[Federal Register Volume 88, Number 39 (Tuesday, February 28, 2023)]
[Rules and Regulations]
[Pages 12572-12602]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-03656]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2021-0041; FF09E21000 FXES1111090FEDR 234]
RIN 1018-BE65


Endangered and Threatened Wildlife and Plants; Endangered Species 
Status for Prostrate Milkweed and Designation of Critical Habitat

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Final rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are listing 
the prostrate milkweed (Asclepias prostrata), a plant species from 
Texas, as an endangered species and designating critical habitat under 
the Endangered Species Act of 1973, as amended (Act). We are 
designating approximately 661.0 acres (267.5 hectares) in Starr and 
Zapata Counties, Texas, as critical habitat for the prostrate milkweed 
under the Act. This rule adds this species to the List of Endangered 
and Threatened Plants and extends the Act's protections to the species 
and its designated critical habitat.

DATES: This rule is effective March 30, 2023.

ADDRESSES: Our February 15, 2022, proposed rule and this final rule are 
available on the internet at https://www.regulations.gov. Comments and 
materials we received, as well as supporting documentation we used in 
preparing this rule, are available for public inspection at https://www.regulations.gov at Docket No. FWS-R2-ES-2021-0041. For the critical 
habitat designation, the coordinates or plot points or both from which 
the maps are generated are included in the decision file for this 
critical habitat designation and are available at https://www.regulations.gov at Docket No. FWS-R2-ES-2021-0041.

FOR FURTHER INFORMATION CONTACT: Chuck Ardizzone, Field Supervisor, 
Texas Coastal Ecological Services Field Office, 17629 El Camino Real 
Suite 211, Houston, TX 77058; telephone 281-286-8282. Individuals in 
the United States who are deaf, deafblind, hard of hearing, or have a 
speech disability may dial 711 (TTY, TDD, or TeleBraille) to access 
telecommunications relay services. Individuals outside the United 
States should use the relay services offered within their country to 
make international calls to the point-of-contact in the United States.

SUPPLEMENTARY INFORMATION: 

Executive Summary

    Why we need to publish a rule. Under the Act, a species warrants 
listing if it meets the definition of an endangered species (in danger 
of extinction throughout all or a significant portion of its range) or 
a threatened species (likely to become endangered within the 
foreseeable future throughout all or a significant portion of its 
range). If we determine that a species warrants listing, we must list 
the species promptly and designate the species' critical habitat to the 
maximum extent prudent and determinable. We have determined that the 
prostrate milkweed meets the definition of an endangered species; 
therefore, we are listing it as such and finalizing a designation of 
its critical habitat. Both listing a species as an endangered or 
threatened species and designating critical habitat can be completed 
only by issuing a rule through the Administrative Procedure Act 
rulemaking process (5 U.S.C. 551 et seq.).
    What this document does. This rule lists the prostrate milkweed as 
an endangered species and designates approximately 661.0 acres (267.5 
hectares) in Starr and Zapata Counties, Texas, as critical habitat for 
this species under the Act.
    The basis for our action. Under the Act, we may determine that a 
species is an endangered or threatened species because of any of five 
factors: (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range; (B) overutilization for 
commercial, recreational, scientific, or educational purposes; (C) 
disease or predation; (D) the inadequacy of existing regulatory 
mechanisms; or (E) other natural or manmade factors affecting its 
continued existence. We have determined that competition from 
introduced invasive grass, habitat loss and degradation from root-
plowing and conversion of native vegetation to improved buffelgrass 
pasture, habitat loss from right-of-way construction and maintenance 
from energy development and road and utility construction, and habitat 
loss from border security development and enforcement activities 
(Factor A), as well as the demographic and genetic consequences of 
small population sizes (Factor E), are threats to the prostrate 
milkweed.
    Section 4(a)(3) of the Act requires the Secretary of the Interior 
(Secretary) to designate critical habitat concurrent with listing to 
the maximum extent prudent and determinable. Section 3(5)(A) of the Act 
defines critical habitat as: (i) the specific areas within the 
geographical area occupied by the species, at the time it is listed, on 
which are found those physical or biological features (I) essential to 
the conservation of the species and (II) which may require special 
management considerations or protections; and (ii) specific areas 
outside the geographical area occupied by the species at the time it is 
listed, upon a determination by the Secretary that such areas are 
essential for the conservation of the species. Section 4(b)(2) of the 
Act states that the Secretary must make the designation on the basis of 
the best scientific data available and after taking into consideration 
the economic impact, the impact on national security, and any other 
relevant impacts of specifying any particular area as critical habitat. 
The Secretary may exclude an area from critical habitat if she 
determines that the benefits of such exclusion outweigh the benefits of 
specifying such area as part of the critical habitat, unless she 
determines, based on the best scientific data available, that the 
failure to designate such area as critical habitat will result in the 
extinction of the species.
    The critical habitat we are designating in this rule, in eight 
units comprising 661.0 acres (ac) (267.5 hectares (ha)), constitutes 
our current best assessment of the areas that meet the definition of 
critical habitat for prostrate milkweed.

Previous Federal Actions

    On February 15, 2022, we published a proposed rule (87 FR 8509) in 
the Federal Register to list prostrate milkweed as an endangered 
species and

[[Page 12573]]

to designate critical habitat for the species under the Act (16 U.S.C. 
1531 et seq.). Please refer to that proposed rule for a detailed 
description of previous Federal actions concerning this species.

Peer Review

    A species status assessment (SSA) team prepared an SSA report for 
the prostrate milkweed. The SSA team was composed of Service biologists 
in consultation with other species experts. The SSA report represents a 
compilation of the best scientific and commercial data available 
concerning the status of the species, including the impacts of past, 
present, and future factors (both negative and beneficial) affecting 
the species.
    In accordance with our joint policy on peer review published in the 
Federal Register on July 1, 1994 (59 FR 34270), and our August 22, 
2016, memorandum updating and clarifying the role of peer review of 
listing actions under the Act, we solicited independent peer review of 
the information contained in the SSA report. As discussed in the 
proposed rule, we sent the SSA report to six independent peer reviewers 
and received two responses. The peer reviews can be found at https://www.regulations.gov. In preparing the proposed rule, we incorporated 
the results of these reviews, as appropriate, into the SSA report, 
which was the foundation for the proposed rule and this final rule. A 
summary of the peer review comments and our responses can be found in 
the proposed rule (87 FR 8509; February 15, 2022).

Summary of Changes From the Proposed Rule

    In preparing this final rule, we reviewed and fully considered 
comments from the public on our February 15, 2022, proposed rule (87 FR 
8509). We did not make any substantial changes to this final rule after 
consideration of the comments we received. We did, however, make the 
revisions to the critical habitat designation described below based on 
new information.
    In this final rule, we revise critical habitat Unit 2 to reflect 
recently constructed border wall, which reduces the area meeting the 
definition of critical habitat in that unit. Specifically, this change 
results in a decrease of 19.7 ac (8.0 ha) of critical habitat from what 
we proposed for Unit 2 on February 15, 2022 (87 FR 8509).
    In this final rule, we also revise critical habitat Unit 5 to 
correct a map projection error of the national wildlife refuge tract 
boundary, which reduces the area of this unit. Specifically, this 
change results in a decrease of 10.6 ac (4.3 ha) of critical habitat 
from what we proposed for Unit 5 on February 15, 2022 (87 FR 8509).
    Overall, these changes to Units 2 and 5 result in a net decrease of 
30.3 ac (12.3 ha) in the critical habitat for prostrate milkweed from 
what we proposed on February 15, 2022 (87 FR 8509).
    We also make minimal nonsubstantive clarifications and editorial 
corrections in this final rule.

Summary of Comments and Recommendations

    In our February 15, 2022, proposed rule (87 FR 8509), we requested 
that all interested parties submit written comments on the proposal by 
April 18, 2022. We also contacted appropriate Federal and State 
agencies, scientific experts and organizations, and other interested 
parties and invited them to comment on the proposed listing 
determination, proposed designation of critical habitat, and draft 
economic analysis. Newspaper notices inviting public comment were 
published in several local newspapers, including The Monitor on 
February 21, 2022. We did not receive any requests for a public 
hearing. All substantive information provided during the comment period 
has either been incorporated directly into this final determination or 
is addressed below.

State Agency Comments

    (1) Comment: Texas Parks and Wildlife Department commented that 
designating critical habitat on private lands where support for the 
designation is not confirmed could harm relationships with landowners 
and ultimately impede voluntary conservation efforts for listed species 
and lead to additional resource protection, management, and partnership 
challenges.
    Our response: We place great value on our partnerships with private 
landowners. Because important areas for prostrate milkweed conservation 
can occur on private lands, collaborative relationships with private 
landowners are key to further recovery. Designation of critical habitat 
does not affect land ownership, establish any restrictions on use of or 
access to the designated areas, establish specific land management 
standards or prescriptions, or prevent access to any land. Further, the 
Act does not authorize the Service to regulate private actions on 
private lands, and landowners are not obligated to incur any costs 
related to the species' conservation or to alter their current land 
management. Therefore, the listing of prostrate milkweed and 
designation of critical habitat will not impact private landowners and 
thus will not impede conservation efforts.
    The Service supports voluntary conservation through our Partners 
for Fish and Wildlife Program and understands concerns for landowner 
privacy regarding rare plant locations. Where consistent with the 
discretion provided by the Act, it is beneficial to implement policies 
that provide positive incentives to private landowners to voluntarily 
conserve natural resources and that remove or reduce disincentives to 
conservation. Voluntary conservation programs may provide technical or 
financial assistance to the landowner. Private landowners may contact 
their local Service field office to obtain information about these 
programs.
    (2) Comment: Texas Parks and Wildlife Department also commented 
that the benefits of excluding private lands from a critical habitat 
designation may outweigh the benefits of including those lands when the 
necessary landowner support has not been secured prior to such a 
designation.
    Our response: According to our Policy Regarding Implementation of 
Section 4(b)(2) of the Endangered Species Act (81 FR 7226; February 11, 
2016), we consider six elements when considering whether or not to 
exclude an area from critical habitat: (1) partnerships and 
conservation plans; (2) conservation plans permitted under section 10 
of the Act; (3) national security and homeland security impacts; (4) 
Tribal lands; (5) Federal lands; and (6) economic impacts. We give 
great weight and consideration to the conservation benefits provided 
through permitted and non-permitted conservation plans, programs, and 
partnerships. We will generally exclude any area covered by non-
permitted conservation where partnerships provide a benefit to the 
species and its habitat. A generalized concern regarding the potential 
impact to landowner support is not sufficient grounds for us to be able 
to undertake an analysis weighing the benefits of exclusion against the 
benefits of inclusion in considering an area for exclusion. Under the 
Services' Policy Regarding Implementation of Section 4(b)(2) of the 
Endangered Species Act (81 Federal Register 7226; February 11, 2016), a 
proponent of such an exclusion must provide a reasoned rationale for 
such exclusion, including measures undertaken to conserve species and 
habitat on the land at issue (such that the benefit of inclusion is 
reduced). Evidence of a permitted conservation plan or non-permitted 
conservation agreement and partnership would be

[[Page 12574]]

required to demonstrate how the affected landowner(s) would provide a 
benefit to the species and its habitat. The commenter did not provide 
sufficient information for us to meaningfully evaluate the benefits of 
exclusion of private lands. Accordingly, we did not consider any areas 
for exclusion based on the potential impact to landowner support.
    (3) Comment: The Office of the Attorney General of Texas commented 
that we should not list prostrate milkweed as an endangered species or 
designate portions of the Texas border as critical habitat under the 
Act because it would have a significant impact on national security by 
preventing Texas's efforts to address the border crisis and national 
security, such as ongoing and future efforts to erect and establish 
deterrents to illegal border crossings, including, but not limited to, 
construction of a border barrier.
    Our response: The Act requires us to make a determination using the 
best available scientific and commercial data after conducting a review 
of the status of the species. For prostrate milkweed, the best 
available scientific and commercial data indicate that the species is 
currently in danger of extinction and therefore we are required to list 
the species as endangered under the Act. For exclusion of an area from 
critical habitat designation, we follow our Policy Regarding 
Implementation of Section 4(b)(2) of the Endangered Species Act (81 FR 
7226; February 11, 2016), which outlines measures we consider when 
excluding any areas from critical habitat. We reviewed the commenter's 
request and applied the February 11, 2016, Policy (81 FR 7226). Based 
on this analysis, we determined that the area should not be excluded 
from this final rule. Please see Consideration of Impacts under Section 
4(b)(2) of the Act, Exclusions Based on Other Relevant Impacts, below, 
for our analysis of the Attorney General of Texas' request for 
exclusion for lands along the Texas border.
    (4) Comment: The Office of the Attorney General of Texas commented 
that two environmental impact analyses conducted by U.S. Customs and 
Border Patrol have concluded that construction activity, such as 
building roads or a border wall, in the counties listed in the February 
15, 2022, proposed rule would have minimal or no significant impact on 
vegetation, including the prostrate milkweed, and, therefore, 
designating critical habitat is not needed to protect the species from 
this activity.
    Our response: Occupied critical habitat is defined under section 3 
of the Act as 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 (PBFs) (I) 
essential to the conservation of the species and (II) which may require 
special management considerations or protection (16 U.S.C. 
1532(5)(A)(i)). We find that the areas included in this final 
designation meet the first prong of the Act's definition of critical 
habitat; therefore, we must include them in the final designation 
unless the benefits of exclusion outweigh the benefits of inclusion. As 
discussed above in response to comment (3), we found that the benefits 
of exclusion did not outweigh the benefits of inclusion. Even if border 
construction activities will have minimal or no significant impacts to 
vegetation itself, critical habitat is meant to conserve all parts of 
the physical and biological habitat that are essential to prostrate 
milkweed. For a list of the PBFs, please refer to Physical or 
Biological Features Essential to the Conservation of the Species, 
below.
    Once critical habitat is designated, we will continue to 
collaborate with DHS and CBP to ensure border security operations can 
still occur in areas designated as critical habitat for prostrate 
milkweed. To the best of our ability, we will work with other Federal 
agencies, including U.S. Customs and Border Patrol, to ensure actions 
they fund, authorize, or undertake are not likely to destroy or 
adversely modify critical habitat, including any of the PBFs essential 
to the conservation of the species. For prostrate milkweed, this 
includes destruction or adverse modification of soil that is well-
drained and sandy overlying strata of sandstone or indurated caliche 
with a high gypsum concentration. However, designating critical habitat 
along the border would not impact CBP's ability to engage in border 
security operations in these areas.

Public Comments

    We received numerous comments that prostrate milkweed is an 
important plant for migratory butterflies and should be protected. The 
commenters did not provide any new substantial information on prostrate 
milkweed's status or threats, and thus our critical habitat designation 
and determination that prostrate milkweed meets the definition of an 
endangered species under the Act did not change. Below, we provide a 
summary of the relevant public comments we received.
    (5) Comment: One commenter stated we should designate critical 
habitat in the occupied areas along U.S. Highway 83 and immediately, 
prior to publishing the final rule, enter into section 7 consultation 
with Texas Department of Transportation regarding their vegetation 
removal in highway rights-of-way (ROWs).
    Our response: As stated in the proposed rule (87 FR 8509; February 
15, 2022), the degree and frequency of soil disturbance along U.S. 
Highway 83 has caused almost complete replacement of the native plant 
community with the introduced, highly invasive buffelgrass (Pennisetum 
ciliare). Maintenance operations for the highway, overhead powerlines, 
and communication cables located in trenches along the ROW will 
continue indefinitely, and it is likely that additional infrastructure 
will be installed in the ROW. The prostrate milkweed population in this 
ROW has declined from about 200 individuals, when it was discovered in 
1988, to 3 or fewer individuals during the last 13 years. Further, PBFs 
4 and 5 are no longer present along this improved highway ROW, and 
therefore we are not designating this area as critical habitat for the 
prostrate milkweed. We are also not including this area as unoccupied 
critical habitat because it located along a ROW with continuous 
disturbance that the species cannot withstand, and thus we are 
reasonably certain that this area will not contribute to the 
conservation of the species.
    (6) Comment: One commenter stated that the Service and Texas 
Department of Transportation should remove buffelgrass and plant native 
species.
    Our response: Addressing nonnative, invasive species may be 
valuable in conserving the prostrate milkweed. However, buffelgrass is 
an extremely difficult plant to control and manage. Efforts to 
eradicate buffelgrass in highway ROWs are unlikely to succeed because 
these areas are continuously disturbed for ROW operations and 
maintenance, making it difficult for native plants to establish and 
persist, and creating ideal circumstances for buffelgrass to 
reestablish. Therefore, we are focusing efforts on the conservation of 
prostrate milkweed in areas that contain the PBFs, including the 
absence of buffelgrass, where special management is likely to be 
effective.
    (7) Comment: One commenter stated that we should remove PBFs 4 
(vegetation composition that includes abundant, diverse pollen and 
nectar plants and healthy populations of native bee and wasp species) 
and 5 (less than 20 percent cover of buffelgrass) because all occupied 
areas should be designated as critical habitat. They state that because 
the species' overall viability requires conservation of all populations

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and genetic diversity, each remaining plant can contribute to genetic 
diversity if managed scientifically. Therefore, the commenter writes 
that no plants should be sacrificed because their habitat is suffering 
from adverse modification or undergoing outright destruction.
    Our response: The Act does not define occupied critical habitat as 
all areas with the species present. Rather, the Act defines occupied 
critical habitat as the specific areas within the geographical area 
occupied by the species, at the time it is listed, on which are found 
those PBFs (I) essential to the conservation of the species and (II) 
which may require special management considerations or protection (16 
U.S.C. 1532(5)(A)(i)). Occupied areas do not need to include all of the 
PBFs essential to the conservation of the species but must contain at 
least one. Using the best available scientific information, we have 
determined the PBFs that are essential to the conservation of prostrate 
milkweed (for more information, see Physical or Biological Features 
Essential to the Conservation of the Species, below). These include 
vegetation composition that includes abundant, diverse pollen and 
nectar plants and healthy populations of native bee and wasp species, 
and areas that have less than 20 percent cover of buffelgrass. Special 
management can also help restore the critical habitat areas that are 
lacking some of the PBFs. Accordingly, we are focusing our conservation 
efforts for prostrate milkweed in areas that contain at least one PBF 
where special management is likely to be effective. Special management 
considerations may include prescribed burning, grazing, and/or brush 
thinning; nonnative, invasive grass control; protection from activities 
that disturb the soil; and propagation and reintroduction of plants in 
restorable areas. Furthermore, plants in areas that are not designated 
as critical habitat may still contribute to genetic diversity of the 
species and will receive any protections due to listing, even if those 
areas are not designated as critical habitat.

I. Final Listing Determination

Background

    Please refer to the SSA report and the February 15, 2022, proposed 
rule (87 FR 8509) for a full summary of species information. Both are 
available on our Southwest Region website at https://www.fws.gov/about/region/southwest and at https://www.regulations.gov under Docket No. 
FWS-R2-ES-2021-0041.

Regulatory and Analytical Framework

Regulatory Framework

    Section 4 of the Act (16 U.S.C. 1533) and the implementing 
regulations in title 50 of the Code of Federal Regulations set forth 
the procedures for determining whether a species is an endangered 
species or a threatened species, issuing protective regulations for 
threatened species, and designating critical habitat for endangered and 
threatened species. In 2019, jointly with the National Marine Fisheries 
Service, the Service issued a final rule that revised the regulations 
in 50 CFR part 424 regarding how we add, remove, and reclassify 
endangered and threatened species and the criteria for designating 
listed species' critical habitat (84 FR 45020; August 27, 2019). On the 
same day, the Service also issued final regulations that, for species 
listed as threatened species after September 26, 2019, eliminated the 
Service's general protective regulations automatically applying to 
threatened species the prohibitions that section 9 of the Act applies 
to endangered species (84 FR 44753; August 27, 2019).
    The Act defines an ``endangered species'' as a species that is in 
danger of extinction throughout all or a significant portion of its 
range, and a ``threatened species'' as a species that is likely to 
become an endangered species within the foreseeable future throughout 
all or a significant portion of its range. The Act requires that we 
determine whether any species is an endangered species or a threatened 
species because of any of the following factors:
    (A) The present or threatened destruction, modification, or 
curtailment of its habitat or range;
    (B) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (C) Disease or predation;
    (D) The inadequacy of existing regulatory mechanisms; or
    (E) Other natural or manmade factors affecting its continued 
existence.
    These factors represent broad categories of natural or human-caused 
actions or conditions that could have an effect on a species' continued 
existence. In evaluating these actions and conditions, we look for 
those that may have a negative effect on individuals of the species, as 
well as other actions or conditions that may ameliorate any negative 
effects or may have positive effects.
    We use the term ``threat'' to refer in general to actions or 
conditions that are known to or are reasonably likely to negatively 
affect individuals of a species. The term ``threat'' includes actions 
or conditions that have a direct impact on individuals (direct 
impacts), as well as those that affect individuals through alteration 
of their habitat or required resources (stressors). The term ``threat'' 
may encompass--either together or separately--the source of the action 
or condition or the action or condition itself.
    However, the mere identification of any threat(s) does not 
necessarily mean that the species meets the statutory definition of an 
``endangered species'' or a ``threatened species.'' In determining 
whether a species meets either definition, we must evaluate all 
identified threats by considering the expected response by the species 
and the effects of the threats--in light of those actions and 
conditions that will ameliorate the threats--on an individual, 
population, and species level. We evaluate each threat and its expected 
effects on the species, then analyze the cumulative effect of all of 
the threats on the species as a whole. We also consider the cumulative 
effect of the threats in light of those actions and conditions that 
will have positive effects on the species, such as any existing 
regulatory mechanisms or conservation efforts. The Secretary determines 
whether the species meets the definition of an ``endangered species'' 
or a ``threatened species'' only after conducting this cumulative 
analysis and describing the expected effect on the species now and in 
the foreseeable future.
    The Act does not define the term ``foreseeable future,'' which 
appears in the statutory definition of ``threatened species.'' Our 
implementing regulations at 50 CFR 424.11(d) set forth a framework for 
evaluating the foreseeable future on a case-by-case basis. The term 
``foreseeable future'' extends only so far into the future as we can 
reasonably determine that both the future threats and the species' 
responses to those threats are likely. In other words, the foreseeable 
future is the period of time in which we can make reliable predictions. 
``Reliable'' does not mean ``certain''; it means sufficient to provide 
a reasonable degree of confidence in the prediction. Thus, a prediction 
is reliable if it is reasonable to depend on it when making decisions.
    It is not always possible or necessary to define the foreseeable 
future as a particular number of years. Analysis of the foreseeable 
future uses the best scientific and commercial data available and 
should consider the timeframes applicable to the relevant threats and 
to the species' likely responses to those threats in view of its life-
history characteristics. Data that are typically

[[Page 12576]]

relevant to assessing the species' biological response include species-
specific factors such as lifespan, reproductive rates or productivity, 
certain behaviors, and other demographic factors.

Analytical Framework

    The SSA report documents the results of our comprehensive 
biological review of the best scientific and commercial data regarding 
the status of the species, including an assessment of the potential 
threats to the species. The SSA report does not represent our decision 
on whether the species should be listed as an endangered or threatened 
species under the Act. However, it does provide the scientific basis 
that informs our regulatory decisions, which involve the further 
application of standards within the Act and its implementing 
regulations and policies.
    To assess prostrate milkweed viability, we used the three 
conservation biology principles of resiliency, redundancy, and 
representation (Shaffer and Stein 2000, pp. 306-310). Briefly, 
resiliency is the ability of the species to withstand environmental and 
demographic stochasticity (for example, wet or dry, warm or cold 
years), redundancy is the ability of the species to withstand 
catastrophic events (for example, droughts, large pollution events), 
and representation is the ability of the species to adapt to both near-
term and long-term changes in its physical and biological environment 
(for example, climate conditions, pathogens). In general, species 
viability will increase with increases in resiliency, redundancy, and 
representation (Smith et al. 2018, p. 306). Using these principles, we 
identified the species' ecological requirements for survival and 
reproduction at the individual, population, and species levels, and 
described the beneficial and risk factors influencing the species' 
viability.
    The SSA process can be categorized into three sequential stages. 
During the first stage, we evaluated the individual species' life-
history needs. The next stage involved an assessment of the historical 
and current condition of the species' demographics and habitat 
characteristics, including an explanation of how the species arrived at 
its current condition. The final stage of the SSA involved making 
predictions about the species' responses to positive and negative 
environmental and anthropogenic influences. Throughout all of these 
stages, we used the best available information to characterize 
viability as the ability of a species to sustain populations in the 
wild over time. We use this information to inform our regulatory 
decision.
    The following is a summary of the key results and conclusions from 
the SSA report; the full SSA report can be found at Docket FWS-R2-ES-
2021-0041 on https://www.regulations.gov and at https://www.fws.gov/office/texas-coastal-ecological-services.

Summary of Biological Status and Threats

    In this discussion, we review the biological condition of the 
species and its resources, and the threats that influence the species' 
current and future condition, in order to assess the species' overall 
viability and the risks to that viability.
    For the prostrate milkweed to maintain viability, its populations 
or some portion thereof must have sufficient resiliency, redundancy, 
and representation. Several factors influence the resiliency of 
prostrate milkweed populations, including abundance and recruitment 
rate, in addition to elements of the species' habitat that determine 
whether prostrate milkweed populations can grow. These resiliency 
factors and habitat elements are discussed in detail in the SSA report 
and summarized here.

Species Needs

Abundance
    Prostrate milkweed abundance is difficult to assess due to its 
ability to remain dormant for multiple years until the necessary 
environmental conditions occur. Individual plants may emerge only a few 
times per decade, and not all plants will emerge at the same time 
(Price 2005, pers. comm.; Best 2017, pers. comm.). Therefore, we 
considered populations to be extant if plants have been observed within 
the past 40 years (Strong 2020, pers. comm.) and with available habitat 
(i.e., not paved over) or with restorable habitat (i.e., nonnative 
grass could be removed).
    Populations of prostrate milkweed must be large enough to have a 
high probability of enduring random demographic and environmental 
variation. For example, species or populations may be considered more 
vulnerable when the probability of persisting 100 years is less than 90 
percent (Mace and Lande 1991, p. 151). This metric of population 
resilience, called minimum viable population (MVP), refers to the 
smallest population size that has a high probability of surviving over 
a specified period. Calculations of MVP require data that are not 
currently available for prostrate milkweed. As a practical alternative, 
we estimated the likely MVP range of prostrate milkweed by comparing it 
to species with similar life-history traits for which MVPs have been 
calculated (Pavlik 1996, p. 137). This method estimates a highly 
resilient population if prostrate milkweed has 1,600 or more adult 
individuals (Service 2020, p. 38).
    Determinations of MVP usually consider the effective population 
size, rather than total number of individuals (Pavlik 1996, entire); 10 
genetically identical individuals (for example, clones or ramets) would 
have an effective population size of one. Because prostrate milkweed is 
likely self-incompatible and does not appear to form clonal colonies, 
the effective population size is likely to be nearly the same as the 
total population size.
Recruitment Rate
    A stable or increasing population requires recruitment rates that 
equal or exceed mortality rates (Service 2020, p. 38). All stages of 
recruitment, from flowering and seed production to germination and 
establishment, occur when the soil has available moisture. The porous 
soils of prostrate milkweed habitat dry quickly after a single heavy 
thunderstorm. Based on observations of other perennial forbs (broad-
leaved herbaceous plants) in this ecosystem, recruitment probably 
occurs during periods of extended rainfall, meaning multiple rain 
events over a period of several weeks (Service 2020, p. 38). These 
events are rare in this semiarid region. Consequently, we expect that 
successful recruitment may occur only once or a few times per decade. 
Similarly, most mortality probably occurs during years of extended 
drought. Hence, both recruitment and mortality would have strong pulses 
and observed population sizes would vary widely from year to year, 
leading to potentially spurious interpretations of demographic trends 
(Service 2020, p. 38).
    Populations of prostrate milkweed require habitats that also 
support healthy populations of large native bees and wasps (Service 
2020, p. 38). Native bees in turn require a diversity and abundance of 
native forb and shrub species that provide pollen and nectar. Tarantula 
hawks (Pepsis spp. and Hemipepsis spp.) may also be important 
pollinators of prostrate milkweed; tarantula hawks require healthy 
populations of their prey species, tarantulas (Best 2020, pers. comm.).

[[Page 12577]]

    Prostrate milkweed populations require competition from grasses and 
forbs to be periodically reduced (Service 2020, p. 38). This 
requirement, which has been observed in other milkweed species, may be 
an adaptation to wildfire (Baum and Sharber 2012, pp. 968-971). 
Although mowing or livestock grazing can also reduce competition, it is 
likely that prostrate milkweed is adapted to grasslands that were 
sustained by periodic wildfires (Service 2020, p. 39).
Canopy Cover
    Canopy cover refers to shade from trees, shrubs, prickly pear 
cactuses, or tall (taller than 1 meter) grass. Sufficiently resilient 
prostrate milkweed populations need an open canopy with little or no 
herbaceous cover (Service 2020, p. 3). Therefore, the species may occur 
in areas that mimic historical wildfire or grazing, such as along mowed 
road ROWs (Service 2020, p. 3).
Ground Cover
    Ground cover refers to vegetation growing at the herbaceous layer 
(shorter than 1 meter tall) that would compete with prostrate milkweed 
plants for resources. Sufficiently resilient prostrate milkweed 
populations need an open canopy with little or no herbaceous cover, so 
there is little competition with other plants (Service 2020, p. 3).

Risk Factors for Prostrate Milkweed

    We reviewed the potential risk factors (i.e., threats, stressors) 
that may affect prostrate milkweed now and in the future. In this rule, 
we will discuss only those factors in detail that could meaningfully 
impact the status of the species. Those risks that are not known to 
have effects on prostrate milkweed populations, such as quarrying/
mining, hybridization, pollinator decline, and climate change, are not 
discussed here but are evaluated in the SSA report. The primary risk 
factors (i.e., threats) affecting the status of prostrate milkweed are: 
(1) Competition from introduced invasive grasses (Factor A from the 
Act); (2) habitat loss from root-plowing and conversion of native 
vegetation to pasture (Factor A); (3) habitat loss from ROW 
construction and maintenance from energy development and road and 
utility construction (Factor A); (4) habitat loss from border security 
development and enforcement activities (Factor A); and (5) the 
demographic and genetic consequences of small population sizes and 
population fragmentation (Factor E).
Competition From Nonnative, Invasive Grasses
    Nonnative, invasive grass species displace native plants by 
competing for water, nutrients, and light, and their dense root systems 
prevent germination of native plant seeds (Texas Invasives 2019, 
unpaginated). Buffelgrass (Pennisetum ciliare) is a perennial 
bunchgrass introduced from Africa that is now one of the most abundant 
introduced grasses in south Texas, and the most prevalent invasive 
grass within the range of prostrate milkweed. Since the 1950s, Federal 
and State land management agencies have promoted buffelgrass as a 
forage grass in south Texas (Smith 2010, p. 113). Buffelgrass is very 
well-adapted to the hot, semi-arid climate of south Texas due to its 
drought resistance and ability to aggressively establish in heavily 
grazed landscapes (Smith 2010, p. 113). Buffelgrass continues to be 
planted in areas affected by drought and overgrazing to stabilize soils 
and to increase rangeland productivity. Buffelgrass often creates 
homogeneous monocultures by out-competing native plants for essential 
resources (Lyons et al. 2013, p. 8), and it produces phytotoxins in the 
soil that inhibit the growth of neighboring native plants (Vo 2013, 
unpaginated). Furthermore, prescribed burning used for brush control 
promotes buffelgrass forage production in south Texas (Hamilton and 
Scifres 1982, p. 11).
    Most prostrate milkweed plants have been observed where buffelgrass 
is absent or at low densities (Eason 2019, pers. comm.; Strong 2019, 
pers. comm.). On national wildlife refuge lands, prostrate milkweed was 
found in areas where native grass was still dominant, but not where 
buffelgrass or woody vegetation was present in dense stands (Best 2005, 
p. 3). The unpaved ROWs on private lands in south Texas for oil and gas 
wells, wind farms, service roads, pipelines, and powerlines could 
benefit prostrate milkweed through the periodic mowing of road margins. 
However, disturbed soils along ROWs are rapidly colonized by 
buffelgrass.
    The Texas Natural Diversity Database (Database) lists invasive 
species, primarily buffelgrass, as a pervasive threat of extreme 
severity to prostrate milkweed. The Database defines a pervasive threat 
as one that affects all or most (71-100 percent) of a species' 
populations, occurrences, or extent. An extreme level of severity is 
one that is likely to destroy or eliminate occurrences or habitat or 
reduce population sizes by 71-100 percent (TXNDD 2016, unpaginated). It 
is likely that buffelgrass has negatively impacted all Texas 
populations (TXNDD 2019-2020, entire; Eason 2019, pers. comm.; 
Kieschnick 2019, pers. comm.). Competition from buffelgrass is the 
greatest threat to prostrate milkweed.
Root-Plowing and Conversion of Native Grassland and Savanna
    Root-plowing is a brush control method that uses powerful tracked 
vehicles to excavate the roots of woody plants with heavy steel subsoil 
rippers that dig several feet into the ground. The dead trees and 
shrubs are then burned, and the root-plowed soils are planted with 
buffelgrass for livestock grazing. Root-plowing and conversion to 
buffelgrass pasture is a widely conducted practice in south Texas and 
northeast Mexico, occurring in much of the potential habitat of 
prostrate milkweed. Extensive areas of recently root-plowed lands can 
be identified in aerial photographs. These practices have been and are 
still subsidized by the United States Department of Agriculture (USDA) 
Natural Resources Conservation Service and its precursor, the USDA Soil 
Conservation Service.
    Root-plowing temporarily reduces the encroachment of woody plants 
into the grassland component of former savannas. The conversion of 
native habitats to improved pastures dominated by buffelgrass or other 
introduced grasses greatly reduces the abundance and diversity of most 
native grass and forb species (Woodin et al. 2010, p. 1). Very few, if 
any, prostrate milkweed plants survive following root-plowing and 
buffelgrass planting. This is likely due to the excavation and 
desiccation of most tubers during root-plowing; subsequently, the few 
remaining individuals decline due to competition from dense buffelgrass 
cover.
    Conversely, prostrate milkweed occurs in well-managed rangelands, 
provided that the soil was not previously root-plowed or otherwise 
disturbed (Service 2020, p. 53). Most milkweed species are unpalatable 
to cattle, and often increase in abundance on grazed lands. Livestock, 
including cattle, sheep, and horses, graze preferentially on grasses 
and forbs, including buffelgrass, and on nontoxic herbaceous plants; 
therefore, livestock grazing may reduce competition with prostrate 
milkweed from these plants (Service 2020, p. 41). In addition to 
grazing, livestock may also reduce competition with prostrate milkweed 
by trampling herbaceous plants (Service 2020, p. 41). Because prostrate 
milkweed is often observed in the wheel ruts of dirt roads, it appears 
to be

[[Page 12578]]

unusually tolerant of trampling; thus, the effect of livestock 
trampling is minimal (Service 2020, pp. 41-42). Periodic livestock 
grazing reduces competition from native and introduced grasses. In 
South Texas, over-grazed rangelands typically become invaded by woody 
plants, reducing the habitat suitability for prostrate milkweed. Hence, 
management practices that promote sustainable grazing of native grasses 
are beneficial to prostrate milkweed (Service 2020, p. 41).
Road and ROW Construction and Maintenance
    Oil and gas exploration and wind energy development are occurring 
at a rapid pace in Starr and Zapata Counties, Texas. Seismic 
exploration and the construction of roads and caliche pads for oil and 
gas wells and wind turbines can destroy plants and their habitats 
within the construction footprint (Reemts et al. 2014, pp. 123, 125; 
Leslie 2016, p. 49). Additionally, graded service roads and other 
permanent structures may indirectly affect the hydrology of surrounding 
habitats by diverting and channeling water through drainage culverts. 
Invasive buffelgrass quickly colonizes disturbed roadsides, then 
invades adjacent habitats. Heavy vehicle traffic during oil and gas 
well drilling and wind farm construction may increase the frequency of 
road maintenance, such as grading or widening (Pe[ntilde]a 2019, pers. 
comm.). Grading or blading a caliche road involves scraping the road's 
surface with a large heavy blade to remove ruts and roadside 
vegetation. Increased frequency of road maintenance that removes above-
ground portions of plants could reduce or eliminate prostrate milkweed 
flower and fruit production. Conversely, grading or blading of caliche 
roads conducted during the milkweed's dormant periods may benefit the 
species by temporarily reducing competition from grasses and forbs 
(TXNDD 2019, p. 11). TXNDD (2019) ranks road expansion as a pervasive 
threat (affects all or most (71-100 percent) of a species' populations, 
occurrences, or extent) of extreme severity to prostrate milkweed.
    All or parts of nine prostrate milkweed occurrences are in the 
margins of improved highway ROWs. All highway ROW populations have 
declined since they were first observed, likely due to the frequency of 
soil disturbance and invasive grass competition (Service 2020, p. 40). 
In addition, from 2010 to 2012, Texas Department of Transportation 
(TxDOT) widened segments of U.S. Highway 83 that affected at least 
three known prostrate milkweed sites: Arroyo del Tigre Grande, Mission 
Mier a Visita, and Arroyo Roma (Strong and Williamson 2015, p. 51; 
Paradise 2019, pers. comm.). TxDOT has also scheduled additional road 
widening or construction at five known prostrate milkweed populations: 
Arroyo del Tigre Grande, Arroyo del Tigre Chiquito, Arroyo de los 
Mudos, Mission Mier a Visita, and Arroyo Roma (TxDOT 2019, 
unpaginated). U.S. Customs and Border Protection (CBP) has scheduled 
road improvements at the prostrate milkweed population site located in 
the Arroyo Morteros tract of the Lower Rio Grande Valley National 
Wildlife Refuge (NWR) (Vallejo 2019, pers. comm.).
    In contrast, all or parts of three prostrate milkweed occurrences 
are in the margins of unpaved rural roads. These relatively stable 
populations have persisted in narrow strips of native vegetation 
between the gravel or caliche roadbeds and the fence lines of adjacent 
private properties. The soils in these narrow, naturally vegetated 
strips have never been excavated, and they have relatively little 
buffelgrass cover.
    The installation of natural gas pipelines and fiber-optic cables 
has removed prostrate milkweed plants in the Dolores and Arroyo del 
Tigre Chiquito populations in the past (Damude and Poole 1990, p. 32; 
Boydston 1993, unpaginated; Campos 1993, unpaginated). In 1995, 
Southwestern Bell installed a fiber-optic cable in the Highway 83 ROW, 
2.6 miles south of the Webb-Zapata County line, which removed at least 
100 individuals at the Dolores population (Service 1995, p. 1). In 
1993, prior to the fiber-optic cable installation, this population was 
estimated to have 100 to 200 individuals (TXNDD 2019, unpaginated) and 
was the largest known population of prostrate milkweed.
    In summary, prostrate milkweed faces risks from ROWs and road 
construction and maintenance associated with oil and gas activities, 
wind energy development, and utility and pipeline corridor 
construction.
Border Security Development and Enforcement Activities
    All known Texas populations of prostrate milkweed are within 9 
miles (14.5 kilometers) of the U.S.-Mexico border. To address border 
security concerns, additional border barrier construction was proposed 
in the Rio Grande Valley, including the Arroyo Morteros tract of the 
Lower Rio Grande Valley NWR. Should border wall construction occur, and 
depending on the alignment, construction could remove prostrate 
milkweed plants that occur within the construction footprint. 
Additionally, CBP plans to improve roads across this tract (Vallejo 
2019, pers. comm.) and may also install new drag strips along existing 
roads. Drag strips are 13- to 16-foot (ft) (4- to 5-meter) -wide swaths 
cleared of all vegetation and regularly scraped to keep the soil 
surface loose, to detect recent foot traffic. Due to the high gypsum 
content, soils in this area are extremely vulnerable to gully erosion. 
Hence, the unvegetated, continually disturbed drag strips may 
exacerbate soil erosion and impact a much wider area. The Database 
ranks drag strip construction within prostrate milkweed populations as 
a small threat (defined as a threat that affects 1-10 percent of the 
total population or occurrences or extent) with an extreme level of 
severity (likely to destroy or eliminate occurrences or habitat, or 
reduce population by 71-100 percent) (TXNDD 2016, unpaginated). 
Consequently, the construction of border barriers, roads, and drag 
strips are potential threats of high magnitude to prostrate milkweed 
populations, depending on their alignment, design, and proximity to 
populations and local topography.
    Native plant populations are legally protected on NWRs, and, if 
listed under the Act, these plants have additional legal protections 
from federally funded or regulated actions. However, a provision of the 
REAL ID Act of 2005 (Pub. L. 109-13, 119 Stat. 302) gives the Secretary 
of Homeland Security authority to waive other Federal laws, including 
the Endangered Species Act, to expedite construction of border 
barriers. Therefore, border barrier construction on private and public 
lands is exempt from consultation with the Service under section 7 of 
the Act. During the previous phase of border barrier construction, 
beginning in 2007, the Department of Homeland Security (DHS) and the 
Service coordinated to establish best management practices for the 
federally listed plants and animals in the project impact area (DHS 
2008, entire); nevertheless, these best management practices did not 
address prostrate milkweed.
Small Population Sizes and Population Fragmentation
    Small, isolated populations are more vulnerable to catastrophic 
losses caused by random fluctuations in recruitment (demographic 
stochasticity) or variations in rainfall or other environmental factors 
(environmental stochasticity) (Service 2016, p. 20). Small, 
reproductively isolated populations are susceptible to the loss of 
genetic diversity, to genetic drift, and

[[Page 12579]]

to inbreeding (Barrett and Kohn 1991, pp. 3-30). Due to the small size 
and isolation of prostrate milkweed populations, several may already 
suffer from genetic bottlenecks, genetic drift, inbreeding, and loss of 
allelic diversity.
    In addition to population size, it is likely that population 
density and connectivity also influence population viability (Service 
2020, p. 51). Prostrate milkweed is very likely to be an obligate 
outcrosser (fertilization between different individuals), as are most 
other Asclepias species, which requires that genetically compatible 
individuals be clustered within the forage range of the native 
pollinators for successful reproduction (Service 2020, p. 51). While 
the specific pollinators of this species have not been revealed, they 
are likely to be large bees or wasps, and the forage range could be up 
to several kilometers. If this is the case, sufficiently viable 
populations of prostrate milkweed could be dispersed at very low 
densities over relatively large areas, provided that they lie within 
fairly contiguous habitats that are traversed by pollinating insects. 
Thus, the small, isolated clusters of prostrate milkweed that have been 
documented, principally along public roads that slice through large 
expanses of potential habitat on private lands, may represent only tiny 
fractions of larger, highly dispersed populations (Service 2020, p. 
51).
    Based strictly on the available scientific data, the documented 
populations of prostrate milkweed are all far below the estimated MVP 
level and may be affected by the demographic and genetic consequences 
of small population sizes and by fragmentation of populations.
Summary
    Our analysis of the past, current, and future influences on the 
needs of prostrate milkweed for long-term viability revealed several 
threats that pose a risk to current and future viability: competition 
from introduced invasive grass (buffelgrass); root-plowing of 
rangelands; development of new oil and gas wells, wind energy farms, 
roads, pipelines, and utility corridors; development of new border 
barriers and drag strips; and the demographic and genetic consequences 
of small population sizes and population fragmentation. Conversely, 
well-managed livestock grazing of rangeland is compatible with 
management of prostrate milkweed habitat and may benefit this species.

Species Condition

    The current condition of prostrate milkweed considers the status 
and risks to its populations. In the SSA report, for each population, 
we developed and assigned condition categories for two demographic 
factors and two habitat factors that are important for viability of 
prostrate milkweed. The condition scores for each factor were then used 
to estimate the probability of persistence over the next 30 years. We 
chose 30 years because it is within the range of available climate 
change model forecasts where we can reasonably foresee the future 
condition of the species. Populations were rated high, moderate, or low 
when that probability is greater than 90 percent, between 60 and 90 
percent, or between 10 and 60 percent, respectively. Functionally 
extirpated populations are not expected to persist over 30 years or are 
already extirpated.
    There are 24 populations of prostrate milkweed remaining in Starr 
and Zapata Counties, Texas, and in Tamaulipas and eastern Nuevo 
Le[oacute]n, Mexico (see table 1, below). The species' range extends 
more than 200 miles (320 kilometers) from northwest to southeast. In 
Texas, one population, Dolores, is somewhat isolated in northern Zapata 
County, with the nearest known population approximately 25 miles (40 
kilometers) away. In Mexico, eight known populations are in isolated 
pockets widely scattered in Tamaulipas and eastern Nuevo Le[oacute]n. 
However, botanists have only surveyed a small proportion of the 
species' range. Furthermore, the species remains dormant and 
undetectable except for short periods of time after infrequent, heavy 
rainfall. Consequently, although the species is certainly rare, its 
actual abundance is difficult to determine. It is likely that, 
historically, populations occurred between these areas, connecting the 
populations in Texas and Mexico. Because they are widely separated, 
natural gene flow or reestablishment following disturbance is very 
unlikely between the 24 known populations. Based upon our analysis of 
current conditions of these 24 extant populations, none are in high 
condition, 5 are in moderate condition, and 19 are in low condition.

      Table 1--Summary of Current Condition for Prostrate Milkweed
------------------------------------------------------------------------
             Population name                     Current condition
------------------------------------------------------------------------
Dolores..................................  Low.
14493....................................  Low.
14491....................................  Low.
Arroyo del Tigre Grande..................  Moderate.
Arroyo del Tigre Chiquito................  Low.
FM 2098..................................  Low.
Falcon...................................  Low.
Los Alvaros..............................  Moderate.
Arroyo Morteros Tract....................  Moderate.
Los Arrieros Loop........................  Low.
Arroyo de los Mudos......................  Low.
Mission Mier a Visita....................  Low.
San Juli[aacute]n Road...................  Moderate.
FM 3167..................................  Moderate.
Arroyo Roma..............................  Low.
Arroyo Ramirez Tract.....................  Low.
Rancho La Coma...........................  Low.
Road to Guerrero Viejo...................  Low.
Carboneras...............................  Low.
Punta de Alambre.........................  Low.
Intersection of 101-180..................  Low.
Rio El Cat[aacute]n......................  Low.
Rancho Loreto North......................  Low.
Rancho Loreto South......................  Low.
------------------------------------------------------------------------

    The two demographic factors used to analyze resiliency of prostrate 
milkweed populations are abundance and recruitment rate. Related to 
abundance, a highly resilient population of prostrate milkweed has 
1,600 or more adult individuals, a moderately resilient population has 
from 800 to 1,600 mature individuals, and a population with fewer than 
800 mature individuals has low resilience (Service 2020, p. 38). 
Prostrate milkweed populations have high resiliency if the recruitment 
rate is greater than or equal to 25 percent of individuals producing 
viable seeds per year. Moderately resilient populations have 
recruitment rates of between 15 and 24 percent per year, and 
populations with low resiliency have recruitment rates of less than 15 
percent per year (Service 2020, p. 57).
    The two habitat factors used to analyze resiliency of prostrate 
milkweed populations were canopy cover and groundcover. Highly 
resilient populations have less than 30 percent canopy cover and have 
all bare ground or are sparsely vegetated with mostly native grass and/
or forbs. Moderately resilient populations have between 30 and 60 
percent canopy cover and are sparsely vegetated with a mixture of 
native and nonnative grasses and/or forbs. Minimally resilient 
populations have between 61 and 100 percent canopy cover and a dense 
groundcover of native or introduced grasses and forbs and little or no 
bare ground (Service 2020, p. 57).
    Redundancy is low for this species due to low numbers of 
populations in moderate to high condition for

[[Page 12580]]

resiliency, making prostrate milkweed populations vulnerable to 
extirpations from catastrophic events. Because buffelgrass invasion is 
prevalent in this area, ecological diversity among the known 
populations is limited and thus species representation is low. 
Furthermore, the populations are isolated and widespread across the 
range, and therefore gene flow among the populations is limited. As a 
consequence of these current conditions, the viability of the prostrate 
milkweed now primarily depends on maintaining and restoring the 
remaining isolated populations and potentially discovering or 
reintroducing new populations where feasible.
    As part of the SSA, we also developed three plausible future 
scenarios to capture the range of uncertainties regarding future 
threats and the projected responses by the prostrate milkweed. Our 
scenarios included a continuing conditions scenario, which incorporated 
the current risk factors continuing on the same trajectory that they 
are on now. We also evaluated a conservation scenario and a scenario 
with increased stressors. Because we determined that the current 
condition of the prostrate milkweed is consistent with an endangered 
species (see Determination of Prostrate Milkweed's Status, below), we 
are not presenting the results of the future scenarios in this rule. 
Please refer to the SSA report (Service 2020, entire) for the full 
analysis of future scenarios.
    We note that, by using the SSA framework to guide our analysis of 
the scientific information documented in the SSA report, we have not 
only analyzed individual effects on the species, but we have also 
analyzed their potential cumulative effects. We incorporate the 
cumulative effects into our SSA analysis when we characterize the 
current and future condition of the species. To assess the current and 
future condition of the species, we undertake an iterative analysis 
that encompasses and incorporates the threats individually and then 
accumulates and evaluates the effects of all the relevant factors that 
may be influencing the species, including threats and conservation 
efforts. Because the SSA framework considers not just the presence of 
the factors, but to what degree they collectively influence risk to the 
entire species, our assessment integrates the cumulative effects of the 
factors and replaces a standalone cumulative effects analysis.

Determination of Prostrate Milkweed's Status

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

Status Throughout All of Its Range

    After evaluating threats to the species and assessing the 
cumulative effect of the threats under the Act's section 4(a)(1) 
factors, we found that, of the 24 known prostrate milkweed populations 
remaining, 19 are small, are isolated, and have low resiliency; 5 have 
moderate resiliency and connection to other populations; and none have 
high resiliency. Several factors pose threats to prostrate milkweed, 
including competition from introduced, invasive grass; habitat loss and 
degradations from root-plowing and conversion of native vegetation to 
improved buffelgrass pasture; habitat loss from ROW construction and 
maintenance from energy development and road and utility construction; 
habitat loss from border security development and enforcement 
activities (Factor A from the Act); and the demographic and genetic 
consequences of small population sizes (Factor E).
    All the aforementioned threats are currently affecting the known 
populations of prostrate milkweed. Buffelgrass has already negatively 
impacted all the Texas populations (TXNDD 2019-2020, entire; Eason 
2019, pers. comm.; Kieschnick 2019, pers. comm.) and will continue to 
do so in the future. Habitat loss and degradation from root-plowing and 
conversion of native vegetation to improved buffelgrass pasture has 
also already been occurring for many years (Service 2020, p. 40). 
Habitat loss from ROW construction and maintenance associated with 
energy development and road and utility construction has already been 
observed from oil and gas development occurring in Zapata County. As of 
November 2019, no wind turbines, oil or gas well pads, pipelines, or 
energy service roads have been constructed directly within known 
prostrate milkweed populations. However, some Starr County prostrate 
milkweed populations are less than 2 kilometers (1.2 miles) from 
existing wind turbines (Service 2020, pp. 42-43), and a few wind energy 
farms are expected to be constructed in the future, which could lead to 
additional habitat loss. Habitat loss from border security development 
and enforcement activities has occurred in recent years and is expected 
to continue. Finally, the demographic and genetic consequences of small 
population sizes are a current threat to the prostrate milkweed. This 
situation is not expected to change into the future.
    In addition to the current threats, redundancy and representation 
are also limited. There are 24 known populations that are distributed 
widely across the species' range, and the majority of those populations 
are currently in low condition. Should a catastrophic event occur, the 
populations are vulnerable to extirpation because they are small and 
isolated from each other. The small, reproductively isolated 
populations are also susceptible to the loss of genetic diversity, 
genetic drift, and inbreeding due to random fluctuations in recruitment 
(demographic stochasticity) or variations in rainfall or other 
environmental factors (environmental stochasticity). Because of the 
species' overall current resiliency, redundancy, and representation, 
prostrate milkweed is currently in danger of extinction throughout all 
of its range. We do not find that the species meets the Act's 
definition of a threatened species because the species has already 
shown low levels in current resiliency, redundancy, and representation 
due to the threats mentioned above. Thus, after assessing the best 
available information, we determine that prostrate milkweed is in 
danger of extinction throughout all of its range.

Status Throughout a Significant Portion of Its Range

    Under the Act and our implementing regulations, a species may 
warrant listing if it is in danger of extinction or likely to become so 
in the foreseeable future throughout all or a significant portion of 
its range. We have

[[Page 12581]]

determined that the prostrate milkweed is in danger of extinction 
throughout all of its range and accordingly did not undertake an 
analysis of any significant portions of its range. Because the 
prostrate milkweed warrants listing as endangered throughout all of its 
range, our determination does not conflict with the decision in Center 
for Biological Diversity v. Everson, 435 F. Supp. 3d 69 (D.D.C. 2020) 
(Everson), which vacated the provision of the Final Policy on 
Interpretation of the Phrase ``Significant Portion of Its Range'' in 
the Endangered Species Act's Definitions of ``Endangered Species'' and 
``Threatened Species'' (Final Policy) (79 FR 37578, July 1, 2014) 
providing that if the Services determine that a species is threatened 
throughout all of its range, the Services will not analyze whether the 
species is endangered in a significant portion of its range.

Determination of Status

    Our review of the best available scientific and commercial 
information indicates that the prostrate milkweed meets the Act's 
definition of an endangered species. Therefore, we are listing 
prostrate milkweed as an endangered species in accordance with sections 
3(6) and 4(a)(1) of the Act.

Available Conservation Measures

    Conservation measures provided to species listed as endangered or 
threatened under the Act include recognition as a listed species, 
planning and implementation of recovery actions, requirements for 
Federal protection, and prohibitions against certain practices. 
Recognition through listing results in public awareness, and 
conservation by Federal, State, Tribal, and local agencies, private 
organizations, and individuals. The Act encourages cooperation with the 
States and other countries and calls for recovery actions to be carried 
out for listed species. The protection required by Federal agencies, 
including the Service, and the prohibitions against certain activities 
are discussed, in part, below.
    The primary purpose of the Act is the conservation of endangered 
and threatened species and the ecosystems upon which they depend. The 
ultimate goal of such conservation efforts is the recovery of these 
listed species, so that they no longer need the protective measures of 
the Act. Section 4(f) of the Act calls for the Service to develop and 
implement recovery plans for the conservation of endangered and 
threatened species. The goal of this process is to restore listed 
species to a point where they are secure, self-sustaining, and 
functioning components of their ecosystems.
    Recovery planning consists of preparing draft and final recovery 
plans, beginning with the development of a recovery outline and making 
it available to the public within 30 days of a final listing 
determination. The recovery outline guides the immediate implementation 
of urgent recovery actions and describes the process to be used to 
develop a recovery plan. Revisions of the plan may be done to address 
continuing or new threats to the species, as new substantive 
information becomes available. The recovery plan also identifies 
recovery criteria for review of when a species may be ready for 
reclassification from endangered to threatened (``downlisting'') or 
removal from protected status (``delisting''), and methods for 
monitoring recovery progress. Recovery plans also establish a framework 
for agencies to coordinate their recovery efforts and provide estimates 
of the cost of implementing recovery tasks. Recovery teams (composed of 
species experts, Federal and State agencies, nongovernmental 
organizations, and stakeholders) are often established to develop 
recovery plans. When completed, the recovery outline, draft recovery 
plan, and the final recovery plan will be available on our website 
(https://www.fws.gov/program/endangered-species), or from our Texas 
Coastal Ecological Services Field Office (see FOR FURTHER INFORMATION 
CONTACT).
    Implementation of recovery actions generally requires the 
participation of a broad range of partners, including other Federal 
agencies, States, Tribes, nongovernmental organizations, businesses, 
and private landowners. Examples of recovery actions include habitat 
restoration (e.g., restoration of native vegetation), research, captive 
propagation and reintroduction, and outreach and education. The 
recovery of many listed species cannot be accomplished solely on 
Federal lands because their range may occur primarily or solely on non-
Federal lands. To achieve recovery of these species requires 
cooperative conservation efforts on private, State, and Tribal lands.
    Once this species is listed, funding for recovery actions will be 
available from a variety of sources, including Federal budgets, State 
programs, and cost-share grants for non-Federal landowners, the 
academic community, and nongovernmental organizations. In addition, 
pursuant to section 6 of the Act, the State of Texas will be eligible 
for Federal funds to implement management actions that promote the 
protection or recovery of the prostrate milkweed. Information on our 
grant programs that are available to aid species recovery can be found 
at: https://www.fws.gov/service/financial-assistance.
    Please let us know if you are interested in participating in 
recovery efforts for this species. Additionally, we invite you to 
submit any new information on this species whenever it becomes 
available and any information you may have for recovery planning 
purposes (see FOR FURTHER INFORMATION CONTACT).
    Section 7(a) of the Act requires Federal agencies to evaluate their 
actions with respect to any species that is listed as an endangered or 
threatened species and with respect to its critical habitat, if any is 
designated. Regulations implementing this interagency cooperation 
provision of the Act are codified at 50 CFR part 402. Section 7(a)(2) 
of the Act requires Federal agencies to ensure that activities they 
authorize, fund, or carry out are not likely to jeopardize the 
continued existence of any endangered or threatened species or destroy 
or adversely modify its critical habitat. If a Federal action may 
affect a listed species or its critical habitat, the responsible 
Federal agency (action agency) must enter into consultation with us.
    Federal agency actions within the species' habitat that may require 
conference, consultation, or both as described in the preceding 
paragraph include management and any other landscape-altering 
activities on Federal lands administered by the U.S. Fish and Wildlife 
Service.
    The Act and its implementing regulations set forth a series of 
general prohibitions and exceptions that apply to endangered plants. 
The prohibitions of section 9(a)(2) of the Act, codified at 50 CFR 
17.61, make it illegal for any person subject to the jurisdiction of 
the United States to import or export; remove and reduce to possession 
from areas under Federal jurisdiction; maliciously damage or destroy on 
any such area; remove, cut, dig up, or damage or destroy on any other 
area in knowing violation of any law or regulation of any State or in 
the course of any violation of a State criminal trespass law; deliver, 
receive, carry, transport, or ship in interstate or foreign commerce, 
by any means whatsoever and in the course of a commercial activity; or 
sell or offer for sale in interstate or foreign commerce an endangered 
plant. Certain exceptions apply to employees of the Service, the 
National Marine Fisheries Service, other

[[Page 12582]]

Federal land management agencies, and State conservation agencies.
    We may issue permits to carry out otherwise prohibited activities 
involving endangered plants under certain circumstances. Regulations 
governing permits are codified at 50 CFR 17.62. With regard to 
endangered plants, a permit may be issued for scientific purposes or 
for enhancing the propagation or survival of the species. The statute 
also contains certain exemptions from the prohibitions, which are found 
in sections 9 and 10 of the Act.
    It is our policy, as published in the Federal Register on July 1, 
1994 (59 FR 34272), to identify to the maximum extent practicable at 
the time a species is listed, those activities that would or would not 
constitute a violation of section 9 of the Act. The intent of this 
policy is to increase public awareness of the effect of a final listing 
on proposed and ongoing activities within the range of the listed 
species. Based on the best available information, the following actions 
are unlikely to result in a violation of section 9, if these activities 
are carried out in accordance with existing regulations and permit 
requirements; this list is not comprehensive:
    (1) Normal agricultural and silvicultural practices, including 
herbicide and pesticide use, that are carried out in accordance with 
any existing regulations, permit and label requirements, and best 
management practices;
    (2) Normal residential landscaping activities on non-Federal lands; 
and
    (3) Recreational use with minimal ground disturbance.
    Based on the best available information, the following activities 
may potentially result in a violation of section 9 of the Act if they 
are not authorized in accordance with applicable law; this list is not 
comprehensive:
    (1) Unauthorized handling, removing, trampling, or collecting of 
prostrate milkweed on Federal land; and
    (2) Removing, cutting, digging up, or damaging or destroying 
prostrate milkweed in knowing violation of any law or regulation of the 
State of Texas or in the course of any violation of a State criminal 
trespass law.
    Questions regarding whether specific activities would constitute a 
violation of section 9 of the Act should be directed to the Texas 
Coastal Ecological Services Field Office (see FOR FURTHER INFORMATION 
CONTACT).

II. Critical Habitat

Background

    Although this critical habitat designation was proposed when the 
regulatory definition of habitat (85 FR 81411; December 16, 2020) and 
the 4(b)(2) exclusion regulations (85 FR 82376; December 18, 2020) were 
in place and in effect, those two regulations have been rescinded (87 
FR 37757; June 24, 2022 and 87 FR 43433; July 21, 2022) and no longer 
apply to any designations of critical habitat. Therefore, for this 
final rule designating critical habitat for the prostrate milkweed, we 
apply the regulations at 424.19 and the 2016 Joint Policy on 4(b)(2) 
exclusions (81 FR 7226; February 11, 2016).
    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. None of the situations 
identified at 50 CFR 424.12(a) for when designation of critical habitat 
would be not prudent or not determinable is present. We therefore are 
designating critical habitat for prostrate milkweed concurrently with 
listing it.
    Critical habitat is defined in section 3 of the Act as:
    (1) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical and biological features (PBFs)
    (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 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 Federal agencies 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 
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. Where a landowner requests Federal 
agency funding or authorization for an action that may affect a listed 
species or critical habitat, the Federal agency would be required to 
consult with the Service under section 7(a)(2) of the Act. However, 
even if the Service were to conclude that the proposed activity would 
likely 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 PBFs (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 PBFs 
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,

[[Page 12583]]

upon a determination that such areas are essential for the conservation 
of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards Under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658)), 
and our associated Information Quality Guidelines provide criteria, 
establish procedures, and provide guidance to ensure that our decisions 
are based on the best scientific data available. They require our 
biologists, to the extent consistent with the Act and with the use of 
the best scientific data available, to use primary and original sources 
of information as the basis for recommendations to designate critical 
habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information from the SSA report and information developed during the 
listing process for the species. Additional information sources may 
include any generalized conservation strategy, criteria, or outline 
that may have been developed for the species; the recovery plan for the 
species; articles in peer-reviewed journals; conservation plans 
developed by States and counties; scientific status surveys and 
studies; biological assessments; other unpublished materials; or 
experts' opinions or personal knowledge.
    Habitat is dynamic, and species may move from one area to another 
over time. We recognize that critical habitat designated at a 
particular point in time may not include all of the habitat areas that 
we may later determine are necessary for the recovery of the species. 
For these reasons, a critical habitat designation does not signal that 
habitat outside the designated area is unimportant or may not be needed 
for recovery of the species. Areas that are important to the 
conservation of the species, both inside and outside the critical 
habitat designation, will continue to be subject to: (1) Conservation 
actions implemented under section 7(a)(1) of the Act; (2) regulatory 
protections afforded by the requirement in section 7(a)(2) of the Act 
for Federal agencies to ensure their actions are not likely to 
jeopardize the continued existence of any endangered or threatened 
species; and (3) the prohibitions found in section 9 of the Act. 
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 this species. Similarly, critical 
habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans 
(HCPs), or other species conservation planning efforts if new 
information available at the time of these 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 PBFs 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 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.

Geological Substrate and Soils

    Prostrate milkweed grows in well-drained sandy soils of the 
Tamaulipan shrubland region of south Texas and northeast Mexico 
(Service 2020, pp. 22-26). In Starr and Zapata Counties, Texas, the 
soils of documented sites overlie Eocene and Oligocene sandstones and 
clays of the Laredo, Yegua, and Jackson geological formations (Stoeser 
et al. 2005, unpaginated). In some occupied sites, a stratum of 
indurated caliche may also be present; in south Texas, caliche refers 
to soil strata of precipitated calcium carbonate formed during the 
early Pliocene (Spearing 1998, pp. 258, 398; Baskin and Hulbert, Jr. 
2008, p. 93). Soil types of these occupied sites include deep eolian 
Hebbronville sands, Copita fine sandy loam, Brennan fine sandy loam, 
eroded Maverick soils, Catarina clay, and Zapata soils (USDA 1972, 
entire; USDA 2011, entire). Elevated levels of gypsum are present at 
some sites.
    The climate of the Tamaulipan shrubland region is subtropical and 
semi-arid. Much of the region's precipitation occurs during infrequent 
periods of heavy rainfall that interrupt prolonged spells of very hot, 
dry weather. Rainfall readily infiltrates into the well-drained sandy 
soils of prostrate milkweed habitats, but moisture does not persist 
long in these soils. Many occupied sites have underlying strata of 
sandstone; these barriers to root growth limit the establishment of 
trees and taller shrubs. The growth of many plant species is also 
limited by high soil gypsum concentrations in some occupied sites. The 
rapid drying of soil, impenetrable rock strata, and high gypsum are all 
factors that reduce competition from woody plants, grasses, and other 
herbaceous plants.
    Prostrate milkweed forms tubers underground that are able to 
persist in a dormant condition for one to several

[[Page 12584]]

years. The species responds very quickly to rainfall; the tubers sprout 
new stems that emerge, flower, and set seed in a matter of weeks, and 
the plants store carbohydrates, minerals, and water in tubers. Then the 
above-ground portions die back during hot, dry weather. Prostrate 
milkweed does not occur in areas of higher rainfall or where moisture 
persists longer in deeper silty or clayey soils. The species does not 
persist when occupied sites develop a dense shrub overstory or dense 
cover of grasses. We conclude that prostrate milkweed is endemic to 
sites where it escapes competition from other plants through its unique 
adaptation to ephemeral soil moisture, prolonged drought, and tolerance 
of high gypsum concentrations.
    Therefore, well-drained sandy soil overlying sandstone or indurated 
caliche strata is an essential physical feature of prostrate milkweed 
critical habitats. A high soil gypsum concentration contributes to the 
habitat suitability of some sites by reducing competition and is an 
essential physical feature.

Ecological Community

    Within the Tamaulipan shrubland ecological region, prostrate 
milkweed inhabits arid subtropical grasslands and shrub savannas. It 
requires an open canopy, where there is little or no shade from trees 
and shrubs, and relatively little competition from grasses and 
herbaceous plants; the estimated combined cover of woody plants, 
grasses, and herbaceous plants at a site in Zapata County was less than 
30 percent (Damude and Poole 1990, p. 16). It is likely that naturally 
occurring wildfires, in the past, maintained the relatively open 
structure of these plant communities (Scifres and Hamilton 1993, pp. 8-
21). We have observed an increased abundance of other Texas species of 
Asclepias, including antelope horns (A. asperula), Emory's milkweed (A. 
emoryi), zizotes milkweed (A. oenotheroides), and wand milkweed (A. 
viridiflora), during the first few years after sites have burned; this 
fire-following effect has been described for green milkweed (A. 
viridis) (Baum and Sharber 2012, entire). Prostrate milkweed, like 
other milkweeds, may also be stimulated to grow and flower after 
wildfires have reduced competition.
    Most Asclepias species require outcrossing for effective 
fertilization of flowers. All Asclepias species have highly specialized 
pollination mechanisms that require animal pollinators to carry pollen 
from one individual to another. Although the effective pollinators of 
prostrate milkweed have not been determined, these are likely to 
include large bees and wasps. For example, the closely related zizotes 
milkweed is effectively pollinated by very large wasps called tarantula 
hawks (Pepsis spp. and Hemipepsis spp.) (Service 2020, pp. 17, 35-36). 
Therefore, prostrate milkweed habitats must also support populations of 
large bees and wasps that, in turn, require abundant, diverse sources 
of pollen and nectar. Much like milkweeds, many pollen and nectar 
plants are fire followers that are most abundant in sites that burn 
periodically, but decline when fires are infrequent.
    Buffelgrass is an African grass that is widely planted in south 
Texas for livestock forage. Buffelgrass is highly invasive, and 
frequently displaces native grasses and herbaceous plants (Best 2009, 
pp. 310-311), including prostrate milkweed (Service 2020, pp. 39-40) 
and the pollen and nectar plants needed to support pollinator 
populations. The majority of prostrate milkweed plants have been 
observed in sites where buffelgrass is absent or at low densities 
(Eason 2019, pers. comm.; Strong 2019, pers. comm.). Prostrate milkweed 
requires an open canopy with less than 30 percent cover of native and 
nonnative grasses and herbaceous plants combined (Damude and Poole 
1990, p. 16); thus, assuming nonnative buffelgrass is more prevalent, 
we estimate that 20 percent or less cover of buffelgrass is at a low 
enough density for prostrate milkweed to survive. Therefore, prostrate 
milkweed habitats must also have less than 20 percent cover of 
buffelgrass for prostrate milkweed to have access to sufficient 
resources such as sunlight.
    In summary, the essential biological features of prostrate milkweed 
critical habitats are: (1) open savannas and grasslands of the 
Tamaulipan shrubland ecological region; (2) vegetation composition that 
includes abundant, diverse pollen and nectar plants and healthy 
populations of native bee and wasp species; and (3) less than 20 
percent cover of buffelgrass.

Summary of Essential Physical or Biological Features

    Additional information can be found in the SSA report (Service 
2020, available on https://www.regulations.gov under Docket No. FWS-R2-
ES-2021-0041). We have determined that the following PBFs are essential 
to the conservation of prostrate milkweed:
    (1) Well-drained sandy soil overlying strata of sandstone or 
indurated caliche;
    (2) High soil gypsum concentration;
    (3) Open savannas and grasslands of the Tamaulipan shrubland 
ecological region;
    (4) Vegetation composition that includes abundant, diverse pollen 
and nectar plants and healthy populations of native bee and wasp 
species; and
    (5) Less than 20 percent cover of buffelgrass.

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 features essential to the conservation of this species 
may require special management considerations or protection to reduce 
the following threats: nonnative, invasive grass; root-plowing and 
conversion of native vegetation to buffelgrass pasture; ROW 
construction and maintenance from energy development and road and 
utility construction; border security development and law enforcement 
activities; and small population sizes. Management activities that 
could ameliorate these threats include, but are not limited to: 
prescribed burning, grazing, and/or brush thinning; nonnative, invasive 
grass control; protection from activities that disturb the soil; and 
propagation and reintroduction of plants in restorable areas. There are 
a variety of ways to manage the land to address the threats facing 
prostrate milkweed.
    In summary, we find that the occupied areas we are designating as 
critical habitat contain the PBFs that are essential to the 
conservation of the species and that may require special management 
considerations or protection. Special management considerations or 
protection may be required of the Federal action agency to eliminate, 
or to reduce to negligible levels, the threats affecting the PBFs of 
each unit.

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

[[Page 12585]]

the geographical area occupied by the species to be considered for 
designation as critical habitat. We are not designating 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. While prostrate milkweed needs additional populations 
to reduce the likelihood of extinction in the future, we are not able 
to identify additional locations that may have a reasonable certainty 
of contributing to conservation at this time due to limited access to 
privately owned lands and information regarding lands that would be 
good candidates for introductions in the species' range. Accordingly, 
we cannot at this time identify unoccupied locations that are essential 
to the conservation of the species.
    We are designating lands as critical habitat that we have 
determined are occupied at the time of listing (i.e., currently 
occupied) and that contain one or more of the PBFs that are essential 
to support life-history processes of the species. Units are based on 
one or more of the PBFs being present to support prostrate milkweed's 
life-history processes. Some units contain all of the identified PBFs 
and support multiple life-history processes. Some units contain only 
some of the PBFs necessary to support the prostrate milkweed's 
particular use of that habitat.
    In summary, for areas within the geographic area occupied by the 
species at the time of listing, we delineated critical habitat unit 
boundaries using the following criteria. First, using ArcGIS software, 
we identified potential habitats in Starr and Zapata Counties that have 
the essential features of geology and soils described above. The 
geographic information we obtained about the known populations exists 
as: (1) vegetation surveys of entire tracts of land; (2) element 
occurrence (EO) polygons represented in the Texas Natural Diversity 
Database (Database); or (3) points and lines represented in the 
Database. We then adapted methods to delineate critical habitats for 
each type of geographic information.
    We delineated all the potential habitats that occur at the Arroyo 
Ramirez tract and the Arroyo Morteros tract of the Lower Rio Grande 
Valley NWR as critical habitat (Units 2 and 5). The Lower Rio Grande 
Valley NWR comprises several disconnected land parcels, rather than one 
big land area, and these parcels are referred to as ``tracts.'' The two 
tracts that are included in Units 2 and 5 are isolated areas of NWR 
land. These NWR tracts are managed for the conservation of native 
plants and animals, and we have conducted plant surveys and have 
extensive knowledge of habitat suitability of these tracts.
    Similarly, we delineated all the potential habitats that occur at a 
private ranch (Unit 6) that is managed for wildlife and plant 
conservation as critical habitat. The landowner has granted access for 
plant surveys and vegetation studies to researchers from the Texas 
Parks and Wildlife Department, academic institutions, and the Service. 
Two of the known populations are represented as polygons in the 
Database located in the ROWs of unpaved county roads in Starr County. 
We have no information about the land uses or habitat suitability of 
areas outside these polygons. We delineated all the potential habitats 
that occur within these polygons (Units 4 and 7) as critical habitat. 
Three of the known populations are represented as one or more points or 
lines in the Database located on privately owned land. We have no 
information about the land uses or habitat suitability of areas outside 
the points and lines. Because critical habitats must be areas, not 
points or lines, we delineated all areas of potential habitat within 50 
meters (m) (164 feet (ft)) from these points and lines as critical 
habitat units; we chose the 50-m distance because the Database also 
used a 50-m distance for most of these features to account for 
estimated geographic precision. To complete the delineations of 
critical habitat areas, we overlaid each critical habitat area 
described above on Digital Ortho-Quarter Quad aerial photographs to 
identify and exclude any portions of sites that consist of unvegetated 
roadbeds that are frequently driven and are maintained by road grading, 
as well as structures and other developed areas that do not contain the 
geological and soil substrates and vegetative cover that are essential 
PBFs.
    We did not include in this designation one historical observation 
that has only approximate location data and cannot be mapped. We also 
did not include any of the populations reported in the U.S. Highway 83 
ROW, all of which have declined since they were first reported. For 
example, part of EO 3 (Dolores) along U.S. Highway 83 had about 200 
individuals in 1988; four surveys conducted from 2009 to 2017 found 
from 0 to 3 individuals. The degree and frequency of soil disturbance 
in the ROWs of improved highways has caused almost complete replacement 
of the native plant community with introduced species, such as 
buffelgrass. Hence, the essential PBFs are no longer present along this 
improved highway ROW. For the same reasons, we did not include one site 
in the road bed of a Starr County park where the species was last 
observed in 1995.
    When determining 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 physical or 
biological features necessary for prostrate milkweed. 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 final rule have been excluded by 
text in the rule and are not designated as critical habitat. Therefore, 
a Federal action involving these lands 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.
    This final 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 Regulation Promulgation. We include more 
detailed information on the boundaries of the critical habitat 
designation in the preamble of this document. We will make the 
coordinates or plot points or both on which each map is based available 
to the public on https://www.regulations.gov at Docket No. FWS-R2-ES-
2021-0041 and on our internet site at https://www.fws.gov/office/texas-coastal-ecological-services.

Final Critical Habitat Designation

    We are designating eight units as critical habitat for prostrate 
milkweed. The critical habitat areas we describe below constitute our 
current best assessment of areas that meet the definition of critical 
habitat for prostrate milkweed. The eight areas we are designating as 
critical habitat units are all Database EOs: Unit 1 (EO 3), Unit 2 (EO 
10), Unit 3 (EO 11), Unit 4 (EO 12), Unit 5 (EO 15), Unit 6 (EO 16), 
Unit 7 (EO 17), and Unit 8 (EO 22). Table 2 shows the critical habitat 
units and the approximate area of each unit. All units are occupied.

[[Page 12586]]



                             Table 2--Critical Habitat Units for Prostrate Milkweed
                    [Area estimates reflect all land within critical habitat unit boundaries]
----------------------------------------------------------------------------------------------------------------
                                                                       Size of unit
          Critical habitat unit             Land ownership by type       in acres              Occupied?
                                                                        (hectares)
----------------------------------------------------------------------------------------------------------------
1 (EO 3)................................  County Road ROW and             10.5 (4.3)  Yes.
                                           Private.
2 (EO 10)...............................  Federal (Service).........     85.7 (34.7)  Yes.
3 (EO 11)...............................  Private...................       4.0 (1.6)  Yes.
4 (EO 12)...............................  County Road ROW...........       4.2 (1.7)  Yes.
5 (EO 15)...............................  Federal (Service).........     51.9 (21.0)  Yes.
6 (EO 16)...............................  County Road ROW and          484.3 (196.0)  Yes.
                                           Private.
7 (EO 17)...............................  County Road ROW and             19.4 (7.8)  Yes.
                                           Private.
8 (EO 22)...............................  Private...................       1.0 (0.4)  Yes.
                                                                     -------------------------------------------
    Total...............................  ..........................   661.0 (267.5)  ..........................
----------------------------------------------------------------------------------------------------------------
Note: Area sizes may not sum due to rounding.

    Below, we present brief descriptions of all units and reasons why 
they meet the definition of critical habitat for prostrate milkweed.

Unit 1: EO 3

    Unit 1 consists of six areas, totaling 10.5 acres (ac) (4.3 
hectares (ha)), east of U.S. Highway 83 in northwest Zapata County. 
This unit is on private land and unpaved county road ROWs. The unit is 
occupied by the species and contains PBFs 1, 3, and 4. Although we have 
no recent information on threats that affect this unit, we conclude 
that this unit is affected by invasive, nonnative grass (buffelgrass) 
and road maintenance operations. Therefore, special management 
considerations may be required to reduce invasion of nonnative species 
and impacts from ROW maintenance.

Unit 2: EO 10

    Unit 2 consists of 85.7 ac (34.7 ha) in the 699.4-acre Arroyo 
Ramirez tract of Lower Rio Grande Valley NWR. This unit is in 
southwestern Starr County adjacent to the Rio Grande on the U.S 
2012;Mexico border. The entire unit is on land owned and managed by the 
Service. The unit is occupied by the species and contains PBFs 1 and 4.
    In this final rule, the designated critical habitat in Unit 2 
reflects recently constructed border wall, which reduces the area 
meeting the definition of critical habitat in the unit. Specifically, 
this change results in a decrease of 19.7 ac (8.0 ha) of critical 
habitat from what we proposed for Unit 2 on February 15, 2022 (87 FR 
8509).
    This unit could be directly impacted by border security operations 
(i.e., drag strips), or indirectly impacted by channeling of runoff 
along the barrier during heavy rainfall, in addition to invasion of 
buffelgrass. Therefore, special management considerations may be 
required to mitigate impacts from border security operations and 
nonnative grass.

Unit 3: EO 11

    Unit 3 consists of three areas, totaling 4.0 ac (1.6 ha), on 
private land in southwestern Starr County. The unit is occupied by the 
species and contains PBFs 1, 2, and 4. We have no recent information on 
threats that affect this unit. Special management considerations may be 
required.

Unit 4: EO 12

    Unit 4 consists of 4.2 ac (1.7 ha) along an unpaved county road ROW 
in southwestern Starr County. This ROW supports a narrow strip of 
diverse native vegetation that has likely not been plowed, bulldozed, 
or graded. The unit is occupied by the species and contains all of the 
PBFs essential to the conservation of prostrate milkweed. This unit is 
affected by invasive, nonnative grass (buffelgrass) and maintenance and 
operation of the county road. Therefore, special management 
considerations may be required to reduce invasion of nonnative species.

Unit 5: EO 15

    Unit 5 consists of 51.9 ac (21.0 ha) in the 90.8-acre Arroyo 
Morteros tract of the Lower Rio Grande Valley NWR. This unit is in 
southwestern Starr County adjacent to the Rio Grande on the U.S. Mexico 
border. The entire unit is on land owned and managed by the Service. 
The unit is occupied by the species and contains all of the PBFs 
essential to the conservation of prostrate milkweed.
    In this final rule, the designated critical habitat in Unit 5 
reflects correction of a map projection error of the NWR tract 
boundary, which reduces the area of this unit. Specifically, this 
change results in a decrease of 10.6 ac (4.3 ha) of critical habitat 
from what we proposed for Unit 5 on February 15, 2022 (87 FR 8509).
    This unit could be directly impacted by border barrier construction 
and security operations (i.e., drag strips), or indirectly impacted by 
channeling of runoff along the barrier during heavy rainfall, in 
addition to invasion of buffelgrass. Therefore, special management 
considerations may be required to mitigate impacts from border security 
operations and nonnative grass.

Unit 6: EO 16

    Unit 6 consists of 484.3 ac (196.0 ha) entirely on the 488.5-acre 
private Martinez Ranch and along a county road ROW. This unit is in 
southern Starr County. The owner of the Martinez Ranch is a willing 
conservation partner in managing the property's native plants and 
wildlife. The unit is occupied by the species and contains all of the 
PBFs essential to the conservation of prostrate milkweed. This unit is 
affected by invasive, nonnative grass (buffelgrass). Therefore, special 
management considerations may be required to reduce invasion of 
nonnative species.

Unit 7: EO 17

    Unit 7 consists of 19.4 ac (7.8 ha) along both sides of an unpaved 
county road ROW and adjacent private land in western Starr County. This 
ROW supports a narrow strip of diverse native vegetation that has 
likely not been plowed, bulldozed, or graded. The unit is occupied by 
the species and contains PBFs 1, 3, 4, and 5. This unit is affected by 
invasive, nonnative grass (buffelgrass) and maintenance and operation 
of the county road. Therefore, special management considerations may be 
required to reduce invasion of nonnative species.

Unit 8: EO 22

    Unit 8 consists of 1.0 ac (0.4 ha) on private land in central 
Zapata County.

[[Page 12587]]

The unit is occupied by the species and contains PBFs 1, 3, and 4. 
Although we have no recent information about threats that affect this 
unit, we estimate that this unit is affected by invasive, nonnative 
grass (buffelgrass) and development and maintenance of oil and gas 
wells and utility corridors. Therefore, special management 
considerations may be required to reduce invasion of nonnative species 
and impacts from ROW construction and maintenance from energy 
development and road and utility construction.

Effects of Critical Habitat Designation

Section 7 Consultation

    Section 7(a)(2) of the Act requires Federal agencies, including the 
Service, to ensure that any action they fund, authorize, or carry out 
is not likely to jeopardize the continued existence of any endangered 
species or threatened species or result in the destruction or adverse 
modification of designated critical habitat of such species.
    We published a final rule revising the definition of destruction or 
adverse modification on August 27, 2019 (84 FR 44976). Destruction or 
adverse modification means a direct or indirect alteration that 
appreciably diminishes the value of critical habitat as a whole for the 
conservation of a listed species.
    If a Federal action may affect a listed species or its critical 
habitat, the responsible Federal agency (action agency) must enter into 
consultation with us. Examples of actions that are subject to the 
section 7 consultation process are actions on State, Tribal, local, or 
private lands that require a Federal permit (such as a permit from the 
U.S. Army Corps of Engineers under section 404 of the Clean Water Act 
(33 U.S.C. 1251 et seq.) or a permit from the Service under section 10 
of the Act) or that involve some other Federal action (such as funding 
from the Federal Highway Administration, Federal Aviation 
Administration, or the Federal Emergency Management Agency). Federal 
actions not affecting listed species or critical habitat--and actions 
on State, Tribal, local, or private lands that are not federally 
funded, authorized, or carried out by a Federal agency--do not require 
section 7 consultation.
    Compliance with the requirements of section 7(a)(2) is documented 
through our issuance of:
    (1) A concurrence letter for Federal actions that may affect, but 
are not likely to adversely affect, listed species or critical habitat; 
or
    (2) A biological opinion for Federal actions that may affect, and 
are likely to adversely affect, listed species or critical habitat.
    When we issue a biological opinion concluding that a project is 
likely to jeopardize the continued existence of a listed species and/or 
destroy or adversely modify critical habitat, we provide reasonable and 
prudent alternatives to the project, if any are identifiable, that 
would avoid the likelihood of jeopardy and/or destruction or adverse 
modification of critical habitat. We define ``reasonable and prudent 
alternatives'' (at 50 CFR 402.02) as alternative actions identified 
during consultation that:
    (1) Can be implemented in a manner consistent with the intended 
purpose of the action,
    (2) Can be implemented consistent with the scope of the Federal 
agency's legal authority and jurisdiction,
    (3) Are economically and technologically feasible, and
    (4) Would, in the Service Director's opinion, avoid the likelihood 
of jeopardizing the continued existence of the listed species and/or 
avoid the likelihood of destroying or adversely modifying critical 
habitat.
    Reasonable and prudent alternatives can vary from slight project 
modifications to extensive redesign or relocation of the project. Costs 
associated with implementing a reasonable and prudent alternative are 
similarly variable.
    Regulations at 50 CFR 402.16 set forth requirements for Federal 
agencies to reinitiate formal consultation on previously reviewed 
actions. These requirements apply when the Federal agency has retained 
discretionary involvement or control over the action (or the agency's 
discretionary involvement or control is authorized by law) and, 
subsequent to the previous consultation: (1) if the amount or extent of 
taking specified in the incidental take statement is exceeded; (2) if 
new information reveals effects of the action that may affect listed 
species or critical habitat in a manner or to an extent not previously 
considered; (3) if the identified action is subsequently modified in a 
manner that causes an effect to the listed species or critical habitat 
that was not considered in the biological opinion; or (4) if a new 
species is listed or critical habitat designated that may be affected 
by the identified action.
    In such situations, Federal agencies sometimes may need to request 
reinitiation of consultation with us, but Congress also enacted some 
exceptions in 2018 to the requirement to reinitiate consultation on 
certain land management plans on the basis of a new species listing or 
new designation of critical habitat that may be affected by the subject 
Federal action. See 2018 Consolidated Appropriations Act, Public Law 
115-141, Div, O, 132 Stat. 1059 (2018).

Application of the ``Adverse Modification'' Standard

    The key factor related to the destruction or adverse modification 
determination is whether implementation of the proposed Federal action 
directly or indirectly alters the designated critical habitat in a way 
that appreciably diminishes the value of the critical habitat as a 
whole for the conservation of the listed species. As discussed above, 
the role of critical habitat is to support PBFs essential to the 
conservation of a listed species and provide for the conservation of 
the species.
    Section 4(b)(8) of the Act requires us to briefly evaluate and 
describe, in any proposed or final regulation that designates critical 
habitat, activities involving a Federal action that may violate section 
7(a)(2) of the Act by destroying or adversely modifying such habitat, 
or that may be affected by such designation.
    Activities that we may, during a consultation under section 7(a)(2) 
of the Act, consider likely to destroy or adversely modify critical 
habitat include, but are not limited to:
    (1) Actions that would degrade or destroy native plant communities. 
Such activities could include, but are not limited to, building roads, 
clearing land for oil and gas exploration or other purposes, 
introducing and encouraging the spread of nonnative species (i.e., 
buffelgrass), and conducting border security operations. However, 
above-ground cutting or thinning of woody plants and prescribed burning 
are recommended management practices for conservation of prostrate 
milkweed and other native grasses and forbs, and would not destroy or 
adversely modify critical habitats.
    (2) Actions that would mechanically disturb the soil structure. 
Such activities could include, but are not limited to, bulldozing, 
root-plowing, ripping, excavating, or other mechanical operations that 
penetrate deep enough into the soil to cut or remove the tubers of 
prostrate milkweed.
    (3) Actions that would increase competition from woody plants or 
introduced grasses. Such activities could include, but are not limited 
to, intentional planting of introduced grass species, such as 
buffelgrass,

[[Page 12588]]

bermudagrass (Cynodon dactylon), or Old World bluestems (introduced 
species of Dichanthium and Bothriochloa).

Exemptions

Application of Section 4(a)(3) of the Act

    Section 4(a)(3)(B)(i) of the Act (16 U.S.C. 1533(a)(3)(B)(i)) 
provides that the Secretary shall not designate as critical habitat any 
lands or other geographical areas owned or controlled by the Department 
of Defense (DoD), or designated for its use, that are subject to an 
integrated natural resources management plan (INRMP) prepared under 
section 101 of the Sikes Act Improvement Act of 1997 (16 U.S.C. 670a), 
if the Secretary determines in writing that such plan provides a 
benefit to the species for which critical habitat is proposed for 
designation. There are no DoD lands with a completed INRMP within the 
final critical habitat designation.

Consideration of Impacts Under Section 4(b)(2) of the Act

    Section 4(b)(2) of the Act states that the Secretary shall 
designate and make revisions to critical habitat on the basis of the 
best available scientific data after taking into consideration the 
economic impact, national security impact, and any other relevant 
impact of specifying any particular area as critical habitat. The 
Secretary may exclude an area from critical habitat based on economic 
impacts, impacts on national security, or any other relevant impacts. 
Exclusion decisions are governed by the regulations at 50 CFR 424.19 
and the Policy Regarding Implementation of Section 4(b)(2) of the 
Endangered Species Act, 81 FR 7226 (February 11, 2016)) (2016 Policy), 
both of which were developed jointly with the National Marine Fisheries 
Service (NMFS). We also refer to a 2008 Department of the Interior 
Solicitor's opinion entitled, ``The Secretary's Authority to Exclude 
Areas from a Critical Habitat Designation under Section 4(b)(2) of the 
Endangered Species Act'' (M-37016). We explain each decision to exclude 
areas, as well as decisions not to exclude, to demonstrate that the 
decision is reasonable.
    The Secretary may exclude any particular area if she determines 
that the benefits of such exclusion outweigh the benefits of including 
such area as part of the critical habitat, unless she determines, based 
on the best scientific data available, that the failure to designate 
such area as critical habitat will result in the extinction of the 
species. In making the determination to exclude a particular area, the 
statute on its face, as well as the legislative history, are clear that 
the Secretary has broad discretion regarding which factor(s) to use and 
how much weight to give to any factor. In this final rule, we are not 
excluding any areas from critical habitat. We describe below the 
process that we undertook for deciding whether to exclude any areas 
taking into consideration each category of impacts and our analyses of 
the relevant impacts.

Exclusions Based on Economic Impacts

    Section 4(b)(2) of the Act and its implementing regulations require 
that we consider the economic impact that may result from a designation 
of critical habitat. In order to consider economic impacts, we prepared 
an incremental effects memorandum (IEM) and screening analysis which, 
together with our narrative and interpretation of effects, we consider 
our economic analysis of the critical habitat designation and related 
factors (IEc 2021, entire). The analysis, dated March 11, 2021, was 
made available for public review from February 15, 2022, through April 
18, 2022 (87 FR 8509). The economic analysis addressed probable 
economic impacts of critical habitat designation for prostrate 
milkweed. Following the close of the comment period, we reviewed and 
evaluated all information submitted during the comment period that may 
pertain to our consideration of the probable incremental economic 
impacts of this critical habitat designation. This final critical 
habitat designation is 30.3 ac (12.3 ha) less than the proposed 
critical habitat designation, and therefore we would expect the 
incremental costs to be the same or slightly less than previously 
estimated in the economic analysis. Additional information relevant to 
the probable incremental economic impacts of the critical habitat 
designation for prostrate milkweed is summarized below and available in 
the screening analysis for the prostrate milkweed (IEc 2021, entire), 
available at https://www.regulations.gov.
    The full description of the findings from the economic analysis are 
outlined in the proposed rule (87 FR 8509; February 15, 2022). The 
estimated incremental costs of the total proposed critical habitat 
designation for prostrate milkweed was found to be less than $37,800 
per year. Therefore, with the removal of 30.3 ac (12.3 ha) of critical 
habitat from this final critical habitat designation to reflect border 
wall construction in Unit 2 and the correction of the map projection 
for Unit 5, the annual administrative burden is very unlikely to reach 
$100 million, which is the threshold for a significant regulatory 
action under Executive Order (E.O.) 12866.
    As discussed above, we considered the economic impacts of the 
critical habitat designation, and the Secretary is not exercising her 
discretion to exclude any areas from this designation of critical 
habitat for the prostrate milkweed based on economic impacts.

Exclusions Based on Impacts on National Security and Homeland Security

    Section 4(a)(3)(B)(i) of the Act may not cover all DoD lands or 
areas that pose potential national-security concerns (e.g., a DoD 
installation that is in the process of revising its INRMP for a newly 
listed species or a species previously not covered). If a particular 
area is not covered under section 4(a)(3)(B)(i), then national-security 
or homeland-security concerns are not a factor in the process of 
determining what areas meet the definition of ``critical habitat.'' 
However, the Service must still consider impacts on national security, 
including homeland security, on those lands or areas not covered by 
section 4(a)(3)(B)(i), because section 4(b)(2) requires the Service to 
consider those impacts whenever it designates critical habitat. 
Accordingly, we will always consider for exclusion from the designation 
areas for which DoD, Department of Homeland Security (DHS), or another 
Federal agency has requested exclusion based on an assertion of 
national-security or homeland-security concerns. We did not receive any 
additional information during the public comment period for the 
proposed critical habitat designation from DoD, DHS, or any other 
Federal agency regarding impacts of the designation on national 
security or homeland security that would support excluding any specific 
areas from the final critical habitat designation under authority of 
section 4(b)(2) and our implementing regulations at 50 CFR 424.19. No 
lands within the designation of critical habitat for prostrate milkweed 
are owned or managed by DoD or DHS.
    We received a comment from the Office of the Attorney General of 
Texas regarding its concerns that including portions of the Texas 
border as critical habitat would impact national security by preventing 
Texas's efforts to address the border crisis. We coordinated with CBP 
in finalizing this rule to ensure appropriate collaboration in our 
national security and conservation efforts, and they did not request 
exclusion of the two units of critical habitat located along the border 
on the

[[Page 12589]]

basis of national security or homeland security concerns. As a result, 
we do not anticipate that there will be an impact on national security 
or homeland security. Accordingly, we evaluated the Office of the 
Attorney General of Texas's request for under the basis of other 
relevant impacts (see Exclusions Based on Other Relevant Impacts) 
below.

Exclusions Based on Other Relevant Impacts

    Under section 4(b)(2) of the Act, we consider any other relevant 
impacts, in addition to economic impacts and impacts on national 
security discussed above. To identify other relevant impacts that may 
affect the exclusion analysis, we consider a number of factors, 
including whether there are permitted conservation plans covering the 
species in the area--such as HCPs, SHAs, or CCAAs--or whether there are 
non-permitted conservation agreements and partnerships that may be 
impaired by designation of, or exclusion from, critical habitat. In 
addition, we look at whether Tribal conservation plans or partnerships, 
Tribal resources, or government-to-government relationships of the 
United States with Tribal entities may be affected by the designation. 
We also consider any State, local, social, or other impacts that might 
occur because of the designation.
Attorney General of Texas--Texas Border Lands
    We received a comment from the Attorney General of Texas requesting 
that areas along the U.S.-Mexico border in Texas be excluded from the 
final critical habitat designation for prostrate milkweed. This request 
involves Units 2 and 5, which are lands owned and managed by the 
Service as part of the Lower Rio Grande Valley NWR.
    The Attorney General of Texas' rationale for requesting the 
exclusion was that designating these lands along the U.S.-Mexico border 
in Texas would prevent Texas' effort to address the border crisis via 
implementing proven deterrence measures to protect its borders from 
illegal immigration, such as building a border barrier and engaging in 
border enforcement activities. In his comment, the Attorney General of 
Texas acknowledged the value in protecting species native to Texas and 
general conservation efforts, but stated that designating critical 
habitat must also account for potential implications to border 
security, and thus national security. The Attorney General of Texas 
discussed the increasing trend in the number of encounters with 
migrants at the border and organized crime, such as human and drug 
trafficking, and discussed the economic impact to ranchers from fence 
and gate damage.
    Additionally, the Attorney General of Texas commented that recent 
environmental analyses conducted by CBP determined that border 
enforcement activities, such as border barrier and road construction, 
are of minimal or no significance to prostrate milkweed, and thus 
designation of critical habitat is not needed to protect the species. 
The Attorney General of Texas writes that these actions by Texas to 
secure the border would reduce foot traffic by enforcing border 
security activities, thus actually benefiting surrounding vegetation, 
including prostrate milkweed. The comment concludes that the border 
crisis in Texas is resulting in increased costs to the State of Texas. 
The Attorney General of Texas concludes that designating critical 
habitat along the U.S.-Mexico border in Texas would prevent the State 
from implementing proven deterrence measures to protect its border.
    Prostrate milkweed occurs in two areas along the U.S.-Mexico border 
on tracts of land owned by the Lower Rio Grande Valley NWR: Arroyo 
Ramirez and Arroyo Morteros, Units 2 and 5 of critical habitat, 
respectively. An 11,086-foot-long border wall was constructed across 
the western and northern part of the Arroyo Ramirez tract, and the 
cleared construction area averages about 200 feet wide and is 46.7 
acres in area. The Arroyo Morteros tract does not currently have a 
border wall, but there was a road proposed for border security purposes 
that has not been constructed, despite the fact that the construction 
was waived from environmental review.
    As stated above, the lands in these two units are owned and managed 
by the Service. The Lower Rio Grande Valley NWR has many tracts of 
refuge land along the border. Service staff regularly collaborate with 
CBP to ensure that border security operations can occur without any 
impediments. The Real ID Act of 2005 granted authority to the DHS to 
override other Federal laws, including the Endangered Species Act, for 
the purpose of border security operations and infrastructure. 
Therefore, designating critical habitat along the border would not 
impact CBP's ability to engage in border security operations in these 
areas. Specifically, the listing and designation of critical habitat 
for prostrate milkweed will not preclude border wall construction or 
security operations. It is also unlikely that there will be future 
restrictions on CBP's border enforcement activities resulting from the 
ongoing requirements from designating critical habitat. We will 
continue to collaborate with DHS and CBP to ensure border security 
operations can still occur in areas designated as critical habitat for 
prostrate milkweed. The requirement to provide a reasonably specific 
justification of an incremental impact on national security that would 
result from the designation of that specific area as critical habitat 
on the basis of national-security or homeland-security impacts applies 
to Federal agencies, including DoD and DHS. We contacted CBP in 
developing this final critical habitat designation but did not receive 
a response. If such information is provided in the future, we will 
conduct a discretionary analysis.
    Further, our 2016 Policy (81 FR 7226; February 11, 2016) states 
that the Secretary may undertake a preliminary evaluation of any plans, 
partnerships, economic considerations, national-security 
considerations, or other relevant impacts identified after considering 
the impacts required by the first sentence of the Act's section 
4(b)(2). Following the preliminary evaluation, the Secretary may choose 
to enter into the discretionary 4(b)(2) exclusion analysis for any 
particular area (81 FR 7226; February 11, 2016). Here, we conducted a 
preliminary evaluation based on the comments we received from Texas, 
but, as set forth above, we have not determined that a full 
discretionary 4(b)(2) analysis is warranted at this time. Accordingly, 
we are not excluding the area from this final rule due to national 
security or any other basis.

Required Determinations

Regulatory Planning and Review (Executive Orders 12866 and 13563)

    Executive Order 12866 provides that the Office of Information and 
Regulatory Affairs (OIRA) in the Office of Management and Budget will 
review all significant rules. OIRA has determined that this rule is not 
significant.
    Executive Order 13563 reaffirms the principles of E.O. 12866 while 
calling for improvements in the nation's regulatory system to promote 
predictability, to reduce uncertainty, and to use the best, most 
innovative, and least burdensome tools for achieving regulatory ends. 
The executive order directs agencies to consider regulatory approaches 
that reduce burdens and maintain flexibility and freedom of choice for 
the public where these approaches are relevant, feasible, and 
consistent with regulatory objectives. E.O. 13563 emphasizes further 
that regulations must be based on the best available science and that

[[Page 12590]]

the rulemaking process must allow for public participation and an open 
exchange of ideas. We have developed this rule in a manner consistent 
with these requirements.

Regulatory Flexibility Act (5 U.S.C. 601 et seq.)

    Under the Regulatory Flexibility Act (RFA; 5 U.S.C. 601 et seq.), 
as amended by the Small Business Regulatory Enforcement Fairness Act of 
1996 (SBREFA; 5 U.S.C. 801 et seq.), whenever an agency is required to 
publish a notice of rulemaking for any proposed or final rule, it must 
prepare and make available for public comment a regulatory flexibility 
analysis that describes the effects of the rule on small entities 
(i.e., small businesses, small organizations, and small government 
jurisdictions). However, no regulatory flexibility analysis is required 
if the head of the agency certifies the rule will not have a 
significant economic impact on a substantial number of small entities. 
The SBREFA amended the RFA to require Federal agencies to provide a 
certification statement of the factual basis for certifying that the 
rule will not have a significant economic impact on a substantial 
number of small entities.
    According to the Small Business Administration, small entities 
include small organizations such as independent nonprofit 
organizations; small governmental jurisdictions, including school 
boards and city and town governments that serve fewer than 50,000 
residents; and small businesses (13 CFR 121.201). Small businesses 
include manufacturing and mining concerns with fewer than 500 
employees, wholesale trade entities with fewer than 100 employees, 
retail and service businesses with less than $5 million in annual 
sales, general and heavy construction businesses with less than $27.5 
million in annual business, special trade contractors doing less than 
$11.5 million in annual business, and agricultural businesses with 
annual sales less than $750,000. To determine if potential economic 
impacts to these small entities are significant, we considered the 
types of activities that might trigger regulatory impacts under this 
designation as well as types of project modifications that may result. 
In general, the term ``significant economic impact'' is meant to apply 
to a typical small business firm's business operations.
    Under the RFA, as amended, and following recent court decisions, 
Federal agencies are required to evaluate the potential incremental 
impacts of rulemaking on those entities directly regulated by the 
rulemaking itself; in other words, the RFA does not require agencies to 
evaluate the potential impacts to indirectly regulated entities. The 
regulatory mechanism through which critical habitat protections are 
realized is section 7 of the Act, which requires Federal agencies, in 
consultation with the Service, to ensure that any action authorized, 
funded, or carried out by the agency is not likely to destroy or 
adversely modify critical habitat. Therefore, under section 7, only 
Federal action agencies are directly subject to the specific regulatory 
requirement (avoiding destruction and adverse modification) imposed by 
critical habitat designation. Consequently, it is our position that 
only Federal action agencies will be directly regulated by this 
designation. There is no requirement under the RFA to evaluate the 
potential impacts to entities not directly regulated. Moreover, Federal 
agencies are not small entities. Therefore, because no small entities 
will be directly regulated by this rulemaking, we certify that this 
critical habitat designation will not have a significant economic 
impact on a substantial number of small entities.
    During the development of this final rule, we reviewed and 
evaluated all information submitted during the comment period on the 
February 15, 2022, proposed rule (87 FR 8509) that may pertain to our 
consideration of the probable incremental economic impacts of this 
critical habitat designation. Based on this information, we affirm our 
certification that this critical habitat designation will not have a 
significant economic impact on a substantial number of small entities, 
and a regulatory flexibility analysis is not required.

Energy Supply, Distribution, or Use--Executive Order 13211

    Executive Order 13211 (Actions Concerning Regulations That 
Significantly Affect Energy Supply, Distribution, or Use) requires 
agencies to prepare Statements of Energy Effects when undertaking 
certain actions. In our economic analysis, we did not find that this 
critical habitat designation will significantly affect energy supplies, 
distribution, or use. Therefore, this action is not a significant 
energy action, and no Statement of Energy Effects is required.

Unfunded Mandates Reform Act (2 U.S.C. 1501 et seq.)

    In accordance with the Unfunded Mandates Reform Act (2 U.S.C. 1501 
et seq.), we make the following finding:
    (1) This rule will not produce a Federal mandate. In general, a 
Federal mandate is a provision in legislation, statute, or regulation 
that would impose an enforceable duty upon State, local, or Tribal 
governments, or the private sector, and includes both ``Federal 
intergovernmental mandates'' and ``Federal private sector mandates.'' 
These terms are defined in 2 U.S.C. 658(5)-(7). ``Federal 
intergovernmental mandate'' includes a regulation that ``would impose 
an enforceable duty upon State, local, or Tribal governments'' with two 
exceptions. It excludes ``a condition of Federal assistance.'' It also 
excludes ``a duty arising from participation in a voluntary Federal 
program,'' unless the regulation ``relates to a then-existing Federal 
program under which $500,000,000 or more is provided annually to State, 
local, and Tribal governments under entitlement authority,'' if the 
provision would ``increase the stringency of conditions of assistance'' 
or ``place caps upon, or otherwise decrease, the Federal Government's 
responsibility to provide funding,'' and the State, local, or Tribal 
governments ``lack authority'' to adjust accordingly. At the time of 
enactment, these entitlement programs were: Medicaid; Aid to Families 
with Dependent Children work programs; Child Nutrition; Food Stamps; 
Social Services Block Grants; Vocational Rehabilitation State Grants; 
Foster Care, Adoption Assistance, and Independent Living; Family 
Support Welfare Services; and Child Support Enforcement. ``Federal 
private sector mandate'' includes a regulation that ``would impose an 
enforceable duty upon the private sector, except (i) a condition of 
Federal assistance or (ii) a duty arising from participation in a 
voluntary Federal program.''
    The designation of critical habitat does not impose a legally 
binding duty on non-Federal Government entities or private parties. 
Under the Act, the only regulatory effect is that Federal agencies must 
ensure that their actions do not destroy or adversely modify critical 
habitat under section 7. While non-Federal entities that receive 
Federal funding, assistance, or permits, or that otherwise require 
approval or authorization from a Federal agency for an action, may be 
indirectly impacted by the designation of critical habitat, the legally 
binding duty to avoid destruction or adverse modification of critical 
habitat rests squarely on the Federal agency. Furthermore, to the 
extent that non-Federal entities are indirectly impacted because they 
receive Federal assistance or participate

[[Page 12591]]

in a voluntary Federal aid program, the Unfunded Mandates Reform Act 
would not apply, nor would critical habitat shift the costs of the 
large entitlement programs listed above onto State governments.
    (2) We do not believe that this rule will significantly or uniquely 
affect small governments because it will not produce a Federal mandate 
of $100 million or greater in any year, that is, it is not a 
``significant regulatory action'' under the Unfunded Mandates Reform 
Act. The designation of critical habitat imposes no obligations on 
State or local governments. Therefore, a Small Government Agency Plan 
is not required.

Takings--Executive Order 12630

    In accordance with E.O. 12630 (Government Actions and Interference 
with Constitutionally Protected Private Property Rights), we have 
analyzed the potential takings implications of designating critical 
habitat for prostrate milkweed in a takings implications assessment. 
The Act does not authorize the Service to regulate private actions on 
private lands or confiscate private property as a result of critical 
habitat designation. Designation of critical habitat does not affect 
land ownership, or establish any closures, or restrictions on use of or 
access to the designated areas. Furthermore, the designation of 
critical habitat does not affect landowner actions that do not require 
Federal funding or permits, nor does it preclude development of habitat 
conservation programs or issuance of incidental take permits to permit 
actions that do require Federal funding or permits to go forward. 
However, Federal agencies are prohibited from carrying out, funding, or 
authorizing actions that would destroy or adversely modify critical 
habitat. Our takings implications assessment concludes that this 
designation of critical habitat does not pose significant takings 
implications for lands within or affected by the designation.

Federalism--Executive Order 13132

    In accordance with E.O. 13132 (Federalism), this rule does not have 
significant Federalism effects. A federalism summary impact statement 
is not required. In keeping with Department of the Interior and 
Department of Commerce policy, we requested information from, and 
coordinated development of this critical habitat designation with, 
appropriate State resource agencies. From a federalism perspective, the 
designation of critical habitat directly affects only the 
responsibilities of Federal agencies. The Act imposes no other duties 
with respect to critical habitat, either for States and local 
governments, or for anyone else. As a result, the rule does not have 
substantial direct effects either on the States, or on the relationship 
between the national government and the States, or on the distribution 
of powers and responsibilities among the various levels of government. 
The designation may have some benefit to these governments because the 
areas that contain the features essential to the conservation of the 
species are more clearly defined, and the PBFs of the habitat necessary 
for the conservation of the species are specifically identified. This 
information does not alter where and what federally sponsored 
activities may occur. However, it may assist State and local 
governments in long-range planning because they no longer have to wait 
for case-by-case section 7 consultations to occur.
    Where State and local governments require approval or authorization 
from a Federal agency for actions that may affect critical habitat, 
consultation under section 7(a)(2) of the Act will be required. While 
non-Federal entities that receive Federal funding, assistance, or 
permits, or that otherwise require approval or authorization from a 
Federal agency for an action, may be indirectly impacted by the 
designation of critical habitat, the legally binding duty to avoid 
destruction or adverse modification of critical habitat rests squarely 
on the Federal agency.

Civil Justice Reform--Executive Order 12988

    In accordance with Executive Order 12988 (Civil Justice Reform), 
the Office of the Solicitor has determined that the rule will not 
unduly burden the judicial system and that it meets the requirements of 
sections 3(a) and 3(b)(2) of the Order. We have designated critical 
habitat in accordance with the provisions of the Act. To assist the 
public in understanding the habitat needs of the species, this rule 
identifies the PBFs essential to the conservation of the species. The 
areas of designated critical habitat are presented on maps, and the 
rule provides several options for the interested public to obtain more 
detailed location information, if desired.

Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.)

    This rule does not contain information collection requirements, and 
a submission to the Office of Management and Budget (OMB) under the 
Paperwork Reduction Act of 1995 (44 U.S.C. 3501 et seq.) is not 
required. We may not conduct or sponsor and you are not required to 
respond to a collection of information unless it displays a currently 
valid OMB control number.

National Environmental Policy Act (42 U.S.C. 4321 et seq.)

    Regulations adopted pursuant to section 4(a) of the Act are exempt 
from the National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et 
seq.) and do not require an environmental analysis under NEPA. We 
published a notice outlining our reasons for this determination in the 
Federal Register on October 25, 1983 (48 FR 49244). This includes 
listing, delisting, and reclassification rules, as well as critical 
habitat designations. In a line of cases starting with Douglas County 
v. Babbitt, 48 F.3d 1495 (9th Cir. 1995), the courts have upheld this 
position.

Government-to-Government Relationship With Tribes

    In accordance with the President's memorandum of April 29, 1994 
(Government-to-Government Relations with Native American Tribal 
Governments; 59 FR 22951), Executive Order 13175 (Consultation and 
Coordination with Indian Tribal Governments), and the Department of the 
Interior's manual at 512 DM 2, we readily acknowledge our 
responsibility to communicate meaningfully with recognized Federal 
Tribes on a government-to-government basis. In accordance with 
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, 
Federal-Tribal Trust Responsibilities, and the Endangered Species Act), 
we readily acknowledge our responsibilities to work directly with 
Tribes in developing programs for healthy ecosystems, to acknowledge 
that Tribal lands are not subject to the same controls as Federal 
public lands, to remain sensitive to Indian culture, and to make 
information available to Tribes. We have determined that no Tribal 
lands fall within the boundaries of the critical habitat designation 
for the prostrate milkweed, so no Tribal lands will be affected by the 
designation.

References Cited

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

Authors

    The primary authors of this rule are the staff members of the U.S. 
Fish and Wildlife Service's Species Assessment

[[Page 12592]]

Team and the Austin and Texas Coastal Ecological Services Field 
Offices.

List of Subjects in 50 CFR Part 17

    Endangered and threatened species, Exports, Imports, Plants, 
Reporting and recordkeeping requirements, Transportation, Wildlife.

Regulation Promulgation

    Accordingly, we amend part 17, subchapter B of chapter I, title 50 
of the Code of Federal Regulations, as set forth below:

PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS

0
1. The authority citation for part 17 continues to read as follows:

    Authority:  16 U.S.C. 1361-1407; 1531-1544; and 4201-4245, 
unless otherwise noted.


0
2. In Sec.  17.12, amend paragraph (h) by adding an entry for 
``Asclepias prostrata'' to the List of Endangered and Threatened Plants 
in alphabetical order under Flowering Plants to read as follows:


Sec.  17.12  Endangered and threatened plants.

* * * * *
    (h) * * *

----------------------------------------------------------------------------------------------------------------
                                                                                              Listing citations
         Scientific name              Common name          Where listed          Status         and applicable
                                                                                                    rules
----------------------------------------------------------------------------------------------------------------
        Flowering Plants
 
                                                  * * * * * * *
Asclepias prostrata.............  Prostrate milkweed.  Wherever found.....               E   87 FR [Insert
                                                                                              Federal Register
                                                                                              page where the
                                                                                              document begins],
                                                                                              February 28, 2023;
                                                                                              50 CFR
                                                                                              17.96(a).\CH\
 
                                                  * * * * * * *
----------------------------------------------------------------------------------------------------------------


0
3. In Sec.  17.96, amend paragraph (a) by adding an entry for ``Family 
Apocynaceae: Asclepias prostrata (prostrate milkweed)'' after the entry 
for ``Family Apiaceae: Lomatium cookii (Cook's lomatium, Cook's desert 
parsley)'', to read as follows:


Sec.  17.96  Critical habitat--plants.

    (a) * * *
Family Apocynaceae: Asclepias prostrata (prostrate milkweed)
    (1) Critical habitat units are depicted for Starr and Zapata 
Counties, Texas, on the maps in this entry.
    (2) Within these areas, the physical or biological features 
essential to the conservation of Asclepias prostrata consist of the 
following components:
    (i) Well-drained sandy soil overlying strata of sandstone or 
indurated caliche;
    (ii) High soil gypsum concentration;
    (iii) Open savannas and grasslands of the Tamaulipan shrubland 
ecological region;
    (iv) Vegetation composition that includes abundant, diverse pollen 
and nectar plants and healthy populations of native bee and wasp 
species; and
    (v) Less than 20 percent cover of Pennisetum ciliare (buffelgrass).
    (3) Critical habitat does not include manmade structures (such as 
buildings, aqueducts, runways, roads, and other paved areas) and the 
land on which they are located existing within the legal boundaries on 
March 30, 2023.
    (4) Data layers defining map units were created using Texas Natural 
Diversity Database (2019-2020) survey data of the documented Asclepias 
prostrata locations in the United States to determine the geological 
formations and soil types they occupy.
    (i) We used the Esri ArcMap software to overlay the geographic 
coordinates of populations on a digitized map of Texas surface geology 
and a digitized soil survey map. We then clipped those areas of 
potential to lands that have documented populations of Asclepias 
prostrata.
    (ii) The maps in this entry, as modified by any accompanying 
regulatory text, establish the boundaries of the critical habitat 
designation. The coordinates or plot points or both on which each map 
is based are available to the public at the Service's internet site at 
https://www.fws.gov/office/texas-coastal-ecological-services, at 
https://www.regulations.gov at Docket No. FWS-R2-ES-2021-0041, and at 
the field office responsible for this designation. You may obtain field 
office location information by contacting one of the Service regional 
offices, the addresses of which are listed at 50 CFR 2.2.
    (5) Index map follows:

BILLING CODE 4333-15-P

[[Page 12593]]

Figure 1 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (5)
[GRAPHIC] [TIFF OMITTED] TR28FE23.000


[[Page 12594]]


    (6) Unit 1: Zapata County, Texas.
    (i) Unit 1 consists of 6 areas totaling 10.5 ac (4.3 ha) east of 
U.S. Highway 83 in northwest Zapata County. This unit is on private 
land and a county road right-of-way.
    (ii) Map of Unit 1 follows:

Figure 2 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (6)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.001


[[Page 12595]]


    (7) Unit 2: Starr County, Texas.
    (i) Unit 2 consists of 85.7 ac (34.7 ha) in the Arroyo Ramirez 
tract of Lower Rio Grande Valley National Wildlife Refuge. This unit is 
in southwestern Starr County adjacent to the Rio Grande on the U.S.-
Mexico border. The entire unit is on land owned and managed by the 
Service.
    (ii) Map of Unit 2 follows:

Figure 3 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (7)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.002


[[Page 12596]]


    (8) Unit 3: Starr County, Texas.
    (i) Unit 3 consists of 4.0 ac (1.6 ha) along both sides of a road 
right-of-way on private land in southern Starr County.
    (ii) Map of Unit 3 follows:

Figure 4 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (8)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.003


[[Page 12597]]


    (9) Unit 4: Starr County, Texas.
    (i) Unit 4 consists of 4.2 ac (1.7 ha) along the unpaved right-of-
way of Los Arrieros Loop, a county road in southwestern Starr County.
    (ii) Map of Unit 4 follows:

Figure 5 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (9)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.004

    (10) Unit 5: Starr County, Texas.
    (i) Unit 5 consists of 51.9 ac (21.0 ha) in the Arroyo Morteros 
tract of the Lower Rio Grande Valley National Wildlife Refuge. This 
unit is in western Starr County adjacent to the Rio Grande on the U.S.-
Mexico border. The entire unit is on land owned and managed by the 
Service.
    (ii) Map of Unit 5 follows:


[[Page 12598]]


Figure 6 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (10)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.005

    (11) Unit 6: Starr County, Texas.
    (i) Unit 6 consists of 484.3 ac (196.0 ha) entirely on privately 
owned land and the adjacent right-of-way of San

[[Page 12599]]

Julian Road. This unit is in western Starr County.
    (ii) Map of Unit 6 follows:

Figure 7 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (11)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.006

    (12) Unit 7: Starr County, Texas.
    (i) Unit 7 consists of 19.4 ac (7.8 ha) along both sides of a 
right-of-way and adjacent private land in western Starr County.

[[Page 12600]]

    (ii) Map of Unit 7 follows:

Figure 8 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (12)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.007

    (13) Unit 8: Zapata County, Texas.
    (i) Unit 8 consists of 1.0 ac (0.4 ha) on private land in central 
Zapata County.
    (ii) Map of Unit 8 follows:


[[Page 12601]]


Figure 9 to Family Apocynaceae: Asclepias prostrata (prostrate 
milkweed) paragraph (13)(ii)
[GRAPHIC] [TIFF OMITTED] TR28FE23.008


[[Page 12602]]


* * * * *

Wendi Weber,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. 2023-03656 Filed 2-27-23; 8:45 am]
BILLING CODE 4333-15-C