Endangered and Threatened Wildlife and Plants; Endangered Status for Dunes Sagebrush Lizard, 77801-77817 [2010-31140]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 75, Number 239 (Tuesday, December 14, 2010)]
[Proposed Rules]
[Pages 77801-77817]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-31140]


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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2010-0041; MO 92210-0-0008]
RIN 1018-AV97


Endangered and Threatened Wildlife and Plants; Endangered Status 
for Dunes Sagebrush Lizard

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to list the 
dunes sagebrush lizard (Sceloporus arenicolus), a lizard known from 
southeastern New Mexico and adjacent west Texas, as endangered under 
the Endangered Species Act of 1973, as amended. If we finalize the rule 
as proposed, it would extend the Act's protections to this species. We 
have determined that critical habitat for the dunes sagebrush lizard is 
prudent but not determinable at this time.

DATES: We will consider comments received or postmarked on or before 
February 14, 2011. We must receive requests for public hearings, in 
writing, at the address shown in the FOR FURTHER INFORMATION CONTACT 
section by January 28, 2011.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. 
Search for docket FWS-R2-ES-2010-0041 and then follow the instructions 
for submitting comments.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: FWS-R2-ES-2010-0041; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.
    We will post all information received on https://www.regulations.gov. This generally means that we will post any 
personal information you provide us (see the Public Comments section 
below for more details).

FOR FURTHER INFORMATION CONTACT: Wally ``J'' Murphy, Field Supervisor, 
New Mexico Ecological Services Field Office, 2105 Osuna, NE., 
Albuquerque, NM 87113; by telephone 505-761-4718 or by facsimile 505-
346-2542. Persons who use a telecommunications device for the deaf 
(TDD) may call the Federal Information Relay Service (FIRS) at 800-877-
8339.

SUPPLEMENTARY INFORMATION: 

Public Comments

    We intend that any final action resulting from this proposed rule 
will be based on the best scientific and commercial data available and 
be as accurate and as effective as possible. Therefore, we request 
comments or information from other concerned governmental agencies, 
Native American Tribes, the scientific community, industry, or any 
other interested parties concerning this proposed rule. We particularly 
seek comments concerning:
    (1) The historical and current status and distribution of the dunes 
sagebrush lizard, its biology and ecology, and ongoing conservation 
measures for the species and its habitat.
    (2) Information relevant to the factors that are the basis for 
making a listing determination for a species under section 4(a) of the 
Endangered Species Act of 1973, as amended (Act) (16 U.S.C. 1531 et 
seq.), which are:
    (a) The present or threatened destruction, modification, or 
curtailment of the species' habitat or range;
    (b) Overutilization for commercial, recreational, scientific, or 
educational purposes;
    (c) Disease or predation;
    (d) The inadequacy of existing regulatory mechanisms; or
    (e) Other natural or manmade factors affecting its continued 
existence and threats to the species or its habitat.
    (3) Which areas would be appropriate as critical habitat for the 
species and why they should be proposed for designation as critical 
habitat.
    (4) The reasons why areas should or should not be designated as 
critical habitat as provided by section 4 of the Act of 1973, including 
whether the benefits of designation would outweigh threats to the 
species that designation could cause, such that the designation of 
critical habitat is or is not prudent.
    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 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 the ADDRESSES section.
    If you submit a comment via https://www.regulations.gov, your entire

[[Page 77802]]

submission--including any personal identifying information--will be 
posted on the Web site. If your submission is made via a hard copy 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 comments on https://www.regulations.gov. Please 
include sufficient information with your comments to allow us to verify 
any scientific or commercial information you include.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov, or by 
appointment, during normal business hours, at the New Mexico Ecological 
Services Field Office (see FOR FURTHER INFORMATION CONTACT).

Background

Previous Federal Action

    On December 30, 1982, we published our notice of review classifying 
the sand dune lizard (dunes sagebrush lizard) as a Category 2 species 
(47 FR 58454). Category 2 status included those taxa for which 
information in the Service's possession indicated that a proposed rule 
was possibly appropriate, but for which sufficient data on biological 
vulnerability and threats were not available to support a proposed 
rule. Please note that we will be referring to this species throughout 
this finding using the currently accepted common name of dunes 
sagebrush lizard (Crother et al. 2008, p. 39).
    On September 18, 1985, we published our notice of review re-
classifying the dunes sagebrush lizard as a Category 3C species (50 FR 
37958). Category 3C status included taxa that were considered more 
abundant or widespread than previously thought or not subject to 
identifiable threats. Species in this category were not included in our 
subsequent notice of reviews unless their status had changed. 
Therefore, in our notice of review on November 21, 1991 (56 FR 58804), 
the dunes sagebrush lizard was not listed as a candidate species.
    On November 15, 1994, our animal candidate notice of review once 
again included the dune sagebrush lizard as a Category 2 species (59 FR 
58982), indicating that its conservation status had changed. On 
February 28, 1996, we published a Candidate Notice of Review (CNOR) 
that announced changes to the way we identify candidates for listing 
under the Act (61 FR 7596). In that document, we provided notice of our 
intent to discontinue maintaining a list of Category 2 species, and we 
dropped all former Category 2 species from the list. This was done in 
order to reduce confusion about the conservation status of those 
species, and to clarify that we no longer regarded them as candidate 
species. As a result, the dunes sagebrush lizard did not appear as a 
candidate in our 1996 (61 FR 7596; February 28, 1996), 1997 (62 FR 
49398; September 19, 1997), or 1999 (64 FR 57534; October 25, 1999) 
notices of review.
    In our 2001 CNOR, the dunes sagebrush lizard was placed on our 
candidate list with listing priority number (LPN) of 2 (66 FR 54807; 
October 30, 2001). Service policy (48 FR 43098, September 21, 1983) 
requires the assignment of an LPN to all candidate species that are 
warranted for listing. This listing priority system was developed to 
ensure that the Service has a rational system for allocating limited 
resources in a way that ensures that the species in greatest need of 
protection are the first to receive such protection. A smaller LPN 
reflects a need for greater protection than a larger LPN. The LPN is 
based on the magnitude and immediacy of threats and the species' 
taxonomic uniqueness with a value range from 1 to 12. A listing 
priority number of 2 for the dunes sagebrush lizard means that the 
magnitude and the immediacy of the threats to the species are high. 
Since 2001, the species has remained on our candidate list with an LPN 
of 2.
    On June 6, 2002, the Service received a petition from the Center 
for Biological Diversity to list the dunes sagebrush lizard. On June 
21, 2004, the United States District court for the District of Oregon 
(Center for Biological Diversity v. Norton, Civ. No. 03-1111-AA) found 
that our resubmitted petition findings for the southern Idaho ground 
squirrel, the dunes sagebrush lizard, and the Tahoe yellow cress that 
we published as part of the CNOR on May 4, 2004 (69 FR 24876), were not 
sufficient. The court indicated we did not specify what listing action 
is proposed for the higher priority species that precluded publishing a 
proposed rule for these three species, and that we did not adequately 
explain the reasons why actions for the identified species are deemed 
higher in priority, or why such actions result in the preclusion of 
listing actions for the southern Idaho ground squirrel, sand dune 
lizard, or Tahoe yellow cress. The court ordered that we publish 
updated findings for these species within 180 days of the order.
    On December 27, 2004, the Service published its 12-month finding, 
which determined that listing was warranted, but precluded by higher 
priorities (69 FR 77167). In that finding, the species remains on the 
candidate list with a LPN of 2.

Species Information

    The dunes sagebrush lizard is a small, light brown phrynosomatid 
lizard (family Phrynosomatidae, genus Sceloporus) with a maximum snout-
to-vent length of 70 millimeters (mm) (2.8 inches (in)) for females and 
65 mm (2.6 in) for males (Degenhardt et al. 1996, p. 160). Sabath 
(1960, p. 22) first described the occurrence of light-colored sagebrush 
lizards in southeastern New Mexico and western Texas. Kirkland L. Jones 
collected the type specimen for Sceloporus arenicolus on April 27, 
1968, in eastern Chaves County, New Mexico (Degenhardt et al. 1996, p. 
159). Degenhardt and Jones (1972, p. 213) described the dunes sagebrush 
lizard (Sceloporus graciosus arenicolus) as a subspecies of the 
sagebrush lizard (Sceloporus graciosus). The dunes sagebrush lizard was 
elevated to a species in 1992 and this elevation was validated with 
molecular and morphological evidence in 1997 (Painter et al. 1999, p. 
3). Much of the previous literature concerning Sceloporus arenicolus 
refers to it by the common name of sand dune lizard (e.g., Degenhardt 
et al. 1996, p. 159); however, the currently accepted common name is 
dunes sagebrush lizard (Crother et al. 2008, p. 39).
    The dunes sagebrush lizard's nearest relative is the sagebrush 
lizard (Sceloporus graciosus), which is found in sagebrush habitat in 
northwestern New Mexico. The dunes sagebrush lizard and sagebrush 
lizard were isolated from each other about 15,000 years ago during the 
late Pleistocene era, when areas that had become warm and dry separated 
suitable habitat for each species. It is estimated that the shinnery 
oak sand dune habitat with which the dunes sagebrush lizard is 
associated was also formed during this time (Bailey and Painter 1994, 
p. 22; Chan et al. 2008, p. 8). The dunes sagebrush lizard is a habitat 
specialist that is native to a small area of shinnery oak dunes in 
southeastern New Mexico and adjacent western Texas. The shinnery oak 
dune habitat extends from the San Juan Mesa in northeastern Chaves 
County, Roosevelt County, through eastern Eddy and southern Lea 
Counties in New Mexico (Fitzgerald et al. 1997, p. 15). In Texas, the 
dunes sagebrush lizard is found in a narrow band of shinnery oak dunes 
in Gaines, Ward, Winkler, and Andrews Counties (Laurencio et al. 2007, 
p. 8).

[[Page 77803]]

    Dunes sagebrush lizards are active between March and October and 
are dormant underground during the colder winter months. Mating has 
been observed in April and May (Sena 1985, p. 17). Females produce one 
to two clutches per year, with three to five eggs per clutch. 
Hatchlings appear between July and September (Hill and Fitzgerald 2007, 
p. 2; Sena 1985, p. 6).
Habitat
    The dunes sagebrush lizard is considered to be a habitat specialist 
because it has adapted to thrive only in a narrow range of 
environmental conditions that exist within shinnery oak dunes. Its 
survival is directly linked to the quality and quantity of available 
shinnery oak dune habitat (Fitzgerald et al. 1997, p. 8). Shinnery oak 
dune habitat is dependent upon the existence of shinnery oak (Quercus 
havardii) in areas of appropriate sediment availability. Each shinnery 
oak tree occurs primarily under ground, with only one-tenth of the 
plant standing 0.6 to 0.8 meters (m) (2 to 3 feet (ft)) above ground 
level. Shinnery oaks are clonal, meaning that each plant in a clone is 
descended asexually from a single ancestor. One clone can cover up to 
81 hectares (ha) (205 acres (ac)) and can live over 13,000 years, 
although individual stems on the surface may not be that old (Peterson 
and Boyd 1998, p. 5). These trees, with large root and stem masses and 
an extensive underground system of horizontal stems, support the 
dynamic dune system that is required by this lizard. Shinnery oak 
generally grows in permeable sandy soils, and does not grow in areas 
with high amounts of calcium carbonate or caliche, a hardened deposit 
of calcium carbonate (Peterson and Boyd 1998, p. 7), as discussed 
further below. Shinnery oak is very drought-tolerant and has a vertical 
root system that extends 4.6 to 6.1 m (15 to 20 ft) below the surface 
(Peterson and Boyd 1998, p. 5).
    The unique shinnery oak dune ecosystem was formed in the late 
Pleistocene era when wind erosion of the Blackwater Draw formation and 
shinnery oak encroachment formed the dune system. The prevailing winds 
blow from the southwest to the northeast, creating the sand 
accumulation along the western edge of the Llano Estacado (a large mesa 
or tableland) (Muhs and Holliday 2001, p. 82). The dune fields of 
western Texas and eastern New Mexico are being stabilized by the 
shinnery oak cover and would flatten without the stability provided by 
this vegetation (Muhs and Holliday 2001, p. 75). The dune system is 
stable in most areas except where land practices have caused vegetation 
removal and shifting sands (Muhs and Holliday 1995, p. 198). It is 
estimated that shinnery oak historically covered 1,068,370 ha 
(2,640,000 ac) in New Mexico and 1,416,400 ha (3,500,000 ac) in Texas 
(Peterson and Boyd 1998, p. 2). Large portions of this shinnery oak 
habitat have been converted to cropland and rangeland. The shinnery oak 
community is not spreading, and its boundaries have not changed since 
early surveys, suggesting that new habitat is not being created 
(Peterson 1992, p. 2).
    In 1982, it was estimated that there was one million acres (404,686 
ha) of shinnery oak dunes in New Mexico (McDaniel et al. 1982, p.12). 
Currently, the amount of shinnery oak dune habitat is estimated to be 
600,000 acres (248,811 ha), a 40 percent loss since 1982. Continued 
loss of shinnery oak dunes within the geographic range of the dunes 
sagebrush lizard since then has likely further decreased the amount of 
habitat available.
    The connection between dunes sagebrush lizards and the shinnery oak 
dune system is very specific, and the range of the species is closely 
linked to the distribution of shinnery oak dunes (Fitzgerald et al. 
1997, p. 4). The landscape created by the shinnery oak dune community 
is a spatially dynamic system. Shinnery oak and sand dunes form large 
dune complexes that are separated by flat areas without dunes called 
shinnery oak flats. It would be feasible to find dunes sagebrush 
lizards in shinnery oak flats that are adjacent to occupied dunes. 
Suitable habitat is separated by a mosaic of habitat types within or 
near the range of dunes sagebrush lizard. Landforms separating habitat 
may include mesquite hummocks, grasslands, and tabosa flats that are 
lacking shinnery oak and dominated by tabosa grass (Hilaria mutica) and 
scattered mesquite (Prosopis glandulosa).
    Shinnery oak dune habitat is altered and moved by natural processes 
like wind and rain. Over time, with wind and rain eroding sand dunes, 
areas that contain dunes flatten out and new dunes form in the flats 
(Muhs and Holliday 2001, p. 75). These new dune complexes may then 
support dunes sagebrush lizards, so that areas that are currently 
unoccupied may become occupied with shifts in dunes over time 
(Fitzgerald et al. 1997, p. 27).
    As discussed above, dunes sagebrush lizards are not found at sites 
lacking shinnery oak dune habitat (Fitzgerald et al. 1997, p. 2). 
Shinnery oak provides structure to the dune system, shelter for 
thermoregulation (regulation of body temperature), and habitat for the 
dunes sagebrush lizard's insect prey base (Bailey and Painter 1994, p. 
22, Fitzgerald et al. 1997, p. 4). Within the shinnery oak dune system, 
dunes sagebrush lizards are found in deep, wind-hollowed depressions 
called blowouts, which are near vegetated edges where they escape under 
leaf litter or loose sand during the hot part of the day and at night 
(Painter et al. 2007, p. 3). The large, steep blowouts provide habitat 
for thermoregulation, foraging, predator avoidance, and the dunes 
sagebrush lizard's prey base. The diet of the dunes sagebrush lizard 
includes ants (Order Hymenoptera, Family Formicidae) and their pupae; 
small beetles (Order Coleoptera), including lady bird beetles (Family 
Coccinellidae) and their larvae; crickets (Order Orthoptera); 
grasshoppers (Order Orthoptera); and spiders (Order Araneae) 
(Degenhardt et al. 1996, p. 160).
    Sand grain size appears to be a limiting factor in the distribution 
and occurrence of the dunes sagebrush lizard within the shinnery oak 
dunes. Laboratory and field experiments designed to determine sand 
grain preference demonstrated that dunes sagebrush lizards select sites 
with more medium sand grains and do not use finer sands (Fitzgerald et 
al. 1997, p. 6). Finer sand grain sizes are thought to limit the dunes 
sagebrush lizard's ability to effectively breathe when they bury 
themselves to avoid predators or to thermoregulate. Dunes sagebrush 
lizards instead prefer sand that is suitable for burying but not too 
fine to prevent respiration (Fitzgerald et al. 1997, p. 23). Sand grain 
size is also important in the establishment of dune blowouts and can 
influence the dune structure (Fitzgerald et al. 1997, p. 6).
    The shinnery oak flats are used for movement of females to find 
nesting sites and for possible dispersal of recent hatchlings (Hill and 
Fitzgerald 2007, p. 5). Females often utilize more than one dune during 
the nesting season and have home range sizes of about 436 square meters 
(m\2\) (4,693 square feet (ft\2\)). The largest recorded home range is 
2,799.7 m\2\ (9,185.4 ft\2\), which includes the movement of the 
tracked female from her primary home range to her nesting site (Hill 
and Fitzgerald 2007, p. 5). Females build nest chambers and lay eggs in 
the moist soil below the surface. Nests have been observed on west-
facing, open sand slopes with little to no vegetation, approximately 18 
centimeters (7.1 in) below the sand surface (Hill and Fitzgerald 2007, 
p. 5).

[[Page 77804]]

Distribution
    The dunes sagebrush lizard is limited to a narrow, isolated band of 
shinnery oak dunes between elevations of 780 and 1,400 m (2,600 and 
4,600 ft) in southeastern New Mexico and adjacent western Texas. 
Populations are separated by vast areas of naturally unsuitable and 
unoccupied habitat (Painter et al. 1999, p. 1).

New Mexico

    The known geographic range of the dunes sagebrush lizard in New 
Mexico includes portions of Chaves, Roosevelt, Lea, and Eddy Counties 
(Fitzgerald et al. 1997, p. 23). At its widest, the dunes sagebrush 
lizard's range is 2,693 hectares (6,654 ac) and in some areas is less 
than 233 hectares (576 ac) wide (Fitzgerald et al. 1997, p. 2).
    The distribution of the dunes sagebrush lizard in New Mexico was 
not formally described until 1997, using the results of 169 
standardized surveys conducted at 157 sites. Of the 157 sites surveyed, 
72 sites were determined to be occupied by dunes sagebrush lizards. 
Thirty of these sites are in Chaves County, 8 in Eddy County, 4 in 
Roosevelt County, and 30 in Lea County (Fitzgerald et al. 1997, 
Appendix 1). During 2008, 54 of the 72 positive sites that were 
surveyed during the 1997 study were re-surveyed. Dunes sagebrush 
lizards were absent from 11 of the 54 sites (20 percent) in which they 
were recorded during the 1997 study (Painter 2008a, p. 1). Not all of 
the 72 positive sites surveyed during the 1997 study were re-surveyed 
in 2008 due to poor weather conditions or access issues. Additional 
surveys were conducted during 2010 to investigate the status of the 
population of dunes sagebrush lizards at the remaining sites. The total 
number of historic sites that were surveyed in 1997 was 72, and 17 of 
those (24 percent) no longer have lizards. Some of these sites have 
been sprayed with tebuthiuron (a herbicide used to remove shinnery 
oak), and some were in areas where the habitat was removed (Painter 
2010, p. 1).
    In New Mexico, there are three genetically and geographically 
distinct populations of dunes sagebrush lizards: the northern 
population (near Kenna, New Mexico), the central population (at the 
Caprock Wildlife Area, north of US Highway 380), and the southern 
population (near Loco Hills and Hobbs, New Mexico). These populations 
are separated by geologic and ecologic landscape barriers, such as the 
caliche caprock of the Llano Estacado plateau, mesquite hummock 
landscapes, highways, roads, and oil and gas pads, that form areas of 
unsuitable vegetation, and dune structure (Chan et al. 2008, p. 13). 
The northernmost population near Kenna is evolutionarily considered to 
be the youngest population that is now genetically isolated from the 
central and southern populations. Genetic divergence of the northern 
population from the central populations has occurred due to natural and 
human-caused habitat conversion, including mesquite hummock landscapes, 
road and pad construction associated with oil and gas development, land 
conversion for agriculture, and the presence of short and tall grass 
prairie (Chan et al. 2008, p. 13).
    The southern population is considered to be the oldest population 
of dunes sagebrush lizard and is genetically isolated from the central 
population due to the presence of the uninhabitable caliche caprock of 
the Llano Estacado plateau. Due to the presence of the caprock, where 
dunes sagebrush lizards do not occur, suitable shinnery oak dune 
habitat is limited to a narrow 8-km (4.9-mile) patch between the 
southern and central populations. Data from Chan et al. (2008, p. 10) 
suggest that conservation of large areas that contain a network of dune 
complexes is needed to maintain historical levels of connectivity, and 
maintain the unique genetic qualities of the three dunes sagebrush 
lizard populations in New Mexico.

Texas

    In Texas, the species was historically found in Andrews, Crane, 
Ward, and Winkler Counties. During 2006 and 2007, surveys were 
conducted to determine the current distribution of the dunes sagebrush 
lizard in the State. Surveys were conducted at 27 sites (19 of these 
sites were historical localities) that contained potential dunes 
sagebrush lizard habitat in Andrews, Crane, Cochran, Edwards, Ward, and 
Winkler Counties. Dunes sagebrush lizards were found at only 3 of the 
27 sites surveyed (Laurencio et al. 2007, p. 7). Two of the sites were 
in large patches of shinnery oak dunes that stretch through Ward, 
Winkler, and Andrews Counties. In north and western Crane County, 
shinnery oak dune habitat exists, but dunes sagebrush lizards were not 
found. One dunes sagebrush lizard was found at a site in Gaines County 
that is within the easternmost contiguous habitat that stretches from 
the southernmost population in New Mexico (Laurencio et al. 2007, p. 
11). The sites where dunes sagebrush lizards were detected in either 
2006 or 2007 likely comprise the last occupied habitat for dunes 
sagebrush lizards in Texas (Laurencio et al. 2007, p. 11). During these 
surveys the search time to find dunes sagebrush lizards was between 68 
and 115 person-minutes. The species is considered rare at sites where 
it takes more than 60 minutes to find a dunes sagebrush lizard. By 
comparison, at some sites in shinnery oak dune habitat in New Mexico, 
74 percent of dunes sagebrush lizards are found within 31 person-
minutes. The longer search time required to encounter individuals in a 
given area may represent a lower number of individuals in that area. 
Future surveys should incorporate detection probabilities and utilize 
standard survey techniques for the species, in order to more accurately 
compare results.
    Dunes sagebrush lizard populations in Texas are all on private land 
except for the population at Monahans Sandhills State Park, a 1,554-ha 
(3,840-ac) park where dunes sagebrush lizards were thought to be 
extirpated after surveys were completed in 2007 (Laurencio et al. 2007, 
p. 11). In 2010, the park was again surveyed, and dunes sagebrush 
lizards were present (Fitzgerald 2010, p. 1). Monahans Sandhills State 
Park is a well-known historic locality that is the only area where 
dunes sagebrush lizards have been known to occur on public lands in 
Texas. It is evident that the dunes sagebrush lizard is still present 
at the park, but the negative survey data from 2007 suggests they may 
be present in small numbers, and that further monitoring should be done 
at this site.

Summary of Factors Affecting the Species

    Section 4 of the Act (16 U.S.C. 1533), and its implementing 
regulations at 50 CFR part 424, set forth the procedures for adding 
species to the Federal Lists of Endangered and Threatened Wildlife and 
Plants. Under section 4(a)(1) of the Act, we may list a species based 
on any of the following five factors: (A) The present or threatened 
destruction, modification, or curtailment of its habitat or range; (B) 
overutilization for commercial, recreational, scientific, or 
educational purposes; (C) disease or predation; (D) the inadequacy of 
existing regulatory mechanisms; and (E) other natural or manmade 
factors affecting its continued existence. Listing actions may be 
warranted based on any of the above threat factors, singly or in 
combination. Each of these factors is discussed below.

[[Page 77805]]

A. The Present or Threatened Destruction, Modification, or Curtailment 
of Its Habitat or Range

    In 1982, there was an estimated 400,000 ha (1,000,000 ac) of 
habitat suitable for the dunes sagebrush lizard in New Mexico. Today, 
there is an estimated 240,000 ha (600,000 ac) of suitable habitat, a 
decrease of 40 percent. Within the remaining suitable habitat, the 
current occupied range is estimated to cover 405,599 ac (165,759 ha) 
(McDaniel et al. 1982, p. 12). Other portions of the range have been 
developed for oil and gas infrastructure. The shinnery oak community 
that supports the dunes sagebrush lizard is now considered a highly 
threatened community (Dhillion et al. 1994, p. 52). Changes in either 
land management practices or climate that impact the vegetative 
community could destabilize the dunes and reduce the potential for the 
habitat to persist (Muhs and Holliday 2001, p. 86).
    In addition to habitat loss, habitat fragmentation breaks up large 
areas of suitable habitat into smaller patches. This causes the removal 
of interior habitat, the loss of vegetation and cover, and an increase 
in the proportion of habitat edge to interior. Habitat edge is the 
outer portion of a patch that abuts converted or otherwise unsuitable 
habitat, and it is where there are the greatest interactions between 
the shinnery oak dune natural habitat and human-altered unsuitable 
habitat (Dramsted et al. 1996, p. 27). Shinnery oak provides basic 
needs that impact survivorship, growth, and reproductive ability for 
the dunes sagebrush lizard. In general, interior habitat provides 
protection from predators, habitat for mating and foraging, shade, and 
habitat for the dunes sagebrush lizard's insect prey base (Degenhardt 
et al. 1996, p. 160). It is thought that habitat edges that are 
adjacent to well pads and roads do not provide the basic structure for 
survivorship, growth, and reproduction. In general, individuals that 
live near the habitat's edge have limited resources because the 
exterior areas do not provide adequate shade, cover, or resources for 
an insect prey base (Dramstad et al. 1996, p. 28).
    We do not know how large habitat patches need to be in order to 
maintain viable populations of dunes sagebrush lizards. However, 
literature published on other lizard species has shown that populations 
within smaller habitat patches have a greater risk of extinction than 
those in large habitat patches because small patches support fewer 
individuals and have a higher proportion of less suitable edge habitat 
than more suitable interior habitat (Dramsted et al. 1996, p. 20). 
Larger habitat patches provide vegetative cover, maintain dune 
structure, and provide habitat for the insect prey base. Dunes 
sagebrush lizard populations move across the landscape with the 
movement of the shinnery oak dune system. The movement of this dynamic 
system could be interrupted by habitat fragmentation that would prevent 
the natural shift in dunes and cause the current dune structures to 
collapse. There is no evidence to suggest that dunes sagebrush lizards 
will traverse unsuitable habitat to find suitable habitat patches 
(Fitzgerald et al. 1997, p. 26). Connectivity and movement between 
patches could play an important role in determining the occupancy and 
sustainability of each patch (Barrows and Allen 2007, p. 66). Removal 
of a patch reduces the size of a population, increasing the probability 
of local extinctions and reducing the stability of the population 
(Dramsted et al. 1996, p. 23). If dunes sagebrush lizards are unable to 
move between habitat patches because of fragmentation and habitat loss, 
genetic diversity will be lost (Chan et al. 2008, p. 10). For this 
reason, areas of apparently suitable, but currently unoccupied habitat 
may be important to the long term survival of dunes sagebrush lizards, 
but we have no data to support this hypothesis for dunes sagebrush 
lizards.
    In the dynamic shinnery oak dune system, habitat patches have not 
been consistent over time, and genetic diversity of populations has 
historically been linked to the connectivity of the entire system (Chan 
et al. 2008, p. 10). The habitat for the dunes sagebrush lizard is 
currently patchy and fragmented throughout the dunes sagebrush lizard's 
range, and populations are not connected by suitable habitat due to 
natural and human-caused processes (Chan et al. 2008, p. 10). 
Therefore, the loss of habitat and fragmentation can lower migration 
rates and genetic connectivity among remaining populations of dunes 
sagebrush lizards, reducing genetic variability and increasing 
extinction risk.
    For the similar sand-dwelling Coachella Valley fringe-toed lizard 
(Uma inornata), a decrease in habitat patch size resulted in an 
increased probability of local extinction. For isolated habitat patches 
to sustain lizard populations, patch size needed to be at least 100 ha 
(247 ac) (Chen et al. 2006, p. 28). When large habitat patches are 
divided into smaller patches, there is increased edge habitat, 
decreased interior habitat, and increased probability of local 
extinction of the species within these patches. Lizards within smaller 
habitat patches have an increased chance of going extinct because they 
have less of a barrier between the core patch and the habitat 
disturbance. The probability of a species going extinct in local 
habitat patches increases with the increasing isolation and decreasing 
size of that patch (Dramstad et al. 1996, pp. 20-24). Additional 
research will verify if this is true for dunes sagebrush lizard.
    The shinnery oak dune system has undergone extensive alteration and 
fragmentation because of past and present land uses, including oil and 
gas development, habitat conversion for cropland and rangeland, and 
off-highway vehicle (OHV) use (Painter et al. 1999, p. 1). Due to 
habitat conversion and fragmentation, there are historical areas that 
no longer support populations of dunes sagebrush lizards (Sias and 
Snell 1997, p. 1; Laurencio et al. 2007, p. 1; Chan et al. 2007, p. 
337). In Texas, dunes sagebrush lizards no longer occupy 86 percent of 
the historically occupied sites (Laurencio et al. 2007, p. 5). Dunes 
sagebrush lizards were not found at 20 percent of historically occupied 
sites that were surveyed during distribution studies in New Mexico 
(Painter et al. 2008, p. 1). Other threats that are also expected to 
contribute to habitat loss, modification, or fragmentation in the 
future include wind and solar energy development, climate change 
(discussed in Factor E, below), and die-off of shinnery oak due to 
natural events.
Oil and Gas Development
    The infrastructure for oil and gas development includes roads, pads 
where well pumps and drilling rigs are placed, battery tanks, power 
lines, pipelines, and injection wells. As discussed below, increased 
oil and gas development in the range of the dunes sagebrush lizard, 
including seismic exploration, has caused direct and indirect effects 
to dunes sagebrush lizard habitat. Removal and fragmentation of dunes 
sagebrush lizard habitat has been caused by a grid of roads and pads, 
pipelines, and power lines that are found throughout the entire range 
of the dunes sagebrush lizard. Oil and gas extraction activities have 
destroyed and fragmented dunes sagebrush lizard habitat and have 
resulted in population losses, including all localities within 
northeastern Crane County, Texas, where historical populations have 
been extirpated (Laurencio et al. 2007, p. 9). A 2007 report from the 
Bureau of Land Management (BLM) (pp. 3-16) states

[[Page 77806]]

that there have been significant reductions of dunes sagebrush lizard 
population sizes in New Mexico that are associated with surface 
disturbance and removal of shinnery oak due to activities such as oil 
and gas development, herbicide treatment, and the creation of roads 
associated with new rights-of-way. According to the BLM's data, 65 
percent of occupied or suitable shinnery oak habitat across the 
lizard's range in New Mexico, has been fragmented with roads and well 
pads (Hill 2008, pers. comm.).
    Much of the dunes sagebrush lizard's current range has been 
developed or is planned for future oil and gas development. In Texas, 
over 50 percent of oil production occurs in Districts 8 and 8A (Texas 
oil and gas districts); these districts overlap the known geographic 
range of dunes sagebrush lizards (Tarver and Dasgupta 1997, p. 3670).
    Currently, 70 percent of land within the New Mexico range of the 
dunes sagebrush lizard has been leased by private entities, BLM, or the 
New Mexico State Land Office (NMSLO) for oil and gas exploration and 
development (Winter 2010, p. 2). Seventy-one percent of the minerals 
within the range of the dunes sagebrush lizard are Federally owned and 
fall under BLM lease stipulations and the Pecos District (NM) Special 
Status Species Resource Management Plan Amendment (RMPA). The RMPA was 
developed to address sensitive species conservation concerns and to 
establish the minimum requirements that will be applied to all future 
Federal activities covered by the RMPA for both the dunes sagebrush 
lizard and the lesser prairie chicken (Tympanuchus pallidicinctus), 
which share some common habitat in New Mexico.

Density of Wells and Well Pads

    In New Mexico, Sias and Snell (1998, p. 3) reported a negative 
relationship between oil well density and dunes sagebrush lizard 
abundance and noted an environmental sensitivity not found in other 
reptile species. Dunes sagebrush lizard abundance declined by 25 
percent when there were 13 oil or gas well pads per section (each 
section has an area of approximately 260 ha (640 ac)), and the number 
of dunes sagebrush lizards declined by 50 percent when there were 29 
pads per section (Sias and Snell 1998, p. 3). Any shinnery oak dune 
habitat within 600 m (1968 ft) of any well supported 31 to 52 percent 
fewer dunes sagebrush lizards than areas farther than 600 m (1968 ft) 
from a well (Sias and Snell 1998, p. 1).
    The 172,900 ha (427,200 ac) of shinnery oak dune habitat that have 
been fragmented with roads and well pads have 5,911 oil well pads or 
injection wells and 529 gas wells. Each oil pad averages 2 or 3 acres, 
and each gas pad averages 3 or 4 acres. Currently there are 
approximately 9,700 ha (24,000 ac) of well pad disturbance in New 
Mexico, not including roads, within the area occupied by the dunes 
sagebrush lizard (Hill et al. 2008, p. 1).
    The oil field with the greatest impact to dunes sagebrush lizard 
habitat is in the southern part of the dunes sagebrush lizard's range, 
where the density of roads and well pads may be contributing to further 
separation of the southern population from the central population of 
dunes sagebrush lizards (Chan et al. 2008, p. 9). This development 
covers an area of shinnery oak dunes measuring 8 km (5 mi) by 26 km (16 
mi) between U.S. Highway 82 and U.S. Highway 62 in Lea and Eddy 
Counties. In this area there are 142 sections (36,780 ha (90,880 ac)) 
where the well pad density is greater than 13 wells per section. 
Throughout the southern part of the dunes sagebrush lizard's range, the 
majority of these sections of land have greater than 20 wells per 
section, and some have greater than 40 wells per section. The highest 
density of well development in this area has more than 60 wells per 
section with a maze of associated roads (Hill et al. 2008, p. 1). In a 
special species planning area within BLM's Pecos District, which 
incorporates all of the dunes sagebrush lizard's habitat on BLM land in 
New Mexico, approximately 100 new wells per year are to be drilled over 
the next 20 years (BLM 2007, p. 4-37).
    An example of the impacts of well placement on the dunes sagebrush 
lizard can be found in two sections (approximately 520 ha (1,280 ac)) 
of shinnery oak dune habitat in the area of Loco Hills in the southern 
part of the dunes sagebrush lizard's range in Eddy County (40 km (25 
mi) east of Artesia). This area once supported one of the most 
persistent populations of dunes sagebrush lizards in the State and was 
used for many years as an observation site for students and researchers 
studying the dunes sagebrush lizard. As of 2003, over 40 oil wells had 
been placed on these sections; extensive surveys conducted in this area 
found no dunes sagebrush lizards present (Service 2007, p. 5; 
Fitzgerald 2008, p. 1).
    Hatchling and adult dunes sagebrush lizards have been found in 
shinnery oak flats between large dunes, suggesting that the area 
between the sand dunes is important for dispersal. Surveys by the BLM 
recorded dunes sagebrush lizards in the shinnery oak flats (Bird 2007, 
p. 2). In the past, oil and gas development has been directed into the 
shinnery oak flats and out of the dune complexes to lessen the impact 
to the dunes sagebrush lizard. However, development in the shinnery oak 
flats may be affecting dispersal of the dunes sagebrush lizards from 
one dune complex to another (Painter et al. 2007, p. 3). Currently 
there are no considerations being made for maintaining these 
undeveloped corridors in shinnery oak flats between dune complexes, 
which may be a significant threat to dunes sagebrush lizard dispersal.

Roads and Well Pads

    Based on various studies in similar lizard species, it would be 
expected that there would be negative impacts to dunes sagebrush lizard 
habitat as a result of roads and pads associated with oil and gas 
development. These impacts include soil compaction, decreased stability 
of microclimates, loss of habitat, decreased habitat quality, division 
of the ecosystem with artificial gaps, abrupt habitat edges, conversion 
of habitat interior to habitat edge, and introduction of nonnative weed 
species (Endriss et al. 2007, p. 320; Delgado-Garcia et al. 2007, p. 
2949). Negative impacts of roads and pads to the lizard populations 
include the subdivision of populations into smaller and more vulnerable 
patches; inhibited access to resources for foraging, breeding, nesting, 
predator avoidance, and thermoregulation; behavior modification; and 
direct mortality due to collisions (Jaeger et al. 2005, p. 329; 
Ingelfinger and Anderson 2004, p. 385; Delgado-Garcia et al. 2007, p. 
2949; Ballesteros-Barrera et al. 2007, p. 736; Sias and Snell 1995, p. 
28). When the shinnery oak dune habitat is destroyed or fragmented by 
roads and pads, the resources provided by the shinnery oak are 
subsequently reduced. In studies of other lizard species where habitat 
is highly fragmented, lizards are limited to small habitat patches. 
These studies have also found increased mortality due to collisions 
with vehicles and inaccessibility to habitat, mates, and prey reduce 
the population size and population persistence (Delgado-Garcia et al. 
2007, p. 2949).
    A common method of creating roads and pads in dune areas is to 
truck caliche (soil with high amounts of calcium carbonate) into the 
sand system. Dunes sagebrush lizards are not found in areas with 
compact soil, like that of caliche roads and well pads (Fitzgerald et 
al. 1997, p. 3). Shinnery oak requires permeable sand in order to

[[Page 77807]]

establish and grow and does not grow in areas with high amounts of 
calcium carbonate (Peterson and Boyd 1998, p. 6).
    The vast network of roads and pads throughout the shinnery oak dune 
habitat alters the habitat, making it difficult for shinnery oak to 
persist; the trees cannot grow through compacted areas, with increased 
calcium carbonate, or through permanently paved areas. Well pad and 
road construction removes shinnery oak, and further degrades the 
habitat by compacting the soil. After well pads are abandoned, shinnery 
oak does not reestablish unless the caliche is removed (Boyd and 
Bidwell 2002, p. 332).
    The current existence and future establishment of roads and well 
pads throughout the dunes sagebrush lizard's habitat is a significant 
threat to the species throughout its range. Impacts from roads and well 
pads cause the loss of basic needs including habitat for foraging, 
breeding, nesting, predator avoidance, and thermoregulation.

Pipelines

    Every oil or gas well has an associated pipeline, and each oil or 
gas company has a separate right-of-way for each pipeline. Pipelines 
located throughout suitable and occupied dunes sagebrush lizard habitat 
destabilize dunes because heavy equipment is used to remove shinnery 
oak and bury the lines in the sand. Pipelines also expose dunes 
sagebrush lizards to petroleum chemical leaks and an increased 
likelihood of being crushed by OHV travel due to maintenance crews 
using vehicles along pipelines (Sias and Snell 1998, p. 3). On May 16, 
2010, a pipeline burst in dunes sagebrush lizard habitat, spraying oil 
into the air and across the landscape (Leavitt 2010, p. 1). These 
spills introduce toxins and contaminants into the soil and cover 
surrounding vegetation.
    There have been numerous recorded instances of reptiles and 
amphibians being trapped in pipeline, waterline, and telecommunication 
line trenches (Hawken 1951, p. 81; Anderson et al. 1952, p. 276). For 
example, in 2001, a 4.8-km (3.0-mi) long telecommunication line trench 
(similar in structure to pipeline trenches) on Albuquerque, New 
Mexico's West Mesa was monitored for trapped animals. During 23 days of 
monitoring, 298 reptiles and amphibians, including several lizard 
species, were removed from the trench (Painter 2008, p. 1). There were 
no escape ramps along the trench, so it was impossible for animals to 
escape.
    During a distribution survey for dunes sagebrush lizards in July 
2008, the New Mexico Department of Game and Fish (NMDGF) found an open 
pipeline ditch that went through State, private, and BLM land. The open 
ditch was approximately 1.2 m (4 ft) wide and 1.2 m (4 ft) deep, 
bisecting a dune complex known to be occupied with dunes sagebrush 
lizards. The large, open ditch had formed a pitfall trap where animals 
could not escape if they fell in. There were no dunes sagebrush lizards 
found in the ditch at the time of the survey, but other reptiles were 
found in the ditch, and surveyors were concerned that dunes sagebrush 
lizards could easily be trapped in the ditch (Currylow et al. 2008, p. 
1).
    Some existing pipelines located within shinnery oak dunes provide 
temporary dune-like areas where dunes sagebrush lizards are found. 
Twenty-four percent of dunes sagebrush lizards found during BLM surveys 
were found along pipelines adjacent to shinnery oak dunes (Bird 2006, 
p. 2), although it is not known how dunes sagebrush lizards utilize 
existing pipelines (Sias and Snell 1998, p. 5; Bird 2005, p. 1; Bird 
2006, p. 1; Bird 2007, p. 1), and it is unclear whether these areas 
provide permanent habitat.
    Pipelines are located throughout the range of the dunes sagebrush 
lizard, are currently being built with every well pad, and will 
continue to be built in the future. There are no established corridors 
for pipelines and each pipeline has its own right-of-way, making for 
new disturbed areas each time a pipeline is established. We believe 
pipelines pose a significant threat to the dunes sagebrush lizard in 
areas where oil and gas infrastructure is most dense, especially as 
increases in oil and gas activities expand in the central and northern 
parts of the range of the species. Unless they are routed around 
habitat, the current existence and future establishment of pipelines 
throughout the dunes sagebrush lizard's habitat is a significant threat 
to the species throughout its range.

Seismic Exploration

    Seismic exploration utilizes artificially induced shock waves to 
search for subsurface deposits of crude oil, natural gas, and minerals, 
and to facilitate the location of prospective drilling sites. Shock 
waves are produced by vibratory mechanisms mounted on specialized 
trucks known as thumper trucks that weigh approximately 60 tons. 
Seismic waves then reflect and refract off subsurface rock formations 
and travel back to acoustic receivers called geophones. The time it 
takes for seismic energy to return aids in the estimation of the 
structure and stratigraphy of subsurface formations (Pendleton et al. 
2008, p. 1). Seismic exploration is conducted prior to the development 
of oil and gas fields, in order to determine the below surface 
availability of oil or gas and refine the placement of well pads.
    Seismic exploration for oil and gas is a periodic threat to the 
dunes sagebrush lizard and its habitat. Threats to dunes sagebrush 
lizard habitat occur because heavy thumper trucks can cause the 
destabilization of dunes by driving through dune complexes (Painter 
2004, p. 4). Seismic exploration can also pose a direct threat to the 
dunes sagebrush lizard. Dunes sagebrush lizards are dormant and 
immobile during colder winter months (October through March). If 
seismic exploration occurs during the winter months when dunes 
sagebrush lizards are dormant beneath the soil surface and unable to 
move, dunes sagebrush lizards could be crushed. If the exploration 
occurs during the nesting season, eggs that are buried below the 
surface could also be destroyed (Painter 2004, p. 4). Seismic 
exploration poses an imminent threat for a short period of time while 
the trucks are crossing a given area. Once an area has been surveyed, 
it will likely not be surveyed again. Proposed seismic explorations in 
an area north of the Loco Hills will cover up to 650 ha (1,600 ac) of 
suitable and occupied dunes sagebrush lizard habitat and pose an 
indirect threat through further development, which will lead to habitat 
fragmentation and isolation (discussed above) north of the already 
dense oil fields in Loco Hills. There are ongoing permit applications 
for seismic exploration within both occupied and unoccupied suitable 
habitat across the range of the dunes sagebrush lizard. We believe that 
seismic exploration is a localized threat with moderate impacts to 
individual dunes sagebrush lizards, but it is usually a prelude to the 
future expansion of oil and gas development in an area.
Wind and Solar Energy Development
    Eastern New Mexico and western Texas are highly suitable areas for 
wind and solar energy development. The NMSLO has leased 1,520 ha (3,757 
ac) of trust land in Chaves and Roosevelt Counties to Xcel Energy for a 
120-megawatt (MW) wind farm. Additionally, two new wind projects are 
under development on State trust lands in Chaves County, and one in 
Eddy County. The Service has also been contacted by a consultant for a 
wind energy farm to be located in Lea County, near Tatum, New Mexico. 
The proposed

[[Page 77808]]

project area is near the range of the dunes sagebrush lizard (Riley 
2008).
    The infrastructure for wind and solar energy would cause similar 
habitat fragmentation as that produced by oil and gas development. 
Potential direct effects to the dunes sagebrush lizard from wind energy 
development include physical disturbance during construction and 
maintenance of a project, habitat loss, and habitat fragmentation 
associated with the infrastructure of the project. A wind farm 
infrastructure typically consists of: (1) The physical disturbance 
around a tower; the area of a turbine workspace during construction 
(temporary) is usually a 46 to 61 m (150 to 200 ft) radius around the 
turbine and permanently a 15 m (50 ft) radius; (2) Gravel access roads 
linking wind turbines strings to each other and to existing roads; (3) 
Area for a concrete batch plant, if required; and (4) Buildings housing 
electrical switchgear, supervisory control and data acquisition central 
equipment, and maintenance facilities. Additionally, vehicle traffic to 
turbines over the life of the facility, expected to average 20 years, 
could pose a threat similar to the infrastructure of oil and gas 
development to the dunes sagebrush lizard. Alteration of habitat 
related to wind energy development could influence habitat suitability 
for this species; however, we are unaware of any studies at wind energy 
development sites that have examined these effects.
    Although there is no specific information available to implicate 
wind or solar energy development as a threat to the dunes sagebrush 
lizard at this time, there is concern regarding potential effects if 
wind and solar development were to occur in the species' habitat. More 
information is necessary to determine if any effects will result from 
specific alternative energy projects that will be located within dunes 
sagebrush lizard habitat. However, the BLM's RMPA states that 
applications to permit either solar or wind energy on public land 
within the RMPA planning area will not be approved unless the applicant 
can demonstrate, using peer-reviewed science, that there will be no 
negative impacts to dunes sagebrush lizards.
Off-Highway Vehicle (OHV) Use
    An OHV is any motorized vehicle capable of or designated for travel 
on or immediately over land, water, or other natural terrain. This 
could include motorcycles and off-highway motor bikes, all terrain 
vehicles, dune buggies, snowmobiles, most four-wheel drive automobiles, 
and any other civilian vehicle specifically designed for off-road 
travel (Ouren et al. 2007, p. 4). Extensive use of OHVs can cause soil 
compaction, reduce plant cover, and degrade habitat (Ouren et al. 2007, 
p. 4), causing the loss of basic needs including habitat for foraging, 
breeding, nesting, predator avoidance, and thermoregulation for lizard 
species (Jaeger et al. 2005, p. 329; Ingelfinger and Anderson 2004, p. 
385; Delgado-Garcia et al. 2007, p. 2949; Ballesteros-Barrera et al. 
2007, p. 736). Research in other dune systems has found that in areas 
where plant cover is reduced, there are greater rates of erosion that 
would lead to dune destabilization. Routes used by OHVs form mazes 
through large areas of dunes, fragmenting the habitat and reducing 
habitat connectivity at a landscape level (Ouren et al. 2007, p. 5). 
Studies on other lizard species have found that OHV travel causes 
increased mortality due to lizard collisions with the vehicles 
themselves (Delgado-Garcia et al. 2007, p. 2949).
    Use of OHVs has been determined to be one of the greatest threats 
to the Coachella Valley fringed toed lizard, which is another dune-
restricted lizard species (Painter 2004, p. 5). The presence of OHV 
pathways throughout dunes sagebrush lizard's habitat led researchers to 
believe that high levels of OHV activities were the cause for 
population losses in Texas (Laurencio et al. 2007, p. 10), but that is 
likely not the primary cause of extirpations in New Mexico (Painter 
2004, p. 5). Nevertheless, OHV use is a factor impacting the species 
within parts of its geographic range. For example, on BLM land in New 
Mexico, established OHV areas such as the Square Lake Dune Complex and 
the Mescalero Sands North Dune OHV Area are adjacent to or within 
habitat occupied by the dunes sagebrush lizard. These OHV areas were 
established to concentrate OHV use to designated areas, and BLM made 
some dune complexes off limits to OHV use. The OHV use planned for the 
Square Lake Dune Complex is limited to existing roads, trails, and 
unvegetated dunes (BLM 2007, p. 4-45). This area is currently being 
used by OHVs, and BLM plans to formally designate this area for OHV 
use. Because the shinnery oak dunes in this area are occupied by dunes 
sagebrush lizards (Fitzgerald et al. 1997, Appendix 1), any violation 
of the limitations of OHV use to existing roads, trails, and 
unvegetated dunes is likely to negatively impact the dunes sagebrush 
lizards in this shinnery oak habitat.
    The Mescalero Sands North Dune OHV Area is considered an open area 
of more than 600 acres (243 ha), where vehicles are not restricted to 
designated trails (BLM 2007, p. 4-45), although this OHV area is 
occupied by dunes sagebrush lizards (Fitzgerald et al. 1997, Appendix 
1). Authorized OHV activities have degraded shinnery oak dunes, 
potentially crushed dunes sagebrush lizards, and introduced weed 
species within the otherwise open dune blowouts (Hill 2008b, p. 1). At 
this OHV area, all surveyed dunes have multiple OHV trails, exposed 
shinnery oak roots, and erosion, and no dunes sagebrush lizards were 
detected in this area (Hill 2008b, p. 1).
    In areas that are not designated for OHV use, there are no signs 
identifying that the area is closed to OHV traffic, and law enforcement 
is limited. There are restrictions to OHV use on lands managed by BLM 
and the State of New Mexico, but there is no signage and little 
enforcement. As a result, dune habitat is being destroyed and modified 
(Hill 2008b, p. 1). Although OHV use is not known to be occurring in 
all portions of the range of the dunes sagebrush lizard, we believe it 
is a significant threat to the species where occupied dunes are located 
in OHV areas and extensive habitat degradation occurs. Off-highway 
vehicle use is not considered to be the most significant threat to the 
dunes sagebrush lizard, but it does contribute to a decline of habitat 
in areas where it is prevalent.
Shinnery Oak Removal
    Shinnery oak is removed for the purpose of clearing for agriculture 
and for grazing. Shinnery oak is toxic to cattle when it first produces 
leaves in the spring, and it also competes with more palatable grasses 
and forbs for water and nutrients (Peterson and Boyd 1998, p. 8). 
Shinnery oak is also managed for the control of boll weevil (Anthonomus 
grandis), which destroys cotton crops. Boll weevils overwinter in areas 
where large amounts of leaf litter accumulate. Fire is used to remove 
leaf litter, and then tebuthiuron, an herbicide, is used to remove 
shinnery oak (Plains Cotton Growers 1998, pp. 2-3). Over 40,000 ha 
(100,000 ac) of shinnery oak in New Mexico and 400,000 ha (1,000,000 
ac) of shinnery oak in Texas have been lost due to the spraying of 
tebuthiuron and other herbicides (Peterson and Boyd 1998, p. 2).
    A 5-year study was conducted to determine the effects of 
tebuthiuron application on the dunes sagebrush lizard. This study 
documented that dunes sagebrush lizards were absent at 50 percent of 
the previously occupied sites where spraying had occurred

[[Page 77809]]

(Painter et al. 1999, p. 2). Shinnery oak removal results in dramatic 
reductions and extirpations of dunes sagebrush lizards (Snell et al. 
1997, p. 8). For example, the extirpation of dunes sagebrush lizards 
was repeatedly confirmed by Snell et al. (1997, p. 1) from areas that 
were treated with herbicides to remove shinnery oak. Dunes sagebrush 
lizard numbers dropped 70 to 94 percent in areas that were chemically 
treated, compared to adjacent untreated plots. Some plots experienced 
100 percent population loss in areas treated with tebuthiuron. Painter 
et al. (1999, p. 38) estimated that about 24 percent of the total dunes 
sagebrush lizard habitat in New Mexico had been eliminated by 1999 due 
to herbicide spraying.
    Habitat loss and dunes sagebrush lizard declines are not linked to 
the actual application of tebuthiuron, but rather to the long-term 
effects associated with the removal of shinnery oak habitat (Snell et 
al. 1997, p. 3). Herbicide spraying removes or reduces natural shinnery 
oak vegetation and creates smaller habitat patches rather than 
naturally occurring large expanses of shinnery oak. Given the history 
and current practices of herbicide application within dunes sagebrush 
lizard habitat, much of the remaining areas are at risk. For example, 
if further parcels of suitable dunes sagebrush lizard habitat are 
treated, smaller habitat patches would be created, and we would expect 
the movement of dunes sagebrush lizards between local populations will 
be restricted. This could lead to further extirpations of dunes 
sagebrush lizards within patches.
    On BLM lands, the RMPA states that tebuthiuron may only be sprayed 
in shinnery oak habitat if there is a 500-m (1,600-ft) buffer around 
dunes, and that no chemical treatments should occur in suitable or 
occupied dunes sagebrush lizard habitat (BLM 2007, p. 4-22). However, 
the NMSLO and private land owners continue to use tebuthiuron to remove 
shinnery oak for cattle grazing and agriculture. The Natural Resource 
Conservation Service's herbicide spraying has treated shinnery oak in 
at least 39 counties within shinnery oak habitat, which includes all of 
the counties with suitable and occupied habitat for the dunes sagebrush 
lizard (Peterson and Boyd 1998, pp. 4). The BLM also treats mesquite 
with herbicides to improve livestock forage. In order to treat 
encroaching mesquite, BLM aerially treats mesquite with a mix of the 
herbicides Remedy (triclopyr) and Reclaim (clopyralid). According to 
the RMPA, occupied and suitable habitat for the dunes sagebrush lizard 
should not be treated. These chemicals are used to treat the adjacent 
mesquite, but can also kill shinnery oak, depending on the 
concentration.
    Ongoing removal of shinnery oak on State and private lands in New 
Mexico and Texas is an imminent threat to the dunes sagebrush lizard 
with long-term negative effects. Buffering an individual dune from 
shinnery oak spraying is not sufficient to keep the habitat intact. 
Because the majority of the shinnery oak plant is underground and acts 
to stabilize the dunes, its removal in the vicinity of the dune will 
cause the dune to collapse (Muhs and Holliday 2001, p. 75).
    We believe that the removal of shinnery oak with herbicides such as 
tebuthiuron is a significant threat to the dunes sagebrush lizard 
throughout its range. Habitat in which shinnery oak is removed with 
herbicides fails to meet the basic needs of the dunes sagebrush lizard, 
including foraging, breeding, nesting, predator avoidance, and 
thermoregulation. Habitat fragmentation has caused and will continue to 
cause inaccessibility to habitat, mates, and prey that could reduce the 
population size; threaten population persistence; and potentially cause 
local extirpations of dunes sagebrush lizards.
Grazing
    As discussed above, removal of shinnery oak to improve rangelands 
is a threat to the dunes sagebrush lizard; however, there may also be 
direct impacts of grazing on dunes sagebrush lizards. While there has 
been no specific research regarding the impacts of grazing on dunes 
sagebrush lizards, dunes sagebrush lizards have been found in areas 
that are moderately grazed (Painter et al. 1999, p. 32). In shinnery 
oak dune habitat, high densities of livestock can lead to 
overutilization and result in reduced ground cover, increased annual 
grasses and forbs, decreased perennial grasses, and increased erosion 
(Painter et al. 1999, p. 32). These conditions can be adverse for the 
dunes sagebrush lizard. Some research has shown that high levels of 
grazing removes grasses and forbs, compacts the soil, increases bare 
ground, and reduces water infiltration. These conditions could alter 
dune structure and decrease vegetation availability for foraging, 
mating, and predator avoidance (Smith et al. 1996, p. 1307; Castellano 
and Valone 2006, p. 87). While it is clear from this discussion that 
shinnery oak removal to improve rangeland conditions is a threat to the 
species, the direct impact of grazing on dunes sagebrush lizards is 
unknown at this time.
Other Factors Impacting Shinnery Oak
    In discussions with BLM habitat specialists, the Service learned 
that there are many natural events that can impact the shinnery oak 
dune system and have results similar to spraying with herbicide. Sudden 
oak death, infestation by root-boring insects, and a known moth 
parasite can quickly defoliate and kill large stands of shinnery oak 
(Hill 2008a, pers. comm.). According to BLM habitat specialists, in a 
system that is susceptible to environmental extremes, events such as 
drought and late freezes could cause dramatic shifts in the available 
habitat. For example, in early May of 2008, thousands of acres of 
shinnery oak dune habitat in the Caprock Wildlife Area in east central 
Chaves County, New Mexico, were defoliated. After reviewing the 
situation, Service and BLM staff determined that the defoliation was 
caused by the combination of low precipitation during the winter and a 
late freeze that stressed the oak. By early June, the trees had leafed 
out and were once again providing habitat for the dunes sagebrush 
lizard (Hill 2008a, pers. comm.). Large habitat patches are more likely 
than small, fragmented sites to be resilient to natural events.
    All of these factors could potentially cause the decline of 
shinnery oak habitat, and thus lead to the decline of dunes sagebrush 
lizards. The likelihood of habitat loss due to natural events is 
unknown and not predictable. Although these factors likely impact 
shinnery oak, we are unable to determine the long-term impact on 
shinnery oak dunes and dunes sagebrush lizards.
Summary of Factor A
    Habitat specialists with limited geographic ranges, such as the 
dunes sagebrush lizard, are more vulnerable to habitat alterations than 
wide-ranging habitat generalists (Ballesteros-Barrera et al. 2007, p. 
733). Habitat fragmentation and the overall reduction of shinnery oak 
dune habitat will impact survivorship, growth, and reproductive ability 
by increasing edge habitat and decreasing available cover. This will 
lead to smaller populations and will d