to Solanum guamense, when applicable.''
Sixteen of the Mariana Islands species were previously listed as
endangered species (80 FR 59424; October 1, 2015): seven plants--
Eugenia bryanii (no common name), Hedyotis megalantha (pao de'do',
p[aring]ode'du', pao doodu), Heritiera longipetiolata (ufa
h[aring]lumt[aring]no', ufa halumt[aring]nu', ufa
h[aring]lomt[aring]no'), Phyllanthus saffordii (maigo' l[aring]lo'),
Psychotria malaspinae ([aring]plohk[aring]teng palao'an, [aring]pplok
hatting palao'an, aplokkating pal[aring]o'an), Solanum guamense, and
Tinospora homosepala (no common name); and nine animals--the Pacific
sheath-tailed bat (Mariana subspecies, Emballonura semicaudata
rotensis; paye'ye', payesyes, fanihen g[aring]nas, paye'yi', payesyis,
fanihin g[aring]nas, paischeey), Slevin's skink (Emoia slevini;
Marianas Emoia, Mariana skink, gu[aring]li'ek h[aring]lomt[aring]no',
gholuuf, guali'ik halumt[aring]nu'), Mariana eight-spot butterfly
(Hypolimnas octocula marianensis; ababang, ababbang, libweibwogh),
Mariana wandering butterfly (Vagrans egistina; ababang, ababbang,
libweibwogh), Rota blue damselfly (Ischnura luta; dulalas Luta),
fragile tree snail (Samoana fragilis; dengdeng, dengding, akaleha',
denden), Guam tree snail (Partula radiolata; dengdeng, dengding,
akaleha', denden), humped tree snail (Partula gibba; dengdeng,
dengding, akaleha', denden), and Langford's tree snail (Partula
langfordi; dengdeng, dengding, akaleha', denden). Seven of the 23
Mariana Islands species, all plants, were previously listed as
threatened species (80 FR 59424; October 1, 2015): Bulbophyllum
guamense (wild onion, siboyas h[aring]lomt[aring]no', siboyas
halumt[aring]nu', siboyan h[aring]lomt[aring]no'), Dendrobium guamense
(no common name), Cycas micronesica (fadang, faadang), Maesa walkeri
(no common name), Nervilia jacksoniae (no common name), Tabernaemontana
rotensis (no common name), and Tuberolabium guamense (no common name).
Additionally, we note that a 5-year status review for Tuberolabium
[[Page 14075]]
guamense was completed on August 4, 2025, recommending we remove the
species from the Federal List of Endangered and Threatened Plants.
Recommendations in 5-year reviews are not final agency decisions and we
have not initiated work on a proposed delisting rule as of publication
of this proposed critical habitat designation; however, if we finalize
a delisting rule for Tuberolabium guamense, the conservation measures
provided by the Act (e.g., through sections 7 and 9) would no longer
apply to Tuberolabium guamense, and we would also remove critical
habitat for the species.
What this document does. We propose the designation of critical
habitat for 22 wildlife and plant species that occur on islands within
the Territory of Guam and the Commonwealth of the Northern Mariana
Islands.
The basis for our action.
Under section 4(a)(3) of the Act, if we determine that a species is
an endangered or threatened species we must, to the maximum extent
prudent and determinable, designate critical habitat.
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 and commercial 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.
Acronyms and Abbreviations Used in This Proposed Rule
For the convenience of the reader, listed below are some of the
acronyms and abbreviations used in this proposed rule:
Act = Endangered Species Act
AFB = Air Force Base
CBA = Conservation Benefit Agreement
CFR = Code of Federal Regulations
CNMI = Commonwealth of the Northern Mariana Islands
CNMI BECQ = CNMI Bureau of Environmental and Coastal Quality
CNMI BTS Program = CNMI Division of Fish and Wildlife Brown Tree
Snake Interdiction Program
CNMI DEQ = CNMI Division of Environmental Quality
CNMI DFW = CNMI Division of Fish and Wildlife
CNMI DPL = CNMI Department of Public Lands
CNMI FDoA = CNMI Forestry Division of Agriculture--Department of
Lands and Natural Resources
CNMI OPD = CNMI Office of the Governor, Office of Planning and
Development
CNMI SWARS = CNMI's Statewide Assessment and Resource Strategy
Council
DHS = Department of Homeland Security
DoD = Department of Defense
DoN = U.S. Department of Navy
GDAWR = Guam Division of Aquatic and Wildlife Resources
GDPR = Guam Department of Parks and Recreation
GPEPP = Guam Plant Extinction Prevention Program
IEM = Incremental Effects Memorandum
INRMP = Integrated Natural Resources Management Plan
JRM = Joint Region Marianas
MOA = Memorandum of Agreement
MCB = Marine Corps Base
NHP = National Historical Park
NMFS = National Marine Fisheries Service
NPS = U.S. National Park Service
NWR = National Wildlife Refuge
PBF = Physical or Biological Feature
RFA = Regulatory Flexibility Act
Service = U.S. Fish and Wildlife Service
SSP = Socio-Economic Pathway
USDA WS = U.S. Department of Agriculture Wildlife Services
USGS = U.S. Geological Survey
UOG = University of Guam
Information Requested
We intend that any final action 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, the
indigenous community, the scientific community, industry, or any other
interested parties concerning this proposed rule. We particularly seek
comments concerning:
(1) Specific information on:
(a) The amount and distribution of habitat for the Mariana Islands
species;
(b) Any additional areas occurring within the range of the Mariana
Islands species 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) Modifications that may be necessary for different types of
projects to ensure protection of physical or biological features for a
given species;
(d) Special management considerations or protection that may be
needed in critical habitat areas we are proposing, including managing
for the potential effects of climate change; and
(e) For the Pacific sheath-tailed bat, whether areas not occupied
at the time of listing qualify as habitat for the species and are
essential for the conservation of the species.
(2) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat.
(3) Information on any specific areas that we have identified as
``uncategorized'' land ownership.
(4) 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.
(5) Information on the extent to which the description of probable
economic impacts in the economic analysis is a reasonable estimate of
the likely economic impacts and any additional information regarding
probable economic impacts that we should consider, particularly the
impact on land values of private lands included in the critical habitat
designation.
(6) Information on how project modifications may impact affected
areas--especially considering the remoteness of some islands and the
role of Federal funding in local economies.
(7) 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, in particular for those that we are
considering for exclusion, including the Memorandum of Agreement (MOA)
for the Mariana Crow ([aring]ga or Corvus kubaryi) Conservation Area
(includes a 684-ac (277-ha) portion of the I'Chenchon Bird Sanctuary),
Rota Local Law No. 9-1 for the Sabana Protected Area (Commonwealth of
Northern Mariana Islands (CNMI) 1994, entire), and the Talakhaya
Integrated Watershed Management Plan (CNMI DEQ 2012, entire). If you
think we should exclude any additional areas, such as the areas under
consideration within the draft Guam Habitat Conservation Plan that is
in an early stage of development, or the Anao, Bolanos, and Cotal
Conservation
[[Page 14076]]
Areas, please provide information supporting a benefit of exclusion.
(8) 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)(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 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 designation may differ from this proposal because we will
consider all comments we receive during the comment period as well as
any information that may become available after this proposal. Based on
the new information we receive (and, if relevant, any comments on that
new information), our final designation may not include all areas
proposed, may include additional areas that meet the definition of
critical habitat, or may exclude 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 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 Hearings
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
It is our intent to discuss in this document only those topics
directly relevant to the proposed designation of critical habitat for
the 22 Mariana Islands species. For more information on the taxonomy,
biology, and ecology of the Mariana Islands species addressed in this
proposed rule, refer to the final listing rule that published in the
Federal Register on October 1, 2015 (80 FR 59424), available online at
<a href="https://www.regulations.gov">https://www.regulations.gov</a> (at Docket No. FWS-R1-ES-2014-0038).
On July 20, 2021, the Center for Biological Diversity (Plaintiff)
filed a complaint (Case No. 21-CV-00017) alleging that the Service
violated the Act by failing to comply with the statutory deadline for
designating critical habitat for 23 Mariana Islands species listed on
October 1, 2015 (80 FR 59424). On April 18, 2022, the parties entered
into a stipulated settlement agreement, which was subsequently approved
by the Court, whereby the Service agreed to submit to the Federal
Register proposed critical habitat designations for the species in the
complaint on or before June 26, 2025. In compliance with the settlement
agreement, this document constitutes the proposed critical habitat
designation for 22 of the species where the Service has jurisdiction to
designate critical habitat. For one of the species (i.e., Solanum
guamense), the areas that meet the definition of critical habitat are
exempt under section 4(a)(3)(B)(i) of the Act (see Exemptions, below).
Therefore, there is no critical habitat designation proposed for
Solanum guamense.
Peer Review
In accordance with our joint policy on peer review published in the
Federal Register on July 1, 1994 (59 FR 34270), and our August 22,
2016, memorandum updating and clarifying the role of peer review in
listing and recovery actions under the Act, we are soliciting
independent scientific review of this proposed critical habitat
designation to ensure that this proposal is based on scientifically
sound data and analysis. We have invited peer reviewers to comment on
our specific assumptions, methodology, and science used in this
proposed rule, and we will consider any comments received, as
appropriate, before a final agency determination.
The Mariana Islands
The Mariana Islands are a longitudinally arranged archipelago
consisting of 15 main islands and various smaller islets located in
western Micronesia between latitudes 21[deg] and 13[deg] N and
longitudes 144[deg] and 146[deg] E. The primarily volcanic northern
islands include Farallon de Medinilla, Anatahan, Sarigan, Guguan,
Alamagan, Pagan, Agrihan, Asuncion, Maug, and Uracas, while the
limestone and volcanic southern islands include Guam, Rota, Aguiguan,
Tinian, and Saipan. The northern islands of Anatahan, Guguan, Alamagan,
Asuncion, Pagan, and Uracas are still volcanically active. Only the
southern islands of Guam (including Cocos Island), Rota, Tinian, and
Saipan are regularly inhabited by humans; all the other Mariana Islands
are considered uninhabited, although some (e.g., Aguiguan, Pagan) may
be visited on occasion. Please see the proposed listing rule (79 FR
59364 at 59367-59377, October 1, 2014) for more background information
on the Mariana Islands' geography, vegetation, hydrology, climate,
biogeography, historical and current human impacts, political division,
island-specific descriptions, and details regarding the ecosystems upon
which the species addressed in this proposed rulemaking action depend.
Common Name Changes
Following publication of the final listing rule (80 FR 59424;
October 1, 2015), we have identified new common names for some of the
Mariana Islands species. Table 1 is a list of the species' Latin names,
and updated common names, including corrected versions (the column
``Common name(s) updated'' includes all currently known common names).
Common names are not regulatory and may be updated without a rulemaking
action; these names are included here for transparency. Diacritical
marks are included in table 1 but not in the proposed regulations.
[[Page 14077]]
Table 1--23 Mariana Islands Species: Latin Names and New Common Names
[\ChG\ = Chamorro name in Guam's spelling, \ChCNMI\ = Chamorro name in
CNMI's spelling, \Ca\ = Carolinian name, NCN = no common name]
------------------------------------------------------------------------
Latin name Common name(s) updated
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Emballonura semicaudata rotensis.. Pacific sheath-tailed bat, paye'ye'
\ChG\, payesyes \ChG\, fanihen
g[aring]nas \ChG\, paye'yi'
\ChCNMI\, payesyis \ChCNMI\,
fanihin g[aring]nas \ChCNMI\,
paischeey \Ca\.
Emoia slevini..................... Slevin's skink, Marianas Emoia,
Mariana skink, gu[aring]li'ek
h[aring]lomt[aring]no' \ChG\,
gholuuf \Ca\, guali'ik
halumt[aring]nu' \ChCNMI\.
Samoana fragilis.................. fragile tree snail, dengdeng \ChG\,
dengding \ ChCNMI\,
akaleha' \ChG>\&\ChCNMI\, denden
\Ca\.
Partula radiolata................. Guam tree snail, dengdeng \ChG\,
dengding \ ChCNMI\,
akaleha' \ChG>\&\ChCNMI\, denden
\Ca\.
Partula gibba..................... humped tree snail, dengdeng \ChG\,
dengding \ ChCNMI\,
akaleha' \ChG>\&\ChCNMI\, denden
\Ca\.
Partula langfordi................. Langford's tree snail, dengdeng
\ChG\, dengding \ChCNMI\,
akaleha' ChG & \ChCNMI\, denden
\Ca\.
Hypolimnas octocula marianensis... Mariana eight-spot butterfly,
ababang \ChG\,
ababbang \ChCNMI\, libweibwogh \Ca\.
Vagrans egistina.................. Mariana wandering butterfly, ababang
\ChG\,
ababbang \ChCNMI\, libweibwogh \Ca\.
Ischnura luta..................... Rota blue damselfly,
dulalas Luta \ChG, ChCNMI, and Ca\.
Bulbophyllum guamense............. wild onion, siboyas
h[aring]lomt[aring]no' \ChG\,
siboyas halumt[aring]nu' \ChCNMI\,
siboyan h[aring]lomt[aring]no'
\Ca\.
Cycas micronesica................. fadang ChG & \ChCNMI\, faadang \Ca\.
Dendrobium guamense............... NCN.
Eugenia bryanii................... NCN.
Hedyotis megalantha............... pao de'do' \ChG\, p[aring]ode'du'
\ChCNMI\, pao doodu \Ca\.
Heritiera longipetiolata.......... ufa h[aring]lomt[aring]no' \ChG\,
ufa halumt[aring]nu' \ChCNMI\,
ufa h[aring]lomt[aring]no' \Ca\.
Maesa walkeri..................... NCN.
Nervilia jacksoniae............... NCN.
Phyllanthus saffordii............. maigo' l[aring]lo' \ChG\.
Psychotria malaspinae............. aplohk[aring]teng palao'an \ChG\,
[aring]pplok hatting palao'an \ChG\
aplokkating pal[aring]o'an
\ChCNMI\.
Solanum guamense.................. birenghenas h[aring]lomt[aring]no'
\ChG\,
biringhenas halumt[aring]nu'
\ChCNMI\, birengenas
h[aring]lomt[aring]no' \Ca\.
Tabernaemontana rotensis.......... NCN.
Tinospora homosepala.............. NCN.
Tuberolabium guamense............. NCN.
------------------------------------------------------------------------
Background
Regulatory Framework
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(5)(A) 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
[[Page 14078]]
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 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 compiled in the Species Status Assessment report and
information developed during the listing process for the species. A
Species Status Assessment was not available for this proposed rule;
however, additional information sources are used that 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
endangered species and the 4(d) rule for the threatened species.
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 scientific data
available 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 for seed germination, protective cover for migration, or
susceptibility to flooding or fire that maintains necessary early-
successional habitat characteristics. Biological features might include
prey species, forage grasses, specific kinds or ages of trees for
roosting or nesting, symbiotic fungi, or absence of a particular level
of nonnative species consistent with conservation needs of the listed
species. The features may also be combinations of habitat
characteristics and may encompass the relationship between
characteristics or the necessary amount of a characteristic essential
to support the life history of the species.
In considering whether features are essential to the conservation
of the species, we may consider an appropriate quality, quantity, and
spatial and temporal arrangement of habitat characteristics in the
context of the life-history needs, condition, and status of the
species. These characteristics include, but are not limited to, space
for individual and population growth and for normal behavior; food,
water, air, light, minerals, or other nutritional or physiological
requirements; cover or shelter; sites for breeding, reproduction, or
rearing (or development) of offspring; and habitats that are protected
from disturbance.
Rationales and Summary Lists of Physical or Biological Features for
Each Species or Grouping of Species
We derive the following specific physical or biological features
(PBFs)
[[Page 14079]]
essential to the conservation of the Mariana Islands species from
studies of the species' habitat, ecology, and life history as described
below. Additional information can be found in the 5-year reviews
(Service 2020a-2020s, entire; Service 2021, entire; Service 2024a-b,
entire), species reports (Service 2020t-2020ao, entire; 2023b-x,
entire), and the recovery plan (Service 2023a, entire); other sources
of information as cited, available on <a href="https://www.regulations.gov">https://www.regulations.gov</a> under
Docket No. FWS-R1-ES-2024-0194). We have determined that the following
PBFs are essential to the conservation of the Mariana Islands species:
Mammals
(1) Pacific Sheath-Tailed Bat (Subspecies, Emballonura semicaudata
rotensis) PBFs
a. Pacific sheath-tailed bat PBF 1: Limestone caves, lava tubes,
overhanging cliffs, and crevasses for roosting.
b. Pacific sheath-tailed bat PBF 2: Intact, contiguous forests near
and surrounding suitable roosting sites.
c. Pacific sheath-tailed bat PBF 3: Prey insects such as ants,
bees, wasps (Hymenoptera), moths (Lepidoptera), and beetles
(Coleoptera) and vegetation to support them.
The last known surviving population of Pacific sheath-tailed bat,
subspecies rotensis (hereafter referred to as ``Pacific sheath-tailed
bat'' unless referring to another subspecies), roosts in a few caves on
Aguiguan (Lemke 1986, entire; Service 2020b, p. 5; Service 2023h, pp.
3, 29), although the species formerly occupied Guam, Rota, and Tinian
(Wiles et al. 2011, pp. 299-300). The species spends more than half its
life in roost caves, which are near forests with well-developed tree
canopy close to cave entrances; the forests maintain relatively stable
cave microclimates, provide food, and allow flight passage (Esselstyn
et al. 2004, p. 307; Gorresen et al. 2009, pp. 337-339; O'Shea and
Valdez 2009, pp. 77-78; Service 2020u, p. 13; Service 2023h, p. 12).
Pacific sheath-tailed bats depend on caves because they roost as lone
adults next to lone young on ceilings or upper walls in caves,
overhangs, lava tubes, or crevasses where limestone karst is present
(Wiles et al. 2011, p. 303; Service 2020b, pp. 4, 6-8; Service 2020u,
p. 5; Service 2023h, pp. 11-12). On Aguiguan, the bats are primarily
detected in native forests, occasionally in nonnative forest, and are
not detected in non-forested habitats (Esselstyn et al. 2004, pp. 306-
307), showing a clear association of the bat with forests on Aguiguan;
non-forest habitats are largely avoided by the species (Esselstyn et
al. 2004, p. 307).
Although the species appears to prefer relatively large caves
(Wiles et al. 2011, pp. 299, 302), on Aguiguan, the species is observed
in multiple cave shapes and structures, including the following: small
(less than 49 ft (15 m) long and 538 square feet (ft\2\) (50 square
meters (m\2\)) in floor area), with low rock overhangs, narrow vertical
crevices, various cavities at the base of cliffs or under large
boulders; medium (538 ft\2\ to 1,076 ft\2\ (50 to 100 m\2\) in floor
area), with wider rooms; and large (over 1,076 ft\2\ (100 m\2\) in
floor area), with ceiling heights reaching 16 to 98 ft (5 to 30 m)
(Wiles and Brooke 2009, pp. 432-433; Wiles et al. 2011, p. 301; Service
2023h, p. 14). It is possible that the species may use even smaller
caves. For example, on Palau where the closely related Pacific sheath-
tailed bat, subspecies palauensis (also insectivorous) is known to
occur, approximately 150 individuals of this subspecies were flushed
from a cave-like formation on a forested hill that was even smaller, at
16 to 32 ft (5 to 10 m) long with a 6.5 ft (2 m) diameter opening
(possibly a World War II tunnel) (Wiles et al. 1997, p. 221), while
another colony, with several hundred bats and a few Mariana swiftlets
(y[aring]yaguak; Aerodramus bartschi), was found in a cave 32 ft (10 m)
wide and 26 ft (8 m) tall (Wiles et al. 1997, p. 221). Thermal
characteristics of Aguiguan cave interiors vary little; temperature
highs range 79 to 86 [deg]F (26 to 30 [deg]C), relative humidity ranges
74 to 96 percent, and there is little air movement (O'Shea and Valdez
2009, pp. 77-78; Service 2020u, p. 9; Service 2023h, p. 13); however,
thermal characteristics of caves on Aguiguan do not limit use by this
species, and it seems unlikely that humidity variations among caves is
a limiting factor (Wiles et al. 2011, p. 305).
Forests are the most important foraging habitat for the Pacific
sheath-tailed bat (Esselstyn et al. 2004, p. 307). The species is
insectivorous, foraging on small insects such as ants, bees, wasps,
moths, and beetles supported by forested habitat (O'Shea and Valdez
2009, pp. 63-65; Valdez et al. 2011, pp. 301-307; Service 2023h, p.
10). On Aguiguan, the bats were regularly seen in the forest understory
to within 3 ft (1 m) of the ground, with some activity at tree-top
level (Esselstyn et al. 2004, p. 306). Canopy heights on Aguiguan are
23-49 ft (7-15 m) tall, which are shorter than forested areas outside
the Mariana Islands partially from frequent intense tropical cyclones
(Wiles et al. 2011, pp. 300, 306; Service 2023h, p. 12). Tropical
cyclones damage and remove trees, leading to a lower canopy level from
defoliation, branch breakage, and tree uprooting from high winds and
heavy rain. Average canopy heights were less than 4.25 ft (1.3 m) in
2016 surveys, indicating canopy cover was absent at most survey points
(CNMI DFW 2016, p. 42). Suitable caves need to be in or near mature,
well-structured, native or nonnative forests to provide attainable food
sources because this species forages almost exclusively in native and
nonnative forests near their roosts, but especially native forests, and
avoids non-forested habitats (Esselstyn et al. 2004, p. 307; Palmeirim
et al. 2005, pp. 7-8; Gorresen et al. 2009, pp. 336-339; O'Shea and
Valdez 2009, p. 44; Wiles et al. 2009, p. 10; Wiles et al. 2011, p.
307; Service 2020u, pp. 6, 11).
On the islands (archipelago) of Palau, which is approximately
113,280 ac (45,843 ha) in size and where the closely related palauensis
subspecies of Pacific sheath-tailed bat exists, at least one of these
individuals has been documented to fly at least 3.1 mi (5 km) from
known roosts (Wiles et al. 1997, p. 221). For comparison, on the small
Aguiguan Island (1,750 ac (4,324 ha) or 2.74 mi\2\ in size), we
anticipate the bats on Aguiguan rely heavily on the forests adjacent to
roosting habitat, depending on prey availability. Suitable foraging
habitat is mature, well-structured forests with a high and dense canopy
near suitable roosting sites. This is necessary to maintain a stable or
growing bat population (Kalko 1995, pp. 262-265; Esselstyn et al. 2004,
p. 307; Palmeirim et al. 2005, pp. 3-5, 7-8; Gorresen et al. 2009, pp.
336-339; Valdez et al. 2011, pp. 306-307; Marques et al. 2016, pp. 481-
484; Service 2023a, p. 25).
Previous disturbance by human occupation and warfare during World
War II and ongoing disturbance of roosting caves by human and feral
goats contribute to the decline of this species (Wiles et al. 2011, p.
306; Service 2020u, p. 10) by affecting mating, rearing young, social
interactions, protection from inclement weather, and causing elevated
energetic costs, physiological stress, and increased risk of
depredation (Palmeirim et al. 2005, p. 7; Kunz and Lumsden 2003, pp. 4,
43, 66; Service 2020u, p. 10). Historical warfare and ongoing
disturbances have contributed to roost abandonment for the Pacific
sheath-tailed bat. The degree and frequency of disturbance resulting in
cave abandonment by the species is not well understood; however,
inhabitation of roosting caves near and/or within suitable foraging
habitat may occur again after physical disturbances have been
alleviated. Feral goats take shelter in caves, disrupt colonies of the
[[Page 14080]]
federally endangered Mariana swiftlet, and likely disturb the Pacific
sheath-tailed bat (Wiles and Worthington 2002, p. 17; Cruz et al. 2008,
p. 243; Scanlon 2015, in litt., entire; Service 2023h, pp. 14-15).
Suitable caves are found unoccupied by this species and were occupied
by goats (GDAWR 1995, p. 95).
Reptiles
(2) Slevin's skink (Emoia slevini) PBFs
a. Slevin's skink PBF 1: Forests such as native limestone forests,
volcanic forests, mixed-nonnative forests, Casuarina equisetifolia
(g[aring]gu, g[aring]go, weighu, beach sheoak, or common ironwood) and
Cocos nucifera (niyok, coconut) dominant forests.
b. Slevin's skink PBF 2: Forest understory and leaf litter and
debris.
c. Slevin's skink PBF 3: Invertebrate prey and vegetation to
support them.
Slevin's skink is the only lizard endemic to the Mariana Islands
and has had a 99 percent decline in its distribution. It is known to
occur only on Alamagan, Asuncion, Cocos Island (which is part of Guam),
and Sarigan, and possibly Pagan, but it is thought to be extinct or
undetected on Guam, Rota, Tinian, and Aguiguan (Service 2023j, p. 3).
Threats to this species include loss and degradation of habitat due to
impacts from feral ungulates, nonnative plants, and development;
predation by invasive species (e.g., rats, brown tree snake); and
competition from nonnative lizards (Service 2023j, pp. 3, 16-38).
The skinks are often seen on forest floors containing leaf litter
and tree debris, and observed on trees, within low hollows of tree
trunks, under logs, within palm fronds, and near abandoned buildings,
but rarely observed in open or sunlit areas (Brown and Falanruw 1972,
p. 110; Rodda et al. 1991, p. 205; CNMI DFW 2000, in litt., pp. 21-26;
GDAWR 2006, p. 107; Vogt 2007, pp. 5-1 to 5-2; Lardner 2013, in litt.,
p. 4). Recorded forest types inhabited by Slevin's skink include
ravine, native, mixed-native, mixed secondary, and forests of Casuarina
equisetifolia and Cocos nucifera (Brown and Falanruw 1972, p. 110;
McCoid et al. 1995, p. 72; CNMI DFW 2005, p. 175; Vogt 2007, in litt.,
pp. 5-1 to 5-2). The species also likely uses forests with habitat
complexity, typical of the Mariana Islands, comprised of limestone or
volcanic substrates and native tree canopy species, such as Elaeocarpus
joga, Pisonia grandis, Hernandia labyrinthica, Hernandia sonora, Ficus
prolixa, Macaranga thompsonii, Pandanus spp., and Intsia bijuga for
limestone forests; and Pisonia grandis, Hernandia sonora, Barringtonia
asiatica, Pandanus tectorius, and Terminalia catappa for volcanic
forests (Service 2023j, p. 15).
Females carry eggs internally, birth live young and require
understory of leaf litter and tree debris to hide from predators and to
stalk prey (insectivorous) (Harrington et al. 2020, p. 14). Like all
insectivorous skinks, individuals require a sufficient abundance of
insects and small invertebrates to complete their development and life
cycle, including mating and breeding (Harrington et al. 2020, p. 15;
Service 2023j, p. 15). Males of many other skink species are
aggressively territorial, and we expect the Slevin's skink to also be
territorial (Service 2023j, p. 15). The territory area necessary for
Slevin's skink is unknown; however, wherever suitable habitat remains
within their historic range, we expect they may be present, just
undetected, because they were undetected on Guam's Cocos Island for
almost two decades (Cocos is approximately 95 ac, or 38 ha) (Service
2020c, p. 4; Service 2023j, p. 16).
Snails
(3) Tree Snails: Fragile tree snail (Samoana fragilis), Guam tree snail
(Partula radiolata), humped tree snail (Partula gibba), and Langford's
tree snail (Partula langfordi) PBFs
a. Tree snail PBF 1: Contiguous closed-canopy limestone, volcanic,
riverine, riparian, ravine, or secondary/mixed forests, or backstrand
beach vegetation, providing relatively stable climatic conditions such
as shade, moisture, high humidity, and low air movement.
b. Tree snail PBF 2: Dense mid-canopy vegetation such as large
leaves, branches, vines, or other structures.
c. Tree snail PBF 3: Understory such as ground cover composed of
short herbs, shrubs, ferns, and small trees.
d. Tree snail PBF 4: Food sources such as dead and decaying plant
material, leaf litter, and tree debris.
The tree snails require sufficiently dense forests that are cool,
shaded, and have high humidity and stable environmental factors
including temperature, relative humidity, and light to prevent
excessive moisture loss to their bodies, and to provide conditions
conducive to growth of fungi and microalgae (Crampton 1925, p. 14;
Cowie 1992, p. 175; Service 2020w, p. 6; Service 2023b, p. 12; Service
2023c, p. 3; Service 2023d, pp. 3, 6; Service 2023e, p. 10). Excessive
light and unstable temperatures and humidity have detrimental impacts
on juvenile survival (Gouveia 2011, pp. 68, 76-78; Service 2023d, p.
12; Service 2023e, p. 10; Service 2023c, p. 10; Service 2023b, p. 12).
The tree snails require forest understory containing live and decaying
leaves and branches, suggesting a diet of fungus or microalgae (Service
2023d, p. 12; Service 2023e, pp. 10-11; Service 2023c, p. 10; Service
2023b, p. 12). Threats to tree snails include loss and degradation of
habitat due to impacts from development, wildfire, invasive plants,
typhoons, and climate change (e.g., increasing temperatures, changes in
precipitation patterns); and predation from invasive animals (Service
2023a, pp. 17-24).
The tree snails are most likely found on broad-leafed plants in
places with canopy and ground cover (Fiedler 2019, pp. 10-11). The
species are commonly observed in forests with a mid-canopy of less than
or equal to 13 ft (4 m), ground cover of short herbaceous plants and
small shrubs (Fiedler 2019, p. 10), and contiguous suitable habitat
(Service 2020t, p. 9; Service 2020w, p. 7; Service 2020v, p. 14).
Partulid snails can be found high in trees, depending on the tree and
location. Tree snails were observed on leaves higher than 26 ft (8 m)
from the ground (Fiedler 2019, p. 13). The snails are not known to have
specific host plant requirements, except a preference for large leaves
(to take refuge under), and they are found on the underside of leaves
of a variety of native and nonnative vegetation. However, based on
limited observational studies, population densities are lower on
nonnative vegetation than those on native vegetation for the fragile
tree snail on Guam and the humped tree snail on Sarigan, CNMI (CNMI DFW
2008, p. 8-4; Fiedler 2019, p. 7; Service 2020v, pp. 6, 12).
Observations of the tree snails on native vegetation most commonly
occur on (but are not limited to) Piper guahamense, Mammea odorata
(chopak, chopag), and Merrilliodendron megacarpum (no common name)
(observed for humped tree snail); Aglaia spp. (observed for Langford's
tree snail); Alocasia macrorrhizos (giant taro), Artocarpus spp., Cocos
nucifera, Epipremnum aureum, Merrilliodendron megacarpum (observed for
Guam tree snail); and Arterocarpus spp. and Merrilliodendron megacarpum
(observed for fragile tree snail) (Service 2023b, pp. 16-17; Service
2023c, p. 14; Service 2023d, pp. 11-12; Service 2023e, pp. 10, 15). The
tree snails are also observed in backstrand beach vegetation--plant
communities near or directly adjacent to the ocean, where the salinity
is higher and the vegetation is more salt-tolerant and that may contain
volcanic or limestone substrates (CNMI
[[Page 14081]]
DFW 2015a, pp. 4-6; Service 2023d, pp. 16-18).
The snails have both male and female reproductive organs and birth
live young, but juvenile mortality rates are very high (Pearce-Kelly et
al. 1995, p. 660; Service 2023d, p. 13; Service 2023e, pp. 11-12;
Service 2023c, p. 11; Service 2023b, p. 13). Another primary threat to
the snails is depredation by the nonnative New Guinea flatworm, a
ground-dwelling flatworm that climbs wet trees and locates snails via
scent (Sugiura and Yamaura 2009, pp. 739-741; Service 2020x, p. 3;
Service 2023d, pp. 3, 14; Service 2023e, pp. 3, 12; Service 2023c, p.
3; Service 2023b, p. 14). Other predators include the nonnative rosy
wolf snail (Hopper and Smith 1992, p. 82; Service 2023c, p. 12) and the
nonnative, invasive yellow crazy ant (Service 2023d, p. 14; Service
2023e, p. 12; Service 2023b, p. 14). Habitat loss and degradation have
contributed substantially to population declines of the tree snails
(Service 2023d, p. 14; Service 2023e, p. 13; Service 2023c, p. 12;
Service 2023b, p. 14).
Insects
(4) Mariana eight-spot butterfly (Hypolimnas octocula marianensis) PBFs
a. Mariana eight-spot butterfly PBF 1: Interconnected native,
closed-canopy limestone forests.
b. Mariana eight-spot butterfly PBF 2: Larval host plants such as
Procris pedunculata (no common name) or Elatostema calcareum (tapun
ayuyu).
c. Mariana eight-spot butterfly PBF 3: Food resources from day-
flowering plants or decaying organic matter (e.g., rotten fruits or
animals).
The Mariana eight-spot butterfly (Nymphalidae family) once occurred
across a much larger range of habitat than its current distribution on
Guam, likely formerly occupying Rota and Tinian (which lie between
currently occupied Guam and formerly occupied Saipan), and host plants
are present on all islands (Schreiner and Nafus 1996, p. 2; Moore 2013,
p. 2; Rubinoff and Holland 2018, p. 221; Service 2023f, pp. 3, 26, 27).
The butterfly historically occupied Guam and Saipan, and on Saipan it
had a range of approximately 21,600 ac (8,741 ha) (70 percent of the
island); however, 99 percent of the native forest ecosystem habitat on
Saipan is gone (Service 2023m, p. 28) and the species not been detected
during anecdotal surveys performed for purposes other than detecting
this species (Schreiner and Nafus 1996, p. 10; Moore 2013, p. 2;
Rubinoff and Holland 2018, pp. 218-220, 222; Service 2023f, p. 27).
Additionally, it is important to note for this and other species that
pollinators and birds are almost entirely absent from Guam due to
depredation by the invasive brown tree snake; the lack of pollinators
and seed dispersers inhibits the reproduction of plant communities that
support these listed species (Egerer et al. 2018, p. 655; Service
2020ak, pp. 2, 14).
Mariana eight-spot butterflies occupy habitat in limestone forest
over karst spires, boulders, and small cliffs where the host plants are
protected from ungulate grazing (Schreiner and Nafus 1996, p. 1;
Rubinoff and Holland 2018, p. 222). Known larval host plants include
Procris pedunculata and Elatostema calcareum (vine-like forest herbs
growing on rocky and karst substrate in native limestone forests)
(Schreiner and Nafus 1996, p. 1; Service 2023f, pp. 12, 14). Adults
rely on ephemeral food sources including rotting fruit and nectar from
day-blooming flowers in limestone forests, and dead animals, mostly
available after the wet season, when plants bloom and fruiting occurs
(Service 2020z, p. 12; Service 2021, p. 5; Service 2023f, pp. 3, 12).
Larvae need safety during pupation and abundant food resources to grow;
caterpillars eat the native host plants (Schreiner and Nafus 1996, p.
1; Service 2023f, pp. 12, 14). Like all butterflies, Mariana eight-spot
butterflies require sufficient host plant material to eat as
caterpillars, a safe place to pupate, and abundant food resources as
adults (Service 2023g, p. 14). The adults require close proximity to
larval host plants; moreover, tropical butterflies, including nymphalid
species (i.e., brush-footed butterflies in the Nymphalidae family), are
less likely to fly through open areas, so forest habitat connectivity
between the specific Mariana eight-spot butterfly larval stage host
plant sites is required (Rubinoff and Kawahara 2011, in litt., entire;
Rubinoff 2013, in litt., p. 1; Rubinoff and Holland 2018, pp. 223, 224;
Scriven et al. 2015, p. 420; Scriven et al. 2017, pp. 206, 212; Service
2023f, p. 15). Threats to this species include loss and degradation of
habitat due to impacts from feral ungulates, nonnative plants, and
herbivory by slugs; and predation from native and nonnative insects
including ants and parasitic wasps (Service 2023f, pp. 3, 16-24).
(5) Mariana wandering butterfly (Vagrans egistina) PBFs
a. Mariana wandering butterfly PBF 1: Interconnected native
limestone forest.
b. Mariana wandering butterfly PBF 2: Native limestone forest
understory vegetation.
c. Mariana wandering butterfly PBF 3: Larval host plants, such as
Maytenus thompsonii (luluhut).
d. Mariana wandering butterfly PBF 4: Food resources from day-
flowering plants or decaying organic matter (e.g., rotten fruits or
animals).
The Mariana wandering butterfly is endemic to Guam and Rota and
likely occurred across a much larger range of habitat than its current
habitat distribution on Guam and Rota (Swezey 1942 p. 35; Schreiner and
Nafus 1997, p. 36; Rubinoff and Holland 2018, p. 218; Service 2020f,
pp. 5-6; Service 2023g, p. 3). The butterfly is in the Nymphalidae
family and is one of seven nymphalid species found in the Mariana
Islands, including the Mariana eight-spot butterfly, from which we
infer much because so little is known of the Mariana wandering
butterfly (Service 2023g, p. 3). The Mariana wandering butterfly likely
relies on camouflage for protection, as the cryptic coloring of the
bottom of the wings, visible when folded up, appear much duller and
leaf-like in color and mimic the surrounding vegetation (Service 2023g,
p. 10). The species is likely very difficult to detect and there have
been no consistent survey efforts (Rubinoff 2024, pers. comm.). Threats
to the species include habitat loss and degradation due to impacts from
feral ungulates and nonnative plants, and predation from native and
nonnative insects (e.g., ants, parasitic wasps) (Service 2023g., pp. 3,
17-22).
Like most nymphalid butterflies, the adults use a long proboscis to
feed on a variety of ephemeral food sources including nectar of day-
blooming flowers, rotting fruit, and occasionally dead animals (Service
2023g, p. 12). The Mariana wandering butterfly is known to rear
successfully on the native plant Maytenus thompsonii, a small shrub-
like tree endemic to the Mariana Islands and found primarily in the
understory of native limestone forests (Swezey 1942, p. 35; Service
2023g, pp. 11-12). Maytenus thompsonii can grow to heights over 13 ft
(4 m), and thickets of the trees can grow impenetrably dense (Rubinoff
and Holland 2018, pp. 222-223), potentially offering protection of eggs
and larvae. Although the species typically occurs within limestone
forests, it is not restricted to rugged karst terrain like the host
plants of the related Mariana eight-spot butterfly (Rubinoff and
Holland 2018, p. 221). Like all butterflies, Mariana wandering
butterflies require sufficient host plant material to eat as
caterpillars, a safe
[[Page 14082]]
place to pupate, and abundant food resources as adults (Service 2023g,
p. 14). Like the Mariana eight-spot, the Mariana wandering butterfly
likely requires high-density host plant distribution within
interconnected native limestone forest (Service 2020ah, pp. 15, 17;
Service 2020z, pp. 14-15; Service 2023g, p. 14); all remaining suitable
limestone forest may be a species need (Service 2020ah, p. 17).
(6) Rota blue damselfly (Ischnura luta) PBFs
a. Rota blue damselfly PBF 1: Contiguous closed-canopy forest
habitats surrounding streams and their tributaries with adequate cool,
clean, clear, moving water.
b. Rota blue damselfly PBF 2: Riparian vegetation adjacent to
streams and their tributaries.
c. Rota blue damselfly PBF 3: Small prey such as water fleas,
larvae, or other small invertebrate or aquatic organisms.
The Rota blue damselfly is endemic to Rota where it inhabits a
single confirmed stream system, the Okgok Stream, in the Talakhaya
watershed (Polhemus et al. 2000, p. 8; Service 2020g, p. 3; Service
2023i, p. 3). Adult damselflies require large areas of high-quality
forest habitat connected to streams because breeding pairs are
territorial, they fly long ranges seeking prey before maturing and
returning to their selected breeding sites, and they have strong
breeding site fidelity and remain relatively close to the aquatic
environment where they lived as naiads (larvae) (Finke 1992, p. 449;
Polhemus and Asquith 1996, p. 7; Service 2020aa, p. 16; Service 2023i,
p. 15). The forest habitat must have sufficient density and
distribution to maintain shaded forest understory conditions along
streams to keep stream temperatures cool and provide refuge, shelter,
adequate area for breeding individuals to expand into, and habitat for
prey (Service 2020aa, pp. 3, 19). Threats to this species include loss
and degradation of habitat due to impacts from feral ungulates,
wildfire, typhoons, nonnative plants, development, and extraction of
water from the steam systems; and predation (i.e., nonnative fish and
amphibians) (Service 2020aa, pp. 4, 32-46).
The species requires streams and tributaries for breeding and
sufficient stream flow for larvae (naiad) development (Service 2020aa,
pp. 3, 19; Service 2023i, p. 14). A primary direct stressor to the
damselfly is water withdrawal from the island's streams necessary for
damselfly use (Service 2023i, p. 4). Female damselflies lay eggs by
inserting them into small slits in aquatic vegetation below the water
surface and by laying eggs on rocks, algal mats, moss, or vegetation
either below or above the water line (Williams 1936, pp. 302-309;
Guillermo-Ferreira and Del-Claro 2011, pp. 275, 278-279). The larval
stage is aquatic and requires clean, oxygenated water with low silt
concentrations because the larvae breathe underwater and eat small
aquatic insects and invertebrates (Polhemus and Asquith 1996, p. 4;
Service 2023i, p. 3). The species is generally intolerant of high
temperatures, pollutants, hypoxic conditions, and silted water, factors
long identified as indicators of poor water quality (Moore 1997, p. 10;
Solimini et al. 1997, pp. 21, 30-31). Rota blue damselfly larvae eat
small aquatic insects and other invertebrates, such as water fleas,
mosquito larvae, and other small aquatic organisms (Polhemus and
Asquith 1996, p. 4; Service 2020aa, p. 17). Adults eat small flying
insects, such as midges and small flies (Polhemus and Asquith 1996, p.
7; Service 2020aa, p. 15).
Epiphytic Orchids
(7) Epiphytic orchids: Bulbophyllum guamense, Dendrobium guamense, and
Tuberolabium guamense PBFs
a. Epiphytic orchids PBF 1: Native limestone or volcanic forests
with native host vegetation such as trees and tall shrubs, including
forests along clifflines, forest edges, mountainous slopes and
secondary/mixed and native volcanic ravine forests providing suitable
host vegetation.
b. Epiphytic orchids PBF 2: Pollinators such as flies, wasps, and
bees, and native vegetation to support them.
Host trees for the orchids are not species specific, but
Bulbophyllum guamense primarily grows on native vegetation and most
individuals (greater than 76 percent) of Dendrobium guamense and
Tuberolabium guamense are found on native vegetation associated with
primary limestone and volcanic, and secondary/mixed forests (Service
2023k, p. 9; Service 2023m, pp. 12, 17; Service 2023x, p. 14). The
orchids are also found on trees and tall shrubs in secondary limestone
and volcanic substrate forests, high in the canopy, in ravine secondary
forests, under the canopy along forest edges and clifflines, and on the
slopes within intact native volcanic forest ecosystems or habitats
(Stone 1970, pp. 27, 38, 155; Falanruw et al. 1989, pp. 6-9; Raulerson
and Rinehart 1991, pp. 61, 73, 96; Mueller-Dombois and Fosberg 1998,
pp. 218, 268; CNMI DFW 2015b, pp. 4-7; Service 2020ab, pp. 17-18, 29;
Service 2020ad, pp. 4, 6-8; Service 2020an, pp. 9, 12; Service 2023m,
pp. 11-13). Most of the native forest ecosystem for these species has
been lost due to natural and anthropogenic disturbance, including
invasive species, development, volcanic eruptions, typhoons, and fire
(Willsey et al. 2019, pp. 2, 13-18, 28); Guam lost 83 percent, Rota
lost 53 percent, Saipan lost 99 percent, Tinian lost 96 percent,
Aguiguan lost 45 percent, and Agrihan lost 32 percent (Service 2023m,
pp. 28-29).
These three epiphytic orchid species reproduce vegetatively and
sexually, and require diverse populations with all age classes present
(seeds, seedlings, juveniles, and adults), and must be distributed
across sufficient quality forest habitat with high levels of habitat
connectivity between populations (Service 2023k, p. 19; Service 2023m,
p. 11 Service 2023x, p. 13). Reproduction requires moss or other debris
on tree trunks or branches that the three orchid species can root into
or cling to (Service 2023k, p. 16; Service 2023m, p. 9; Service 2023x,
p. 10). Mother plants disperse seeds onto a host plant surface where
they require microbial partners, such as mycorrhizal fungi, to
germinate and grow to adults (Alghamdi 2019, p. 502; Service 2020h, p.
7; Service 2020l, p. 8; Service 2020ab, pp. 10, 17). Flies are the most
likely pollinator for Bulbophyllum guamense, but the three orchid
species may also be pollinated by wasps and bees (Borba et al. 1999, p.
205; Humeau et al. 2011, p. 591; Service 2023k, p. 18; Stpiczynska et
al. 2018, p. 565). Seed dispersal likely occurs with wind and rain
(Service 2023k, p. 17).
Invasive species are the primary driver of island extinctions and
are a primary factor underlying the alteration and degradation of
native plant communities and habitats in the Mariana Islands (Service
2023a, p. 12; Spatz et al. 2017, p. 1). Steady ongoing habitat
degradation and loss occurs from the following sources: ungulates eat
native vegetation, prevent native vegetation growth, spread invasive
species, and cause severe erosion; rodents eat seeds and plants and
affect regeneration; reptiles eat seed-dispersing birds; and
invertebrates kill the plants or change the ecosystem that supports
them (Service 2023a, pp. 21-22; Willsey et al. 2019, pp. 15-16). Small
population abundance and distribution of these epiphytic orchid species
increases their vulnerability to threats (Service 2023a, p. 17).
Bulbophyllum guamense is endemic to Guam and Rota, growing on
trunks and branches of tall trees and shrubs in native, secondary/mixed
forests, and native volcanic ravine forests containing
[[Page 14083]]
exact amounts of moisture, light, and wind (the species derives
moisture from the atmosphere and moisture and nutrients from host
vegetation) (Service 2023k, pp. 3, 16). Historically, this species was
likely widely distributed in the native forest habitat along the
clifflines and mountainous slopes of the southern Mariana Islands of
Guam and Rota (Service 2023k pp. 27, 32). Common host vegetation for
the orchids includes Hernandia labyrinthica, Elaeocarpus joga, Pisonia
umbellifera (birdlime tree or bird-catcher tree), Artocarpus spp.,
Persea americana (avocado), and Areca catechu (betel nut) (Stone 1970,
p. 158; CNMI DFW 2015b, pp. 2, 4-7; Service 2023k, p. 16). Bulbophyllum
guamense are found along slopes at relatively high elevations in native
limestone and secondary forest habitats, which appears to protect them
from stochastic events (e.g., hurricanes) (Service 2020ab, pp. 3, 6-7,
9, 29).
Dendrobium guamense is endemic to Guam, Rota, Saipan, Tinian,
Aguiguan, and Agrihan, growing predominately on native (93 percent)
tree trunks and branches of trees in the top of the tree canopy
(Service 2023m, pp. 3, 5, 12), but also terrestrially under the canopy
where it is found along forest edges and clifflines (CNMI DFW 2015b,
pp. 3-5). Dendrobium guamense are mostly (76 percent) found on native
trees, such as (but not limited to) Elaeocarpus joga, Glochidion
marianum (chosg[ocirc]), and Pandanus tectorius (Service 2023m, p. 12).
Tuberolabium guamense is endemic to forest ecosystems of Guam and
Rota with limestone and volcanic substrata, growing in low sunlight,
low in the tree canopy, on tree trunks or shrubs of primarily native
species (Service 2023x, p. 3; Stone 1970, pp. 14, 18-24). Known host
vegetation includes (but is not limited to) Aglaia mariannensis
(mapunyao, mapu[ntilde]ao, fischil liyoos), Eugenia reinwardtiana
(cedar bay cherry), and Merrilliodendron megacarpum (see Service 2023x,
pp. 14, 16 for full list). Tuberolabium guamense has little apparent
specificity for precipitation within the current ranges recorded on
Guam and Rota; it occupies sites across gradients in space spanning
large differences in rainfall, temperature, and elevation (Service
2023x, p. 17).
Forest Plants
Historically, forest plant communities in the Mariana Islands were
described as a diverse ecosystem where 10 or more species grew side by
side in approximately equal abundance; these communities were
represented by a diverse group of families and species, and none were
dominated by any single species or by small groups of species (Glassman
1948, p. 177). The forests were not matted with undergrowth except
where trees were few, and the ground cover species were usually
confined to the forests (Glassman 1948, p. 179). Less than 17 percent
of native forests remain on Guam, less than 47 percent remain on Rota
(Willsey et al. 2019, p. 4), and less than 2 percent of native coastal
habitats remain on any island in the Mariana Islands (Service 2023a, p.
21). Invasive species are the primary driver of island extinctions and
are a primary factor underlying the alteration and degradation of
native plant communities and habitats in the Mariana Islands (Service
2023a, p. 12; Spatz et al. 2017, p. 1) and for all of the forest
plants. And as stated above, it is important to note that pollinators
and birds are almost entirely absent from Guam due to depredation by
the invasive brown tree snake, which can severely inhibit a plant's
ability to reproduce (pollinators) and distribute (seed dispersers)
(Egerer et al. 2018, p. 655; Service 2020ak, pp. 2, 14). Overall, we
know very little about these rare forest plants as surveys and reports
are few; therefore, we relied on the best available scientific
information to identify their essential PBFs.
Forests in the Mariana Islands are characterized by a closed canopy
of broadleaf trees with an understory of younger trees, vines,
epiphytic ferns, and orchids (Willsey et al. 2019, p. 3). Present day
limestone forests are largely (but not limited to) Hibiscus tiliaceus,
Morinda citrifolia (lada', noni, Indian mulberry), Psychotria mariana
([aring]pplok hating, aplohkateng, aplu kati, gathemach, aploghating,
[aring]plokhating), Aidia cochinchinensis (sumak), Aglaia mariannensis,
Ficus prolixa, Melanolepis multiglandulosa ([aring]lom), Pandanus
tectorius, and Pipturus spp. The undergrowth is sparse, except for
young trees of the above species and vines such as (but not limited to)
Abrus spp., Freycinetia spp., and Operculina spp.; very common are
Asplenium nidus (g[aring]lak, fedda', bird's nest fern) and
Phymatosorus scolopendria (monarch fern, k[aring]hlao) (Mueller-Dombois
and Fosberg 1998, pp. 216-217; Harrington et al. 2012, entire).
Coastal strand forests comprise the following components: They
contain sandy soils, coastal strand vegetation, mangroves, and bare
sand, rock, and karst; are contained within near-shore areas that are
bounded by the ocean on one side and have a less distinct inland
border; are found only in older and larger southern islands (i.e., Guam
and Rota); and support a narrow plant community along the shore from
loose sand just above the high tide line extending to increasingly less
saline volcanic or limestone soil conditions inland (Fosberg 1960, pp.
15-17; Plentovich et al. 2020, p. 186; Service 2020ac, p. 9; Service
2023l, pp. 11-12). Present-day coastal strand vegetation in the
Marianas includes (but is not limited to) Barringtonia asiatica, Bikkia
tetrandra, Cassytha filiformis, Casuarina equisetifolia, Cordia
subcordata, Heliotropium foertherianum, Hernandia nymphaeifolia,
Hibiscus tiliaceus, Ipomoea pes-caprae (halaihai, goats foot morning
glory, bayhops, beach morning glory, railroad vine), Lepturus repens,
Mammea odorata, Ochrosia mariannensis, Pandanus tectorius, Pemphis
acidula, Scaevola taccada (nan[aring]su, beach naupaka, beach cabbage),
Sesuvium portulacastrum, Sporobolus virginicus, Thespesia populnea,
Thuarea involuta, and Vigna marina (akankang manulasa, akangkang
malolusa, nanea, beach pea) (Plentovich et al. 2020, p. 187).
(8) Cycas micronesica PBFs
a. Cycas micronesica PBF 1: Closed-canopy native limestone or
volcanic forests with native vegetation such as (but not limited to)
Hibiscus tiliaceus, Morinda citrifolia, Psychotria mariana, Aidia spp.,
Aglaia spp., Ficus spp., Melanolepis multiglandulosa, Pandanus spp.,
and Pipturus spp.
b. Cycas micronesica PBF 2: Closed-canopy native coastal strand
forest with sandy soils and native vegetation such as Barringtonia
asiatica, Bikkia tetrandra (torchwood, gaus[aring]li), Casuarina
equisetifolia, Cocos nucifera, Hernandia nymphaeifolia (doko,
Hernandia, Jack-in-the-box, lantern tree, nonak), Hibiscus tiliaceus,
Ipomoea pes-caprae, Mammea odorata, Pemphis acidula (bantigue, nigas),
Scaevola taccada, Sesuvium portulacastrum (sea purselane), Sporobolus
virginicus (banalo, binalo, Pacific rosewood, Portia tree), Thespesia
populnea (banalo, binalo, Pacific rosewood, Portia tree), Thuarea
involuta (kuroiwa grass, tropical beachgrass, bird's beak grass), and
Vigna marina.
c. Cycas micronesica PBF 3: Native pollinators such as moths and
beetles, and native vegetation to support them.
d. Cycas micronesica PBF 4: Native seed dispersers such as birds
and fruit bats.
Cycas micronesica is a rare gymnosperm (usually an unbranched tree
with a thick trunk) native to Guam, Rota, and possibly Pagan, where it
is found in the limestone and volcanic forests and coastal (strand)
habitats
[[Page 14084]]
(Service 2020ac, p. 9; Service 2023l, pp. 3, 11-12). Populations were
continuous across Guam as recently as 2002, but fragmented after the
cycad aulacaspis scale (Aulacaspis yasumatsui) was first detected in
2003. Once established, infestations spread rapidly and are extremely
difficult to control, and there is no chemical or biological control
method effective at a landscape scale. This invasive armored scale
insect infests leaves, stems, and roots of Cycas micronesica, causing
extensive tissue damage, defoliation, and eventually death. Since its
introduction, Aulacaspis yasumatsui has caused declines in Cycas
micronesica populations throughout its range, with mortality rates of
up to 93 percent across all life stages, from seedlings to mature
plants (Marler 2013, pers. comm). The continued presence of the cycad
scale as a primary threat to Cycas micronesica increases its risk of
extinction throughout its range.
Cycas micronesica is unique among Mariana Islands species as the
only native gymnosperm (seed producer), has nitrogen-fixing root
symbionts (organisms living in symbiosis with another), lives up to 40
years (B[ouml]senberg 2022, p. 8), and hosts the specialist native
beetle Dihammus marianarum that feeds on stem tissue and a specialist
native moth pollinator (Anatrachyntis sp.) that feeds on dispensable
male cone tissue (Marler and Dongol 2016, p. 4; Service 2020i, p. 7;
Service 2023l, p. 10). Cycas micronesica is food for the Mariana fruit
bat and was historically used by humans as food after much processing.
Threats to this species include loss and degradation of habitat due to
impacts from invasive animal and plant species, development, wildfire,
and climate change (e.g., changes in precipitation patterns); herbivory
from nonnative invertebrates and ungulates; and catastrophic events
such as typhoons (Service 2023l, pp. 3, 17-19).
Cycas micronesica reproduces vegetatively and sexually and requires
pollinators (Service 2023l, p. 12) such as moths and beetles
(Carpophilus spp. beetles, Nitidulidae family), it hosts native insect
pollinator species, and pollen is dispersed by wind from April to
August during the dry season (Hamada et al. 2015, entire; Schneider et
al. 2002, p. 282; Service 2020i, p. 7; Service 2020m, p. 7; Terry et
al. 2009, pp. 83, 96). Males create very strongly scented cones when
pollen matures, and females produce a cone-like structure that opens
outward to receive fertilization by pollen (Service 2023l, p. 9).
Specialist pollinators are attracted to the cones' chemical cues
(Schneider et al. 2002, p. 282; Terry et al. 2009, pp. 83, 96). Seeds
require 3 to 6 months to germinate (Raulerson and Rinehart 1991, p. 4;
Service 2023l, p. 9).
(9) Eugenia bryanii PBFs
a. Eugenia bryanii PBF 1: Limestone forests with moisture,
including (but not limited to) forest edge perimeters, exposed
limestone cliffs, and limestone forests with karst as the primary
substrate.
b. Eugenia bryanii PBF 2: Native seed dispersers such as birds and
fruit bats.
c. Eugenia bryanii PBF 3: Native pollinators and native vegetation
to support them.
Eugenia bryanii are small-to-medium-sized shrubs in the Myrtaceae
family and are endemic to Guam, where they comprise part of the shrub
community in limestone forest habitats, where limestone karst is the
primary substrate; the species occupies a relatively narrow habitat
niche along the perimeter of forest edges and exposed limestone cliffs
(Costion and Lorence 2012, pp. 54, 82; Service 2020ae, p. 3; Service
2023n, pp. 3, 11). The species occurs in limestone forests where
limestone karst is the primary substrate. However, it is unknown
whether the species has any habitat requirements or limitations besides
needing limestone soils or limestone karst, and it may previously have
been more widely distributed; fewer ungulates can traverse karst
substrates, potentially explaining why the species is only found along
these edges (Service 2020k, pp. 7-8; Service 2023n, p. 11). Like other
forest plants on Guam, the species likely requires pollinators, seed
dispersers, water availability and vegetation communities consistent
with native limestone forests, sunlight levels consistent with
limestone karst forest edge habitat, limestone substrates, seasonal
precipitation fluctuations, and relatively constant temperatures
(Service 2023n, p. 12). Threats to this species include loss and
degradation of habitat due to impacts from human activity and
development, invasive species (e.g., invertebrates and grazing by
ungulates), and climate change (i.e., increasing variability in
temperatures, more severe alternating periods of droughts and floods,
stronger typhoons) (Service 2023n, pp. 14-15).
Seeds require undisturbed substrates and moisture to survive. They
are sensitive to desiccation, which affects seed germination and
survival (Andrade et al. 2003, p. 131; Maluf et al. 2003, p. 471), and
are dispersed by seed-eating birds and fruit bats (Gawel et al. 2018,
p. 8). Habitats free from invasive pests are required for seed
survival. Seed survival can be reduced by these factors: rats eat
plants and seeds (possibly dispersing seeds as well); ungulates eat and
crush plants and prevent regeneration; snakes remove plant-pollinating
and seed-dispersing birds; and invasive plants outcompete native plants
and overgrow native vegetation communities.
(10) Heritiera longipetiolata PBFs
a. Heritiera longipetiolata PBF 1: Closed-canopy native limestone
forests where there are substrates of karsts, clifflines, and
outcroppings.
b. Heritiera longipetiolata PBF 2: Sufficient space within
limestone vegetation communities composed of plants such as (but not
limited to) Asplenium nidus, Hibiscus tiliaceus, Morinda citrifolia,
Phymatosorus scolopendria, Psychotria mariana, and Abrus spp., Aidia
spp., Aglaia spp., Ficus spp., Freycinetia spp., Melanolepis spp.,
Operculina spp., Pandanus spp., and Pipturus spp.
c. Heritiera longipetiolata PBF 3: Individuals in close proximity
to each other and adequate access by native seed dispersers such as
birds and fruit bats.
d. Heritiera longipetiolata PBF 4: Native pollinators and native
vegetation to support them.
Heritiera longipetiolata, a medium to large hibiscus tree in the
Malvaceae family, is found in the limestone forest habitats of Guam,
Tinian, Saipan, and Rota where there are substrates of karst,
clifflines, or outcroppings (Service 2023p, p. 10; Willsey et al. 2019,
p. 4). Tree roots grow into rough limestone crevices, especially on
cliffs and plateaus (Raulerson and Rinehart 1991, p. 94). On Tinian,
Heritiera longipetiolata are observed only in karsts within native
limestone forest (Stone 1970, p. 420; Service 2020m, pp. 7-8; DoN 2018,
in litt., entire). The species is restricted to native limestone forest
habitats where they are considered a canopy tree (University of Guam
(UOG) 2018, in litt., pp. 5, 11, 40) comprising a closed-canopy system
of broadleaf trees with an understory of younger trees, vines,
epiphytic ferns, and orchids (Stone 1970, pp. 419-420; Vogt and
Williams 2018, p. 66; Willsey et al. 2019, p. 3). Specifically, these
forests contain upper canopy tall trees (33 ft; 10 m or taller), mid-
story small to mid-size trees (10 to 33 ft (3 to 10 m)), and an
understory of shrubs and herbs (Falanruw et al. 1989, pp. 6, 8). The
vegetation community comprises species commonly associated with
limestone forests including (but not limited to) Asplenium nidus,
Hibiscus tiliaceus, Morinda citrifolia,
[[Page 14085]]
Phymatosorus scolopendria, Psychotria mariana, Abrus spp., Aidia spp.,
Aglaia spp., Ficus spp., Freycinetia spp., Melanolepis spp., Operculina
spp., Pandanus spp., and Pipturus spp. (Willsey et al. 2019, pp. 5-6;
Service 2023p, p. 12). Threats to this species include loss and
degradation of habitat due to impacts from invasive animal and plant
species, development, and climate change (i.e., increased precipitation
and increased typhoon intensity and severity); loss of pollinators due
to brown tree snake; herbivory by pigs, deer, rodents, invasive
invertebrates, and leaf miners; and plant pathogens (Service 2023p, pp.
17-19).
Heritiera longipetiolata requires sufficient space for sexual and
vegetative reproduction because individuals grow in clusters and
compete for sunlight and space (Service 2020m, p. 7). Sexual
reproduction requires close proximity to other conspecifics where
pollinators and seed dispersers can access individuals (Service 2020ag,
p. 9; Hawaii and Pacific Plants Recovery Coordinating Committee
(HPPRCC) 2011, p. 1). Seed dispersers, such as fruit-eating animals
like native birds and fruit bats, are necessary for population growth
and maintaining genetic diversity (Service 2023p, p. 13). Mutualists
(i.e., an organism that associates with a different species and both
benefit), such as H. longipetiolata, require abundant and reliable
sources of nectar, pollen, and fruits, and absence or low abundance of
invasive animals such as the brown tree snake and rodents (Service
2023p, pp. 12-13).
(11) Maesa walkeri PBFs
a. Maesa walkeri PBF 1: Native limestone forest and forest edge
habitats ranging in elevation between 656-1,312 ft (200-400 m).
b. Maesa walkeri PBF 2: Adequate sunlight, variable amounts of
moisture, and relatively constant temperatures.
c. Maesa walkeri PBF 3: Native vegetation such as Pandanus spp.,
and Hernandia-Elaeocarpus.
d. Maesa walkeri PBF 4: Native seed dispersers such as birds and
fruit bats.
e. Maesa walkeri PBF 5: Native pollinators such as insects and
native vegetation to support them.
Maesa walkeri are small to medium shrubs (family Myrsinaceae)
endemic to Guam and Rota limestone forests; they are most common along
sunny edges of Pandanus spp. forests in limestone substrate or karsts,
at 656-1312 ft (200-400 m) elevation, where there are variable amounts
of moisture and relatively constant temperatures (Fosberg and Sachet,
1979, pp. 368-369; Fosberg 1960, pp. 22, 42; Raulerson and Rinehart
1991, p. 67; Costion and Lorence 2012, p. 84; Service 2020n; p. 6;
Service 2020ai, p. 7; Service 2023q, pp. 3, 5, 10, 11). Maesa walkeri
are strongly tied to the extent and amount of limestone forest habitat
(Service 2023q, p. 13). Survival of the species depends on a number of
genetically well-maintained populations that can exchange genes. This
requires population distributions across a variety of habitat types
(Service 2020ai, pp. 7-8). Maesa walkeri is most abundant in grassland/
Pandanus spp. forest edges, lesser in forest/abandoned pasture edges
and species in the Hernandia and Elaeocarpus family (referred to as
Hernandia-Elaeocarpus) canopy with Pandanus tectorius understory, and
least abundant in Pandanus spp. forest/road edges (Service 2023q, pp.
10-11). Threats to this species include loss and degradation of habitat
due to impacts from development, feral ungulates, and brown tree
snakes; predation by rats, and climate change (i.e., increased periods
of drought and severe storm frequency) (Service 2023q, pp. 3, 14-15).
Maesa walkeri produces fruit and is assumed to be pollinated by
insects (Service 2023q, p. 10). The species reproduces sexually and
vegetatively (Service 2023q, pp. 6, 10). Seeds are likely dispersed by
native fruit-eating birds fruit bat (Gawel et al. 2018, p. 8; Service
2023q, pp. 10, 11), and seed dispersers are required for recruitment
and maintaining genetic diversity (Service 2023q, pp. 11, 14, 16;
Wandrag et al. 2015, p. 1).
(12) Nervilia jacksoniae PBFs
a. Nervilia jacksoniae PBF 1: Connected closed-canopy native
limestone, volcanic ravine, and mixed forests with leaf-littered humus
or sandy forest floors, shade, minor to moderate light, and moisture.
b. Nervilia jacksoniae PBF 2: Native limestone forest understory
with plants such as (but not limited to) Elaeocarpus joga, Hernandia
labyrinthica, Pandanus dubius (p[aring]hong, bakong, or knob-fruited
screwpine), Pandanus tectorius, Pisonia umbellifera, and Psychotria
malaspinae.
c. Nervilia jacksoniae PBF 3: Native volcanic forest understory
with plants such as (but not limited to) Barringtonia asiatica,
Hernandia sonora, Pandanus tectorius, Pisonia grandis, and Terminalia
catappa.
d. Nervilia jacksoniae PBF 4: Pollinators including insects, such
as small bees and wasps, and native vegetation to support them.
This ground orchid is a small terrestrial herb in the Orchidaceae
family that grows in canopy-covered, shady, moist, leaf-littered humus
or sand on forest floors of Guam and Rota; the orchids are found only
in native limestone and mixed-forest subtypes and native volcanic
forests of ravines in southern Guam (Service 2020o, p. 8; Service
2023r, pp. 5, 14). The species requires soils with sand or humus
(Service 2020aj, p. 14) for its subterranean reproductive tuber to
grow; it then rises to produce a flower and seed pods that are
dispersed by wind (Service 2023r, p. 8). Nervilia jacksoniae occur only
where there is minor to moderate moisture because all life stages
require precipitation during both rainy and dry seasons (Service
2020aj, p. 14; Service 2023r, pp. 9, 14).
Nervilia jacksoniae requires plant genera and substrates typical of
native limestone or volcanic forests in the Mariana Islands, growing
under native plants in limestone substrates such as Pandanus tectorius,
Pandanus dubius, Hernandia labyrinthica, Elaeocarpus joga, Pisonia
umbellifera, and the federally endangered Psychotria malaspinae
(Service 2020aj, pp. 9, 14) and growing under native plants in volcanic
substrates such as Pisonia grandis, Hernandia sonora, Barringtonia
asiatica, Pandanus tectorius, and Terminalia catappa (Willsey et al.
2019, pp. 5-6). Species observations are limited to areas containing
shade with minor to moderate filtered light (Service 2020aj, p. 14;
Service 2023r, p. 9). Substrate required for volcanic forests are
volcanic soils and associated plant species that may include Pisonia
grandis, Hernandia sonora, Barringtonia asiatica, Pandanus tectorius,
and Terminalia catappa (Willsey et al. 2019, pp. 5-6).
Reproduction requires wind and rain for seed dispersal (Service
2020aj, p. 15; Service 2023r, pp. 5, 17) and pollination by insects,
such as small bees and wasps (Pettersson 1991, p. 19; Service 2020aj,
p. 16). The flowers of the plant evolved to attach pollen masses to the
stigma of the flower (Johnson and Edwards 2000, pp. 243, 255; Mosquera-
Mosquera et al. 2019, pp. 363, 365-366). However, if there is an
inadequate number of individual plants present, they are unlikely to
attract pollinators (Gale 2007, p. 59). Germination rates are likely
very low on forest floors (0 to 12 percent) compared to in vitro
cultured seeds (76 to 99 percent) (Gale et al. 2010, p. 166), possibly
caused by a lack of mycorrhizal fungi for seed development, and
sometimes bacteria, which many orchid species require (Alghamdi 2019,
p. 502; Gale et al. 2010,
[[Page 14086]]
pp. 166, 175; Ray and Vadramne 2015, p. 2; Tsavkelova et al. 2007, pp.
69, 75). Fungi play an important role in overcoming light inhibition of
seed germination (Alghamdi 2019, p. 495). Reproduction also occurs by
vegetative growth through multiple tuber development (Service 2023r, p.
8) requiring adequate space in humus and sand to allow new tubers to
develop (Service 2020aj, pp. 14-15). Nervilia jacksoniae reproduction
and survival requires minimal disturbance. However, habitat disturbance
is frequent on Guam and caused by nonnative pigs, water buffalo
(Bubalus bubalis), deer, rats, reptiles (e.g., brown tree snakes),
invertebrates (e.g., cycad scale, slugs (e.g., pancake slug
(Veronicella sloanii)), and snails (e.g., giant African land snail) (80
FR 59424 at 59437 and 59449, October 1, 2015; Willsey et al. 2019, p.
16). On Rota, reproduction and survival can be inhibited by deer, rats,
and invertebrates (e.g., cycad scale, slugs, and snails) because they
eat, trample, or otherwise destroy seeds and plants (80 FR 59424 at
59437 and 59449, October 1, 2015; Willsey et al. 2019, p. 16). In
addition to the habitat-based threats from invasive, nonnative animals,
N. jacksoniae experiences loss and degradation of habitat due to
impacts from invasive plants, development, wildfire, and climate change
(i.e., increased precipitation, typhoon intensity, and frequency)
(Service 2023r, pp. 20-25).
(13) Psychotria malaspinae PBFs
a. Psychotria malaspinae PBF 1: Interconnected native limestone
forest habitat.
b. Psychotria malaspinae PBF 2: Sufficient space within a
vegetation community where there is closed canopy or where partial to
full sunlight is available with plants such as (but not limited to)
Abrus spp., Aglaia mariannensis, Aidia cochinchinensis, Asplenium
nidus, Ficus spp., Freycinetia spp., Hibiscus tiliaceus, Melanolepis
multiglandulosa, Morinda citrifolia, Operculina spp., Pandanus spp.,
Phymatosorus scolopendria, Pipturus argenteus (amah[aring]yan,
atmah[aring]yan, amahadyan, ghasooso, native mulberry), and Psychotria
mariana.
c. Psychotria malaspinae PBF 3: Native seed dispersers such as
birds and fruit bats.
d. Psychotria malaspinae PBF 4: Native pollinators and native
vegetation to support them.
Psychotria malaspinae, a rare endemic shrub or small tree in the
Rubiaceae family, is found only in undisturbed, connected, native
limestone forests with limestone soils and karsts on Guam (Service
2020ak, pp. 8, 9, 13, 16; Service 2023t, pp. 9-10; Stone 1970, pp. 554-
555). The species requires predominantly native vegetation typical of
limestone forests in the Mariana Islands that provide for their
reproduction and recruitment (for specific vegetation species see
Raulerson and Rinehart 1991, p. 83; Service 2020ak, p. 9; Service
2023t, p. 10; Stone 1970, pp. 554-555; Willsey et al. 2019, pp. 5-6),
including closed canopy of broadleaf trees with an understory of
younger trees, vines, epiphytic ferns, and orchids (Stone 1970, pp.
554-555; Vogt and Williams 2018, p. 66); tall trees (32 ft (10 m))
comprising the upper canopy, small to mid-size trees (10 to 33 ft (3 to
10 m)) as mid-story, and shrubs and herbs that form the understory
(Falanruw et al. 1989, pp. 6, 8).
Population connectivity results when seeds are dispersed across
contiguous limestone forests, and this is necessary to maintain genetic
diversity in multiple populations (Service 2020p, pp. 8-9; Service
2023t, p. 14). More than 83 percent of Guam's native forests are gone
or have severely impaired habitat connectivity (Service 2020an, p. 3),
but this species' persistence has been attributed to its distribution
in native limestone forests (Service 2023t, p. 15). Fruits and flowers
are eaten and dispersed by birds (Service 2023t, p. 9), which may
account for the current scattered distribution of the remaining
populations within the forest ecosystems on the northeast and southeast
sides of Guam (Stone 1970, pp. 554-555; Raulerson and Rinehart 1991, p.
83; Costion and Lorence 2012, pp. 54, 85-86, 96).
Seed dispersers are required to ensure seeds are moved farther away
from conspecifics allowing for increased recruitment to grow the
populations and to maintain genetic diversity (Service 2023t, p. 14;
Service 2020p, p. 9). Deposited seeds have low germination rates and
sow themselves nearby and produce seedlings (Service 2023t, p. 9).
Invasive ungulates and rodents cause significant rates of mortality to
seedlings and immature plants (i.e., by eating the seeds or disturbing
soils and substrates, exposing the seeds and ultimately killing them)
(Kessler 2011, p. 320; Rubinoff and Holland 2018, pp. 222-224). The
species requires pollination and seed dispersal by native species,
including birds. As stated previously, pollinators and birds are almost
entirely absent from Guam (Egerer et al. 2018, p. 655; Service 2020ak,
pp. 2, 14). Threats to this species include loss and degradation of
habitat due to impacts from invasive animal (e.g., brown tree snake)
and plant (e.g., vines) species, development, and increasing typhoon
intensity; loss of pollinators due to brown tree snake and rodents;
herbivory by pigs, Philippine deer, and rodents (Service 2023t, pp. 3,
15-16).
(14) Tabernaemontana rotensis PBFs
a. Tabernaemontana rotensis PBF 1: Interconnected native limestone
forests, open patches, and forest edges providing moderate to full
sunlight.
b. Tabernaemontana rotensis PBF 2: Native limestone forest habitat
vegetation such as (but not limited to) Abrus spp., Aidia spp., Aglaia
spp., Aglaia mariannensis, Aidia cochinchinensis, Asplenium nidus,
Elaeocarpus spp., Ficus spp., Freycinetia spp., Guamia spp., Hernandia
spp., Hibiscus tiliaceus, Intsia bijuga, Macaranga thompsonii,
Melanolepis spp., Morinda citrifolia, Operculina spp., Pandanus spp.,
Phymatosorus scolopendria, Pipturus spp., Pisonia grandis, Pouteria
spp., Premna spp., Psychotria mariana, and Trema spp.
c. Tabernaemontana rotensis PBF 3: Native seed dispersers such as
birds and fruit bats.
d. Tabernaemontana rotensis PBF 4: Native pollinators, such as
butterflies and other generalist pollinators, and native vegetation to
support them.
Tabernaemontana rotensis is a medium-sized tree (approximately 30
ft (9 m) tall) in the Apocynaceae family that requires interconnected
limestone forest habitat dominated by native vegetation (Service
2020al, pp. 10-11; UOG 2007, in litt., pp. 4, 11), which is found only
in the limestone forest habitat of Guam and Rota (Stone 1970, p. 485).
The species requires sufficient limestone forests with limestone soils
and karst for reproduction and recruitment, pollinators, and plant
species typical of a native limestone forest in the Mariana Islands,
which may include the species noted above in PBF 2 (Service 2020al, p.
11; Willsey et al. 2019, pp. 5-6). Sufficient space is needed for the
species to reproduce sexually or vegetatively (Service 2020al, p. 10),
preferably in open patches or forest edges where partial to full
sunlight is available (Service 2020al, p. 10; UOG 2007, in litt., pp.
4, 14-15). Germination and seedling emergence are maximized in partial
to full sunlight conditions if an adequate seed bank is available (UOG
2007, pp. 4, 14-15). Threats to this species include loss and
degradation of habitat due to impacts from invasive animal (e.g., brown
tree snake) and plant (e.g., vines) species, development, fire, and
climate change
[[Page 14087]]
(i.e., typhoons with intense winds); loss of pollinators from brown
tree snake and rodents; herbivory by invasive invertebrates and
rodents; and trampling by ungulates (i.e., pigs and Philippine deer)
(Service 2023t, pp. 3, 15-17).
Tabernaemontana rotensis population distribution is clustered
because seedling establishment is restricted to the vicinity of the
parent tree due to the loss of frugivorous bird species on Guam (from
being depredated by brown tree snakes) (UOG 2007, pp. 4-5, 9, 28;
Service 2017, pp. 80-82). The species requires seed dispersers and
contiguous limestone forest for population growth, maintaining genetic
diversity (Service 2020al, p. 11), aiding recruitment, and ensuring
seeds are dispersed away from conspecifics to increase recruitment
(Service 2023v, p. 16). Without dispersal from the parent, the seeds
develop in extreme competition with each other, and almost complete
mortality occurs (Rogers et al. 2017, p. 2; Service 2023v, p. 16; UOG
2007, pp. 22, 73). Fruit-eating animals benefit plant recruitment by
increasing germination during gut passage and moving seeds away from
the parent plants, consequently increasing distribution and resiliency
of the species (Service 2020al, p. 11). The pollinators are sustained
by abundant, diverse, and reliable sources of native nectar and pollen
plants, and stable habitats that are sufficiently free of nonnative
plants and animals (i.e., invertebrates, brown tree snake, rodents, and
ungulates) (Service 2020q, pp. 6-7, 9, 12, 20; Service 2020al, p. 11;
Service 2023v, p. 3).
(15) Tinospora homosepala PBFs
a. Tinospora homosepala PBF 1: Tall-canopy native limestone forests
with limestone soils and karst substrates.
b. Tinospora homosepala PBF 2: Native pollinators and native
vegetation to support them.
c. Tinospora homosepala PBF 3: Native seed dispersers such as
native birds and fruit bats.
Tinospora homosepala is a woody, climbing vine in the
Menispermaceae family that comprises the shrub or herbaceous components
of the limestone forest ecosystem of central Guam (Service 2023w, p.
5). The species requires limestone soils to limestone karst, its
primary substrate, and can inhabit backstrand habitat. It is most
likely found where there are tall trees that it can climb, likely to
obtain levels of sunlight consistent with limestone karst forest edge
habitat (GPEPP 2024, in litt., entire; Service 2020am, pp. 9-10).
Seasonal fluctuations (wet and dry season) typical of the Mariana
Islands may be necessary for completion of its life cycle (Service
2020am, p. 6), as are relatively constant temperature ranges and
precipitation requirements consistent with native limestone forests
(Ohba 1994, pp. 13-16; Mueller-Dombois and Fosberg 1998, p. 241;
Service 2023w, p. 9).
Tinospora homosepala reproduces both sexually and vegetatively and
is limited by the very low population abundance of 150 individuals
spread across only 4 locations; 120 of the plants are from 1
population, and the sexes of the plants are unknown (Service 2023w, p.
13). Sexual reproduction requires male and female plants and
pollination from insects (Service 2020am, pp. 6-7). Reproduction also
occurs via cloning (unisexual), in which severed vines send new roots
into the ground (Stone 1970, p. 277; Service 2023w, p. 9). Seed-
dispersing vertebrates, such as Mariana fruit bat, Mariana crow (Corvus
kubaryi), and Micronesian megapode (Megapodius laperouse) are also
likely necessary, because otherwise the plants would deposit their
seeds directly below themselves with little successful reproduction due
to low light, competition with more established plants, and high seed
density (Willsey et al. 2019, p. 3).
Nonnative animals have severely degraded the habitat and life
history requirements of Tinospora homosepala. The invasive brown tree
snake decimated the avian and small animal community that likely
functioned as seed dispersers (Service 2020r, pp. 8-9). Rodents
eliminated native plant species by eating the plants and their seeds
(although they possibly disperse seeds as well) (Service 2020r, pp. 8-
9). Nonnative invertebrates kill and otherwise reduce the abundance of
native invertebrates that likely serve as pollinators and provide other
functions supporting a healthy ecosystem (Service 2020r, pp. 8-9). In
addition to the nonnative brown tree snake, rodents, and other
invertebrates previously discussed, the fruit-piercing moth (Eudocima
fullonia) is an especially damaging invasive invertebrate that severely
reduces the female vines' fruit production by puncturing it, causing
the fruit to rot and decay (only female vines' fruit), with only male
plants remaining (Service 2023w, p. 14). Other threats include loss and
degradation of habitat due to development, feral ungulates, and climate
change (i.e., increased period of droughts and severe storm frequency)
(Service 2023w, pp. 3, 11-12).
Savanna Plants
This rare Guam savanna habitat rises from highly weathered volcanic
clay soils, and its distribution is associated with volcanic clay
substratum (Service 2020af, p. 11; Service 2023o, p. 10). The volcanic
clay soils are highly acidic in most places from the abundance of
aluminum in the soil (Mueller-Dombois and Fosberg, 1998, pp. 269-270;
Carroll and Hathaway 1963, pp. 29-30) and are characterized as nutrient
deficient (Boj[oacute]rquez-Quintal et al. 2017, pp. 1-4). Soils
containing aqueous aluminum may stimulate plant growth by promoting
nutrient intake depending on the environmental conditions,
concentration of the aluminum, and the plant species (Boj[oacute]rquez-
Quintal et al. 2017, pp. 2-10). This savanna habitat has a uniquely
stable climate with daily temperatures ranging between 73 and 86 [deg]F
(22 and 30 [deg]C), 6 to 8 hours of sunlight, distinct dry and wet
seasons averaging 96 in (218 centimeters (cm)) of rain annually, and
underlying volcanic substratum with very low porosity causing most
rainwater to run off into streams and the ocean (Service 2020af, p. 15;
Service 2023o, p. 14). There are five plant communities in the savanna
habitat, including (1) Miscanthus (silver grass or maiden grass), (2)
Dimeria spp. (a type of woody/herbaceous grass), (3) erosion scar
(pioneer species of grasses, ferns, and shrubs within heavily eroded
savanna areas), (4) Phragmites (common reed), and (5) the weed
community which follows disturbance (Fosberg 1960, pp. 64-66).
(16) Hedyotis megalantha PBFs
a. Hedyotis megalantha PBF 1: Native savanna habitats with volcanic
soils.
b. Hedyotis megalantha PBF 2: Grasses, ferns, shrubs, and other
savanna vegetation such as (but not limited to) Decaspermum fruticosum
(no common name), Dicranopteris linearis (Old World forked fern, uluhe,
chacha), Dimeria spp., Fimbristylis spp., Geniostoma micranthum (no
common name), Lycopodium cernuum (p[aring]tas ng[aring]nga', staghorn
clubmoss, nodding clubmoss), Machaerina mariscoides (tropical
twigrush), Melastoma malabathricum var. mariannum (melastoma, gafao,
gafau), Myrtella benningseniana (no common name), Phyllanthus
saffordii, and Rhynchospora rubra (sweet broom, macao tea).
c. Hedyotis megalantha PBF 3: Native pollinators, such as
butterflies and other generalist pollinators, and native vegetation to
support them.
[[Page 14088]]
Hedyotis megalantha is a long-lived woody herb in the coffee family
Rubiaceae and is endemic to Guam savanna (Global Biodiversity
Information Facility 2024, website; Mueller-Dombois and Fosberg 1998,
pp. 269-270; UOG 2018, in litt., pp. 10-11; Service 2020af, p. 7;
Service 2023o, pp. 3, 10, 13). Hedyotis megalantha may require acidic
soils for optimal growth, but research on other Hedyotis species
indicates a preference for acidic soils, not confinement to them
(Fosberg 1960, pp. 22-23, 31-32, 34-35; Service 2020af, p. 15). The
species may require only minimal nutrients for survival or may have an
enhanced ability to absorb soil nutrients (Service 2023o, p. 14).
Hedyotis megalantha benefits from the presence of aqueous aluminum and
may have other biological mechanisms allowing its survival in low-
nutrient environments, including a symbiotic relationship with the
microbial community or through commensalism (where a species receives
benefits but there are no effects on the other organism) (Service
2020l, p. 7; Service 2023o, p. 14). Threats to this species include
loss and degradation of habitat due to impacts from development,
nonnative animals and plants, wildfire, erosion, off-road vehicle use,
and possibly changes in frequency and intensity of precipitation and
typhoon events (Service 2023o, pp. 3, 18-25).
Hedyotis megalantha is limited primarily to high-quality native
savanna habitat with little human disturbance, often found growing in
clusters with native ferns including Dicranopteris linearis, in Dimeria
spp. plant communities, and in erosion scar communities (Frager et al.
2019, p. 4; Demeulenaere 2020, in litt., entire; Service 2020l, pp. 6-
7; Service 2023o, pp. 10, 14). Dimeria spp. communities are dominated
by Dimeria chloridiformis (no common name), a low-growing grass, with
Hedyotis megalantha and Phyllanthus saffordii scattered throughout
(Demeulenaere 2020, in litt., entire). Erosion scar communities contain
Hedyotis megalantha growing in between low-growing shrubs such as
Melastoma malabathricum var. mariannum, Decaspermum fruticosum,
Myrtella benningseniana, Phyllanthus saffordii, and Geniostoma
micranthum; low-growing sedges such as Rhynchospora rubra, Fimbristylis
spp., and Machaerina mariscoides (relatively taller than Hedyotis
megalantha); and ferns such as Lycopodium cernuum, and Dicranopteris
linearis (Demeulenaere 2020, in litt., entire; Service 2020l, pp. 6-7;
Service 2023o, p. 14).
Hedyotis megalantha reproduction may include self-pollination,
inability to self-pollinate, and sexual reproduction; no studies have
yet determined the breeding system (Service 2023o, p. 15). Pollinators
are undocumented but the species likely requires cross-pollination for
optimal breeding success, with pollinators likely consisting of a
variety of insects similar to other species within the genus Hedyotis
(Service 2020l, p. 7). The white flowers with purple anthers of
Hedyotis megalantha may attract butterflies and other generalist insect
pollinator species. Seed dispersal for Hedyotis megalantha likely
occurs via abiotic factors such as wind, gravity, or water (Service
2020af, p. 17; Service 2023o, p. 16). Seeding likely occurs during the
wet season, maturing occurs into the dry season, and the species may
require dry seasons to set fruit and for seed germination (Service
2023o, pp. 15-16). Prolonged hours of sunlight may be needed for both
seed germination and for seedlings to mature, including production of
the next generation of seeds (Service 2020af, p. 15; Service 2023o, p.
14).
(17) Phyllanthus saffordii PBFs
a. Phyllanthus saffordii PBF 1: Savanna habitats with volcanic
substrates containing lateritic soils, including (but not limited to)
Dimeria spp. communities and erosion scar communities.
b. Phyllanthus saffordii PBF 2: Forest edges, steep slopes, and
eroded soils on volcanic substrates containing lateritic soils.
c. Phyllanthus saffordii PBF 3: Savanna vegetation such as (but not
limited to) Decaspermum fruticosum, Dicranopteris linearis, Dimeria
chloridiformis, Fimbristylis spp., Geniostoma micranthum, Melastoma
malabathricum var. mariannum, Myrtella benningseniana, Machaerina
mariscoides, Lycopodium cernuum, Phyllanthus saffordii, and
Rhynchospora rubra.
d. Phyllanthus saffordii PBF 4: Native pollinators, such as bees,
ants, moths, butterflies, and other generalist pollinators, and native
vegetation to support them.
e. Phyllanthus saffordii PBF 5: Native seed dispersers such as
birds and fruit bats.
Phyllanthus saffordii is a short-stature and short-lived woody
shrub in the Phyllanthaceae family and persists only in southern Guam
in the savanna habitats with deeply weathered volcanic substrates that
contain lateritic soils (high iron and aluminum content, red clay, and
highly acidic), including erosion scar and Dimeria spp. communities,
and the plants are also found along forest edges, steep slopes, and
severely eroded soils; the species does not occur in alkaline soils of
northern Guam (Service 2020s, p. 5; Service 2023s, pp. 2, 15). The
species most commonly occurs among other low-growing plants including
the native grass Dimeria chloridiformis, and among the native scar
community, consisting of the low-growing shrubs, low-growing sedges,
and fern species identified above (Demeulenaere 2020, in litt.,
entire). Both Phyllanthus saffordii and Hedyotis megalantha can be
found growing between grass, sedges, shrubs, and ferns (Demeulenaere
2020, in litt., entire; Service 2023s, p. 4). Threats to this species
include loss and degradation of habitat due to impacts from
development, invasive animals (e.g., ungulates) and plants (e.g.,
nonnative grasses), erosion, wildfire, and climate change (i.e.,
increased precipitation and increased typhoon intensity and frequency)
(Service 2023s, pp. 16-23).
Like other species within the Phyllanthus genus, Phyllanthus
saffordii likely relies on bees, ants, moths, butterflies, and other
generalist pollinators rather than avian or fruit bat or wind for
pollination (Kawakita 2010, p. 13; Service 2020y, p. 13). Phyllanthus
saffordii is not known to be capable of self-pollinating or reproducing
without fertilization (Service 2023s, p. 14; Sharma et al. 2009, p.
286). Phyllanthus saffordii likely depends on dry seasons for fruiting
and seed germination, and seed dispersal likely involves fruit-eating
avian species that distribute seeds (Prasad et al. 2004, entire;
Service 2020y, p. 13; Service 2023s, p. 14). Prolonged hours of
sunlight are likely needed for seed germination and for seedlings to
mature, including the production of the next generation of seeds
(Service 2020y, pp. 12-13).
Special Management Considerations or Protection
When designating critical habitat, we assess whether the specific
areas within the geographical area occupied by the species at the time
of listing contain features that are essential to the conservation of
the species, and which may require special management considerations or
protection. The specific PBFs essential to the conservation of the
Mariana Islands species may require special management considerations
or protection to reduce the threats affecting those features. Threats
to the Mariana Islands species are described in the final listing rule
(80 FR 59424; October 1, 2015) and summarized in this proposed
[[Page 14089]]
rule; noting that some information, descriptions, and references used
herein are new since the final listing determination. The threats and
associated special management considerations or protection addressed in
this document are specific to the PBFs and grouped into six threat
categories based on the primary threats to the PBFs. Each of these
threats and associated special management considerations or protection
are summarized below.
(1) Development--includes agricultural, military, urban, and
commercial development, as well as activities associated with
construction, repair, and maintenance of roads, bridges, and utilities
(e.g., power plants and renewable energy facilities).
Habitat clearing for development is among the greatest threats to
the recovery of the Mariana Islands species. Development causes habitat
loss and degradation by reducing the available habitat and foraging,
breeding, and sheltering sites for the species (Service 2023a, p. 17).
This may lead to habitat fragmentation, which separates populations,
limits pollination, and can be deleterious to plant-pollinator
mutualisms, especially invertebrates (Newman et al. 2013, p. 16). Many
sites that species once occupied have been developed on several
islands, thus reducing the amount of suitable habitat available for the
species (80 FR 59424 at 59429-59430, October 1, 2015). Agricultural
development can include land clearing to grow a wide range of
agricultural products, including livestock (grazing), vegetable farms,
and plant nurseries for commercial sale. Military development can
include construction of housing and a wide variety of military
activities, such as the placement and removal of objects, and
unexploded ordnance management (although areas where this may occur are
exempt under section 4(a)(3) of the Act (see Exemptions, below). Urban
and commercial development can include the construction of residential
homes and various commercial buildings, including parking lots.
Activities associated with development can include limestone rock
quarrying; construction or maintenance of renewable power plants; and
construction, repair, and maintenance of roads, bridges, and utilities
including renewable energy. Actions associated with development also
include stream diversions for municipal water supply that directly
reduce the amount of available stream habitat annually (Service 2020aa,
p. 4). For example, on the island of Rota, the reduction of and changes
to forest landscape due to urban or agricultural development have
changed the quantity and quality of the groundwater that the aquifer
feeds to the island's streams. Additional/future impacts may also
further degrade or reduce forest habitat and the capacity for the
Sabana Plateau to replenish the aquifer water available for stream
habitat (Service 2020aa, p. 50). Examples of special management and
considerations or protections that could reduce the threat of
development may include (but are not limited to):
<bullet> Use best management practices to limit or reduce erosion/
stream sedimentation, retain natural barriers/culverts, or construct
barriers that prevent erosion of the stream edge;
<bullet> Minimize the destruction of native forest vegetation,
especially large-growth trees and species-specific host plants;
<bullet> Require qualified and experienced surveyors to conduct
preconstruction surveys to locate and avoid listed species and PBFs;
<bullet> Conduct habitat restoration;
<bullet> Limit ground-disturbing activities;
<bullet> Cover open trenches and excavated pits and visually
inspect excavated areas before backfilling;
<bullet> Implement stream stabilization and erosion control
protocols;
<bullet> Create riparian buffers if land abuts streams to reduce
soil erosion and filter water flowing from croplands;
<bullet> Restore disturbed areas using native plants once projects
are completed;
<bullet> Avoid or limit vegetation and soil disturbance;
<bullet> Protect sensitive areas where they abut project boundaries
by installing and maintaining plastic construction fencing or brightly
colored flagging around these areas; and
<bullet> Use dust abatement techniques along roadways to minimize
dust to vegetation.
(2) Invasive species--includes animals (ungulates, rodents, brown
tree snake, ants, slugs) and nonnative plants.
Invasive animals (e.g., ungulates, rodents, brown tree snake, ants,
and slugs) degrade native forest, savanna, and stream habitats that are
required by the Mariana Islands species. Ungulates damage mature
vegetation and clear forest understory through grazing and trampling,
contributing to erosion, and preventing the regeneration of seeds or
seedlings by eating or damaging them (Service 2023a, pp. 17-18). They
also contribute to the spread of invasive plants by transporting seeds
and plant parts (Cuddihy and Stone 1990, p. 65). For Langford's tree
snail, suitable habitat has been severely impacted on Aguiguan as
nonnative goats have destroyed much of the forest on the island
(Service 2020d, p. 5). Rodents reduce native plant reproduction and
vigor by eating fruits, seeds, flowers, stems, roots, and other plant
parts (Atkinson and Atkinson 2000, p. 23).
Forest degradation from invasive species is associated with
declines in Slevin's skink populations, and skink populations increased
following forest regeneration from ungulate removal on Sarigan and
rodent eradication on Guam's Cocos Island (Kessler 2011, p. 320;
Richmond et al. 2021, p. 69). Tree snails also increased in abundance
within forested areas following ungulate removal on Sarigan (CNMI DFW
2008, p. 8-5). The ungulate removal on Sarigan Island was a mitigation
measure that the U.S. Department of Navy (DoN) implemented to improve
habitat and population sizes of the federally endangered Micronesian
megapode (Megapodius laperouse) to offset the impacts of military
bombing activities that occurred on Farallon de Medinilla.
Host plants for the Mariana eight-spot butterfly have become
restricted to cliff edges and pinnacle karst terrain where they are
less accessible to ungulates. Where brown tree snakes occur, they have
caused the extirpation of most of the forest birds (and fruit bat) that
were pollinators or seed dispersers (Fritts and Rodda 1998, p. 129).
Invasive ants prey on vertebrate and invertebrate eggs, pupae, larvae,
and adults as well as transport plant pests such as aphids, white
flies, and scale insects, affecting the pollinators and seed dispersers
required to maintain and grow native forests (Wild 2014, in litt.,
entire; Hawaii Invasive Species Council 2021, in litt., entire). Ants
also exert direct predatory pressure on tree snails. Slugs damage both
host plants of the Mariana eight-spot butterfly and other native forest
plants, causing mortality and altering native forests (Service 2023a,
p. 22). Invasive plants (e.g., Spathodea campanulata (African tulip
tree), Areca catechu, Citrus sp., Cocos nucifera, Delonix regia (flame
tree), Casuarina equisetifolia, Pithecellobium dulce (kamachile),
Mangifera sp. (mango), Acacia confusa (sosugi), Leucaena leucocephala
(tangant[aring]ngan), Samanea saman (trongkon-mames or monkeypod), and
Vitex parviflora (vitex) forests degrade native forests by modifying
light availability, soil-water regimes, nutrient cycling, fire regimes,
and converting plant communities from native to nonnative (Willsey et
al. 2019, pp. 5-6, 16-17). Invasive plants and ungulates may reduce
water input into the aquifer feeding the streams (Service 2020aa, p.
34). Examples of special management considerations and protections that
could reduce the threat
[[Page 14090]]
of invasive animals and nonnative vegetation may include (but are not
limited to):
<bullet> Implement biosecurity protocols to prevent the
introduction or movement of invasive species in or out of the project
area;
<bullet> Conduct habitat restoration;
<bullet> Control or remove/eradicate ungulates, rodents, brown tree
snakes, invasive invertebrates (e.g., New Guinea flatworm, parasitic
wasps, and ants), and significant habitat-modifying invasive plants;
and
<bullet> Install and monitor exclusion fencing to prevent
reintroduction of invasive species into project areas after
eradication.
(3) Wildfire--Wildfire is not a part of the ecosystem in the
Mariana Islands, and natural fires in the Mariana Islands are uncommon
due to moist environmental conditions; however, hunters and poachers
are known to intentionally ignite fires to encourage new plant growth
to attract prey animals (Guam Department of Agriculture 2021, p. 67).
These intentionally ignited fires can spread out of control to become a
wildfire. Wildfires destroy individual plants and alter suitable
habitat conditions, allowing nonnative plants to dominate plant
communities after the fire. Fires in the forest and savanna can convert
these habitats to bare ground or grasslands, leading to either
colonization by invasive plants or conversion to bare ground that
cannot support plant growth due to severe erosion (Willsey et al. 2019,
p. 18). Fires in these habitats may also lead to erosion and deposits
of silt into streams and the ocean (Guam Department of Agriculture
2021, p. 55). Areas converted to grass facilitate the spread of future
fires and reduce the area of remaining suitable forest and savanna
habitats each successive dry season (Tunison et al. 2001, p. 126).
Examples of special management considerations or protection may include
(but are not limited to):
<bullet> Restrict activities that entail the use of extreme heat to
areas that are kept bare of vegetation, such as paved or maintained
gravel areas;
<bullet> Limit activities that are potential fire risks to the wet
season (July-December);
<bullet> Create and maintain a system of firebreak roads between
action areas and suitable habitat for listed species;
<bullet> Prescribe burning, mowing, vegetation removal, or planting
native vegetation that is more fire resistant; and
<bullet> Minimize destruction of forest vegetation when
implementing fire management actions such as firebreaks, vegetation
removal, or prescribed burning, especially large-growth trees and
species-specific host trees/plants.
(4) Climate change--includes increase in typhoon frequency and
changes to precipitation seasonality and temperature.
Potential impacts of climate change to the Mariana Islands species
include an increase in typhoon intensity and alteration to normal
ranges for precipitation and temperature due to extreme El Ni[ntilde]o
events. Ocean surface temperature increases are expected to result in
increased typhoon intensity in the Mariana Islands and may result in
changes to habitat by defoliating or uprooting trees or breaking
primary branches and creating space for invasive, disturbance-tolerant
species to dominate (Emanuel 2013, p. 12,219; Camargo 2013, p. 9,896;
Grecni et al. 2021, p. 5). Typhoons exacerbate other threats and
adversely affect habitat and food resources and pose a particular
threat to small and isolated populations, such as the Pacific sheath-
tailed bat population on Aguiguan (Service 2023a, pp. 17-24; Service
2020u, p. 12). Typhoons can also cause landslides or flooding. An
increase in extreme El Ni[ntilde]o events can change normal
precipitation and temperature ranges that may exacerbate the wildfire
threat, alter stream flows, and change microclimate and suitability of
habitats that support the Mariana Islands species (Grecni et al. 2021,
p. 23). Anticipated sea level rise and coastal erosion are expected to
remove low-lying and coastal sites from future terrestrial species
conservation use, coupled with the effects of typhoons (Grecni et al.
2021, pp. 27, 32-33).
Examples of special management considerations or protections that
could reduce the negative effects of climate change may include (but
are not limited to):
<bullet> Conduct habitat restoration and debris cleanup after
typhoons;
<bullet> Implement erosion control protocols to protect coastal
strand areas from sea level rise;
<bullet> Implement watershed management plans to maintain waterflow
and decrease the effects of flooding; and
<bullet> Ensure communication with external partners on preferred
response methodologies, such as post-typhoon debris cleanup to prevent
the spread of invasive species and consultations with local partners on
the typhoon recovery actions to protect or restore degraded habitat
after typhoons.
(5) Recreational land use--includes the use of essential and
nonessential off-roading vehicles and recreational access/use, such as
hiking and camping.
Land use for recreational purposes may have an impact to the
Mariana Islands species and their habitats. Off-road vehicle use
through savanna and forest habitats reduces suitable habitat by
increasing erosion. For example, within savanna habitat on the island
of Rota, vehicles tend to consistently follow the same paths causing
soil trails to deepen and worsen erosion, which deposits silt into
streams and the ocean, altering the water quality of streams and ponds
occupied by the Rota damselfly. Off-road vehicle use also compacts the
soil, decreasing the soil porosity, which is already low for volcanic
clay soils of the savanna, and increasing soil erosion (Swaddell 2024,
in litt., entire). Recreational access to caves and forests occupied by
the Pacific sheath-tailed bat may lead to roost abandonment and alter
food availability for the bat (Service 2023a, p. 24). An increase in
human activity may also lead to movement of invasive plants and animals
in and out of recreational areas. Examples of special management
considerations or protections that could reduce threats related to
recreational land use may include (but are not limited to):
<bullet> Implement and enforce policies that restrict access to
highly weathered off-road trails during the wet season when the
possibility of soil erosion is higher;
<bullet> Implement habitat restoration projects to help contain
sediments during the wet season;
<bullet> Plant native vegetation to stabilize highly weathered
savanna habitat;
<bullet> Implement biosecurity protocols within conservation areas
and educate the public on their use and effectiveness;
<bullet> Avoid or reroute off-road trails away from stream
crossings or prioritize closure of these routes;
<bullet> Restore the areas where high levels of erosion occur;
<bullet> Conduct micropropagation and develop ex situ populations
of federally listed plants; and
<bullet> Implement wildfire prevention protocols and educate the
public on the prevention of wildfires in areas where hiking and camping
occur.
(6) Pesticides--includes herbicides and insecticides.
This threat may injure or kill listed plants and animals or harm
their habitat. Pesticides alter foraging habitat for listed animal
species addressed in this proposed rule by disrupting the life cycle of
forest vegetation through decreasing or removing pollinators and
reducing the availability of food sources (e.g., insect prey for the
Pacific sheath-tailed bat and the Slevin's skink) (Kearns et al. 1998,
entire; Service
[[Page 14091]]
2020u, pp. 11-12; Harrington et al. 2020, p. 14). Examples of special
management considerations or protections that could reduce the threat
of pesticides may include (but are not limited to):
<bullet> Limit use of insecticides, herbicides, or fungicides and
follow labeled instructions, or use natural predators or remedies to
reduce pests;
<bullet> Avoid applying pesticides during the wet season (July-
December) or if rainfall is expected within 24 hours to decrease the
likelihood that pesticides will wash into streams and rivers;
<bullet> Avoid applying pesticides when wind speed is greater than
12 mph and direction may cause it to drift to sensitive sites;
<bullet> Protect nontargeted species (vegetation, vertebrates, or
invertebrates) by monitoring for drift or accidental application and
using a spotter to monitor application;
<bullet> Flag or otherwise identify native or listed plants and use
plant guards to protect these plants in the application area; and
<bullet> For herbicides, cut or mow target vegetation first and
subsequently treat cut stems or resprouting vegetation to reduce
potential drift to nontargeted plants.
(7) Inadequate regulatory mechanisms--In addition to the six
primary threats identified above, the listing rule and recovery plan
identified inadequate regulatory mechanisms or failure to enforce these
regulations as a factor affecting the status of all the Mariana Islands
species (80 FR 59424 at 59467-59468, October 1, 2015; Service 2023a, p.
23). To date, these mechanisms do not address all of the species in
this proposed rule:
<bullet> Existing Commonwealth and Territorial laws including Fish,
Game, and Endangered Species Act (Public Law 2-51) and the Wildlife
Conservation Act (CNMI 1994, entire) within the Sabana Heights and
I'Chenchon Bird Sanctuary areas, Mariana Crow Conservation Area, and
Sabana Protected Area;
<bullet> Memorandum of agreement between the Service's Pacific
Islands Fish and Wildlife Office and the CNMI Department of Public
Lands, with the Northern Mariana Islands Department of Land and Natural
Resources, for the Mariana Crow Conservation Area (Service 2011,
entire); and
<bullet> Management and action plans including CNMI Forest Action
Plan 2020-2030 (CNMI Forestry Division of Agriculture--Department of
Lands and Natural Resources (CNMI FDoA 2020, entire), CNMI Wildlife
Action Plan 2015-2025 (CNMI Division of Fish and Wildlife 2015a,
entire), MAC Plan (MAC Working Group 2014, entire), CNMI Comprehensive
Public Land Use Plan Update for Rota, Tinian, Saipan, and the Northern
Islands (CNMI Department of Public Lands (CNMI DPL) 2019, entire), and
CNMI's Comprehensive Sustainable Development Plan 2021-2030 (CNMI OPD
2021, entire).
Inadequate regulatory mechanisms threaten the Mariana Islands
species and their habitats by allowing development that degrades and
destroys suitable habitat and allows spread of invasive/nonnative
species by not employing biosecurity measures (Service 2023a, p. 23).
The laws do not prohibit or address the intentional introduction of
ungulates or intentional ignition of wildfires, except for Public Law
35-134, which extends the definition of arson to include destruction or
damage to forest lands (Territory of Guam 2020, entire). Local laws in
the Territory of Guam and the CNMI have not been updated to include all
of the federally endangered and threatened species addressed in this
proposed rule. As a result, ``take'' of endangered or threatened
wildlife is not prohibited under local law during development and other
activities, nor are endangered or threatened plants considered. This
limits protection of these species and their habitats to projects with
a Federal nexus (Service 2023a, p. 23). Examples of special management
considerations or protection that could address inadequate regulatory
mechanisms or failure to enforce these regulations may include (but are
not limited to):
<bullet> Locally list federally listed species and ensure local
laws are updated;
<bullet> Encourage the passage and enforcement of laws, ordinances,
and codes that protect federally endangered and threatened species and
their habitat, where applicable;
<bullet> Encourage Territorial and Commonwealth governments to
adopt policies that support less development, address biosecurity
inadequacies, prevent the intentional introduction of ungulates, and
prevent the intentional ignition of wildfires; and
<bullet> Employ full-time enforcement officers that can educate the
public about regulations and have the power to prosecute violations of
local laws, ordinances, and codes.
Criteria Used To Identify Critical Habitat
As required by section 4(b)(2) of the Act, we use the best
scientific data available to designate critical habitat. In accordance
with the Act and our implementing regulations at 50 CFR 424.12(b), we
review available information pertaining to the habitat requirements of
the species and identify specific areas within the geographical area
occupied by the species at the time of listing and any specific areas
outside the geographical area occupied by the species to be considered
for designation as critical habitat.
<bullet> For 9 animal species (Pacific sheath-tailed bat, Slevin's
skink, Mariana eight-spot butterfly, Mariana wandering butterfly, Rota
blue damselfly, fragile tree snail, Guam tree snail, humped tree snail,
and Langford's tree snail) and 13 plant species (Bulbophyllum guamense,
Cycas micronesica, Dendrobium guamense, Eugenia bryanii, Hedyotis
megalantha, Heritiera longipetiolata, Maesa walkeri, Nervilia
jacksoniae, Phyllanthus saffordii, Psychotria malaspinae,
Tabernaemontana rotensis, Tinospora homosepala, and Tuberolabium
guamense), we are proposing to designate critical habitat in areas
within the geographical area that these species occupied at the time of
listing (see tables 3-24 and descriptions for Areas 1-41, below). We
are not proposing to designate any areas outside the geographical area
occupied by the species because we have not identified any unoccupied
areas that meet the definition of critical habitat. These occupied
areas encompass the varying habitat types and distribution of these
Mariana Islands species and provide sufficient habitat to allow for
maintaining and potentially expanding their distributions, areas of
which are essential to the species' conservation.
<bullet> For one plant species, Solanum guamense, we are not
proposing critical habitat because the area that meets the definition
of critical habitat is exempt under section 4(a)(3)(B)(i) of the Act
(see Exemptions, below). We are also not proposing to designate any
areas outside the geographical area occupied by Solanum guamense
because we have not identified any unoccupied areas that meet the
definition of critical habitat. This species was last seen in 1994 on
DoD lands within the exempted area, and most other locations with
historical records of this species have been developed or converted to
unsuitable habitat (Service 2023u, p. i).
<bullet> For the Mariana subspecies of the Pacific sheath-tailed
bat, we are proposing to designate critical habitat in one location
that is within the geographical area occupied by the species at the
time of listing (the island of Aguiguan) and also one location that is
outside the geographical area occupied by the species at the time of
listing (the island of Rota) because we
[[Page 14092]]
have determined the unoccupied area is essential for the conservation
of the species (see table 2 and descriptions for Areas 9 and 14,
below).
The Mariana subspecies of Pacific sheath-tailed bat occurs only on
Aguiguan Island, but historically occupied seven islands within the
Marianas (Service 2023a, p. 10). The bat is highly susceptible to
stochastic and catastrophic events, especially considering the threats
it faces, such as depredation by nonnative animals, disturbance at
roost caves, and habitat loss from deforestation and overgrazing by
ungulates (Service 2023a, pp. 10, 41-43, 63). Therefore, we have
determined that the area currently occupied by this subspecies, on
Aguiguan, is insufficient to support the species' representation,
redundancy, and resiliency. We anticipate that recovery will require
continued protection of the existing population and its habitat, and
reintroduction of the Mariana subspecies of the Pacific sheath-tailed
bat into other areas, ensuring there are adequate numbers of the bats
in multiple locations. The delisting criteria specified in the species'
recovery plan includes a minimum of six stable or increasing
populations with consistently occupied roosts on three or more islands
(noting that stable populations have at least 500 individuals over a
10-year period (Service 2023a, pp. 41-43)). Therefore, we have
identified three locations necessary to recover the Mariana subspecies
of Pacific sheath-tailed bat: the occupied island of Aguiguan (see
Proposed Critical Habitat Designation, Area 9, below) and the
unoccupied islands of Rota (see Proposed Critical Habitat Designation,
Area 14, below) and Guam (on DoD lands that are exempt under section
4(a)(3) (see Exemptions, below)).
The Pacific sheath-tailed bat was historically found on Guam and
Rota, and the caves and foraging habitat present on the islands provide
the resources (i.e., PBFs) needed by the species. At this time for
Guam, the U.S. Department of Defense (DoD) has a contract with the U.S.
Geological Survey (USGS) to survey for Pacific sheath-tailed bats using
acoustic monitors and cameras in caves on DoD lands that are currently
or were historically occupied by the endangered Mariana swiftlet, which
is known to co-occur with the Pacific sheath-tailed bat (Duenas 2024,
pers. comm.; Lemke 1986, p. 744). This roosting and foraging habitat
meets the definition of critical habitat and occurs on DoD lands;
therefore, in accordance with section 4(a)(3)(B)(i) of the Act, we have
determined that the identified lands on Guam are subject to the Joint
Region Marianas (JRM) INRMP and that conservation efforts identified in
the JRM INRMP will provide a benefit to the Pacific sheath-tailed bat
(see Exemptions, below).
At this time on Rota, communications are underway with CNMI
Division of Fish and Wildlife and Biodiversity Research Institute to
plan for potential future translocations of Pacific sheath-tailed bat
from Aguiguan to Rota (Guilbert et al. 2024, pers. comm.). With the
best available scientific information, we identified the unoccupied
area on Rota as containing one or more of the PBFs that support the
life history requirements of the subspecies and meeting the definition
of critical habitat. Designating this unoccupied area as critical
habitat for this subspecies also promotes conservation actions to
restore the historical, geographical, and ecological representation
that is important for its recovery (Service 2023a, p. 42). In general,
this species, and others occupying CNMI and Guam, are so rare in the
wild that they are at a high risk of extirpation or even extinction
from various catastrophic events, such as typhoons. Therefore,
supporting resiliency and redundancy for the Pacific sheath-tailed bat
through the establishment of multiple, robust populations is a key
component of conservation of the species (Service 2023a, p. 42). A
designation limited to the single occupied area on Aguiguan is
inadequate to ensure the conservation of this subspecies. Areas that
may have been unoccupied at the time of listing, together with the area
occupied at the time of listing, are reasonably certain to provide some
or all of the habitat necessary for the expansion of existing wild
populations and reestablishment of wild populations within the
historical range of the subspecies to support viability.
For all of the Mariana Islands species addressed in this proposed
rule, we evaluated the following information to determine and select
appropriate areas occupied at the time of listing that also contain the
PBFs essential to the conservation of each species: (1) the 2015
listing rule (80 FR 59424; October 1, 2015), (2) 5-year reviews
(Service 2020a-u, entire; Service 2021, entire; Service 2024a-b,
entire), (3) species reports (Service 2020t-ao, entire; Service 2023b-
x, entire), (4) habitat status assessments (Frager et al. 2019, entire;
Plentovich et al. 2020, entire; Polhemus and Richardson 2020, entire;
Willsey et al. 2019, entire), (5) the recovery plan for the 23 species
in the Marianas (Service 2023a, entire), (6) section 7 consultations
and technical assistance requests, (7) multiple published and
unpublished reports included in the literature cited section, and (8)
our database information relevant to species presence and suitable
habitat.
All of the species in this proposed rule had not been thoroughly
surveyed prior to the time of listing in 2015, which required our
consideration of and reliance on updated species occurrence data from
our Federal and local partner agencies. Therefore, to determine if an
area was occupied at the time of listing, either: (1) individuals were
observed prior to listing; or (2) if surveys were not conducted until
after listing, an area was considered occupied if the habitat had not
changed since listing and the best available information indicated that
the area was likely occupied at the time of listing (e.g., individuals
of a species were observed within adjacent and/or connected suitable
habitat areas that have no barriers to dispersal). In some of these
instances, recent surveys have confirmed individuals within these new
areas.
In this proposed rule, we propose critical habitat for 22 species
in CNMI and Guam that include 122 critical habitat units. Each proposed
critical habitat unit contains all or some of the PBFs essential to the
conservation of the species that occupy their respective units. In some
instances, limited data sources were available on the species itself or
surrogates to provide specificity for features such as food, water
quality parameters, nutritional or physiological requirements,
reproduction requirements, and the specific amount of space necessary
for individual and population growth. Therefore, in some instances we
use general descriptions of the PBFs based on the best scientific
information available. The proposed critical habitat includes the soil
substrate, vegetation, and (if applicable) cave or stream system that
supports the life history requirements for each of the species. Some
species may require more than one type of substrate and vegetation
(e.g., Cycas micronesica occurs on volcanic, limestone, or coastal
strand substrates, each with the associated forest plant communities
typical of their respective substrates).
Because multiple species within this proposed rule have similar
life history requirements, the species are grouped together within this
preamble based on these related requirements. The eight species groups
include:
(1) mammals (1 species--Pacific sheath-tailed bat);
(2) reptiles (1 species--Slevin's skink);
[[Page 14093]]
(3) tree snails (4 species--fragile tree snail, Guam tree snail,
humped tree snail, and Langford's tree snail);
(4) butterflies (2 species--Mariana eight-spot butterfly, Mariana
wandering butterfly);
(5) damselflies (1 species--Rota blue damselfly);
(6) epiphytic orchids (3 species--Bulbophyllum guamense, Dendrobium
guamense, and Tuberolabium guamense);
(7) forest plants (9 species--Eugenia bryanii, Heritiera
longipetiolata, Maesa walkeri, Psychotria malaspinae, Tabernaemontana
rotensis, Nervilia jacksoniae, Cycas micronesica, and Tinospora
homosepala); this grouping also included our evaluation of information
for Solanum guamense (see Exemptions, below); and
(8) savanna plants (2 species--Hedyotis megalantha and Phyllanthus
saffordii).
We used similar methods to identify critical habitat unit
boundaries for each of the species and species groups. The species
groups were considered together because spatial data used for
delineating critical habitat are similar among the species in each
group, and these species all occur within similar habitat types, such
as limestone forests or savannas. When delineating critical habitat, we
considered each species separately to determine the respective unit
boundaries and subsequently overlapped units to determine if there were
shared boundaries to also be able to report the total proposed critical
habitat on each island and within geographic locations (i.e., area
descriptions). Critical habitat boundaries for all species were
delineated to clearly depict and promote conservation of these species
by identifying habitats that contain features on which each species
depends. For units consisting of multiple habitat types, such as the
cave and forest habitats for the Pacific sheath-tailed bat, the
proposed critical habitat designation includes the entire suitable
habitat area for the species because both habitat types contain the
roosting and foraging features essential to the conservation of the
species.
To delineate proposed critical habitat units, we relied on a
conservation strategy in which each of the species was considered
separately using a common approach for each grouping. The goal of the
conservation strategy was to identify the specific areas for each
species that provide essential PBFs while also taking into account
range-wide resiliency, redundancy, and representation (Species Reports)
(Service 2020t-ao, entire; Service 2023b-x, entire).
In general, we completed the following four basic steps for each
species to delineate critical habitat: (a) We compiled the best
scientific data available on observations and distributions of the
Mariana Islands species that were extant at the time of listing or
assumed extant at the time of listing; (b) we compiled the best
available location and landcover data within the range of all the
species, including soil substrate, vegetation, elevation, temperature,
and precipitation, and identified areas containing the PBFs that may
require special management considerations or protection; (c) we
circumscribed boundaries of potential critical habitat units based on
the above information specific to the resource needs of each species;
and (d) we removed, to the extent practicable, areas that did not have
the specific PBF components.
In summary, for areas within the geographical area occupied by the
species at the time of listing, we delineated critical habitat unit
boundaries using the following criteria:
(1) Obtain and evaluate species observation and distribution data
sources--We obtained and evaluated observation and distribution data to
include in our Geographic Information System (GIS) database for each of
the species, including our Pacific Islands Fish and Wildlife Office's
threatened and endangered species database, which contains current and
historical species observation and distribution survey report data from
Federal and local partners. We also obtained recent biological surveys
and reports and discussed that information with experts familiar with
the species and their habitats. We used historical and current species
distribution information to understand occupancy at the time of listing
and to develop initial critical habitat boundaries within the habitats
occupied by each of the species. The initial boundaries were
superimposed over digital topographical maps of each of the islands
that one or more of the species occupied and further evaluated to (a)
remove locations identified as highly degraded or developed, and (b)
use natural or constructed features (e.g., ridge lines, valleys,
streams, coastlines, roads, etc.) to refine the proposed critical
habitat boundaries.
(2) Identify areas containing PBFs--Data layers defining map units
were created using Environmental Systems Research Institute ArcGIS Pro
World Imagery (2021). We obtained and compiled temperature (Fick and
Hijmans 2017, entire), precipitation (Fick and Hijmans 2017, entire),
elevation (USGS 2013), soil substrate (Guam Bureau of Statistics and
Plans 2013, entire; Natural Resources Conservation Service 2019,
entire), landcover (Amidon et al. 2017, entire), and cave or stream
system data sources for each island within the Mariana archipelago. We
evaluated areas to ensure each unit for each species contained one or
more of the PBFs essential to the conservation of the species and which
may require species management considerations or protection.
Areas that were known to be occupied at the time of listing and
containing one or more of the PBFs were evaluated and included as
proposed critical habitat. These areas include the contiguous habitat
surrounding survey points that were known at the time of listing, all
of which contain one of more of the PBFs and where there were no
barriers to dispersal (e.g., no changes in landcover from forest to
grassland or developed areas since 2015); recent surveys have confirmed
occupancy in some of these contiguous habitat areas. We considered the
degree to which the PBFs were present or absent in areas as an
indication of habitat suitability for each species and removed areas
lacking the identified PBFs. Areas within proposed critical habitat
units that contained obvious unsuitable habitat (e.g., grasslands, bare
rock, agricultural lands) were removed from the unit boundaries because
they do not contain one or more of the PBFs needed by the species.
(3) Circumscribe boundaries of potential critical habitat units--We
considered several features in the selection of specific boundaries for
critical habitat units, including occupancy of the area at the time of
listing (i.e., consideration of historical and current location data,
as described above), the Service's landcover information, and the
presence of adequate habitat to allow for increases in numbers of
individuals and for the expansion of populations necessary for recovery
(Service 2023a, entire). For example, if data layers indicated that
substrate and vegetation type were present on small or disjunct parcels
within developed communities, these areas were not included as proposed
critical habitat. Areas of contiguous suitable habitat were included
within a unit boundary if data layers indicated that substrate and
vegetation were similar to that of the occupied areas, there were no
barriers to dispersal to allow for future population expansion, and the
areas contained one or more of the PBFs. Critical habitat boundaries
for all species were delineated to promote
[[Page 14094]]
the conservation of these species by identifying the PBFs essential to
the conservation of each species (i.e., the resources on which each
species depends).
(4) For the unoccupied unit for the Mariana subspecies of Pacific
sheath-tailed bat--For the one unit on the island of Rota for the
Mariana subspecies of Pacific sheath-tailed bat, which is outside the
geographic area occupied by the subspecies at the time of listing, we
delineated critical habitat unit boundaries using the following
criteria:
First, we obtained and evaluated the historical observation and
distribution data for the subspecies and superimposed the data layers
over topographical maps. We identified areas containing the PBFs using
information including temperature, precipitation, elevation, soil
substrate, land cover, and cave system maps, which we inferred from
information known from the occupied unit on Aguiguan. Similar to the
occupied unit on Aguiguan, we considered historically occupied areas,
the Service's landcover information, and habitat to allow for the
expansion of populations. Finally, we removed areas that did not
include the PBFs required by the subspecies (e.g., coastlines or bare
rock).
Then, to ensure the unit boundary of the unoccupied unit on Rota is
based on the best available science, we examined all known sources of
relevant information. Many potentially suitable roosting caves occur in
southern Rota (Duenas 2024, pers. comm.). Cave system data layers were
used to identify suitable bat roosting habitat while the landcover data
layer was used to identify suitable foraging habitat (Keel et al. 2005,
entire; Taborosi 2006, entire). We considered data on the current or
historical locations of the Mariana swiftlet because the species is
known to co-locate with the Pacific sheath-tailed bat in the same caves
on Aguiguan (Lemke 1986, p. 744; Service 1991, pp. 8, 10-11; Wiles et
al. 1997, p. 221). On Rota, the unit boundaries extend 3.1 mi (5 km)
around roosting caves within the adjacent forested area to provide
adequate adjacent foraging habitat. This distance is based on data from
the Pacific sheath-tailed bat subspecies Emballonura semicaudata
palauensis, a species also co-occurring with a cave-dwelling swiftlet
on the island of Palau in the Pacific. The best available information
indicates that the palauensis subspecies bats flew up to 3.1 mi (5 km)
from caves to forage (Wiles et al. 1997, p. 221). Contiguous forested
habitat surrounding or very near suitable roosting sites is necessary
for the species (the whole of Emballonura semicaudata) because they
avoid non-forest habitats (Esselstyn et al. 2004, p. 307).
When determining proposed critical habitat boundaries, we made
every effort to avoid including developed areas such as lands covered
by buildings, pavement, and other structures because such lands lack
PBFs necessary for the Mariana Islands species. The scale of the maps
we prepared under the parameters for publication within the Code of
Federal Regulations may not reflect the exclusion of such developed
lands. Any such lands inadvertently left inside critical habitat
boundaries shown on the maps of this proposed rule have been excluded
by text in the proposed rule and are not proposed for designation as
critical habitat. Therefore, if the critical habitat is finalized as
proposed, a Federal action involving these lands (and not affecting the
designated critical habitat) would not trigger section 7 consultation
with respect to critical habitat and the requirement of no adverse
modification unless the specific action would affect the PBFs in the
adjacent critical habitat.
The proposed critical habitat designation is defined by the map or
maps, as modified by any accompanying regulatory text, presented at the
end of this document under Proposed Regulation Promulgation.
Proposed Critical Habitat Designation
We are proposing approximately 59,886 ac (24,235 ha) as critical
habitat in 41 distinct geographic areas that include 122 critical
habitat units for 22 Mariana Islands species, including 9 animals (the
Mariana subspecies of the Pacific sheath-tailed bat, Slevin's skink,
fragile tree snail, Guam tree snail, humped tree snail, Langford's tree
snail, Mariana eight-spot butterfly, Mariana wandering butterfly, and
Rota blue damselfly) and 13 plants (Bulbophyllum guamense, Cycas
micronesica, Dendrobium guamense, Eugenia bryanii, Hedyotis megalantha,
Heritiera longipetiolata, Maesa walkeri, Nervilia jacksoniae,
Phyllanthus saffordii, Psychotria malaspinae, Tabernaemontana rotensis,
Tinospora homosepala, and Tuberolabium guamense). Critical habitat is
not proposed for one plant, Solanum guamense, because we have
determined that the area identified that meets the definition of
critical habitat is exempt from designation under section 4(a)(3)(B) of
the Act (see Exemptions, below). The critical habitat areas we describe
below constitute our current best assessment of areas that meet the
definition of critical habitat for each species. The 122 units we
propose as critical habitat are presented in the following tables for
each species. All units are occupied with the exception of one unit on
the island of Rota for the Pacific sheath-tailed bat. A second unit for
the Pacific sheath-tailed bat that was identified on Guam meets the
definition of critical habitat but is exempt from critical habitat
designation under section 4(a)(3)(B) of the Act (see Exemptions,
below). Many of the units and acreage for a given species overlap in
part or whole with units for other species in this proposed rule on
most of the islands; additional overlap with existing critical habitat
designations also occurs on the Islands of Rota and Guam. The
landownership in many (but not all) of the proposed critical habitat
units also include a category called ``uncategorized lands.'' For the
purposes of this analysis and the proposed critical habitat
designation, this category refers to lands where we were unable to
determine local government or private ownership.
To ensure clarity for the public and landowners managing for
multiple species in a given area, Table 2 identifies the 41 individual
areas across CNMI and the Territory of Guam, as well as all species
with proposed critical habitat units in each of those areas. Table 3
identifies the total number of areas, species, and acreage proposed as
critical habitat on each island. Tables 4-26 show the proposed critical
habitat units, land ownership, acreage size, and occupancy status for
each of the 22 species. Unit names correspond to the specific species
and island where they occur, with additional numbers or letters
corresponding to the locations/areas, thereby providing the ability to
cross reference to situations with overlapping units.
The islands of Asuncion, Pagan, Alamagan, Sarigan, Saipan, Tinian,
and Aguiguan do not have any existing designated critical habitat;
thus, there is no overlapping designated critical habitat on these
islands and all proposed critical habitat in this rule is new to these
islands. On the islands of Rota (Areas 10-14) and Guam (Areas 15-41),
there are existing designated critical habitat units that overlap with
critical habitat proposed in this rule. For Rota, this proposed rule
includes 13,023 ac (5,270 ha) of proposed critical habitat for 13 of
the 22 Mariana Islands species (Table 3), of which 63 percent (8,244 ac
(3,336 ha)) overlap with existing critical habitat; thus, 37 percent
(4,779 ac (1,934 ha)) of proposed critical habitat is new to this
island. For Guam (which
[[Page 14095]]
includes Cocos Island), this proposed rule includes 36,473 ac (14,760
ha) of proposed critical habitat for 19 of the 22 Mariana Islands
species (Table 3), of which 0.7 percent (257 ac (104 ha)) overlap with
existing critical habitat; thus, 99 percent (36,216 ac (14,656 ha)) of
proposed critical habitat is new to this island.
Table 2--Proposed Critical Habitat for Each of the 41 Areas and the Species Represented Within Each Area
[Area estimates reflect the total proposed critical habitat acres within each geographical area. The total
acreage for each area does not double-count any acres of overlapping units, where applicable.]
----------------------------------------------------------------------------------------------------------------
Total proposed critical
Geographic area Species represented habitat in acres
(hectares)
----------------------------------------------------------------------------------------------------------------
Area 1--Asunci[oacute]n, CNMI................. Slevin's skink....................... 750 (304)
Area 2--Pagan, CNMI........................... Slevin's skink....................... 1,846 (747)
humped tree snail....................
Area 3--Alamagan, CNMI........................ Slevin's skink....................... 1,420 (574)
humped tree snail....................
Area 4--Sarigan, CNMI......................... Slevin's skink....................... 402 (163)
humped tree snail....................
Area 5--Tapochau, Saipan, CNMI................ humped tree snail.................... 3,290 (1,332)
Area 6--American Memorial Park, Saipan, CNMI.. humped tree snail.................... 35 (14)
Area 7--I'Naftan, Saipan, CNMI................ Heritiera longipetiolata............. 779 (315)
Area 8--Kastiyu, Tinian, CNMI................. Heritiera longipetiolata............. 651 (263)
Area 9--Aguiguan, CNMI........................ Pacific sheath-tailed bat............ 1,217 (492)
Langford's tree snail................
Dendrobium guamense..................
Area 10--Mochong, Rota, CNMI.................. Bulbophyllum guamense................ * 3,497 (1,415)
Tabernaemontana rotensis.............
Area 11--Sabana, Rota, CNMI................... Bulbophyllum guamense................ * 6,875 (2,782)
Cycas micronesica....................
Dendrobium guamense..................
Maesa walkeri........................
Nervilia jacksoniae..................
Tabernaemontana rotensis.............
Tuberolabium guamense................
Area 12--Rota, CNMI........................... fragile tree snail................... 12,282 (4,970)
humped tree snail....................
Mariana wandering butterfly..........
Area 13--Talakhaya, Rota, CNMI................ Rota blue damselfly.................. 1,133 (459)
Area 14--Southern Rota, CNMI.................. Pacific sheath-tailed bat............ *\+\ 7,632 (3,089)
Area 15--Ritidian, Guam....................... fragile tree snail................... 856 (346)
Guam tree snail......................
humped tree snail....................
Mariana eight-spot butterfly.........
Bulbophyllum guamense................
Cycas micronesica....................
Dendrobium guamense..................
Eugenia bryanii......................
Heritiera longipetiolata.............
Tabernaemontana rotensis.............
Tuberolabium guamense................
Area 16--Two Lovers' Point, Guam.............. fragile tree snail................... 1,245 (504)
Guam tree snail......................
humped tree snail....................
Mariana eight-spot butterfly.........
Bulbophyllum guamense................
Cycas micronesica....................
Dendrobium guamense..................
Eugenia bryanii......................
Heritiera longipetiolata.............
Tabernaemontana rotensis.............
Tuberolabium guamense................
Area 17--Anao, Guam........................... fragile tree snail................... 2,166 (877)
Guam tree snail......................
humped tree snail....................
Mariana eight-spot butterfly.........
Bulbophyllum guamense................
Cycas micronesica....................
Dendrobium guamense..................
Eugenia bryanii......................
Heritiera longipetiolata.............
Psychotria malaspinae................
Tabernaemontana rotensis.............
Tuberolabium guamense................
[[Page 14096]]
Area 18--Tre Vista, Guam...................... fragile tree snail................... 445 (180)
Guam tree snail......................
Area 19--Yigo, Guam........................... Guam tree snail...................... 147 (59)
Area 20--Barrigada, Guam...................... Guam tree snail...................... 267 (108)
Bulbophyllum guamense................
Area 21--Taguan, Guam......................... Mariana eight-spot butterfly......... 242 (98)
Area 22--Anigua Cliffline, Guam............... Tinospora homosepala................. 11 (5)
Area 23--Asan Ridge, Guam..................... Tinospora homosepala................. 12 (5)
Area 24--Asan Hillside, Guam.................. Tinospora homosepala................. ** 124 (50)
Area 25--Nimitz Hill Savanna, Guam............ Phyllanthus saffordii................ 236 (95)
Area 26--Piti Savanna, Guam................... Phyllanthus saffordii................ 82 (33)
Area 27--Sasa Valley, Guam.................... Tinospora homosepala................. 2 (1)
Area 28--Central Guam......................... fragile tree snail................... 4,313 (1,745)
Guam tree snail......................
Area 29--Fadi'an, Guam........................ Guam tree snail...................... 61 (25)
Area 30--Piti, Guam........................... fragile tree snail................... 1,965 (795)
Guam tree snail......................
Area 31--Yo[ntilde]a, Guam.................... Bulbophyllum guamense................ 5,938 (2,403)
Hedyotis megalantha..................
Phyllanthus saffordii................
Area 32--Mangilao, Guam....................... Eugenia bryanii...................... 195 (79)
Heritiera longipetiolata.............
Area 33--Ylig, Guam........................... fragile tree snail................... 1,863 (754)
Guam tree snail......................
Area 34--Cross Island, Guam................... Bulbophyllum guamense................ 2,377 (962)
Cycas micronesica....................
Dendrobium guamense..................
Hedyotis megalantha..................
Heritiera longipetiolata.............
Phyllanthus saffordii................
Tuberolabium guamense................
Area 35--H[aring]gat, Guam.................... fragile tree snail................... 720 (291)
Guam tree snail......................
Bulbophyllum guamense................
Cycas micronesica....................
Dendrobium guamense..................
Heritiera longipetiolata.............
Maesa walkeri........................
Nervilia jacksoniae..................
Phyllanthus saffordii................
Psychotria malaspinae................
Tabernaemontana rotensis.............
Tuberolabium guamense................
Area 36--Talo'fo'fo', Guam.................... fragile tree snail................... 5,697 (2,306)
Guam tree snail......................
Area 37--Sella Bay, Guam...................... fragile tree snail................... 64 (26)
Guam tree snail......................
Area 38--Cetti Bay, Guam...................... Guam tree snail...................... 102 (41)
Area 39--Bolanos, Guam........................ Guam tree snail...................... 10,874 (4,400)
Bulbophyllum guamense................
Cycas micronesica....................
Dendrobium guamense..................
Eugenia bryanii......................
Hedyotis megalantha..................
Phyllanthus saffordii................
Tabernaemontana rotensis.............
Tuberolabium guamense................
Area 40--Inal[aring]han, Guam................. fragile tree snail................... 457 (185)
Guam tree snail......................
Area 41--Cocos Island (Islan D[aring]no'), Slevin's skink....................... 63 (25)
Guam.
--------------------------
Total..................................... ..................................... 59,886 ac (24,235 ha)
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding. Additionally, the forest plant Solanum guamense also occurs in the
vicinity of Area 15 and 17 on DoD lands (but not within any proposed critical habitat units); the range of
this species resides solely on DoD lands and is exempt under section 4(a)(3) of the Act (see Exemptions,
below).
[[Page 14097]]
* Areas 10, 11, and 14 lie within/overlap Areas 12 and 13; in addition, there is some overlap between Areas 12
and 13; therefore, only acres for Area 12 and 13 minus the overlap are included to prevent double counting in
the overall total acreage of the proposed critical habitat designation.
** Area 24 lies within/overlaps Area 28; therefore, only acres for Area 28 are included to prevent double
counting in the overall total acreage of the proposed critical habitat designation. Additionally, there is
partial overlap between Areas 28 and 31, Areas 34 and 36, and Areas 36 and 39.
\+\ The Pacific sheath-tailed bat is not present at this time, but critical habitat is proposed within Area 14,
which is the only unoccupied unit within this proposed critical habitat designation.
Table 3--Areas, Number of Species, and Total Acres (Hectares) Proposed as Critical Habitat for Each Island
[Area estimates reflect all land within critical habitat units combined.]
----------------------------------------------------------------------------------------------------------------
Island Area names # of species Acres Hectares
----------------------------------------------------------------------------------------------------------------
Asuncion.............................. Area 1.................. 1 750 304
Pagan................................. Area 2.................. 2 1,846 747
Alamagan.............................. Area 3.................. 2 1,420 574
Sarigan............................... Area 4.................. 2 402 163
Saipan................................ Areas 5, 6, and 7....... 2 4,104 1,661
Tinian................................ Area 8.................. 2 651 263
Aguiguan.............................. Area 9.................. 3 1,217 492
Rota.................................. Areas 10-14............. 13 13,023 5,270
Guam.................................. Areas 15-41............. 19 36,473 14,760
-----------------------------------------------
Total............................. ........................ .............. 59,886 24,235
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.
Table 4--Proposed Critical Habitat Units for Pacific Sheath-Tailed Bat
[Area estimates reflect all land within critical habitat unit boundaries.]
----------------------------------------------------------------------------------------------------------------
Landownership by
Critical habitat unit Area # type in acres Size of unit in Occupied?
(hectares) acres (hectares)
----------------------------------------------------------------------------------------------------------------
1. Pacific Sheath-tailed Bat-1, 9 Federal 0.......... 589 ac.............. Yes.
Aguiguan. Commonwealth 589 (238 ha)............
(238)..
Private 0..........
Uncategorized 0....
2. Pacific Sheath-tailed Bat-1, 14 Federal 0.......... 7,633 ac............ No.
Rota. Commonwealth 6,178 (3,089 ha)..........
(2,500)..
Private 1,418
(574)..
Uncategorized 36
(15)..
----------------
Total....................... .............. Federal 0.......... 8,221 ac............
Commonwealth 6,767 (3,327 ha)..........
(2,738)..
Private 1,418
(574)..
Uncategorized 36
(15)..
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding. Within Area 9, the unit acreages presented for this species
overlap proposed critical habitat units in full or in part for Langford's tree snail and Dendrobium guamense.
For Area 14, the unit acreage presented is a full unit only for the Pacific sheath-tailed bat.
Table 5--Proposed Critical Habitat Units for Slevin's Skink
[Area estimates reflect all land within critical habitat unit boundaries.]
----------------------------------------------------------------------------------------------------------------
Landownership by
Critical habitat unit Area # type in acres Size of unit in Occupied?
(hectares) acres (hectares)
----------------------------------------------------------------------------------------------------------------
1. Slevin's Skink-1, Asuncion... 1 Federal 0.......... 750 ac.............. Yes.
Commonwealth 750 (304 ha)............
(304)..
Private 0..........
Uncategorized 0....
2. Slevin's Skink-1, Pagan...... 2 Federal 0.......... 1,846 ac............ Yes.
Commonwealth 1,846 (747 ha)............
(747)..
Private 0..........
Uncategorized 0....
3. Slevin's Skink-1, Alamagan... 3 Federal 0.......... 1,420 ac............ Yes.
Commonwealth 1,420 (574 ha)............
(574)..
Private 0..........
Uncategorized 0....
4. Slevin's Skink-1, Sarigan.... 4 Federal 0.......... 402 ac.............. Yes.
Commonwealth 402 (163 ha)............
(163)..
Private 0..........
Uncategorized 0....
[[Page 14098]]
5. Slevin's Skink-1, Cocos 41 Federal 0.......... 63 ac............... Yes.
Island (Guam). Territory 0........ (25 ha).............
Private 30 (12)....
Uncategorized 33
(13)..
----------------
Total....................... .............. Federal 0.......... 4,481 ac............ ...................
Commonwealth or (1,813 ha)..........
Territory 4,418
(1,788)..
Private 30 (12)....
Uncategorized 33
(13)..
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding. Within Areas 2, 3, and 4, the unit acreages presented for this
species overlap proposed critical habitat units in full or in part for the humped tree snail and multiple
plant species in this proposed rule. For Areas 1 and 41, the unit acreage presented is a full unit only for
Slevin's skink.
Table 6--Proposed Critical Habitat Units for Fragile Tree Snail
[Area estimates reflect all land within critical habitat unit boundaries.]
----------------------------------------------------------------------------------------------------------------
Landownership by
Critical habitat unit Area # type in acres Size of unit in Occupied?
(hectares) acres (hectares)
----------------------------------------------------------------------------------------------------------------
1. Fragile Tree Snail-1, Rota... 12 Federal 0.......... 12,282 ac........... Yes.
Commonwealth 9,294 (4,970 ha)..........
(3,761)..
Private 2,954
(1,195)..
Uncategorized 34
(14)..
2. Fragile Tree Snail-1, Guam... 15 Federal 262 (106).. 856 ac.............. Yes.
Territory 68 (27).. (346 ha)............
Private 408 (165)..
Uncategorized 118
(48)..
3. Fragile Tree Snail-2, Guam... 16 Federal 0.......... 1,245 ac............ Yes.
Territory 1,081 (504 ha)............
(437)..
Private 108 (44)...
Uncategorized 56
(23)..
4. Fragile Tree Snail-3, Guam... 17 Federal 0.......... 2,166 ac............ Yes.
Territory 1,549 (877 ha)............
(627)..
Private 270 (109)..
Uncategorized 347
(141)..
5. Fragile Tree Snail-4, Guam... 18 Federal 0.......... 445 ac.............. Yes.
Territory 0........ (180 ha)............
Private 361 (146)..
Uncategorized 84
(34)..
6. Fragile Tree Snail-5, Guam... 28 Federal 210 (85)... 4,313 ac............ Yes.
Territory 0........ (1,745 ha)..........
Private 1,954
(791)..
Uncategorized 2,149
(869)..
7. Fragile Tree Snail-6, Guam... 30 Federal 102 (41)... 1,965 ac............ Yes.
Territory 0........ (795 ha)............
Private 756 (396)..
Uncategorized 1,107
(448)..
8. Fragile Tree Snail-7, Guam... 33 Federal 0.......... 1,863 ac............ Yes.
Territory 0........ (754 ha)............
Private 983 (398)..
Uncategorized 880
(356)..
9. Fragile Tree Snail-8, Guam... 35 Federal 16 (6)..... 629 ac.............. Yes.
Territory 84 (34).. (254 ha)............
Private 344 (139)..
Uncategorized 185
(75)..
10. Fragile Tree Snail-9, Guam.. 36 Federal 0.......... 5,697 ac............ Yes.
Territory 142 (57). (2,306 ha)..........
Private 3,915
(1,584)..
Uncategorized 1,640
(665)..
11. Fragile Tree Snail-10, Guam. 37 Federal 0.......... 64 ac............... Yes.
Territory 0........ (26 ha).............
Private 57 (23)....
Uncategorized 7
(3)..
[[Page 14099]]
12. Fragile Tree Snail-11, Guam. 40 Federal 0.......... 457 ac.............. Yes.
Territory 0........ (185 ha)............
Private 154 (62)...
Uncategorized 303
(123).
---------------------------------------------------------------
Total....................... .............. Federal 590 (238).. 31,982 ac........... ...................
Commonwealth or (12,942 ha).........
Territory 12,218
(4,943)..
Private 12,264
(4,962)..
Uncategorized 6,910
(2,799)..
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding. For all areas, the unit acreages presented for this species
overlap proposed critical habitat units in full or in part for multiple animal and plant species in this
proposed rule.
Table 7--Proposed Critical Habitat Units for Guam Tree Snail
[Area estimates reflect all land within critical habitat unit boundaries.]
----------------------------------------------------------------------------------------------------------------
Landownership by
Critical habitat unit Area # type in acres Size of unit in Occupied?
(hectares) acres (hectares)
----------------------------------------------------------------------------------------------------------------
1. Guam Tree Snail-1, Guam...... 15 Federal 262 (106).. 856 ac.............. Yes.
Territory 68 (27).. (346 ha)............
Private 408 (165)..
Uncategorized 118
(48)..
2. Guam Tree Snail-2, Guam...... 16 Federal 0.......... 1,245 ac............ Yes
Territory 1,081 (504 ha)............
(437)..
Private 108 (44)...
Uncategorized 56
(23)..
3. Guam Tree Snail-3, Guam...... 17 Federal 0.......... 2,166 ac............ Yes.
Territory 1,549 (877 ha)............
(627)..
Private 270 (109)..
Uncategorized 347
(141)..
4. Guam Tree Snail-4, Guam...... 18 Federal 0.......... 445 ac.............. Yes.
Territory 0........ (180 ha)............
Private 361 (146)..
Uncategorized 84
(34)..
5. Guam Tree Snail-5, Guam...... 19 Federal 0.......... 147 ac.............. Yes.
Territory 0........ (59 ha).............
Private 110 (44)...
Uncategorized 37
(15).
6. Guam Tree Snail-6, Guam...... 20 Federal 0.......... 99 ac............... Yes.
Territory 0........ (40 ha).............
Private 44 (18)....
Uncategorized 55
(22)..
7. Guam Tree Snail-7, Guam...... 28 Federal 210 (85)... 4,313 ac............ Yes.
Territory 0........ (1,745 ha)..........
Private 1,954
(791)..
Uncategorized 2,149
(869)..
8. Guam Tree Snail-8, Guam...... 29 Federal 0.......... 61 ac............... Yes.
Territory 0........ (25 ha).............
Private 61 (25)....
Uncategorized 0....
9. Guam Tree Snail-9, Guam...... 30 Federal 102 (41)... 1,965 ac............ Yes.
Territory 0........ (795 ha)............
Private 756 (306)..
Uncategorized 1,107
(448)..
10. Guam Tree Snail-10, Guam.... 33 Federal 0.......... 1,863 ac............ Yes.
Territory 0........ (754 ha)............
Private 983 (398)..
Uncategorized 880
(356)..
11. Guam Tree Snail-11, Guam.... 35 Federal 16 (6)..... 629 ac.............. Yes.
Territory 84 (34).. (254 ha)............
Private 344 (139)..
Uncategorized 180
(73)..
12. Guam Tree Snail-12, Guam.... 36 Federal 0.......... 5,697 ac............ Yes.
Territory 142 (57). (2,306 ha)..........
Private 3,915
(1,584)..
Uncategorized 1,640
(665)..
[[Page 14100]]
13. Guam Tree Snail-13, Guam.... 37 Federal 0.......... 64 ac............... Yes.
Territory 0........ (26 ha).............
Private 57 (23)....
Uncategorized 7
(3)..
14. Guam Tree Snail-14, Guam.... 38 Federal 0.......... 102 ac.............. Yes.
Territory 0........ (41 ha).............
Private 27 (11)....
Uncategorized 75
(30)..
15. Guam Tree Snail-15, Guam.... 39 Federal 0.......... 184 ac.............. Yes.
Territory 19 (8)... (74 ha).............
Private 31 (13)....
Uncategorized 134
(53)..
16. Guam Tree Snail-16, Guam.... 40 Federal 0.......... 457 ac.............. Yes.
Territory 0........ (185 ha)............
Private 154 (62)...
Uncategorized 303
(123)..
---------------------------------------------------------------
Total....................... .............. Federal 590 (238).. 20,293 ac........... ...................
Territory 2,943 (8,211 ha)..........
(1,190)..
Private 9,583
(3,878)..
Uncategorized 7,177
(2,905)..
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding. For Areas 19 and 38, the unit acreage presented are full units
only for the Guam tree snail. Within all other areas, the unit acreages presented for this species overlap
proposed critical habitat units in full or in part for multiple animal and plant species in this proposed
rule.
Table 8--Proposed Critical Habitat Units for Humped Tree Snail
[Area estimates reflect all land within critical habitat unit boundaries.]
----------------------------------------------------------------------------------------------------------------
Landownership by
Critical habitat unit Area # type in acres Size of unit in Occupied?
(hectares) acres (hectares)
----------------------------------------------------------------------------------------------------------------
1. Humped Tree Snail-1, Pagan... 2 Federal 0.......... 843 ac.............. Yes.
Commonwealth 843 (341 ha)............
(341)..
Private 0..........
Uncategorized 0....
2. Humped Tree Snail-1, Alamagan 3 Federal 0.......... 1,420 ac............ Yes.
Commonwealth 1,420 (574 ha)............
(574)..
Private 0..........
Uncategorized 0....
3. Humped Tree Snail-1, Sarigan. 4 Federal 0.......... 402 ac.............. Yes.
Commonwealth 402 (163 ha)............
(163)..
Private 0..........
Uncategorized 0....
4. Humped Tree Snail-1, Saipan.. 5 Federal 0.......... 3,290 ac
[…truncated; see source link]Indexed from Federal Register on March 24, 2026.
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