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Endangered and Threatened Wildlife and Plants; Withdrawal of the Proposed Rule To List the Flat-Tailed Horned Lizard as Threatened
Note: EPA no longer updates this information, but it may be useful as a reference or resource.
[Federal Register: June 28, 2006 (Volume 71, Number 124)]
[Proposed Rules]
[Page 36745-36752]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr28jn06-42]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
RIN 1018-AU58
Endangered and Threatened Wildlife and Plants; Withdrawal of the
Proposed Rule To List the Flat-Tailed Horned Lizard as Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule; withdrawal.
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SUMMARY: We, the Fish and Wildlife Service (Service), have determined
that the proposed listing of the flat-tailed horned lizard (Phrynosoma
mcallii) as a threatened species under the Endangered Species Act (Act)
of 1973, as amended, is not warranted and, thus, we withdraw our
November 29, 1993, proposed rule (58 FR 62625). As stated in our
January 3, 2003, withdrawal of the proposed rule to list the species as
threatened (68 FR 331), we have made this determination because threats
to the species as identified in the November 29, 1993, proposed rule
are not significant, and available data do not indicate that the
threats to the species and its habitat, as analyzed under the five
listing factors described in section 4(a)(1) of the Act, are likely to
endanger the species in the foreseeable future throughout all or a
significant portion of its range. The analyses and conclusions
contained in the January 3, 2003, withdrawal (68 FR 331) are
incorporated herein by reference subject to the revisions contained in
this notice. In this revised withdrawal, we have re-examined the lost
historical habitat of the flat-tailed horned lizard in relation to our
January 3, 2003, withdrawal of the proposed listing rule and have
determined that the lost historical habitat is not a significant
portion of the flat-tailed horned lizard's range and does not result in
the species likely becoming endangered in the foreseeable future
throughout all or a significant portion of its range.
ADDRESSES: Supporting documentation for this rulemaking is available
for public inspection, by appointment, during normal business hours at
the U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office,
6010 Hidden Valley Road, Carlsbad, CA 92011.
FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, at the
above address (telephone, 760-431-9440, or fax, 760-431-9624).
SUPPLEMENTARY INFORMATION:
Background
Information on the biology and ecology of this species, factors
affecting the species, and current conservation measures applicable to
this species can be found in the January 3, 2003, withdrawal of the
proposed listing rule (68 FR 331). This document primarily contains
information relevant to the current and historical range of this
species and the issue of the significance of the lost habitat. We also
address the status of several projects and ongoing actions as they
relate to the flat-tailed horned lizard and provide an update on
several of the actions outlined in the 1997 Flat-Tailed Horned Lizard
Conservation Agreement (see ``Summary of Comments and Recommendations''
section).
The flat-tailed horned lizard is most commonly found in sandy flats
and valleys within creosote (Larrea tridentata) and white bursage
(Ambrosia dumosa) plant associations or series (Turner et al. 1980;
Muth and Fisher 1992; Foreman 1997). This series is generally found on
alluvial fans and upland slopes with well-drained soils that often have
a pavement surface (Sawyer and Keeler-Wolf 1995), but flat-tailed
horned lizards are usually found in areas with windblown sand deposits.
The flat-tailed horned lizard is endemic to the northern Sonoran Desert
in southern California, southwestern Arizona, and adjoining portions of
northwestern Sonora and Baja California Norte, Mexico (Turner and
Medica 1982). Within California, the flat-tailed horned lizard
currently ranges in the Colorado Desert portion of the Sonoran Desert,
from the Coachella Valley (the northernmost extent of its range), south
along both sides of the Imperial Valley. On the west side of the
Imperial Valley, the species ranges into the Borrego Valley, Ocotillo
Wells area, West Mesa, and Yuha Basin. On the east side of Imperial
Valley, the species occurs in the Bureau of Land Management (BLM) Dos
Palmas Area of Critical Environmental Concern (ACEC), but predominantly
occurs in East Mesa and in areas adjoining the Algodones Dunes (i.e.,
Imperial Sand Dunes, Glamis Sand Dunes). In Arizona, the flat-tailed
horned lizard is found in the Yuma Desert portion of the Sonoran
Desert, south of the Gila River and west of the Gila and Butler
Mountains (Rorabaugh et al. 1987). The flat-tailed horned lizard is
patchily distributed at varying densities throughout its range, and
although the species was once recorded at 1,706 feet (ft) (520 meters
(m)) above sea level, it is more commonly found below 820 ft (250 m) in
flat areas or areas with gentle slopes (Turner et al. 1980).
The range of the flat-tailed horned lizard extends into Mexico from
the international border in the Yuha Basin in California, south along
the west side of Laguna Salada in Baja California; and from the
international border in the Yuma Desert in Arizona, south and east
through the Pinacate Region to the sandy plains around Puerto Penasco
and Bahia de San Jorge, Sonora (Johnson and Spicer 1985, Gonzales-
Romero and Alvarez-Cardenas 1989).
Most of the range of the flat-tailed horned lizard in California
and Baja California Norte is in the Salton Trough, a low-lying
depression that is an extension of the Gulf of California. The lowest
areas of the Salton Trough are below sea level and are protected from
inundation from the ocean by the Colorado River delta. The geological
record indicates that, as the Colorado River meandered across its river
delta, it would periodically flow into the Salton Trough and form Lake
Cahuilla in the bottom of the Trough. Over time,
[[Page 36746]]
the river would again flow into the Gulf of California, and Lake
Cahuilla would evaporate (Waters 1983). As a result of dams,
channelization, and water usage, such flooding no longer occurs.
As discussed in the January 3, 2003, withdrawal of the proposed
listing rule (68 FR 331), the range of this species in the United
States has been analyzed by Hodges (1997) and the range of the species
in the United States and Mexico has been analyzed by Johnson and Spicer
(1985). The 2003 revision of the 1997 Flat-tailed Horned Lizard
Rangewide Management Strategy (herein referred to as the 2003 Rangewide
Management Strategy) is the most recent analysis of the species' range
in the United States and Mexico (FTHL-ICC 2003).
Hodges (1997) estimated that the flat-tailed horned lizard
historically (prior to agricultural or urban development of either the
Coachella or Imperial Valleys) occupied up to 2,419,200 acres (ac)
(979,037 hectares (ha)) in Arizona and California. Approximately 51
percent (1,243,339 ac (503,161 ha)) of the historical habitat
identified by Hodges remains in the United States, with about 140,300
ac (56,770 ha) in Arizona and 1,103,040 ac (446,390 ha) in California
(Hodges 1997). Hodges (1997) included the Salton Sea as historical
habitat. However, we noted in the January 3, 2003, withdrawal that the
Salton Sea area could arguably be considered ephemeral historical
habitat, present or absent at times, as the area changed through time
as a result of intermittent flooding and drying. At that time we did
not consider the effect of the larger Lake Cahuilla. We estimated that
if the area now occupied by the Salton Sea was not considered
historical habitat, then, using Hodges' (1997) numbers, approximately
57 percent of historical habitat remains in the United States. Hodges'
(1997) analysis did not include current or historical habitat for this
species in Mexico.
Johnson and Spicer (1985) analyzed the current range and threats to
the species in the United States and Mexico at that time. They
estimated that in 1981 approximately 59 percent of the species' range
occurred in Mexico (569,578 ac (230,500 ha)), with the majority of the
range in Mexico occurring in the state of Sonora (492,975 ac (199,500
ha)). Johnson and Spicer (1985) also estimated that 50 percent of the
species' habitat in California, Arizona, and Baja California Norte and
14 percent of the species' habitat in Sonora was in danger of
conversion to agriculture or urban development and/or degradation due
to factors such as off-highway vehicle recreation. Overall, 21 percent
of the species' habitat throughout its range was considered in danger
of being lost or degraded (Johnson and Spicer 1985).
The 2003 Rangewide Management Strategy contained updated
information on the current and historical range of the species in the
United States and Mexico and made available data on historical and
current range in geographic information system (GIS) format (FTHL-ICC
2003). We analyzed the GIS data used in the 2003 Rangewide Management
Strategy and estimated the size of the historical and current ranges.
We estimated the extent of historic Lake Cahuilla by using a GIS
digital elevation model and the estimated elevation the lake reached.
We estimated the historical range of the flat-tailed horned lizard in
the United States and Mexico to be 4,875,624 ac (1,973,095 ha).
Previous Federal Actions
On November 29, 1993, we published in the Federal Register a
proposed rule to list the flat-tailed horned lizard as a threatened
species pursuant to the Act (58 FR 62624). On May 16, 1997, in response
to a lawsuit filed by the Defenders of Wildlife to compel us to make a
final listing determination on the flat-tailed horned lizard, the
District Court in Arizona ordered the Service to issue a final listing
decision within 60 days. A month after the District Court's order,
seven State and Federal agencies signed the Flat-Tailed Horned Lizard
Conservation Agreement (referred to herein as the 1997 Conservation
Agreement) to implement a Flat-tailed Horned Lizard Rangewide
Management Strategy to protect the flat-tailed horned lizard on Federal
lands. Pursuant to the 1997 Conservation Agreement, cooperating parties
agreed to take voluntary steps aimed at ``reducing threats to the species,
stabilizing the species'' populations, and maintaining its ecosystem.''
On July 15, 1997, we published in the Federal Register a final
decision to withdraw the proposed rule to list the flat-tailed horned
lizard as a threatened species (62 FR 37852). We based the withdrawal
on three factors: (1) Population trend data did not conclusively
demonstrate significant population declines; (2) some of the threats to
the flat-tailed horned lizard habitat were misunderstood previously;
and (3) we believed that the recently approved ``conservation agreement
w[ould] ensure further reductions in threats.''
Six months following our withdrawal of the proposed listing rule,
the Defenders of Wildlife filed a lawsuit challenging our decision. On
June 16, 1999, the District Court for the Southern District of
California granted summary judgment in our favor upholding our decision
not to list the flat-tailed horned lizard. However, on July 31, 2001,
the Ninth Circuit Court of Appeals reversed the lower court's ruling
and directed the District Court to remand the matter back to us for
further consideration in accordance with the legal standards outlined
in its opinion. The case was remanded back to the Service because (1)
the withdrawal did not expressly consider whether the flat-tailed
horned lizard is likely to become an endangered species within the
foreseeable future in a significant portion of its range; and (2) the
withdrawal did not "address the lizard's viability in a site-specific
manner with regard to the putative benefits of the Conservation Agreement."
On October 24, 2001, the District Court ordered the Service to
reinstate the previously effective proposed listing rule within 60
calendar days and, thereafter, commence a 12-month statutory time
schedule for a final listing decision, and render our final listing
determination in compliance with the mandate of the Ninth Circuit
Court's order. Accordingly, we published a notice in the Federal
Register on December 26, 2001, announcing the reinstatement of the
November 29, 1993, proposed rule to list the flat-tailed horned lizard
as threatened and the opening of a 120-day public comment period on the
reinstated proposed rule (66 FR 66384).
On January 3, 2003, we again published in the Federal Register a
decision to withdraw the November 29, 1993, proposed rule to list the
flat-tailed horned lizard as a threatened species (68 FR 331). The
Service found the lizard to be in danger of extirpation in the
Coachella Valley; however, we determined that the Coachella Valley is
not a significant portion of the species' range. We concluded in the
January 3, 2003, withdrawal that the flat-tailed horned lizard
populations on either side of the Imperial Valley/Salton Sea and in
Arizona were not likely to become endangered in the foreseeable future
and that listing the species was not warranted.
The Tucson Herpetological Society and other environmental
organizations and individuals filed a lawsuit challenging our January
3, 2003, withdrawal. On August 30, 2005, the U.S. District Court for
the District of Arizona set aside our withdrawal of the proposed rule
to list the flat-tailed horned lizard as a threatened species on the
grounds that our withdrawal violated the Act because it failed to
[[Page 36747]]
determine whether the lost historical habitat for the flat-tailed
horned lizard was a significant portion of the range for this species.
With this exception, all other aspects of the January 3, 2003,
withdrawal were upheld by the District Court.
On November 17, 2005, the District Court ordered the Service to
submit for publication in the Federal Register by November 23, 2005, or
as soon thereafter as was practicable, a notice advising the public
that the January 3, 2003, withdrawal was vacated and that the November
29, 1993, proposed listing rule was reinstated. On December 7, 2005, we
published a notice in the Federal Register vacating the January 3,
2003, withdrawal and restoring proposed status to the flat-tailed
horned lizard (70 FR 72776).
The November 17, 2005, order limited the scope of the remand to
specifically address whether the lost historical habitat is a
significant portion of the range for the flat-tailed horned lizard. The
Court further required the Service to publish a determination in the
Federal Register by April 30, 2006, as to whether the lost historical
habitat of the flat-tailed horned lizard constitutes a significant
portion of the species' range based on the best scientific and
commercial data available. On March 2, 2006, we published a notice
announcing the reopening of a 14-day public comment period on the
November 29, 1993, proposed rule to list the flat-tailed horned lizard
under the Act (71 FR 10631). To ensure the public was provided with an
adequate opportunity to comment on the matters identified by the Court,
the parties filed a Joint Stipulation with the Court on March 28, 2006,
to allow for an additional public comment period. On March 29, 2006,
the Court granted our request for an extension of the April 30, 2006,
deadline, and ordered us to submit the new final listing determination
for the flat-tailed horned lizard to the Federal Register on or before
the date 6 weeks after the close of the second comment period. The
second comment period was opened from April 21, 2006 to May 8, 2006 (71
FR 20637). This withdrawal of the November 29, 1993, proposed listing
rule complies with the Court's August 30, 2005, and November 17, 2005,
orders.
For your convenience, here is a list of the primary Federal
Register documents pertaining to the proposed listing of the flat-
tailed horned lizard as threatened:
------------------------------------------------------------------------
Action Date FR citation
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Proposed rule to list the flat- November 29, 1993. 58 FR 62624
tailed horned lizard as
threatened.
Withdrawal of proposed rule.... July 15, 1997..... 62 FR 37852
Reinstatement of proposed rule; December 26, 2001. 66 FR 66384
reopening of comment period.
Withdrawal of proposed rule.... January 3, 2003... 68 FR 331
Reinstatement of proposed rule. December 7, 2005.. 70 FR 72776
Reopening of comment period.... March 2, 2006..... 71 FR 10631
Reopening of comment period.... April 21, 2006.... 71 FR 20637
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Summary of Comments and Recommendations
During both public comment periods on the December 7, 2005
reinstatement of the proposed rule to list, we requested all interested
parties to submit information pertaining to the flat-tailed horned
lizard's lost historical habitat. We requested this information to make
a reexamination based on the best scientific and commercial data
currently available. We also reopened the comment period to admit into
the record the 2003 revision of the Flat-tailed Horned Lizard Rangewide
Management Strategy. During the public comment periods, we received
written comments from a total of 29 entities. Nineteen entities
advocated listing of the species, 5 entities advocated not listing the
species, and 5 entities did not advocate either decision.
As stated previously, in its November 17, 2005 Order, the Court
ordered that ``on remand the agency need only address the matters on
which the court's August 30, 2005 Order * * * found the January 3, 2003
Withdrawal unlawful, which may summarily be identified as whether the
lizard's lost historical habitat renders the species in danger of
extinction in a significant portion of its range.'' We received two
comments directly related to the issue of the flat-tailed horned
lizard's lost historical habitat. However, for informational purposes,
we have also provided responses to comments on other substantive issues
as well. Similar comments are grouped together.
Comment 1: One commenter stated that there does not appear to be
strong scientific evidence to establish the extent of the historical
range of the lizard. The commenter stated that claims that east
Imperial County and west Yuma County were historically occupied by
flat-tailed horned lizards are unsupportable. The commenter indicates
that the present range seems adequate to prevent the extinction of this
species.
Our Response: Delineation of historical habitat is retrospective
and not testable in the way that other scientific models are. However,
based on knowledge of habitat preference for the species, early
descriptions of habitat before development, and early museum records, a
reasonable and defensible theoretical estimation of the broad-scale
historical range of the species is possible. While there are a number
of records of flat-tailed horned lizards from the Imperial Valley and
the Yuma Valley in areas that are now developed, locality records do
not fully delineate the theoretical range of the flat-tailed horned
lizard. Historical museum records are summarized in Funk (1981).
Comment 2: One commenter stated that the habitat destroyed by human
mediated processes and no longer available for the flat-tailed horned
lizard in the Imperial, Coachella, and Yuma valleys was significant to
the species from a metapopulation dynamics perspective because the
availability of large, continuous patches of potentially available
habitat provides areas for species to persist as resources (i.e. food,
water, and habitat) shift geographically over time.
Our Response: We interpreted the commenter's statements to pertain
to the importance of maintaining large-scale metapopulation dynamics
between populations in the Imperial, Coachella, and Yuma valleys.
Metapopulation dynamics refers to the process exhibited when local
populations become extirpated in response to local conditions but are
later recolonized by adjacent patches.
We acknowledge that large-scale metapopulation dynamics and gene
flow have been disrupted by the loss of connectivity between
populations in these areas; however, this loss of connectivity
endangers primarily Coachella Valley populations because the other
populations are large enough to be self-sustaining. We recognized the
precarious status and possibility of extinction of the flat-tailed horned
[[Page 36748]]
lizard in the Coachella Valley in the January 3, 2003, withdrawal,
further acknowledging that if the Coachella Valley populations go
extinct, there is no connectivity for repopulation from other areas
(e.g., Imperial Valley). However, we determined that the Coachella
Valley populations are not a distinct vertebrate population segment and
that the Coachella Valley is not a significant portion of the species'
range.
Relevant to the importance of maintaining large-scale
metapopulation dynamics between Imperial and Yuma Valley populations,
most of the intermittent and permanent habitat that has been lost due
to human mediated processes (e.g., urbanization and agriculture) was
lost early in the 20th century. This lost habitat is not considered
significant because of its small size relative to the entire range and
because this area has been lost for nearly a century and the flat-
tailed horned lizard has persisted in these areas.
As discussed in detail in the January 3, 2003, withdrawal of the
proposed listing rule (68 FR 331), the available data concerning
population abundance, trends, and threats do not suggest, outside the
Coachella Valley, that flat-tailed horned lizard populations are
declining in any of the geographic areas, or that because of this
habitat loss and degradation the species is likely to become endangered
within the foreseeable future throughout all or a significant portion
of its range. As discussed below, recent estimates of population sizes
in several management areas in the Imperial Valley (Ocotillo Wells
Research Area, West Mesa, Yuha Basin, and East Mesa) and Yuma Valley
(Yuma Desert Management Areas) since the January 3, 2003, withdrawal of
the proposed listing rule indicate that, overall, no large decline in
population size has occurred between 2003 and 2005 in areas for which
we have more than one year of data.
Therefore, we do not believe the lost habitat is significant to the
species from a large-scale metapopulation perspective, because
populations in the Imperial and Yuma valleys appear to be large enough
to be self-sustaining despite the loss of habitat between these valleys
that occurred early in the 20th century.
Comment 3: Several commenters stated that this species needs the
protection of the Endangered Species Act.
Our Response: As stated in our January 3, 2003, withdrawal of the
proposed rule to list the species as threatened (68 FR 331), we have
made this determination because threats to the species as identified in
the November 29, 1993, proposed rule are not significant, and available
data do not indicate that the threats to the species and its habitat,
as analyzed under the five listing factors described in section 4(a)(1)
of the Act, are likely to endanger the species in the foreseeable
future throughout all or a significant portion of its range.
Also, we have determined, as discussed in this notice, that the
lost historical habitat does not render the species in danger of
extinction throughout all or a significant portion of its range.
Commenters did not provide new information or data during either
comment period on additional threats not already considered in the
January 3, 2003, withdrawal.
Comment 4: Several commenters noted the impacts to the flat-tailed
horned lizard that would be associated with the construction of the
proposed Yuma Area Service Highway.
Our Response: The Yuma Area Service Highway has been discussed at
many Arizona Interagency Coordinating Committee (ICC) meetings. Arizona
ICC members met repeatedly with Arizona Department of Transportation
(DOT) engineers to ensure compliance with the 2003 Rangewide Management
Strategy. The Arizona DOT already had long-term plans to construct this
highway when the 1997 Conservation Agreement was signed. Therefore, the
western border of the Yuma Desert Management Area was defined as the
edge of the right-of-way of the future Yuma Area Service Highway. Until
the highway is built, the lands under jurisdiction of the signatories
of the Conservation Agreement will be managed as part of the Yuma
Desert Management Area. The highway, as proposed, would destroy 623 ac
(252 ha) of flat-tailed horned lizard habitat and isolate 3,734 ac
(1,511 ha) from the Yuma Desert Management Area. Thus, the Yuma Area
Service Highway shrinks the 131,000-ac (53,000-ha) Yuma Desert
Management Area by a relatively small amount. It is our understanding
from the Arizona members of the ICC that Arizona DOT intends to pay
compensation for 4,277 ac (1,731 ha) of flat-tailed horned lizard
habitat impacted or isolated by the project and that fencing will be
installed to deter lizards from crossing the pavement where they may be
subject to mortality because of traffic.
Comment 5: Several commenters noted that the Bureau of Reclamation
plans to construct a new reservoir, the All American Canal Drop 2
reservoir, on East Mesa in flat-tailed horned lizard habitat.
Our Response: The All American Canal Drop 2 reservoir, proposed for
construction in Imperial County, California, was discussed extensively
at the flat-tailed horned lizard ICC meetings. The 621-acre (251-ha)
reservoir, as proposed, will be built on the site formerly used for the
Brock Ranch Experimental Research Station and will be adjacent to, but
outside the boundaries of the 115,300-acre (46,660-ha) East Mesa
Management Area. A map released by the Bureau of Reclamation (BOR)
showed that half of the reservoir would be within the boundaries of the
East Mesa Management Area. However, according to the BLM, that map was
in error. The input canal from the Coachella Canal to the Drop 2
reservoir will cross BLM land in the East Mesa Management Area, along
the southern boundary, and will directly impact 295 ac (119 ha) in the
Management Area. The input canal will also isolate two small areas of
the Management Area; however, these areas are of limited value to flat-
tailed horned lizards. The first area is 120 ac (49 ha) in the
southeast corner of the Management Area that is already highly impacted
by off-highway vehicle (OHV) activity. The second area is 320 ac (129
ha) on private land that is currently an abandoned jojoba farm and not
suitable habitat for flat-tailed horned lizards. It is our
understanding from BLM staff that all areas impacted, including the
areas to be isolated, will be compensated for by BOR at the ratio
dictated by the 2003 Rangewide Management Strategy. Since this
Management Area is not fenced, the location of the input canal will
benefit the Management Area by creating a barrier that will discourage
illegal OHV activity. The amount of habitat impacted will fall below
the 1 percent of Federal lands allowed by the 2003 Rangewide Management
Strategy.
Comment 6: Several commenters pointed out plans for geothermal
plants in flat-tailed horned lizard habitat.
Our Response: It is our understanding from BLM staff that several
applications for geothermal leases in the West Mesa Management Area and
the Ocotillo Wells State Vehicle Recreation Area have been submitted.
At this point in time, the construction of geothermal plants is
speculative. A lease allows a project applicant to evaluate the site
for geothermal energy. If it is then suitable, the applicant and the
BLM must go through the National Environmental Policy Act (NEPA)
process prior to constructing the geothermal facilities. The NEPA
requires the Federal agencies to consider the environmental impacts,
including impacts to listed and sensitive
[[Page 36749]]
species, of their proposed actions and reasonable alternatives to those
actions.
Comment 7: Several commenters noted the proposal for a large solar
energy plant in flat-tailed horned lizard habitat in Imperial Valley.
Our Response: The solar plant was originally proposed to be built
in the West Mesa Management Area, but because of the 2003 Rangewide
Management Strategy the BLM asked that it be moved out of the West Mesa
Management Area and the project proponents agreed. According to the
BLM, the current proposed site is on BLM land, is not within any
Management Area occupied by the flat-tailed horned lizard, and
compensation for any flat-tailed horned lizard lost habitat will be
applied, if applicable.
Comment 8: Several commenters noted the extensive Border Patrol
activity in flat-tailed horned lizard habitat.
Our Response: The Border Patrol is not a signatory of the 1997
Conservation Agreement; however, the ICC works with them on
conservation issues. In California, new Border Patrol agents are
educated on the impacts to biological and archaeological resources by
driving off-road. Recently, an educational video paid for by flat-
tailed horned lizard compensation funds was distributed to Border
Patrol offices and they agreed to show the video to all existing agents
as well as incorporate it into the training for new agents. It is our
understanding that the ICC intends to continue working with the Border
Patrol to minimize impacts to flat-tailed horned lizard and its habitat
associated with the performance of their duties along the border.
Comment 9: Several commenters stated that the 1997 Conservation
Agreement and Rangewide Management Strategy are not working.
Our Response: Progress toward the goals of the 1997 Rangewide
Management Strategy was evaluated during the 2003 revision of the
Rangewide Management Strategy and yearly in annual reports. Some of the
progress made includes the following: Between 1997 and 2003, surface
disturbance was kept well below the 1 percent cap in each of the five
Management Areas. Designation of the Management Areas has occurred and
the 2003 Rangewide Management Strategy has become an official part of
the BLM California Desert Conservation Area plan. The Management Areas
comprise 485,000 ac (196,273 ha) or 758 square miles (1,963 square
kilometers) of presumably the best flat-tailed horned lizard habitat on
Federal lands. Compensation funds have been collected for projects in
flat-tailed horned lizard habitat and will continue to be collected.
These funds have been used to purchase private lands within Management
Areas.
As outlined in the 1997 Conservation Agreement, research and
monitoring for this species have been funded. Research on basic biology
such as significant predators, home range size, diet, and reproduction
has been conducted since the 1997 Conservation Agreement was signed.
Research on impacts such as edge effects and OHV effects has also been
conducted. Studies have also been conducted, or are planned, on the
efficacy of mitigation measures such as relocation of lizards from
project sites and use of under-highway culverts by this species.
Methods to monitor this species, such as scat counts, mark-recapture,
presence/absence, trapping webs, distance sampling, and occupancy
estimation have been tested for this species, and population estimates
have been obtained for four Management Areas and the Research Area.
Based on these actions as well as others not explicitly mentioned
above, we believe that the 1997 Conservation Agreement is helping to
conserve the flat-tailed horned lizard and its habitat.
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1531 (et seq.) and the regulations
(50 CFR part 424) that implement the listing provisions of the Act set
forth the procedures for adding species to the Federal list of
endangered and threatened species. They provide that a species may be
determined to be endangered or threatened if one or more of the
following five factors are met:
A. The present or threatened destruction, modification, or
curtailment of its habitat or range.
B. Overutilization for commercial, recreational, scientific, or
educational purposes.
C. Disease or predation.
D. The inadequacy of existing regulatory mechanisms.
E. Other natural or manmade factors affecting its continued existence.
As stated above, the November 17, 2005, Court Order limited the
scope of the remand to specifically address whether the lost historical
habitat is a significant portion of the range for the flat-tailed
horned lizard. (See the January 3, 2003, withdrawal of the proposed
listing rule [68 FR 331] for the full discussion of the five factors
and their application to the flat-tailed horned lizard.) Therefore, the
sole purpose of this withdrawal is to reexamine and expand upon our
previous discussions of the five factors in order to address whether
the lost historical habitat is a significant portion of the range for
the flat-tailed horned lizard. The analysis in this document will
primarily reflect lost historical habitat as a component of factor A
because factor A requires an analysis of whether the curtailment of a
species' habitat or range is a threat to its continued existence.
Historical and Current Range, and Temporal Baseline
We consider the 2003 Rangewide Management Strategy to be the best
scientific and commercial information available on the historical and
current range of the species. The 2003 Rangewide Management Strategy
builds on previous information on the range of the species (i.e.,
Johnson and Spicer 1985; Hodges 1997) and bases the delineation of
historical and current range on the presence of suitable habitat, known
localities, and elevation (flat-tailed horned lizards have rarely been
found above 750 ft in elevation). As stated above, we analyzed the GIS
data used in the 2003 Rangewide Management Strategy, which depicted the
approximate current and historical distribution of the flat-tailed
horned lizard. We also used GIS to estimate the extent of historic Lake
Cahuilla, which was subtracted from the current and historical range of
the species. We used our analysis to estimate the historical range of
the flat-tailed horned lizard in the United States and Mexico to be
4,875,624 ac (1,973,095 ha).
Temporal Baseline
In the memorandum of support for the District Court order of August
30, 2005, the Court ``found that the Service had failed to satisfy the
Ninth Circuit's mandate in a prior phase of this case, by failing to
examine whether lost historical habitat constituted a `significant
portion' of the species' range.'' In citing the Ninth Circuit, the
District Court noted that the Service `has discretion to choose the
point in time at which to examine the range because neither the Ninth
Circuit nor the [Endangered Species Act] provide `a temporal baseline
for assessing a species' total range' * * *. The point in time must be
sometime in the past, however, and cannot be the current range.'' In
identifying the lost historical habitat for the flat-tailed horned
lizard, we determined it was appropriate to consider the available
recorded historical information.
[[Page 36750]]
Lake Cahuilla
Lake Cahuilla is an important consideration in determining the
historical range of the flat-tailed horned lizard. From prehistoric
times to the formation of the current-day Salton Sea, Lake Cahuilla
intermittently filled a portion of the Salton Trough. Thus, the lakebed
was intermittent habitat for the flat-tailed horned lizard. Lake
Cahuilla completely filled and evaporated 4 times between 700 to 1580
AD (Waters 1983). At other times, spring floods on the Colorado River
would partially fill the trough. During the 1800s, reported episodes of
inundation occurred in 1828, 1840, 1849, 1852, 1859, 1862, 1867, and
1897 (Littlefield 1966). A flood in 1891 created a water body of
approximately the same surface area as the current Salton Sea (Sykes
1914). The 2003 Rangewide Management Strategy, in discussing the
historical range of the flat-tailed horned lizard, states: ``The Salton
Basin [Salton Trough] had been subjected to frequent inundation from
the Colorado River even prior to the accidental flooding from 1905
through 1907, and it is questionable whether this area can be
considered historic habitat.'' Flat-tailed horned lizards were likely
killed during floods as the water rushed into the basin and
recolonization occurred as the water evaporated.
Even when the lake was dry, a large portion of the dry lakebed was
likely unsuitable habitat for flat-tailed horned lizards. The lowest
point of the trough was covered in a thick deposit of salt left behind
when the water evaporated (Free 1914), which was likely devoid of plant
and animal life. This area is now covered by the Salton Sea. Desert
sinks and playas like the Salton Trough are typically inhabited by a
salt-tolerant community dominated by Atriplex (saltbush) species
(Baldwin et al. 2002). In the saltiest and wettest parts of a desert
sink, Atriplex is replaced by more salt-tolerant plants such as
pickleweed (Salicornia), iodine bush (Allenrolfea), and seepweed
(Suaeda). Parish (1914) defined the ``Salton Sink'' as the area between
the shoreline of Lake Cahuilla and the then-shrinking Salton Sea. He
characterized the vegetation within the Salton Sink as the Atriplex
zone, because of the domination by Atriplex in the sink. ``Of this
general flora of the Colorado Desert the xerophytic vegetation of the
Sink is a part, differentiated mainly by the great preponderance of
Atriplex spp. in its composition, so that it may be fittingly
denominated the Atriplex zone'' (Parish 1914, p. 89). Creosote, a
typical habitat associate for flat-tailed horned lizards, was
characterized as ``frequent in arid soil throughout the Sink, but
scattered and seldom dominant'' (Parish 1914, p. 109). Parish described
white bursage, another typical habitat associate for flat-tailed horned
lizards, as ``frequent in detrital soil and occasional in light
alluvium. [Locations:]
Mecca, Caleb, Durmid, Westmorland.'' He
described detrital soils as primarily occurring on the northeast margin
of the Sink. Thus, the lakebed of Lake Cahuilla was not the typical
creosote-bursage habitat association as has been described for this
species (Turner and Medica 1982, Turner et al. 1980, FTHL-ICC 2003).
The Atriplex community in the lakebed was, at best, likely marginal
habitat for flat-tailed horned lizards. Flat-tailed horned lizards have
been found in association with Atriplex in the Dos Palmas area and San
Sebastian Marsh area, but a mark-recapture plot in desert sink scrub
with no sand in the Dos Palmas ACEC found no flat-tailed horned lizards
(Mark Massar, Wildlife Biologist, BLM, Palm Springs, pers. comm. 2005).
The area surrounding San Sebastian Marsh is in the lakebed of Lake
Cahuilla and mirrors the vegetation associations described by Parish
(1914) with areas of Atriplex, iodine bush, and mesquite, but the San
Sebastian Marsh area has yielded very few flat-tailed horned lizards
(FTHL-ICC 2003). Turner et al. (1980) recognized that the lakebed
appeared to be lesser quality habitat: ``In Imperial County, habitats
above the old shoreline of Lake Cahuilla are better than those below
the shoreline, possibly because soils above the old shoreline tend to
be sandier.''
The first known historical record of a flat-tailed horned lizard
from the lakebed of Lake Cahuilla was collected near the present-day
city of Calexico (Klauber 1932). Other flat-tailed horned lizards were
collected early in the 20th century near the present-day cities of
Westmorland and Holtville and from the edges of the Salton Sea (Klauber
1932; Funk 1981; Turner et al. 1980). These areas are now urban or
agricultural areas. Turner and others (1980), noting the few flat-
tailed horned lizards found in association with Atriplex, suggested
they may represent dispersing individuals. In most cases, flat-tailed
horned lizard populations in Atriplex habitat appear to be sparse. The
exception to this rule may be the high densities of flat-tailed horned
lizards found associated with Atriplex in the Coachella Valley (FTHL-
ICC 2003). However, the windblown sand preferred by flat-tailed horned
lizards is found in adequate amounts in the Coachella Valley Preserve
(Barrows 1996). The San Sebastian Marsh and Dos Palmas areas described
above have little windblown sand. Parish (1914) describes the soils of
the southern part of the sink (south of the current-day Salton Sea) as
``loams of very fine compact grain * * * with very small percentages of
sand. They are permeable by water only to a slight degree.'' No
information has been found on the amount of wind-deposited sand that
was present in the lakebed. Free (1914) alludes to accretion dunes in
the lakebed that may have been good flat-tailed horned lizard habitat.
But Parish (1914), describing the vegetation of the Imperial Valley,
reported ``wide expanses absolutely devoid of a single plant save in
the infrequent furrows and channels which constitute the drainage system.''
The precise proportion of the lakebed that historically was
habitat, and the quality of that habitat, is difficult to accurately
determine. We do not know the precise proportions of specific plant
communities that were present in the Salton Sink. We do not know the
patterns of windblown sand deposition. Despite the difficulty in
accurately determining historic conditions in the dry lakebed, we
believe that it contained only a limited amount of suitable habitat,
most of which is likely to have been marginal at best. Thus, even if
the lakebed were considered historical habitat, it would not be
significant to the species.
Additionally, recent work on the genetics of the flat-tailed horned
lizard suggests that gene flow across the lakebed between the east and
west sides of the Salton trough was low even before the current
fragmentation due to development and agriculture (Mulcahy et al. 2006).
The authors state: ``* * * suggesting that there has not been
substantial gene flow across the Imperial Valley since the drying of
Lake Cahuilla. Although historic localities exist in the Imperial
Valley, genetic differences suggested limited gene flow across this
region prior to human development.''
Lost Habitat
As discussed above, the area of the historical range periodically
inundated by Lake Cahuilla was not important to the long-term viability
of the flat-tailed horned lizard because this area was frequently
unavailable and likely contained little quality habitat. Much of the
area within the former Lake Cahuilla lakebed likely was not only
intermittent, but low-quality habitat for the flat-tailed horned
lizard, particularly the central salt deposit and saltier, less sandy
portions of the Atriplex community. Thus, we determined this area
should not be considered part of the species'
[[Page 36751]]
historical habitat. The remainder of this analysis considers the
historical habitat outside the area of the former Lake Cahuilla to be
the appropriate baseline for assessing the species' total range. Using
our estimate that the former Lake Cahuilla was 1,309,409 ac (529,899
ha) based on a 39 ft (12 m) shoreline (Waters 1983) calculated with a
GIS digital elevation model, the baseline for assessing the species'
range (which excludes the former Lake Cahuilla) was approximately
4,875,624 ac (1,973,095 ha). Below we describe the significance of lost
habitat within this delineated historical habitat (outside the area of
the former Lake Cahuilla).
Approximately 1,103,201 ac (446,450 ha) have been lost, nearly
entirely within two areas: the Coachella Valley, and Mexicali and Yuma
areas. In the January 3, 2003, withdrawal, we determined that the
Coachella Valley, including its lost associated habitat, is not a
significant portion of the range. Near Mexicali, agriculture extends
from Mexicali south to near the Gulf of California and east to the
Colorado River. This block of lost habitat is contiguous (across the
Colorado River) with the block of lost habitat in the Yuma area. The
block of habitat that encompasses northeastern Baja California Norte
and southwestern Arizona is the largest block of lost habitat.
These habitat areas were likely converted to agriculture early in
the 20th century, similar to that described for the Imperial Valley
(Imperial Irrigation District 2002). The lost habitat is not
significant because of its small size relative to the entire range and
because this area has been lost to agriculture for nearly a century and
the flat-tailed horned lizard has persisted. Since the early 20th
century, the species has persisted on East Mesa and West Mesa, and in
the Yuha Basin over many generations. Flat-tailed horned lizards rarely
live more than 4 years in the wild and can reproduce in their first or
second year (FTHL-ICC 2003). If the median generation time is 2 years,
then more than 25 generations of flat-tailed horned lizards have come
and gone since most of the habitat conversion to agriculture production
took place. This continued persistence over a span of nearly 100 years
is a strong indication that the species will continue to persist into
the foreseeable future despite the loss of historical habitat.
We do not expect additional conversion of flat-tailed horned lizard
habitat to agriculture in the future in the Imperial Valley and
elsewhere along the Colorado River given the existing limitations on
the availability of water for irrigation (Imperial Irrigation District
2002). In fact, a recent water transfer agreement with San Diego
required some fields to remain fallow (unirrigated); therefore,
agricultural use may even decrease in this area (Imperial Irrigation
District 2006).
Though the lost habitat is situated between the Arizona-Sonora and
California-Baja California Norte populations, the Colorado River
already isolated these populations to some degree. The lost habitat of
the flat-tailed horned lizard in the United States and Mexico is not
viable for flat-tailed horned lizards in the foreseeable future. Much
of this habitat has been permanently lost due to urbanization and/or
flooding of the Salton Sea. Habitat lost due to agricultural uses may
be restored in certain cases in the future, though most agricultural
fields are isolated from existing flat-tailed horned lizard populations
by irrigation canals like the Coachella Canal, Highline Canal, and All-
American Canal. We do not anticipate any significant amount of
previously lost habitat could become viable habitat in the future.
In sum, we believe the lost habitat does not represent a
significant portion of the range of the flat-tailed horned lizard
because the lost habitat was lost decades ago and the species has
persisted. Most of the lost habitat was lost early in the century and
that lost habitat was not significant enough to lead to the species'
extirpation within intact habitat through edge effects or
fragmentation. There were no attributes or specific uses of the lost
habitat by flat-tailed horned lizards that made it any more significant
than any other habitat. For example, a significant part of a range for
a species might be a breeding ground or lek site, but there is nothing
of the sort for flat-tailed horned lizards. Additionally, as discussed
in detail in the January 3, 2003, withdrawal of the proposed listing
rule (68 FR 331), the available data concerning population abundance,
trends, and threats do not suggest, outside the Coachella Valley, that
flat-tailed horned lizard populations are declining in any of the
geographic areas, or that because of this habitat loss and degradation
the species is likely to become endangered within the foreseeable
future throughout all or a significant portion of its range. Recent
estimates of population sizes have been conducted in the West Mesa,
Yuha Basin, East Mesa, and the Yuma Desert Management Areas and
Ocotillo Wells Research Area since the January 3, 2003, withdrawal of
the proposed listing rule (Young et al. 2004; Hollenbeck, Environmental
Scientist, California Department of Parks and Recreation, pers. comm.
2005; Grant 2005). Overall, no large decline in population size
occurred between 2003 and 2005 in areas for which we have more than one
year of data (Grant 2005, Hollenbeck, Environmental Scientist,
California Department of Parks and Recreation, pers. comm. 2005).
Finding
On January 3, 2003 (68 FR 331), the Service issued a decision to
withdraw the proposal to list the flat-tailed horned lizard. The Tucson
Herpetological Society and other environmental organizations and
individuals filed a lawsuit to challenge our decision. The U.S.
District Court for the District of Arizona upheld our decision with the
exception that we had failed to consider whether the lost historical
range of the flat-tailed horned lizard constituted a significant
portion of the range. This notice addresses this issue.
We reviewed the best scientific and commercial data available and
determined that the lost habitat is not a significant portion of the
species range, and does not render the species likely to become
endangered within the foreseeable future throughout all or a
significant portion of its range. We conclude that the lost habitat is
not significant because the species has persisted despite a large
amount of habitat loss in the early 20th century, the species remains
viable throughout most of its current extant range, and there were no
particular attributes of the lost habitat that made it any more
significant than any other part of the range. Therefore, based on the
above reasoning and the reasoning presented in the January 3, 2003
withdrawal of the proposed rule to list the flat-tailed horned lizard
(68 FR 331), we have determined that the flat-tailed horned lizard is
not likely to become in danger of extinction in the foreseeable future
throughout all or a significant portion of its range.
[[Page 36752]]
References Cited
A complete list of all references cited is available at the
Carlsbad Fish and Wildlife Office (see ADDRESSES above).
Author
The primary author of this document is the Carlsbad Fish and
Wildlife Office (see ADDRESSES above).
Authority
The authority for this action is section 4(b)(6)(B)(ii) of the
Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: June 20, 2006.
Marshall Jones, Jr.,
Acting Director, U.S. Fish and Wildlife Service.
[FR Doc. E6-10138 Filed 6-27-06; 8:45 am]
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