Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for the Northern Mexican Gartersnake and Narrow-Headed Gartersnake
| Published date | 28 April 2020 |
| Citation | 85 FR 23608 |
| Record Number | 2020-08069 |
| Section | Proposed rules |
| Court | Fish And Wildlife Service,Interior Department |
Federal Register, Volume 85 Issue 82 (Tuesday, April 28, 2020)
[Federal Register Volume 85, Number 82 (Tuesday, April 28, 2020)]
[Proposed Rules]
[Pages 23608-23668]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-08069]
[[Page 23607]]
Vol. 85
Tuesday,
No. 82
April 28, 2020
Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR 17
Endangered and Threatened Wildlife and Plants; Designation of Critical
Habitat for the Northern Mexican Gartersnake and Narrow-Headed
Gartersnake; Proposed Rule
Federal Register / Vol. 85 , No. 82 / Tuesday, April 28, 2020 /
Proposed Rules
[[Page 23608]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R2-ES-2020-0011; FF09E21000 FXES11110900000 201]
RIN 1018-BD96
Endangered and Threatened Wildlife and Plants; Designation of
Critical Habitat for the Northern Mexican Gartersnake and Narrow-Headed
Gartersnake
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Revised proposed rule; request for public comments.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), are revising
our proposed designation of critical habitat for the northern Mexican
gartersnake (Thamnophis eques megalops) and narrow-headed gartersnake
(Thamnophis rufipunctatus) under the Endangered Species Act, as amended
(Act). In total, approximately 27,784 acres (11,244 hectares) in La
Paz, Mohave, Yavapai, Gila, Cochise, Santa Cruz, and Pima Counties in
Arizona, and in Grant County in New Mexico, fall within the boundaries
of the revised proposed critical habitat designation for the northern
Mexican gartersnake; and 18,701 acres (7,568 hectares) in Greenlee,
Graham, Apache, Yavapai, Gila, and Coconino Counties in Arizona, as
well as in Grant, Hidalgo, and Catron Counties in New Mexico, fall
within the boundaries of the revised proposed critical habitat
designation for the narrow-headed gartersnake. We also announce the
availability of a draft economic analysis of the revised proposed
designation of critical habitat for northern Mexican and narrow-headed
gartersnakes. We request comments from all interested parties on this
revised proposed rule and the associated draft economic analysis.
Comments submitted on our July 10, 2013, proposed rule need not be
resubmitted as they will be fully considered in the preparation of the
final rule. If we finalize this rule as proposed, it would extend the
Act's protections to these species' critical habitat.
DATES: We will accept comments on this revised proposed rule or the
draft economic analysis that are received or postmarked on or before
June 29, 2020. Comments submitted electronically using the Federal
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59
p.m. Eastern Time on the closing date. We must receive requests for
public hearings, in writing, at the address shown in FOR FURTHER
INFORMATION CONTACT by June 12, 2020.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal:
http://www.regulations.gov. In the Search box, enter FWS-R2-ES-
2020-0011, which is the docket number for this rulemaking. Then, click
on the Search button. On the resulting page, in the Search panel on the
left side of the screen, under the Document Type heading, check the
Proposed Rule box to locate this document. You may submit a comment by
clicking on ``Comment Now!''
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: FWS-R2-ES-2020-0011, U.S. Fish and Wildlife Service,
MS: JAO/1N, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on http://www.regulations.gov. This
generally means that we will post any personal information you provide
us (see the Information Requested, below, for more information).
Availability of supporting materials: The draft economic analysis
is available at http://www.fws.gov/southwest/es/arizona/, at http://www.regulations.gov at Docket No. FWS-R2-ES-2020-0011, and at the
Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION
CONTACT).
For the critical habitat designation, the coordinates or plot
points or both from which the maps are generated are included in the
administrative record and are available at http://www.fws.gov/southwest/es/arizona, at http://www.regulations.gov under Docket No.
FWS-R2-ES-2020-0011 and at the Arizona Ecological Services Field Office
(see FOR FURTHER INFORMATION CONTACT). Any additional tools or
supporting information that we may develop for this critical habitat
designation will also be available at the Fish and Wildlife Service
website and Field Office set out above, and may also be included in the
preamble and/or at http://www.regulations.gov.
FOR FURTHER INFORMATION CONTACT: Jeff Humphry, Field Supervisor, U.S.
Fish and Wildlife Service, Arizona Ecological Services Field Office,
Fish and Wildlife Office, 9828 North 31st Ave #C3, Phoenix, AZ 85051-
2517; telephone 602-242-0210. Persons who use a telecommunications
device for the deaf (TDD), may call the Federal Relay Service at 800-
877-8339.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Critical habitat shall be
designated, to the maximum extent prudent and determinable, for any
species determined to be an endangered or threatened species under the
Act. Both gartersnakes are listed as threatened under the Act (79 FR
38678; July 8, 2014). Designations and revisions of critical habitat
can only be completed by issuing a rule.
What this document does. This is a revised proposed rule to
designate critical habitat for northern Mexican gartersnake and narrow-
headed gartersnake under the Act.
For reasons described later in this document, this revised proposed
rule reduces the proposed critical habitat designation from what we
proposed on July 10, 2013, as follows:
For the northern Mexican gartersnake, the proposed
designation is reduced from approximately 421,423 acres (170,544
hectares) to approximately 27,784 acres (11,244 hectares); and
For the narrow-headed gartersnake, the proposed
designation is reduced from approximately 210,189 acres (85,060
hectares) to approximately 18,701 acres (7,568 hectares).
The basis for our action. 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 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. 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.
Peer review. In accordance with our joint policy on peer review
published in the Federal Register on July 1, 1994 (59 FR 34270), and
our August 22, 2016, memorandum updating and clarifying
[[Page 23609]]
the role of peer review of listing actions under the Act, we sought the
expert opinions of eight independent specialists on the July 10, 2013,
proposed rule to ensure that our critical habitat proposal was based on
scientifically sound data, assumptions, and analyses. We received
responses from three of the peer reviewers. We reviewed all comments we
received from the peer reviewers for substantive issues and new
information regarding critical habitat for the two gartersnakes. Peer
reviewers substantive comments have been addressed or incorporated into
this revised proposed rule. Because we will consider all comments and
information we receive during the comment period, our final
determinations may differ from this proposal. Such final decisions
would be a logical outgrowth of this proposal, as long as we: (1) Base
the decisions on the best scientific and commercial data available
after considering all of the relevant factors; (2) do not rely on
factors Congress has not intended us to consider; and (3) articulate a
rational connection between the facts found and the conclusions made,
including why we changed our conclusion.
Information Requested
We intend that any final action resulting from this revised
proposed rule will be based on the best scientific and commercial data
available and be as accurate and as effective as possible. Therefore,
we request comments or information from other concerned government
agencies, Native American tribes, the scientific community, industry,
or any other interested party concerning this revised proposed rule. We
particularly seek comments concerning:
(1) The reasons why we should or should not designate habitat as
``critical habitat'' under section 4 of the Act (16 U.S.C. 1531 et
seq.), including information to inform the following factors that the
regulations identify as reasons why designation of critical habitat may
be not prudent:
(a) The species is threatened by taking, collecting, or other human
activity and identification of critical habitat can be expected to
increase the degree of such threat to the species;
(b) The present or threatened destruction, modification, or
curtailment of a species' habitat or range is not a threat to the
species, or threats to the species' habitat stem solely from causes
that cannot be addressed through management actions resulting from
consultations under section 7(a)(2) of the Act;
(c) Areas within the jurisdiction of the United States provide no
more than negligible conservation value, if any, for a species
occurring primarily outside the jurisdiction of the United States; or
(d) No areas meet the definition of critical habitat.
(2) Specific information on:
(a) The amount and distribution of northern Mexican or narrow-
headed gartersnake habitat;
(b) Which areas, that were occupied at the time of listing (2013)
and that contain the physical or biological features essential to the
conservation of these species, should be included in the designation
and why;
(c) What period of time should be used to ascertain occupancy at
time of listing (2013) and why, and whether or not data from 1998 to
the present should be used in this determination;
(d) Whether it is appropriate to use information from a long-term
dispersal study on neonate, juvenile, and adult age classes of the
Oregon gartersnake (Thamnophis atratus hydrophilus) in a free-flowing
stream environment in northern California (Welsh et al. 2010, entire)
as a surrogate for juvenile northern Mexican gartersnake and narrow-
headed gartersnake dispersal;
(e) Special management considerations or protection that may be
needed in critical habitat areas we are proposing, including managing
for the potential effects of climate change; and
(f) What areas not occupied at the time of listing are essential
for the conservation of these species and why. We particularly seek
comments regarding:
(i) Whether occupied areas are inadequate for the conservation of
the species; and
(ii) Specific information that informs the determination of whether
unoccupied areas will, with reasonable certainty, contribute to the
conservation of the species and contain at least one physical or
biological feature essential to the conservation of the species.
(3) Land use designations and current or planned activities in the
subject areas and their possible impacts on proposed critical habitat.
(4) Information on the projected and reasonably likely impacts of
climate change on the northern Mexican or narrow-headed gartersnake and
proposed critical habitat.
(5) Any probable economic, national security, or other relevant
impacts of designating any area that may be included in the final
designation, and the benefits of including or excluding areas that may
be impacted.
(6) Information on the extent to which the description of probable
economic impacts in the draft economic analysis is a reasonable
estimate of the likely economic impacts.
(7) Whether any specific areas we are proposing for critical
habitat designation should be considered for exclusion under section
4(b)(2) of the Act, and whether the benefits of potentially excluding
any specific area outweigh the benefits of including that area under
section 4(b)(2) of the Act, in particular for those lands discussed in
each critical habitat unit and in tables 3a and 3b, below.
(8) Whether we could improve or modify our approach to designating
critical habitat in any way to provide for greater public participation
and understanding, or to better accommodate public concerns and
comments.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include.
Please note that submissions merely stating support for, or
opposition to, the action under consideration without providing
supporting information, although noted, will not be considered in
making a determination, as section 4(b)(1)(A) of the Act directs that
determinations as to whether any species is an endangered or a
threatened species must be made ``solely on the basis of the best
scientific and commercial data available.''
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
If you submit information via http://www.regulations.gov, your
entire submission--including any personal identifying information--will
be posted on the website. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on http://www.regulations.gov.
Comments and materials we receive, as well as supporting
documentation we used in preparing this proposed rule, will be
available for public inspection on http://www.regulations.gov, or by
appointment, during normal business hours, at the U.S. Fish and
Wildlife Service, Arizona Ecological Services Field Office (see FOR
FURTHER INFORMATION CONTACT).
[[Page 23610]]
Public Hearing
Section 4(b)(5) of the Act provides for a public hearing on this
proposal, if requested. Requests must be received within 45 days after
the date of publication of this proposed rule in the Federal Register
(see DATES, above). Such requests must be sent to the address shown in
FOR FURTHER INFORMATION CONTACT. We will schedule a public hearing on
this proposal, if requested, and announce the date, time, and place of
the hearing, as well as how to obtain reasonable accommodations, in the
Federal Register and local newspapers at least 15 days before the
hearing. For the immediate future, we will provide these public
hearings using webinars that will be announced on the Service's
website, in addition to the Federal Register. The use of these virtual
public hearings is consistent with our regulation at 50 CFR
424.16(c)(3).
Previous Federal Actions
On July 10, 2013, we published in the Federal Register (78 FR
41550) a proposed rule to designate critical habitat for northern
Mexican gartersnake and narrow-headed gartersnake. In that proposed
rule, we proposed to designate approximately 421,423 acres (ac)
(170,544 hectares (ha)) as critical habitat in 14 units for the
northern Mexican gartersnake and 210,189 ac (85,060 ha) as critical
habitat in 6 units for the narrow-headed gartersnake. That proposal had
a 60-day comment period, ending September 9, 2013. We received
substantive comments during the comment period that have contributed to
the current revised proposed rule.
Background
It is our intent to discuss in this document only those topics
directly relevant to the designation of critical habitat for northern
Mexican gartersnake and narrow-headed gartersnake. For more information
on the two species, their corresponding habitats, and previous Federal
actions concerning the two species, refer to the proposed designation
of critical habitat published in the Federal Register on July 10, 2013
(78 FR 41550). The proposed rule is available online at http://www.regulations.gov (at Docket No. FWS-R2-ES-2020-0011) or from the
Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION
CONTACT).
Critical habitat is defined in section 3 of the Act as:
(1) The specific areas within the geographical area occupied by the
species, at the time it is listed in accordance with the Act, on which
are found those physical or biological features
(a) Essential to the conservation of the species, and
(b) Which may require special management considerations or
protection; and
(2) Specific areas outside the geographical area occupied by the
species at the time it is listed, upon a determination that such areas
are essential for the conservation of the species.
Our regulations at 50 CFR 424.02 define the geographical area
occupied by the species as an area that may generally be delineated
around species' occurrences, as determined by the Secretary of the
Interior (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. Designation also does not allow the government
or public to access private lands, nor does designation 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 result in
destruction or adverse modification of the critical habitat, the
Federal action agency and the landowner are not required to abandon the
proposed activity, or to restore or recover the species; instead, they
must implement ``reasonable and prudent alternatives'' to avoid
destruction or adverse modification of critical habitat.
Under the first prong of the Act's definition of critical habitat,
areas within the geographical area occupied by the species at the time
it was listed are included in a critical habitat designation if they
contain physical or biological features (1) which are essential to the
conservation of the species and (2) which may require special
management considerations or protection. For these areas, critical
habitat designations identify, to the extent known using the best
scientific and commercial data available, those physical or biological
features that are essential to the conservation of the species (such as
space, food, cover, and protected habitat). In identifying those
physical or biological features that occur in specific occupied areas,
we focus on the specific features that are essential to support the
life-history needs of the species, including, but not limited to, water
characteristics, soil type, geological features, 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.
Under the second prong of the Act's definition of critical habitat,
we can designate critical habitat in areas outside the geographical
area occupied by the species at the time it is listed, upon a
determination that such areas are essential for the conservation of the
species. When designating critical habitat, the Secretary will first
evaluate areas occupied by the species. The Secretary will only
consider unoccupied areas to be essential where a critical habitat
designation limited to geographical areas occupied by the species would
be inadequate to ensure the conservation of the species. In addition,
for an unoccupied area to be considered essential, the Secretary must
determine that there is a reasonable certainty both that the area will
contribute to the conservation of the
[[Page 23611]]
species and that the area contains one or more of those physical or
biological features essential to 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 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 Act's prohibitions on taking any individual of the
species, including taking caused by actions that affect habitat.
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.
Prudency Determination
Section 4(a)(3) of the Act, as amended, and implementing
regulations (50 CFR 424.12) require that, to the maximum extent prudent
and determinable, the Secretary shall designate critical habitat at the
time the species is determined to be an endangered or threatened
species. Our regulations (50 CFR 424.12(a)(1)) state that the Secretary
may, but is not required to, determine that a designation would not be
prudent in the following circumstances:
(i) The species is threatened by taking or other human activity and
identification of critical habitat can be expected to increase the
degree of such threat to the species;
(ii) The present or threatened destruction, modification, or
curtailment of a species' habitat or range is not a threat to the
species, or threats to the species' habitat stem solely from causes
that cannot be addressed through management actions resulting from
consultations under section 7(a)(2) of the Act;
(iii) Areas within the jurisdiction of the United States provide no
more than negligible conservation value, if any, for a species
occurring primarily outside the jurisdiction of the United States;
(iv) No areas meet the definition of critical habitat; or
(v) The Secretary otherwise determines that designation of critical
habitat would not be prudent based on the best scientific data
available.
As discussed in the final listing rule published on July 8, 2014
(79 FR 38678), there is currently no imminent threat of take attributed
to collection or vandalism identified under Factor B for these species,
and identification and mapping of critical habitat is not expected to
initiate any such threat. In our proposed listing rule for the northern
Mexican gartersnake and narrow-headed gartersnake (78 FR 41500; July
10, 2013), we determined that the present or threatened destruction,
modification, or curtailment of habitat or range is a threat to these
species and that those threats in some way can be addressed by section
7(a)(2) consultation measures. The species occurs wholly in the
jurisdiction of the United States, and we are able to identify areas
that meet the definition of critical habitat. Therefore, because none
of the circumstances enumerated in our regulations at 50 CFR
424.12(a)(1) has been met and because there are no other circumstances
the Secretary has identified for which this designation of critical
habitat would be not prudent, we have determined that the designation
of critical habitat is prudent for these species.
Critical Habitat Determinability
Having determined that designation is prudent, under section
4(a)(3) of the Act we must find whether critical habitat for the
Mexican gartersnake and narrow-headed gartersnake is determinable. Our
regulations at 50 CFR 424.12(a)(2) state that critical habitat is not
determinable when one or both of the following situations exist:
(i) Data sufficient to perform required analyses are lacking, or
(ii) The biological needs of the species are not sufficiently well
known to identify any area that meets the definition of ``critical
habitat.''
When critical habitat is not determinable, the Act allows the
Service an additional year to publish a critical habitat designation
(16 U.S.C. 1533(b)(6)(C)(ii)).
We reviewed the available information pertaining to the biological
needs of these species and habitat characteristics where these species
are located. This and other information represent the best scientific
and commercial data available and led us to conclude that the
designation of critical habitat is determinable for the Mexican
gartersnake and narrow-headed gartersnake.
Changes From Previously Proposed Critical Habitat
In this document, we are revising our proposed critical habitat
designations for the northern Mexican gartersnake and narrow-headed
gartersnake (78 FR 41550; July 10, 2013). We based these revisions on
information we received during the comment period on the July 10, 2013,
proposed rule, as well as on relevant scientific research conducted
after the publication of that proposed rule. After the publication of
the proposed rule, we found that there was
[[Page 23612]]
substantial scientific disagreement in the criteria we used to define
what areas were occupied at the time of listing for each species, and
the criteria we used to identify the lateral extent of critical habitat
boundaries. We also received additional information including locations
of each species at the time of listing, and the biological needs and
corresponding habitat characteristics of each species. We also note
that we no longer use primary constituent elements (PCEs) to identify
areas as critical habitat. The Service eliminated primary constituent
elements due to redundancy with the physical or biological features
(PBFs). This change in terminology is in accordance with a February 11,
2016 (81 FR 7414), rule to implement changes to the regulations for
designating critical habitat. We used the comments and additional
information to revise: (1) The PBFs that are essential to the
conservation of the species and which may require special management
considerations or protection under the Act, (2) the criteria used to
define the areas occupied at the time of listing for each species, and
(3) the criteria used to identify critical habitat boundaries. We then
apply the revised PBFs and identification criteria for each gartersnake
species along with additional information we received regarding where
these PBFs exist on the landscape to determine the geographic extent of
each critical habitat unit. Finally, we provide clarification of some
of the terms we used to define critical habitat for each species.
Primary Constituent Elements
Background
In accordance with section 3(5)(A)(i) of the Act and regulations at
50 CFR 424.12(b), in determining which areas we will designate as
critical habitat from within the geographical area occupied by the
species at the time of listing, we consider the physical or biological
features that are essential to the conservation of the species and that
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, alkali 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, the Service 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.
Previous Proposed Rule's Primary Constituent Elements
As stated above, we now use only PBFs that are essential to the
conservation of the species to describe critical habitat. We have
modified the PCEs from the previous critical habitat rule, which are
now PBFs in this rule. For your convenience, we are providing the PCEs
from the previous proposed critical habitat rule for you to compare the
changes.
The northern Mexican gartersnake's previous PCEs were:
(1) Aquatic or riparian habitat that includes:
a. Perennial or spatially intermittent streams of low to moderate
gradient that possess appropriate amounts of in-channel pools, off-
channel pools, or backwater habitat, and that possess a natural,
unregulated flow regime that allows for periodic flooding or, if flows
are modified or regulated, a flow regime that allows for adequate river
functions, such as flows capable of processing sediment loads; or
b. Lentic wetlands such as livestock tanks, springs, and cienegas;
and
c. Shoreline habitat with adequate organic and natural inorganic
structural complexity to allow for thermoregulation, gestation,
shelter, protection from predators, and foraging opportunities (e.g.,
boulders, rocks, organic debris such as downed trees or logs, debris
jams, small mammal burrows, or leaf litter); and
d. Aquatic habitat with characteristics that support a native
amphibian prey base, such as salinities less than 5 parts per thousand,
pH greater than or equal to 5.6, and pollutants absent or minimally
present at levels that do not affect survival of any age class of the
northern Mexican gartersnake or the maintenance of prey populations.
(2) Adequate terrestrial space (600 feet (ft) (182.9 meter (m))
lateral extent to either side of bankfull stage) adjacent to designated
stream systems with sufficient natural structural characteristics to
support life-history functions such as gestation, immigration,
emigration, and brumation (extended inactivity).
(3) A prey base consisting of viable populations of native
amphibian and native fish species.
(4) An absence of nonnative fish species of the families
Centrarchidae and Ictaluridae, bullfrogs (Lithobates catesbeianus),
and/or crayfish (Orconectes virilis, Procambarus clarki, etc.), or
occurrence of these nonnative species at low enough levels such that
recruitment of northern Mexican gartersnakes and maintenance of viable
native fish or soft-rayed, nonnative fish populations (prey) is still
occurring.
The narrow-headed gartersnake's previous PCEs were:
(1) Stream habitat, which includes:
a. Perennial or spatially intermittent streams with sand, cobble,
and boulder substrate and low or moderate amounts of fine sediment and
substrate embeddedness, and that possess appropriate amounts of pool,
riffle, and run habitat to sustain native fish populations;
b. A natural, unregulated flow regime that allows for periodic
flooding or, if flows are modified or regulated, a flow regime that
allows for adequate river functions, such as flows capable of
processing sediment loads;
c. Shoreline habitat with adequate organic and natural inorganic
structural complexity (e.g., boulders, cobble bars, vegetation, and
organic debris such as downed trees or logs, debris jams), with
appropriate amounts of shrub- and sapling-sized plants to allow for
[[Page 23613]]
thermoregulation, gestation, shelter, protection from predators, and
foraging opportunities; and
d. Aquatic habitat with no pollutants or, if pollutants are
present, levels that do not affect survival of any age class of the
narrow-headed gartersnake or the maintenance of prey populations.
(2) Adequate terrestrial space (600 ft (182.9 m) lateral extent to
either side of bankfull stage) adjacent to designated stream systems
with sufficient natural structural characteristics to support life-
history functions such as gestation, immigration, emigration, and
brumation.
(3) A prey base consisting of viable populations of native fish
species or soft-rayed, nonnative fish species.
(4) An absence of nonnative fish species of the families
Centrarchidae and Ictaluridae, bullfrogs (Lithobates catesbeianus),
and/or crayfish (Orconectes virilis, Procambarus clarki, etc.), or
occurrence of these nonnative species at low enough levels such that
recruitment of narrow-headed gartersnakes and maintenance of viable
native fish or soft-rayed, nonnative fish populations (prey) is still
occurring.
Stream Flow
In the July 10, 2013, proposed rule (78 FR 41550) under PCE 1 for
each species we use the terms ``perennial'' and ``spatially
intermittent,'' but we did not include a definition of perennial or
spatially intermittent flow.
In this revised proposed rule, we are defining the terms perennial,
spatially intermittent, and ephemeral as related to stream flow in PBF
1 for each gartersnake species. We are clarifying the spectrum of
stream flow regimes that provide stream habitat for each gartersnake
species based on stream flow definitions in Levick et al. (2008, p. 6)
and Stromberg et al. (2009, p. 330). A perennial stream or portion of a
stream is defined as having surface flow continuously year round,
except for infrequent periods of severe drought (Levick et al. 2008, p.
6). An intermittent stream is a stream where portions flow continuously
only at certain time of the year (Levick et al. 2008, p. 6). An
intermittent stream flows when it receives water from a spring, a
ground-water source, or a surface source (such as melting snow [i.e.,
seasonal]). During the dry seasons, frequently compounded by high
evapotranspiration of watershed vegetation, the ground water table may
drop below the elevation of the streambed, causing surface flow to
cease or reduce to a series of separate pools or short areas of flow
(Gordon et al. 2004, p. 51). An ephemeral stream is usually dry except
for brief periods immediately following precipitation, and its channel
is at all times above the groundwater table (Levick et al. 2008, p. 6).
In the range of each gartersnake species, many streams have reaches
with year-round water that are separated by intermittent or ephemeral
reaches of flow, as a result of differences in geology along the
stream. This variation of flow along a stream is common enough in the
Southwest that hydrologists use the terms ``interrupted,'' ``perennial
interrupted,'' or ``spatially intermittent'' to describe the spatial
segmentation of a dryland stream into reaches that are perennial,
intermittent, or ephemeral (Levick et al. 2008, p. 6; Stromberg et al.
2009, p. 330; Stromberg et al. 2013, p. 413). A stream that is
interrupted, perennially interrupted, or spatially intermittent has
perennial flow occurring in areas with shallow bedrock or high
hydraulic connectivity to regional aquifers, and ephemeral to
intermittent flow occurring in areas with deeper alluvial basins or
greater distance from the headwaters (Stromberg et al. 2009, p. 330).
The spatial patterning of wet and dry reaches on spatially intermittent
streams changes through time in response to climatic fluctuations and
to human modifications of the landscape (Stromberg et al. 2009, p.
331). In the remainder of this document, we use the terms
``perennial,'' ``spatially intermittent,'' and ``ephemeral'' in
accordance with the above definitions.
For northern Mexican gartersnake, streams that have perennial or
spatially intermittent flow can provide stream habitat for the species.
Ephemeral reaches of streams can serve as habitat for northern Mexican
gartersnakes, and are included in critical habitat as a separate PBF
(#7) if such reaches are between perennial sections of a stream that
were occupied at the time of listing. Streams that have ephemeral flow
over their entire length do not usually provide habitat for the
northern Mexican gartersnake, but are considered critical habitat when
they may serve as corridors between perennial streams and lentic
aquatic habitats including springs, cienegas, and natural or
constructed ponds (livestock tanks) that were occupied at the time of
listing.
For narrow-headed gartersnake, streams that have perennial flow or
limited spatially intermittent flow that is primarily perennial provide
stream habitat for the species. Narrow-headed gartersnakes have been
documented in pools and shallow portions of an intermittent flow reach
of the Blue River with wet areas separated by dry segments of 0.6 to
1.2 miles (1 to 2 kilometers (km)) in length (Cotten et al. 2017, p.
687). The wetted areas where gartersnakes were detected also had
abundant native prey of the narrow-headed gartersnake, indicating that
these areas may provide greater foraging opportunities during low flow
periods (Cotten et al. 2017, p. 687). However, ephemeral reaches of
streams do not provide habitat for narrow-headed gartersnakes. Within
the range of the narrow-headed gartersnake, perennial streams become
ephemeral as they approach their headwaters. However, narrow-headed
gartersnakes have not been found in these ephemeral reaches because
their fish prey base is likely absent and there is no upstream
perennial habitat, so the ephemeral reaches do not provide
connectivity.
Hydrologic Processes
In the previous proposed critical habitat rule, hydrologic
processes of a stream were captured in PCE 1 as part of a component of
aquatic habitat: ``[aquatic habitat that possesses] a natural,
unregulated flow regime that allows for periodic flooding or, if flows
are modified or regulated, a flow regime that allows for adequate river
functions, such as flows capable of processing sediment loads.'' These
processes are not the aquatic habitat or terrestrial habitat components
themselves, but the flow regime and physical hydrologic and geomorphic
connection that create and maintain a stream channel and continuously
redefine the boundary between aquatic and riparian habitat used by both
gartersnake species.
Both gartersnake species are dependent on terrestrial and aquatic
habitat for all of their life-history functions, so it is important
that hydrologic processes are present to maintain both the terrestrial
and aquatic components of habitat for both gartersnake species.
Therefore, we established a PBF (#2) for hydrological processes that is
separate from the aquatic and terrestrial habitat PBF (#1).
Lentic Wetlands
For northern Mexican gartersnake, we removed lentic wetlands
included in PCE 1 of the previous proposed rule and created a separate
PBF (#6) that includes the aquatic and terrestrial components of these
habitats.
Shoreline Habitat
In the previous proposed rule, shoreline habitat is included in PCE
1. For northern Mexican gartersnake, PCE 1 was ``aquatic or riparian
habitat'' and for the narrow-headed gartersnake it was ``stream
habitat.'' For both gartersnakes, we defined shoreline
[[Page 23614]]
habitat as areas having ``adequate organic and inorganic structural
complexity'' with examples such as boulders, rocks, and organic debris
for thermoregulation, gestation, shelter, protection from predators,
and foraging opportunities.
In this revised proposed rule, we are no longer including the term
``shoreline habitat,'' because shorelines fluctuate and can include
both terrestrial and aquatic habitat features used by either
gartersnake species. Instead, a component of PBF 1 focuses on the
organic and natural inorganic structural features important to each
gartersnake species that fall within the stream channel that
encompasses a fluctuating shoreline.
Water Quality
In the July 10, 2013, proposed rule, for the northern Mexican
gartersnake under PCE 1, we state: ``Aquatic habitat with
characteristics that support a native amphibian prey base, such as
salinities less than 5 parts per thousand, pH greater than or equal to
5.6, and pollutants absent or minimally present at levels that do not
affect survival of any age class of the northern Mexican gartersnake or
the maintenance of prey populations'' (78 FR 41550, July 10, 2013, p.
78 FR 41584). In that proposed rule, for the narrow-headed gartersnake
under PCE 1, we state: ``Aquatic habitat with no pollutants or, if
pollutants are present, levels that do not affect survival of any age
class of the narrow-headed gartersnake or the maintenance of prey
populations'' (78 FR 41550, July 10, 2013, p. 78 FR 41601).
In this revised proposed rule, we are removing the specific
salinity and pH requirement for habitat characteristics that support a
native amphibian prey base for the northern Mexican gartersnake. As
mentioned in the July 10, 2013, proposed rule, while native leopard
frogs can be the primary prey base for adult northern Mexican
gartersnakes in some areas, these gartersnakes feed on a variety of
organisms that do not necessarily require the salinity and pH specified
in the PCE (78 FR 41550, July 10, 2013, pp. 78 FR 41553-41554). Because
we do not have salinity and pH values needed for the variety of aquatic
organisms that the different age classes of northern Mexican
gartersnakes eat, we are making this PBF more general. We did not make
substantive changes to the relevant PBF component for narrow-headed
gartersnake.
Prey Base
In the July 10, 2013, proposed rule, we described a wholly native
prey base of amphibians and fish for the northern Mexican gartersnake
in PCE 3, but in PCE 4, we state that nonnative fish are also prey for
the species. In the discussion of PBFs, we noted that northern Mexican
gartersnakes consume primarily amphibians and fishes, but that
occasional invertebrates and other vertebrate taxa may be eaten
opportunistically (78 FR 41550, July 10, 2013, p. 78 FR 41554) and that
the success of northern Mexican gartersnake populations is, in some
cases, tied to nonnative prey species consisting of larval and juvenile
bullfrogs. We did not include these other taxa and bullfrogs in the
PCEs because they are either relatively rare in the diet (in the case
of invertebrates and other vertebrates) or in the case of bullfrogs,
the adult frogs prey voraciously on gartersnake, and so despite the
fact that the snakes eat the juveniles, the presence of bullfrogs
indicates that the habitat is degraded.
We received additional information regarding the prey base of
northern Mexican gartersnake. Additional research confirms that in some
areas where native aquatic prey species are not available, viable
populations of northern Mexican gartersnakes likely rely on bullfrogs
and nonnative, soft-rayed and potentially spiny-rayed fish as a primary
food source (Emmons et al. 2016, pp. 556-557; Emmons and Nowak 2016a,
p. 44; Emmons and Nowak 2013, pp. 6, 15; Lashway 2012, p. 7). In other
areas where native ranid frogs are no longer present, we have
additional information to support that northern Mexican gartersnakes
consume other anurans (frogs and toads), small mammals, lizards, and
invertebrate species (Caldwell 2014, p. 1; d'Orgeix et al. 2013, p.
214; Emmons and Nowak 2016b, p. 9; Manjarriez et al. 2017, table 1).
In this revised proposed rule, for northern Mexican gartersnake, we
are removing the requirement for a wholly native prey base and
including the additional prey species described above in PBF 3. We also
used ``anurans'' (frogs and toads) instead of ``amphibians'' to more
accurately describe the gartersnake's primary prey. We do not make
substantive changes to PBF 3 for narrow-headed gartersnake.
Primary Constituent Elements/Critical Habitat Boundaries
Terrestrial Space Along Streams
In the previous proposed rule, PCE 2 for both gartersnakes included
``[a]dequate terrestrial space (600 ft (182.9 m) lateral extent to
either side of bankfull stage) adjacent to designated stream systems
with sufficient structural characteristics to support life-history
functions such as gestation, immigration, emigration, and brumation
[extended inactivity]'' (78 FR 41550, July 10, 2013, pp. 78 FR 41584
and 78 FR 41601). In the discussion of the PBFs and PCEs, we stated
that the northern Mexican gartersnake has been found up to 330 ft (100
m) away from permanent water (Rosen and Schwalbe 1988, p. 27), and the
narrow-headed gartersnake has been found up to 650 ft (200 m) from
water (Nowak 2006, pp. 19-21; 78 FR 41550, July 10, 2013, p. 78 FR
41557). We then state that ``[b]ased on the literature, we expect the
majority of terrestrial activity for both species occurs within 600 ft
(182.9 m) of permanent water in lotic habitat'' and that ``we believe a
600-ft (182.9-m) lateral extent to either side of bankfull stage will
sufficiently protect the majority of important terrestrial habitat;
provide brumation, gestation, and dispersal opportunities; and reduce
the impacts of high flow events, thereby providing adequate protection
to proposed critical habitat areas'' (78 FR 41550, July 10, 2013, p. 78
FR 41557). We go on to say that we determined 600-ft (182.9-m) lateral
extent from bankfull width for four biological reasons, including
maintaining the biological integrity and natural dynamics of the river
system and associated riparian habitat, nutrient recharge, general
aquatic habitat values, and providing adequate space for normal
gartersnake behaviors.
We received numerous comments and additional scientific information
regarding our definition of adequate terrestrial space for the two
gartersnakes in two general categories. First, using a single distance
of 600 ft (182.9 m) lateral extent from bankfull stage for both
gartersnake species includes areas outside the area typically used by
each gartersnake species and can include areas that do not have any of
the PBFs essential to the conservation of each species, especially in
higher order streams (Nowak 2006, pp. 19-20; Jennings and Christman
2012, pp. 8-12; Emmons and Nowak 2016a, p. 30; Myrand et al. 2017 p.
36). Second, using ``bankfull width'' as a measurement point for the
lateral extent of critical habitat is difficult to determine on the
ground as evidenced by our lack of mapping it as such in the July 10,
2013, proposed rule. Instead, we mapped critical habitat as a 1,200-ft
(366-m) polygon surrounding the centerline of a stream (78 FR 41550,
July 10, 2013, pp. 78 FR 41585, 78 FR 41601). We discuss both issues
below.
At the time of the publication of the July 10, 2013, proposed rule,
most of the
[[Page 23615]]
information we had on locations of both gartersnake species was from
studies where traps were set within water to capture gartersnakes and
then gartersnakes were subsequently released. This survey method does
not provide information on how these species use terrestrial habitat.
Nowak et al. (2006, entire), the study we referenced in our July 10,
2013, proposed rule, was the first study that used radio-telemetered
narrow-headed gartersnakes to look at habitat use. This study only
reported an individual narrow-headed gartersnake moving in a straight-
line distance of 650 ft (200 m) from water location, which we used to
inform lateral extent of critical habitat for both gartersnake species
because this was the best available information. However, since the
publication of the 2013 proposed rule, E. Nowak (2015) provided the
Service a correct interpretation of her telemetry data for this
individual and for the other narrow-headed gartersnakes recorded in
this study. Nowak clarified that the narrow-headed gartersnake was
found on a steep slope approximately 390 ft (150 m) above a stream in a
narrow canyon in a brumation site (Nowak 2006, p. 17). Nowak further
clarified that other narrow-headed gartersnakes were recorded using
brumation sites on the steep slope, reporting horizontal distances from
brumation sites to stream centerline between 276 and 328 ft (84 and 100
m). Nowak (2006, pp. 19-20) also reported at least five other
individual narrow-headed gartersnakes overwintering at brumation sites
not on steep slopes at 66 to 98 ft (20 to 30 m) from water. The
important difference in the distance from the stream is dependent on
the adjacent terrestrial topography. If the topography is steep slopes,
then the gartersnake is found farther from the stream, but this
additional distance is vertical, not horizontal, from the stream bank.
Since we published the 2013 proposed rule, researchers have
completed additional telemetry studies for each gartersnake species
that provide information on how each gartersnake species uses
terrestrial habitat (Jennings and Christman 2012; Boyarski et al. 2015;
Emmons and Nowak 2016a; Myrand et al. 2017; Sprague 2017; Nowak et al.
2019). For northern Mexican gartersnake, telemetry studies indicate
home ranges of individuals ranging from 1.7 acres (0.7 ha) at a highly
modified lentic site to 47.0 acres (19.04 ha) along a spatially
intermittent stream (Boyarski et al. 2015, p. 12; Emmons and Nowak
2016a, pp. 27-28; Nowak et al. 2019, p. 31). Maximum longitudinal
length within these home ranges varied from approximately 148 ft (45 m)
at the lentic site to 2,736 ft (834 m) along the spatially intermittent
stream (Boyarski et al. 2015, p. 12; Emmons and Nowak 2016a, pp. 27-28;
Nowak et al. 2019, p. 31). Mean distance to water of northern Mexican
gartersnake locations ranged from 3.87 to 312.5 ft (1.18 to 95.25 m)
along Tonto Creek in north-central Arizona (Nowak et al. 2019, p. 40).
These studies of northern Mexican gartersnake indicate that this
species overwinters in rodent burrows, cavities below boulders and rock
fields, and below debris piles located 1.6 ft (0.5 m) to approximately
558 ft (170 m) from the water's edge (Boyarski et al. 2015, p. 8;
Emmons and Nowak 2016a, p. 30; Myrand et al. 2017, p. 21). Brumation
sites were located an average of 129 ft (39.27 m) from the water's edge
in two different areas along the Verde River in Arizona (Emmons and
Nowak 2016a, p. 30). Nowak et al. (2019, p. 36) reported brumation
sites for 14 northern Mexican gartersnakes that ranged from 2 to 1,257
ft (0.7 to 383 m) from the water's edge along the Tonto River in
Arizona. Overwintering of seven gartersnakes at brumation sites was
also recorded within 230 ft (70 m) of ponds, and one gartersnake
overwintered at a site approximately 1,115 ft (350 m) from a pond
(Boyarski et al. 2015, pp. 8, 11).
For narrow-headed gartersnake, telemetry studies in New Mexico on
the Tularosa River, Gila River, and Whitewater Creek found individuals
an average of 58.7 ft (17.9 m) from water, with a maximum distance of
285 ft (87 m) across four different sites on the three streams with a
sample size of 69 individuals (Jennings and Chirstman 2012, pp. 9-10).
Researchers found most snakes within 3.28 ft (1 m) of the water's edge
(Jennings and Christman 2012, pp. 9-10). Narrow-headed gartersnakes
were found with lowest average distance of 22.7 ft (6.9 m) during the
dry season of 2010, and highest average distance of 88.3 ft (26.9 m)
during the wet season in 2010 (Jennings and Chirstman 2012, pp. 9-10).
Although, Nowak (2006, p. 19) reported that the maximum distance moved
by one individual was 650 ft (200 m) from water on a steep hillside in
a narrow canyon, she also reported that during the active season, she
most often found individuals outside of water under boulders, small
rocks, and broken concrete slabs located less than 328 ft (100 m) from
the water's edge within the floodplain of Oak Creek and West Fork Oak
Creek, Arizona.
Based on a review of this new information, clarification of Nowak's
data, and comments we received, it is likely that 600 ft (182.9 m) does
not accurately capture the lateral extent of terrestrial habitat used
by either species. Consequently, we have modified the lateral extent
boundary of critical habitat for both species. For northern Mexican
gartersnake, we are defining the lateral extent to include the wetland
or riparian zone adjacent to a stream or lentic water body, whichever
is greater. Delineating based on riparian zone rather than delineating
a set distance more accurately captures the foraging habitat used by
the northern Mexican gartersnake. As described above in this section
and under ``Hydrologic Processes,'' most northern Mexican gartersnake
detections ranged from in water in the stream channel up to meadows or
woodlands within the floodplain at the limit of the riparian zone. We
are defining the riparian zone as the strip of vegetation along a
stream that is of distinct composition and density from the surrounding
uplands, or the area between the stream channel and the upland
terrestrial ecosystem (Levick et al. 2008, pp. 6, 47). Although
northern Mexican gartersnakes have been found in a variety of
vegetation types within this riparian zone (i.e., grasses, shrubs, and
wetland plants), the underlying characteristic of this habitat needed
by the gartersnake appears to be dense vegetation or other natural
structural components that provide cover for the species. Size of the
riparian zone and composition of plants within the riparian zone varies
widely across the range of northern Mexican gartersnake. The width of
critical habitat for northern Mexican gartersnake along streams varies
from approximately 50 to 7,000 ft (15 to 2,134 m). Because the width of
wetland and riparian zone varies along and among streams, and some
streams have little to no riparian habitat but have wetland habitat
that includes some terrestrial components, delineating these areas
rather than delineating a set distance from the stream channel better
captures the needed habitat for the northern Mexican gartersnake.
For narrow-headed gartersnake, we have modified the lateral extent
boundary of critical habitat to include aquatic and terrestrial
features within 89 ft (27 m) of the active channel of a stream. This
distance captures the greatest average distance moved from the water
during the wet season on the Tularosa River in New Mexico from a 3-year
study with a sample size of 69 individuals at two different sites
(Jennings and Christman 2012, p. 12). This is the largest study to
date.
In addition, we have modified the delineation of where terrestrial
habitat
[[Page 23616]]
begins. We chose to use the active channel instead of bankfull width
because the active channel effectively defines a river or stream as a
feature on the landscape (Mersel and Lichvar 2014, pp. 11-12). The
active channel is established and maintained by flows that occur with
some regularity (several times per year to several times per decade),
but not by very rare and extremely high flood events. The outer limits
of the active channel can generally be defined by three primary
indicators that together form a discernable mark on the landscape: A
topographic break in slope, change in vegetation characteristics, and
change in sediment characteristics (Mersel and Lichvar 2014, pp. 13-
14). The active channel is often a fairly obvious and easy feature to
identify in the field, allowing for rapid and consistent identification
(Mersel and Lichvar 2014, p. 14). Further, the active channel can be
consistently recognized by the public.
These changes in determining lateral extent from streams have
reduced the proposed critical habitat designation by 3,458 ac (1,399
ha), or less than 1 percent, of the area included in the July 10, 2013,
proposed rule for critical habitat for northern Mexican gartersnake,
and 41,927 ac (16,967 ha), or 20 percent, of the area included in that
proposed rule for critical habitat for narrow-headed gartersnake (see
tables 1a and 1b, below).
In addition, we are no longer including terrestrial space as a
separate PBF, but are including both terrestrial and aquatic features
that make up a stream in a single PBF (PBF 1) that more accurately
captures the habitat requirements essential to each gartersnake
species.
Overland Areas for Northern Mexican Gartersnake
In the July 10, 2013, proposed rule, for northern Mexican
gartersnake, 5 of the 14 critical habitat units included additional
terrestrial space beyond the 600-ft (182.9-m) lateral extent from
bankfull stage of streams (overland areas or terrestrial space). In the
discussion of space for individual and population growth for normal
behavior under PBFs, we state that ``records for northern Mexican
gartersnakes from semi-remote livestock tanks and spring sources
suggest the species moves across the local landscape as part of its
foraging ecology,'' (78 FR 41550, July 10, 2013, p. 78 FR 41554), and
we cite observations by Drummond and Marcias-Garcia (1983, pp. 24, 35)
of northern Mexican gartersnakes wandering hundreds of meters away from
water, as well as Rosen and Schwalbe (1988, p. 27) observing a northern
Mexican gartersnake 330 ft (100 m) away from permanent water. We
described these areas as overland areas or terrestrial space between
springs, seeps, streams, and stock tanks. We did not include these
areas in a PCE, but we included them in the proposed designation of
critical habitat. Upland areas that are distant from riparian habitat
that the snakes use for foraging may be used while moving between
habitats, but specific habitat attributes in these areas that are
essential to the snakes have not been identified. In determining which
areas we will designate as critical habitat from within the
geographical area occupied by the species at the time of listing, the
Act directs us to consider the physical or biological features (or PCEs
under our previous regulations) that are essential to the conservation
of the species and that may require special management considerations
or protection. A common characteristic of these overland areas was the
presence of natural or constructed livestock ponds within a grassland
landscape in southern Arizona, although we did not define or discuss
the scope of this grassland landscape in the July 10, 2013, proposed
rule. We did not know how northern Mexican gartersnakes used the
grassland landscape in between water features, so we used property and
watershed boundaries to delineate large landscapes that encompassed the
features that the species may use. We used a U.S. Geological Survey
(USGS) Hydrological Unit Code (HUC) level 10 watershed boundary to
delineate the Upper Santa Cruz River Subbasin Unit. We used property
ownership boundaries to delineate the following units and subunits:
Buenos Aires National Wildlife Refuge Unit, Las Cienegas National
Conservation Area Subunit and Cienega Creek Natural Preserve Subunit in
the Cienega Creek Subbasin Unit, Appleton-Whittell Research Ranch
Subunit and Canelo Hills Cienega Preserve Subunit in the Babocomari
River Subbasin Unit, and San Bernardino National Wildlife Refuge Unit.
While property boundaries can delineate individual land management
prescriptions and affect the likelihood for species persistence,
property boundaries themselves are not linked to the PBFs that are
essential to the conservation of northern Mexican gartersnake, where
more accurate mapping methods are available, they should be used as an
alternative to property boundaries. These overland areas encompassed
290,620 acres (47,441 ha) in the previous proposed rule, but only
12,745 acres (5,158 ha) had water bodies within them that contained PCE
1 and PCE 2, and were considered occupied at the time of listing. In
other words, 96 percent of these lands included in critical habitat did
not have PCEs for northern Mexican gartersnake as defined in the July
10, 2013, proposed rule.
Upon further inspection of all known locations of the species, no
northern Mexican gartersnakes have been detected in the aforementioned
overland areas in southern Arizona outside of stream floodplains. These
eight lentic sites occupied at the time of listing, including natural
and constructed ponds, all fall within a stream floodplain, although
some of these streams are ephemeral. Data are still lacking to explain
how the species moves through the overland areas between perennial or
intermittent aquatic features, but we used our re-assessment of
gartersnake locations in relation to stream floodplains, along with
additional information obtained since the publication of the July 10,
2013, proposed rule, to refine the definition of terrestrial space used
by the species. There is new information about how northern Mexican
gartersnakes exploit seasonal amphibian prey species in ephemeral
waters during the rainy season when prey is abundant within these
grassland landscapes in southern Arizona (d'Orgeix et al. 2013, entire;
Caldwell 2014, entire). After the first heavy rains of the monsoon
season in 2012, northern Mexican gartersnakes were found foraging on
seasonal amphibian prey (spadefood (Spea multiplicata)) and basking at
the bases of Sacaton grass (Sporobolus wrightii) in and around a ponded
area within an ephemeral section of the floodplain in O'Donnell Canyon.
These northern Mexican gartersnakes were 0.75 miles (1.2 km) overland
and 1.49 miles (2.3 km) along O'Donnell Canyon upstream of the closest
known population of northern Mexican gartersnakes at Finley Tank
(d'Orgeix 2013, p. 214). Caldwell (2014, p. 1) also found northern
Mexican gartersnakes in wetted ephemeral habitat within the Cienega
Creek floodplain: One in an off-channel marsh, and one in pool of water
on a road that also contained spadefoot larva and metamorphs. We also
have updated information on telemetered snakes moving in other
terrestrial habitats along stream channels in northern Arizona (Emmons
and Nowak 2013, entire; Emmons and Nowak 2016a, entire; Myrand et al.
2017, entire), as described earlier. This research has also
[[Page 23617]]
shown that when northern Mexican gartersnakes were surface active in
habitats with perennial stream flow in northern Arizona, they were
observed outside of water concealed under dense vegetative most of the
time. While we do not have similar information for gartersnakes in
grassland habitats, ephemeral channels in southern Arizona usually have
more vegetative cover than the surrounding uplands, so we can deduce
that it is more likely that gartersnakes are using these more densely
vegetated areas that provide more cover to successfully move between
aquatic sites in these grasslands. Based on this information, we are
not including the overland terrestrial space between springs, seeps,
streams, and stock tanks. In this revised proposed rule, we are
including the springs, seeps, streams, and stock tanks and the
ephemeral drainages that connect these wetlands to perennial streams.
The resulting proposed critical habitat better represents our current
understanding of the life history of the northern Mexican gartersnake
and the habitat characteristics that facilitate its life-history
functions. Consequently, no units or subunits include overland
grassland areas, and all areas considered occupied under this revised
proposed rule are adjusted in size to appropriately reflect the PBFs
(see table 1a, below).
The removal of overland terrestrial space in these large grasslands
has reduced the proposed critical habitat designation for northern
Mexican gartersnake by 285,837 ac (115,674 ha), or 68 percent, of the
area included in the July 10, 2013, proposed rule.
Elevation
In the July 10, 2013, proposed rule, we erroneously included some
areas that are not within the elevation range of narrow-headed
gartersnake, including portions of the West Fork Gila River, Black
Canyon, Iron Creek, Diamond Creek, and Whitewater Creek.
In this revised proposed rule, we add the elevation range of each
corresponding gartersnake species as a PBF to capture the range of
where each species has been documented and exclude the areas that are
outside the elevation ranges where the species occur. This reduces the
proposed critical habitat designation by 2,320 ac (939 ha), or 1
percent, of the area included in the July 10, 2013, proposed rule for
critical habitat for narrow-headed gartersnake (see table 1b, below).
Changes to Criteria Used To Identify Critical Habitat
Occupancy Records
On July 10, 2013, we published proposed rules to list both
gartersnake species (78 FR 41500) and to designate critical habitat for
both gartersnake species (78 FR 41550). On July 8, 2014, we published a
final rule (79 FR 38678) listing both species.
In the proposed rule to designate critical habitat (78 FR 41550;
July 10, 2013), we considered an entire stream as occupied at the time
of listing for each corresponding gartersnake if it was within the
historical range of the species, contained aquatic and terrestrial
components of habitat defined by PCE 1 and PCE 2, had at least one
record of the species dated 1980 or later, and had at least one native
prey species present (78 FR 41550, July 10, 2013, p. 78 FR 41556). For
the northern Mexican gartersnake, we also considered large overland
areas (grasslands) within specific land ownership or watershed as
occupied if they met the above criteria. We have reconsidered the use
the criteria of one record of the species dated 1980 or later as a
proxy for what was occupied at the time of listing. We received
comments that using records dated 1980 or later to determine which
streams are occupied at the time of listing is inconsistent with
definitions we used to define the status of the northern Mexican
gartersnake in prior Service status assessment documents, that our
approach is not supported by the scientific literature, and that low
gartersnake detection probabilities do not justify a broad historical
approach to designate critical habitat. Thus, in this revised proposed
rule, we take a more accurate approach (described below) to conclude
what areas were likely occupied at the time of listing in 2014.
For northern Mexican gartersnake, the definition of occupancy we
used to determine critical habitat in the July 10, 2013, proposed rule
is significantly different from the criteria that we used to define
what areas we considered the northern Mexican gartersnake extant or
extirpated in other previous Service documents. In the 2006 and 2008
12-month findings (71 FR 56228, September 26, 2006; and 73 FR 71788,
November 25, 2008, respectively), as well as in updates to the
``Species Assessment and Listing Priority Form'' described in our
annual candidate notices of review (see 73 FR 75176, December 10, 2008;
74 FR 57804, November 9, 2009; 75 FR 69222, November 10, 2010; 76 FR
66370, October 26, 2011), ``extant'' was defined as areas where the
species is expected to reliably occur in appropriate habitat as
supported by museum records or recent, reliable observations. Based on
this definition, only 42 percent of the total area considered occupied
at the time of listing by the species in the July 10, 2013, proposed
critical habitat designation was considered extant from 2006 to 2011.
From 2006-2011, the Service defined ``extirpated'' as that there have
been no individuals reported for a decade or longer at a site within
the historical distribution of the species, despite survey efforts, and
there is no expectation of natural recovery at the site due to the
presence of known or strongly suspected causes of extirpation.
Furthermore, the Service defined ``unknown'' as the species occurred
based on museum records (mostly historically) but access is restricted,
or survey data unavailable or insufficient, or where threats could
preclude occupancy. Of the total area considered occupied by the
species in the July 10, 2013, proposed critical habitat designation, 16
percent would have been considered extirpated, 23 percent would have
been considered unknown, and 19 percent would have had no status based
on the 2006-2011 definitions of status for northern Mexican
gartersnake. In the July 10, 2013, proposed listing rule (78 FR 41500),
we changed how we defined status to correspond with our definition of
``occupied'' in the July 10, 2013, proposed critical habitat rule (78
FR 41550). The most significant change in those 2013 publications was
that we considered a gartersnake species extant in an area if it had
been reported in an area in the past 33 years regardless of negative
survey efforts or threats precluding occupancy. We justified using
records of each species from the 1980s to determine that an area was
occupied at the time of listing by stating that ``both species of
gartersnake are cryptic, secretive, difficult to detect, quick to
escape underwater, and capable of persisting in low or very low
population densities that make positive detections nearly impossible in
structurally complex habitat'' (78 FR 41550, July 10, 2013, p. 78 FR
41556). For narrow-headed gartersnake, we had no previous Service
documents that addressed occupancy of the species.
For this revised proposed rule, we reassessed occupancy at the time
of listing for each gartersnake by reviewing all records for each
gartersnake that we used in the July 10, 2013, proposed critical
habitat rule in conjunction with expected survivorship of each species,
subsequent surveys in areas that had no
[[Page 23618]]
detection of the corresponding gartersnake species, and changes in
threats that may have prevented occupancy at time of listing.
Understanding longevity of a species can inform how long we can
reasonably expect a species is still extant in an area, regardless of
detection probability. The oldest estimated northern Mexican
gartersnake is between 14 and 16 years old, although growth rate
calculations are still preliminary (M. Ryan 2020). The longest years
between recaptures from these mark-recapture studies is 9 years (M.
Ryan 2020, pers. comm.). Narrow-headed gartersnakes may live up to 10
years or longer in the wild (Rosen and Schwalbe 1988, p. 38). An
individual narrow-headed gartersnake captured in the wild as an adult
was kept in captivity for 11 years; and estimated to be 16 years old
(M. Ryan 2020). Based on this information, we estimate maximum
longevity for each gartersnake species is 15 years, so that it is
reasonable to conclude that a gartersnake detected in 1998 or later
represents a population that could still be present at the time of
proposed listing in 2013, depending on the extent of threats in the
area. Although it is possible that gartersnakes are still extant in
areas where they were detected only during the 1980s, we have
determined that the best available information reflecting occupancy at
the time of listing supports a more recent date of records since 1998.
In the July 10, 2013, proposed critical habitat rule, 8 percent of
the critical habitat designation for northern Mexican gartersnake and
17 percent of the designation for narrow-headed gartersnake was
considered occupied at the time of listing, based solely on records of
the corresponding species dated before 1998. For northern Mexican
gartersnake, these areas included Mule Creek Unit, Upper Salt River
Subbasin Unit, and Agua Fria River Subbasin Unit in their entirety, and
Bear Canyon Creek Subunit in San Pedro River Subbasin Unit and Turkey
Creek Subunit in Babocomari River Subbasin Unit. For narrow-headed
gartersnake, areas included Turkey Creek Subunit in Upper Gila River
Subbasin Unit; and Salt River, White River, Carrizo Creek, Cibecue
Creek, and Diamond Creek subunits in Upper Salt River Subbasin Unit. We
note that the San Bernardino National Wildlife Refuge Unit did not have
a verified northern Mexican gartersnake record dated 1998 or later.
This unit was not included in the revised proposed rule. In addition,
Parker Canyon and Parker Canyon Lake were specifically mentioned as
part of the occupied Upper Santa Cruz River Unit for northern Mexican
gartersnake in the July 10, 2013, proposed rule, but the last detection
of the species in this area was in 1979 (Holycross et al. 2006,
appendix A). Redrock Canyon does not have a record of the northern
Mexican gartersnake, and was also erroneously included in the July 10,
2013, proposed rule. Instead, the species was found in nearby Cott Tank
Drainage and is included in this revised proposed rule (Jones 2009).
For narrow-headed gartersnake, we note that the Gila River Subunit in
the Middle Gila River Subbasin Unit had no records of the species and
was erroneously included in the July 10, 2013, proposed rule. In
addition, East Fork Gila River had no confirmed post-1980 records of
the species and was erroneously included in the July 10, 2013, proposed
rule (Propst 2015).
Based on our analyses in the rule listing the two garternakes (79
FR 38678; July 8, 2014), we conclude that there has been a significant
decline in both species over the past 50 years. This decline appeared
to accelerate during the two decades immediately before listing
occurred. From this observation, we conclude that many areas that were
occupied by the species in surveys during the 1980s are likely no
longer occupied because those populations have disappeared. To
determine where loss of populations was likely, we reviewed survey
efforts after 1989 that did not detect gartersnakes in some of the
areas mentioned above, and portions of other units and subunits
included in the July 10, 2013, proposed critical habitat rule. We
analyzed this to determine whether the cryptic nature of the species
was a valid argument for considering areas that only have gartersnake
records from the 1980s as still occupied at the time of listing in
2013. All of the surveys conducted since the 1980s included at least
the same amount or more search effort than those surveys that detected
each species in the 1980s. Since 1998, researchers have detected each
gartersnake species in many areas where they were found in the 1980s.
Areas where each gartersnake was found after 1997 are included in this
revised proposed rule. This includes portions of 9 of the 13 units for
northern Mexican gartersnake, and portions of 6 of the 7 units for
narrow-headed gartersnake from the July 10, 2013, proposed rule.
Resurveyed areas with no confirmed detection of northern Mexican
gartersnakes since the 1980s include Mule Creek (Hotle et al. 2012, p.
1), Black River (Holycross et al. 2006, p. 30), Big Bonito Creek
(Holycross et al. 2006, p. 64), Verde River downstream of Beasley Flat
(Holycross et al. 2006, p. 26; Emmons and Nowak 2012, pp. 11-13), Agua
Fria River (Holycross et al. 2006, pp. 15-18; Burger 2016, p. 3),
Little Ash Creek (Holycross et al. 2006, p. 19; Emmons and Nowak 2012,
p. 32; Burger 2016, p. 3), and Black Draw and lentic habitats on San
Bernardino National Wildlife Refuge (Radke 2006).
Resurveyed areas with no confirmed detection of narrow-headed
gartersnakes since the 1980s include the Gila River Subunit downstream
of the Middle Box (Christman and Jennings 2017, pp. 4-12; Jennings et
al. 2017, pp. 13-14; Jennings et al. 2018, pp. 10-13; Jennings and
Christman 2019, p. 5); San Francisco River downstream of confluence
with Whitewater Creek (Holycross et al. 2006, p. 66; Hellekson 2012),
and Salt River (Holycross et al. 2006, pp. 38-39). It is reasonable to
conclude that areas surveyed within 15 years of listing with no
detection of the corresponding gartersnake species were not occupied at
the time of listing. Survey efforts in these areas were comparable to
or greater than surveys conducted in the 1980s that detected the
species. Additionally, comparable surveys did detect gartersnakes in
other areas where the species was present in the 1980s. Finally, we
would expect that some populations would be lost during the decades
preceding listing when numbers of both gartersnakes were declining.
These declines are what eventually led to the need to list both
species.
As explained extensively in the final listing rule for both
gartersnake species (79 FR 38678, July 8, 2014, pp. 79 FR 38688-79 FR
38702), aquatic vertebrate survey efforts throughout the range of both
species indicate that native prey species of both gartersnakes have
decreased or are absent, while nonnative predators, including
bullfrogs, crayfish, and spiny-rayed fish, continue to increase in many
of the areas where both gartersnakes were present in the 1980s (Emmons
and Nowak 2012, pp. 11-14; Gibson et al. 2015, pp. 360-364; Burger
2016, pp. 21-32; Emmons and Nowak 2016a, pp. 43-44; Christman and
Jennings 2017, p. 14; Hall 2017, pp. 12-13; Jennings et al. 2018, p.
19). We acknowledge that both gartersnake species are extant in some
areas that have abundant nonnative, aquatic predators, some of which
also are prey for gartersnakes, so presence of nonnative aquatic
predators is not always indicative of absence of these gartersnakes
(Emmons and Nowak 2012, p. 31; Emmons and Nowak 2016a, p. 13; Emmons et
al. 2016, entire; Nowak et al. 2016, pp. 5-6; Lashway 2015, p. 5). We
[[Page 23619]]
also acknowledge that we do not have a good understanding of why
gartersnake populations are able to survive in some areas with aquatic
predators and not in other areas (Burger 2016, pp. 13-15). However, we
think it is reasonable to conclude that streams, stream reaches, and
lentic water bodies were not occupied at the time of listing if they
have only gartersnake records older than 1998 and have experienced a
rapid decline in native prey species coupled with an increase in
nonnative aquatic predators since gartersnakes were detected in these
areas in the 1980s.
In summary, through this review of gartersnake occupancy, we
determined that a stream, stream reach, or lentic water body was
occupied at the time of listing for each gartersnake species if it is
within the historical range of the species, contains all PBFs for the
species, (although the PBFs concerning prey availability and presence
of nonnative predators are often in degraded condition), and a last
known record of occupancy in 1998 or later. As a result, six subunits
in five units of critical habitat for northern Mexican gartersnake and
nine subunits in four units of critical habitat for narrow-headed
gartersnake included in the July 10, 2013, proposed rule are no longer
included in this revised proposed critical habitat designation their
entirety. This change reduced the proposed critical habitat designation
by 35,426 ac (14,336 ha), or 9 percent, of the area included in the
July 10, 2013, proposed rule for northern Mexican gartersnake, and
47,535 ac (19,237 ha), or 23 percent, of the area included in that
proposed rule for narrow-headed gartersnake (see tables 1a and 1b,
below). Other units and subunits are shortened in length due to our
definition of occupancy as described below under Stream Length.
We included gartersnake detections of each gartersnake that
occurred after the species was listed because these areas were likely
occupied at the time of listing in 2014. Both of these species are
cryptic in nature and may not be detected without intensive surveys.
Because populations for these species are generally small, isolated,
and in decline it is not likely that the species have colonized new
areas since 2014; these areas were most likely occupied at the time of
listing, but either had not been surveyed or the species were present
but not detected during surveys. However, we did not include streams or
lentic water bodies where gartersnakes were released for recovery
purposes after the species was listed that had not been historically
occupied by the species. This added one new unit and five subunits in
four existing units of critical habitat for northern Mexican
gartersnake (7,040 ac (2,848 ha)) and five subunits in two units of
critical habitat for narrow-headed gartersnake (1,181 ac (478 ha)) in
this revised proposed rule (see tables 1a and 1b, below).
Stream Length
In the July 10, 2013, proposed critical habitat rule, if a stream
had at least one known record for the each gartersnake species and at
least one record of a native prey species currently present, the entire
stream length was included in proposed critical habitat. In the
discussion, we stated, ``With respect to length (in proposed
designations based on flowing streams), the proposed areas were
designed to provide sufficient aquatic and terrestrial habitat for
normal behaviors of northern Mexican and narrow-headed gartersnakes of
all age classes'' (78 FR 41550, p. 78 FR 41556). We received numerous
general comments and comments on specific stream reaches that are not
habitat for the corresponding gartersnake.
In this revised proposed rule, for each gartersnake species, we
used comments we received and reports on water availability, prey
availability, and gartersnake surveys to re-evaluate all streams and
determine which stream reaches contain PBFs and where PBFs are lacking.
Stream reaches that lack PBFs include areas where water flow became
completely ephemeral along an otherwise perennial or spatially
intermittent stream, hydrologic processes needed to maintain streams
could not be recovered, nonnative aquatic predators outnumbered native
prey species, or streams were outside the elevation range. In addition,
reaches with multiple negative surveys without a subsequent positive
survey or reaches that have no records of the corresponding gartersnake
species are not included, as described above under Occupancy Records.
We do include stream reaches that lack survey data for the
corresponding gartersnake, if they have positive observation records of
the species dated 1998 or later both upstream and downstream of the
stream reach and have all of the PBFs.
We also reviewed the best available information we have on home
range size and potential dispersal distance for each gartersnake
species to inform upstream and downstream boundaries of each unit and
subunit of critical habitat. As explained earlier, the maximum
longitudinal distance measured across home range areas of northern
Mexican gartersnake tracked for at least one year was 4,852 ft
(1,478.89 m) for one individual, and ranged from 587.9 to 2,580 ft
(179.2 to 481.58 m) for eight other northern Mexican gartersnakes
(Nowak et al. 2019, pp. 24-25). Maximum longitudinal distance measured
across home range areas of narrow-headed gartersnakes ranged from 82 to
285 feet (25 to 87 m) (Jennings and Christman 2012, pp. 9-10). These
longitudinal home range distances were all determined from adult
gartersnakes, and did not inform how juvenile gartersnakes are
dispersing along a stream. Juvenile dispersal is important because
snakes of different age classes behave differently, and juvenile
gartersnakes may move farther along a stream as they search for and
establish suitable home ranges than do adults with established home
ranges. Because we have no information on how juvenile northern Mexican
gartersnakes and narrow-headed gartersnakes disperse, we used
information from a long-term dispersal study on neonate, juvenile, and
adult age classes of the Oregon gartersnake (Thamnophis atratus
hydrophilus) in a free-flowing stream environment in northern
California (Welsh et al. 2010, entire). This is the only dispersal
study available for another aquatic Thamnophis species in the United
States, so we used it as a surrogate for determining upstream and
downstream movements of both northern Mexican and narrow-headed
gartersnakes, which are also aquatic Thamnophis species. The greatest
movement was made by a juvenile recaptured as an adult 2.2 mi (3.6 km)
upstream from the initial capture location (Welsh et al. 2010, p. 79).
Therefore, in this revised proposed rule, we delineate upstream and
downstream critical habitat boundaries of a stream reach at 2.2 mi (3.6
km) from a known gartersnake observation record.
These changes in determining stream length reduced the proposed
critical habitat designation by 72,955 ac (29,524 ha), or 17 percent,
of the area included in the July 10, 2013, proposed rule for critical
habitat for northern Mexican gartersnake, and 101,597 ac (41,115 ha),
or 48 percent, of the area included in that proposed rule for critical
habitat for narrow-headed gartersnake (see tables 1a and 1b, below).
[[Page 23620]]
Table 1a--Changes to Northern Mexican Gartersnake Proposed Critical Habitat Units
--------------------------------------------------------------------------------------------------------------------------------------------------------
Length miles (kilometers) Area acres (hectares)
Previous unit Previous subunit New unit New subunit ---------------------------------------------------------------------
Previous New Previous New
--------------------------------------------------------------------------------------------------------------------------------------------------------
Upper Gila River............. ................ Upper Gila River ............... 148 (239) 13 (21) 21,135 (8,553) 1,132 (458)
Subbasin.
................ ................ Gila River..... 148 (239) 9 (14) 21,135 (8,553) 1,028 (416)
................ ................ Duck Creek..... 0 4 (6) 0 104 (42)
Mule Creek................... ................ Removed *....... ............... 19 (30) 0 2,579 (1,044) 0
Upper Salt River............. ................ Removed *....... ............... 156 (251) 0 22,218 (8,991) 0
Black River..... ................ Removed *...... 114 (184) 0 16,392 (6,634) 0
Big Bonito Creek ................ Removed *...... 42 (67) 0 5,826 (2,358) 0
Tonto Creek.................. ................ Tonto Creek..... ............... 65 (105) 32 (52) 8,936 (3,616) 4,302 (1,741)
Verde River.................. ................ Verde River ............... 201 (323) 61 (99) 29,191 (11,813) 5,246 (2,123)
Subbasin.
Upper Verde ................ Verde River.... 140 (225) 35 (56) 20,526 (8,307) 4,133 (1,672)
River.
Oak Creek....... ................ Oak Creek...... 39 (62) 23 (37) 5,533 (2,239) 1,014 (410)
Spring Creek.... ................ Spring Creek... 23 (36) 4 (6) 3,131 (1,267) 99 (40)
Agua Fria River.............. ................ Removed *....... ............... 56 (91) 0 7,946 (3,215) 0
Agua Fria River ................ Removed *...... 49 (80) 0 6,989 (2,828) 0
Mainstem.
Little Ash Creek ................ Removed *...... 10 (11) 0 957 (387) 0
Bill Williams River.......... ................ Bill Williams ............... 36 (58) 29 (46) 5,412 (2,190) 4,049 (1,639)
River Subbasin.
................ ................ Bill Williams 36 (58) 15 (24) 5,412 (2,190) 1,805 (730)
River.
................ ................ Big Sandy River 0 8 (13) 0 932 (377)
................ ................ Santa Maria 0 5 (9) 0 1,312 (531)
River.
................ Lower Colorado ............... 0 n/a 0 4,467 (1,808)
River.
Buenos Aires NWR............. ................ Arivaca Cienega. ............... n/a 3 (5) 117,313 (47,475) 211 (86)
Cienega Creek Subbasin....... ................ Cienega Creek ............... n/a 46 (73) 50,393 (20,393) 2,030 (821)
Subbasin.
Cienega Creek... ................ Cienega Creek 1 7+ (11+) 30 (48) 1,113 (450) 1,613 (653)
Cienega Creek ................ Removed *...... n/a n/a 4,260 (1,724) 0
Natural
Preserve.
Las Cienegas NCA ................ Removed *...... n/a n/a 45,020 (18,219) 0
2.
................ ................ Empire Gulch n/a 7 (11) n/a 326 (132)
and Empire
Wildlife Pond.
................ ................ Gardner Canyon n/a 7 (11) n/a 74 (30)
and Maternity
Wildlife Pond.
................ ................ Unnamed n/a 2 (3) n/a 15 (6)
Drainage and
Gaucho Tank.
Redrock Canyon............... ................ Removed * 3..... ............... 14 (23) 0 1,972 (798) 0
Upper Santa Cruz River ................ Upper Santa Cruz ............... n/a 23 (36) 113,895 (46,092) 496 (201)
Subbasin 4. River Subbasin.
................ ................ Sonoita Creek.. 0 3 (5) 0 224 (91)
................ ................ Cott Tank n/a 2 (3) 0 13 (5)
Drainage.
................ ................ Santa Cruz 14 (22) 7 (11) n/a 161 (65)
River.
[[Page 23621]]
................ ................ Unnamed n/a 5 (7) n/a 42 (17)
Drainage and
Pasture 9 Tank.
................ ................ Unnamed n/a 2 (3) n/a 25 (10)
Drainage and
Sheehy Spring.
................ ................ Scotia Canyon.. n/a 4 (7) n/a 31 (13)
................ ................ FS799 Tank..... n/a n/a n/a 0.7 (0.3)
................ ................ Unnamed n/a n/a n/a 0.1 (http://www.regulations.gov at Docket No. FWS-R2-ES-
2020-0011, on our internet site at http://www.fws.gov/southwest/es/arizona, and at the field office responsible for the designation (see
FOR FURTHER INFORMATION CONTACT above).
Areas Occupied at the Time of Listing
We are proposing for designation of critical habitat lands that we
have determined were occupied at the time of listing and contain one or
more of the physical or biological features to support life-history
processes essential to the conservation of the species. As explained
under Occupancy Records, above, this proposed critical habitat
designation does not include all streams known to have been occupied by
the species historically or the entire stream known to have been
occupied by the species historically. Instead, it focuses on occupied
streams or stream reaches within the historical range with positive
survey records from 1998 to 2019 that have retained the necessary PBFs
that will allow for the maintenance and expansion of existing
populations. 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:
Northern Mexican Gartersnake
1. We mapped records of observations of northern Mexican
gartersnake from 1998 to 2019. We then examined these areas to
determine if northern Mexican gartersnake could still occur in them, as
described below.
2. We identified streams in which northern Mexican gartersnakes
were found since 1980 (used flowline layer in the USGS National
Hydrography Dataset to represent stream centerlines).
3. We identified and removed upstream and downstream ends of
streams that were below 130 ft or above 8,500 ft elevation using USGS
National Elevation Dataset.
4. We identified perennial, intermittent, and ephemeral reaches of
streams. We removed end reaches of streams that are ephemeral based on
FCode attribute of the flowline layer in the USGS National Hydrography
Dataset or information from peer review and public comments. We
identified native prey species along each stream using geospatial
datasets, literature, peer review, and public comments.
5. We identified prey species along each stream using geospatial
datasets, literature, peer review, and public comments. We removed
stream reaches that were documented to not contain prey species.
6. We identified and removed stream reaches with an abundance of
nonnative predators including fish, crayfish, or bullfrogs. (We used a
combination of factors to determine nonnative presence and impact to
the species. This evaluation included records from 1980 by looking at
subsequent negative survey data for northern Mexican gartersnakes along
with how the nonnative predator community had changed since those
gartersnakes were found, in addition to the habitat condition and
complexity. Most of the areas surveyed in the 1980s that had been re-
surveyed with negative results for gartersnakes had significant changes
to the nonnative predator community, which also decreased prey
availability for the gartersnakes. These areas were removed from
revised proposed critical habitat.)
7. We identified and removed stream reaches where stocking or
management of predatory sportfish is a priority and is conducted on a
regular basis.
8. We identified and included those stream reaches on private land
without public access that lack survey data but that have positive
survey records from 1998 forward both upstream and downstream of the
private land and have stream reaches with PBFs 1 and 2.
9. We used a surrogate species to determine potential neonate
dispersal along a stream, which is 2.2 miles (3.5 km). We then
identified the most upstream and downstream records of northern Mexican
gartersnake along each continuous stream reach determined by criteria 1
through 8, above, and extended the stream reach to include this
dispersal distance.
10. After identifying the stream reaches that met the above
parameters, we then connected those reaches between that have the PBFs.
We consider these areas between survey records occupied because the
species occurs upstream and downstream and multiple PBFs are present
that allow the species to move through these stream reaches.
11. We identified the springs, cienegas, and natural or constructed
ponds (livestock tanks) in which records of observations of the species
from 1998 to 2019 were found and included them in this revised proposed
critical habitat.
12. We identified ephemeral reaches of occupied perennial or
intermittent streams that serve as corridors between springs, cienegas,
and natural or constructed ponds (livestock tanks).
13. We identified and included the wetland and riparian area
adjacent to streams, springs, cienegas, and ponds to capture the
wetland and riparian habitat needed by the species for
thermoregulation, foraging, and protection from predators. We used the
wetland and riparian layers of the Service's National Wetlands
Inventory dataset and aerial photography in Google Earth Pro to
identify these areas.
Narrow-headed Gartersnake
1. We mapped records of narrow-headed gartersnake from 1998 to
2019. We then examined these areas to determine if narrow-headed
gartersnake could still occur here, as described below.
2. We identified the streams in which narrow-headed gartersnakes
were found since 1998 (used flowline layer in the USGS National
Hydrography Dataset to represent stream centerlines).
3. We identified and removed upstream and downstream ends of
streams that were below 2,300 ft or above 8,200 ft in elevation using
USGS National Elevation Dataset.
4. We identified perennial, intermittent, and ephemeral reaches of
streams. We removed end reaches of streams that are ephemeral or
intermittent based on FCode attribute of the flowline layer in the USGS
National Hydrography Dataset or information from peer review and public
comments.
5. We identified native and nonnative prey species along each
stream using geospatial datasets, literature, peer review, and public
comments. We removed stream reaches that did not have prey species.
6. We identified and removed stream reaches with an abundance of
nonnative predators including fish, crayfish, and bullfrogs. (We
examined a combination of factors to determine nonnative presence and
impact to the species. This included evaluating gartersnake records
from 1998 by looking at subsequent negative survey data for narrow-
headed gartersnakes along with how the nonnative predator community had
changed since those gartersnakes were found, in addition to the habitat
condition and complexity. Most of the areas surveyed in the 1980s that
had been re-surveyed with negative results for gartersnakes had
significant changes to the nonnative predator community, which also
decreased prey availability for the gartersnakes. These areas were
removed from revised proposed critical habitat.)
7. We identified and removed stream reaches where stocking or
management of predatory sportfish is a priority and is conducted on a
regular basis.
8. We identified and included those stream reaches on private land
without
[[Page 23626]]
public access that lack survey data but that have positive narrow-
headed gartersnake survey records from 1998 forward both upstream and
downstream of the private land and have stream reaches with PBFs 1 and
2.
9. We used a surrogate species to determine potential neonate
dispersal along a stream, which is 2.2 mi (3.5 km). We then identified
the most upstream and downstream records of narrow-headed gartersnake
along each continuous stream reach determined by criteria 1 through 8,
above, and extended the reach to include this dispersal distance.
10. After identifying the stream reaches that met the above
parameters, we then connected those reaches between that had the PBFs.
We consider these areas between survey records occupied because the
species occurs upstream and downstream and multiple PBFs are present
that allow the species to move through these stream reaches.
11. We identified the average distance narrow-headed gartersnakes
moved laterally from the water's edge in streams, which is 89 ft (27
m), to capture the wetland and terrestrial habitat needed by the
species for thermoregulation and protection from predators. We used the
wetland layer of the Service's National Wetlands Inventory dataset and
aerial photography in Google Earth Pro to identify the water's edge in
streams.
When determining proposed critical habitat boundaries, we made
every effort to avoid including developed areas such as lands covered
by buildings, pavement, and other structures because such lands lack
physical or biological features necessary for northern Mexican and
narrow-headed gartersnakes. However, constructed fish barriers in
streams within the proposed designated critical habitat are part of the
designation and are needed to manage the exclusion of nonnative
species. The scale of the maps we prepared under the parameters for
publication within the Code of Federal Regulations may not reflect the
exclusion of such developed lands. Any such lands inadvertently left
inside critical habitat boundaries shown on the maps of this proposed
rule have been excluded by text in the proposed rule and are not
proposed for designation as critical habitat. Therefore, if the
critical habitat is finalized as proposed, a Federal action involving
these lands 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 physical or biological features in
the adjacent critical habitat.
We are proposing for designation of critical habitat lands that we
have determined were occupied at the time of listing and contain one or
more of the physical or biological features that are essential to
support life-history processes of the species.
Proposed Critical Habitat Designation
Northern Mexican Gartersnake
We are proposing 241 stream mi (388 km) within the identified
wetland and riparian habitat needed for basking, cover, and foraging,
totaling 27,784 ac (11,244 ha) in nine units as the revised proposed
critical habitat for northern Mexican gartersnake. Land ownership
within proposed critical habitat for the northern Mexican gartersnake
in acres is broken down as follows: Federal (62 percent), State
(Arizona and New Mexico) (5 percent), Tribal (0.3 percent), and private
(32 percent) (see table 2a, below). The critical habitat areas we
describe below constitute our current best assessment of areas that
meet the definition of critical habitat for northern Mexican
gartersnake. We consider all units occupied at the time of listing, and
all units contain essential PBFs that may require special management
considerations or protection.
Table 2a--Land Ownership and Size of Northern Mexican Gartersnake Proposed Critical Habitat Units
[Area estimates reflect all land within critical habitat unit boundaries. County-owned lands are considered as private lands.]
--------------------------------------------------------------------------------------------------------------------------------------------------------
Land ownership by type acres (hectares) Total size
Unit Subunit ---------------------------------------------------------------- acres
Federal State Tribal Private (hectares)
--------------------------------------------------------------------------------------------------------------------------------------------------------
1. Upper Gila River Subbasin.............. Gila River.................. .............. 22 (9) .............. 1,006 (407) 1,028 (416)
Duck Creek.................. .............. .............. .............. 104 (42) 104 (42)
-------------------------------------------------------------------------------
Unit Total............................ ............................ .............. 22 (9) .............. 1,110 (449) 1,132 (458)
2. Tonto Creek............................ ............................ 3,337 (1,350) .............. .............. 966 (391) 4,302 (1,741)
-------------------------------------------------------------------------------
Unit Total............................ ............................ 3,337 (1,350) .............. .............. 966 (391) 4,302 (1,741)
3. Verde River Subbasin................... Verde River................. 646 (261) 570 (231) 88 (36) 2,829 (1,145) 4,133 (1,672)
Oak Creek................... 193 (78) 134 (54) .............. 687 (278) 1,014 (410)
Spring Creek................ 17 (7) 1 (http://www.regulations.gov and upon request from the
Arizona Ecological Services Field Office (see FOR FURTHER INFORMATION
CONTACT).
Authors
The primary authors of this proposed rulemaking are the staff
members of the Arizona Ecological Services Field Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Proposed Regulation Promulgation
Accordingly, we propose to 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. Amend Sec. 17.11(h) by revising the entries for ``Gartersnake,
narrow-headed'' and ``Gartersnake, northern Mexican'' under REPTILES in
the List of Endangered and Threatened Wildlife to read as follows:
Sec. 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
----------------------------------------------------------------------------------------------------------------
Listing citations
Common name Scientific name Where listed Status and applicable
rules
----------------------------------------------------------------------------------------------------------------
* * * * * * *
Reptiles
* * * * * * *
Gartersnake, narrow-headed....... Thamnophis Wherever found...... T 79 FR 38677, 7/8/
rufipunctatus. 2014; 50 CFR
17.95(c).\CH\
Gartersnake, northern Mexican.... Thamnophis eques Wherever found...... T 79 FR 38677, 7/8/
megalops. 2014; 50 CFR
17.42(g);\4d\ 50
CFR 17.95(c).\CH\
* * * * * * *
----------------------------------------------------------------------------------------------------------------
0
3. In Sec. 17.95, amend paragraph (c) by adding, in the same
alphabetical order that the species appear in the table at Sec.
17.11(h), entries for ``Narrow-headed Gartersnake (Thamnophis
rufipunctatus)'' and ``Northern Mexican Gartersnake (Thamnophis eques
megalops)'' to read as follows:
Sec. 17.95 Critical habitat--fish and wildlife.
* * * * *
(c) Reptiles.
* * * * *
Narrow-Headed Gartersnake (Thamnophis rufipunctatus)
(1) Critical habitat units are depicted for Apache, Coconino, Gila,
Graham, Greelee, and Yavapai Counties in Arizona, and Catron, Grant,
and Hidalgo Counties in New Mexico, on the maps in this entry.
(2) Within these areas, the physical or biological features
essential to the conservation of narrow-headed gartersnake consist of
the following components:
(i) Perennial streams or spatially intermittent streams that
provide both aquatic and terrestrial habitat that allows for
immigration, emigration, and maintenance of population connectivity of
narrow-headed gartersnakes and contain:
(A) Pools, riffles, and cobble and boulder substrate, with low
amount of fine sediment and substrate embeddedness;
(B) Organic and natural inorganic structural features (e.g., cobble
bars, rock piles, large boulders, logs or
[[Page 23648]]
stumps, aquatic and wetland vegetation, logs, and debris jams) in the
stream channel for basking, thermoregulation, shelter, prey base
maintenance, and protection from predators;
(C) Water quality that is absent of pollutants or, if pollutants
are present, at levels low enough such that recruitment of narrow-
headed gartersnakes is not inhibited; and
(D) Terrestrial habitat within 89 feet (27 meters) of the active
stream channel that includes boulder fields, rocks, and rock structures
containing cracks and crevices, small mammal burrows, downed woody
debris, and vegetation for thermoregulation, shelter sites, and
protection from predators.
(ii) Hydrologic processes that maintain aquatic and riparian
habitat through:
(A) A natural flow regime that allows for periodic flooding, or if
flows are modified or regulated, a flow regime that allows for the
movement of water, sediment, nutrients, and debris through the stream
network, as well as maintenance of native fish populations; and
(B) Physical hydrologic and geomorphic connection between the
active stream channel and its adjacent terrestrial areas.
(iii) Prey base of native fishes, or soft-rayed, nonnative fish
species.
(iv) An absence of nonnative predators, such as fish species of the
families Centrarchidae and Ictaluridae, bullfrogs, and crayfish, or
occurrence of nonnative predators at low enough densities such that
recruitment of narrow-headed gartersnakes is not inhibited and
maintenance of viable prey populations is still occurring.
(v) Elevations of 2,300 to 8,200 feet (700 to 2,500 meters).
(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
the effective date of this rule.
(4) Critical habitat map units. Data layers defining map units
included the U.S. Geological Survey's 7.5' quadrangles, National
Hydrography Dataset and National Elevation Dataset; the Service's
National Wetlands Inventory dataset; and aerial imagery from Google
Earth Pro. Line locations for lotic streams (flowing water) and
drainages are depicted as the ``Flowline'' feature class from the
National Hydrography Dataset geodatabase. The active channel along a
stream is depicted as the ``Wetlands'' feature class from the Service's
National Wetlands Inventory dataset. Any discrepancies between the
``Flowline'' and ``Wetlands'' feature classes were resolved using
aerial imagery from Google Earth Pro. Elevation range is masked using
the ``Elev_Contour'' feature class of the National Elevation Dataset.
The administrative boundaries for Arizona and New Mexico were obtained
from the Arizona Land Resource Information Service and New Mexico
Resource Geographic Information System, respectively. This includes the
most current (as of the effective date of this rule) geospatial data
available for land ownership, counties, States, and streets. Locations
depicting critical habitat are expressed as decimal degree latitude and
longitude in the World Geographic Coordinate System projection using
the 1984 datum (WGS84). 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 http://www.fws.gov/southwest/es/arizona/, at http://www.regulations.gov at Docket No. FWS-R2-ES-2020-0011, 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) Note: Index map follows:
BILLING CODE P
[[Page 23649]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.000
(6) Unit 1: Upper Gila River Subbasin Unit, Grant and Hidalgo
Counties, New Mexico.
(i) General description: Unit 1 consists of 5,429 ac (2,197 ha) in
Grant and Hidalgo Counties, and is composed of lands in Federal (2,827
ac (1,144 ha)), State (278 ac (113 ha)), and private (2,323 ac (940
ha)) ownership in eight subunits west of the town of Glenwood, north of
Silver City, and South of Gila and Cliff.
(ii) Map of Unit 1 follows:
[[Page 23650]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.001
(7) Unit 2: San Francisco River Subbasin Unit, Catron County, New
Mexico.
(i) General description: Unit 2 consists of 4,905 ac (1,985 ha) in
Catron County, and is composed of lands in Federal (2,753 ac (1,114
ha)) and private (2,152 ac (871 ha)) ownership in six subunits near the
towns of Glenwood and Reserve.
(ii) Map of Unit 2 follows:
[[Page 23651]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.002
(8) Unit 3: Blue River Subbasin Unit, Greenlee County, Arizona, and
Catron County, New Mexico.
(i) General description: Unit 3 consists of 2,971 ac (1,202 ha) in
Greenlee County, Arizona, and Catron County, New Mexico, and is
composed of lands in Federal (2,510 ac (1,016 ha)) and private (460 ac
(186 ha)) ownership in three subunits near the towns of Blue, Arizona,
and Luna, New Mexico.
(ii) Map of Unit 3 follows:
[[Page 23652]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.003
(9) Unit 4: Eagle Creek Unit, Graham and Greenlee Counties,
Arizona.
(i) General description: Unit 4 consists of 336 ac (136 ha) in
Graham and Greenlee Counties, and is composed of lands in Federal (99
ac (40 ha)), Tribal (236 ac (96 ha)), and private (1 ac (http://www.fws.gov/southwest/es/arizona/, at http://www.regulations.gov at Docket No. FWS-R2-ES-2020-0011, 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) Note: Index map follows:
BILLING CODE P
[[Page 23659]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.009
(6) Unit 1: Upper Gila River Subbasin Unit, Grant County, New
Mexico.
(i) General description: Unit 1 consists of 1,132 ac (458 ha) in
Grant County, and is composed of lands in State (22 ac (9 ha)), and
private (1,110 ac (449 ha)) ownership in two subunits near the towns of
Cliff and Gila.
(ii) Map of Unit 1 follows:
[[Page 23660]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.010
(7) Unit 2: Tonto Creek Unit, Gila County, Arizona.
(i) General description: Unit 2 consists of 4,302 ac (1,741 ha) in
Gila County, and is composed of lands in Federal (3,337 ac (1,350 ha)),
and private (966 ac (391 ha)) ownership near the towns of Gisela and
Punkin Center.
(ii) Map of Unit 2 follows:
[[Page 23661]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.011
(8) Unit 3: Verde River Subbasin Unit, Yavapai County, Arizona.
(i) General description: Unit 3 consists of 5,246 ac (2,123 ha) in
Yavapai County, and is composed of lands in Federal (856 ac (346 ha)),
State (705 ac (285 ha)), Tribal (88 ac (36 ha), and private (3,597 ac
(1,456 ha)) ownership in three subunits near the towns of Cottonwood,
Cornville, Page Springs, and Camp Verde.
(ii) Map of Unit 3 follows:
[[Page 23662]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.012
(9) Unit 4: Bill Williams River Subbasin Unit, La Paz and Mohave
Counties, Arizona.
(i) General description: Unit 4 consists of 4,049 ac (1,639 ha) in
La Paz and Mohave Counties, and is composed of lands in Federal (2,121
ac (858 ha)), State (202 ac (82 ha)), and private (1,727 ac (699 ha))
ownership in three subunits near the towns of Parker and Signal.
(ii) Map of Unit 4 follows:
[[Page 23663]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.013
(10) Unit 5: Lower Colorado River Unit, Mojave County, Arizona.
(i) General description: Unit 5 consists of 4,467 ac (1,808 ha) in
Mojave County and is composed of lands in Federal ownership within the
Havasu National Wildlife Refuge.
(ii) Map of Unit 5 follows:
[[Page 23664]]
[GRAPHIC] [TIFF OMITTED] TP28AP20.014
(11) Unit 6: Arivaca Cienega Unit, Pima County, Arizona.
(i) General description: Unit 6 consists of 211 ac (86 ha) in Pima
County and is composed of lands in Federal (149 ac (60 ha)), State (1
ac (
