Federal Register / Vol. 75, No. 169 / Wednesday, September 1, 2010 / Proposed Rules 53615 

accurately portray the unit level control 

installations that have occurred at 

power plants during the past several 

years. In general, about 25% of coal 

plants have a 2009 NOX rate that reflects 

a change from the 2007 that is greater 

than 0.1 lb/mmbtu and 10% of the 2007 

value. The 2009 unit level data can be 

retrieved from EPA’s Data and Maps at 

http://camddataandmaps. 

epa.gov/gdm/. 

EPA also intends to update 

information related to new units, new 

installation of pollution controls, and 

planned retirements. Information on 

changes in these areas that EPA believes 

have happened since IPM v4.10 version 

of the model has been finalized is also 

included in the docket. 

Between now and the time that EPA 

finalizes the Transport Rule, additional 

information used to support the final 

transport rulemaking may be placed in 

the docket. 

Dated: August 25, 2010. 

Dina W. Kruger, 

Acting Director, Office of Atmospheric 

Programs. 

[FR Doc. 2010–21699 Filed 8–31–10; 8:45 am] 

BILLING CODE 6560–50–P 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[FWS-R2-ES-2009-0039] 

[MO 92210-0-0008] 

Endangered and Threatened Wildlife 

and Plants; 12-Month Finding on a 

Petition to List the White-Sided 

Jackrabbit as Threatened or 

Endangered 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Notice of 12–month petition 

finding. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), announce a 

12–month finding on a petition to list 

the white-sided jackrabbit as 

endangered and to designate critical 

habitat under the Endangered Species 

Act of 1973, as amended. After review 

of all available scientific and 

commercial information, we find that 

listing the full species, Lepus callotis, is 

not warranted at this time. We further 

find that listing one or both of the 

subspecies, Lepus callotis callotis and 

Lepus callotis gaillardi, is not warranted 

at this time. We find that listing the 

northern populations of the subspecies 

L. c. gaillardi as a Distinct Population 

Segment is not warranted at this time. 

However, we ask the public to submit to 

us any new information that becomes 

available concerning the threats to the 

full species of the white-sided 

jackrabbit, or to either of the two 

currently recognized subspecies, or the 

species’ habitat at any time. 

DATES: The finding announced in this 

document was made on September 1, 

2010. 

ADDRESSES: This finding is available on 

the Internet at http:// 

www.regulations.gov at Docket Number 

FWS-R2-ES-2009-0039. Supporting 

documentation we used in preparing 

this finding is available for public 

inspection, by appointment, during 

normal business hours at the U.S. Fish 

and Wildlife Service, New Mexico 

Ecological Services Field Office, 2105 

Osuna NE, Albuquerque, NM 87113. 

Please submit any new information, 

materials, comments, or questions 

concerning this finding to the above 

address. 

FOR FURTHER INFORMATION CONTACT: 

Wally Murphy, Field Supervisor, New 

Mexico Ecological Services Field Office, 

2105 Osuna NE, Albuquerque, NM 

87113; by telephone at 505-346-4781; or 

by facsimile at 505-346-2542. If you use 

a telecommunications device for the 

deaf (TDD), please call the Federal 

Information Relay Service (FIRS) at 800- 

877-8339. 

SUPPLEMENTARY INFORMATION: 

Background 

Section 4(b)(3)(B) of the Endangered 

Species Act of 1973, as amended (Act) 

(16 U.S.C. 1531 et seq.), requires that, 

for any petition to revise the Federal 

Lists of Endangered and Threatened 

Species that contains substantial 

scientific or commercial information 

that listing the species may be 

warranted, we make a finding within 12 

months of the date of receipt of the 

petition. In this finding, we will 

determine that the petitioned action is: 

(1) Not warranted, (2) warranted, or (3) 

warranted, but the immediate proposal 

of a regulation implementing the 

petitioned action is precluded by other 

pending proposals to determine whether 

species are threatened or endangered, 

and expeditious progress is being made 

to add or remove qualified species from 

the Federal Lists of Endangered and 

Threatened Species. We must publish 

this 12–month finding in the Federal 

Register. 

Previous Federal Action 

On October 15, 2008, we received a 

petition dated October 9, 2008, from 

WildEarth Guardians requesting that the 

white-sided jackrabbit (Lepus callotis) 

be emergency listed as endangered 

under the Act and critical habitat be 

designated. Included in the petition was 

supporting information regarding the 

species’ taxonomy and ecology, 

historical and current distribution, 

present status, and actual and potential 

causes of decline. We acknowledged the 

receipt of the petition in a letter to 

WildEarth Guardians, dated November 

26, 2008. However, emergency listing a 

species is not a petitionable action 

under the Act or the Administrative 

Procedure Act (APA; 5 U.S.C. 

Subchapter II), and is treated solely as 

a petition to list. In our letter we also 

stated that we had reviewed the petition 

and determined that available 

information did not indicate that the 

species was at significant risk of wellbeing, thereby necessitating the need to 

provide the temporary protections 

under section 4(b)(7)the Act (i.e., 

emergency listing). In our letter, we 

advised the petitioner that, to the 

maximum extent practicable, we would 

address the petition within 90 days. 

During our review of the petition, we 

found that the majority of information 

cited in the petition was not readily 

available to us. Therefore, on January 

13, 2009, we requested that the 

petitioner provide additional references. 

On February 13, 2009, the petitioner 

provided references. We received a 60– 

day notice of intent to sue from the 

petitioner dated January 28, 2009, and 

on April 15, 2009, the petitioner brought 

a lawsuit against us for failure to 

respond to the petition within 90 days 

of its receipt. On July 22, 2009, we 

published a 90–day finding indicating 

that the petition presented substantial 

information that listing the jackrabbit 

may be warranted, and initiated a status 

review (74 FR 36152). This notice 

constitutes the 12–month finding on the 

October 9, 2008, petition to list the 

white-sided jackrabbit as endangered. 

The white-sided jackrabbit was first 

listed as a candidate (Category 2) for 

Federal listing as either a threatened or 

endangered species under the Act in the 

1982 Candidate Notice of Review (47 FR 

58454, December 30, 1982). Category 2 

status included those taxa for which 

information in the Service’s possession 

indicated that a proposed listing rule 

was possibly appropriate, but for which 

sufficient data on biological 

vulnerability and threats were not 

available to support a proposed rule. In 

the Candidate Notice of Review 

published on February 28, 1996, we 

announced a revised list of animal and 

plant taxa that were regarded as 

candidates for possible addition to the 


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Lists of Endangered and Threatened 

Wildlife and Plants (61 FR 7595). The 

revised candidate list included only 

former Category 1 species. All former 

Category 2 species were dropped from 

the list to reduce confusion about the 

conservation status of these species and 

to clarify that the Service no longer 

regarded these species as candidates for 

listing. Because the white-sided 

jackrabbit was a Category 2 species, it 

was no longer recognized as a candidate 

species. 

The petition requests that we list the 

full species of the white-sided 

jackrabbit, Lepus callotis, as threatened 

or endangered. The petition also 

requests that we list each of the 

recognized subspecies of the whitesided jackrabbit, Lepus callotis callotis 

and Lepus callotis gaillardi as 

threatened or endangered, should we 

conclude that the full species does not 

warrant listing, and the petition states 

that these recognized subspecies are 

taxonomically valid. The petition 

further requests that we list the northern 

populations of the subspecies currently 

recognized as L. c. gaillardi as a distinct 

population segment under the Act. We 

will examine each of these requests 

separately below. 

Species Information: Lepus callotis 

Taxonomy and Species Description 

There has been some dispute and 

inconsistency regarding the taxonomy of 

the species and its subspecies, and 

much of the literature remains 

inconclusive. In his book, Wildlife of 

Mexico: The Game Birds and Mammals, 

Leopold (1959, p. 345) included four 

species of jackrabbits under his 

description of the common name 

‘‘white-sided jackrabbits’’: Lepus alleni, 

Lepus gaillardia, Lepus callotis, and 

Lepus flavigularis. In their 1962 paper, 

A Classification of the White-sided 

Jackrabbits of Mexico, Anderson and 

Gaunt concurred with Leopold and 

others in the existence of four species, 

with non-overlapping geographic 

ranges, assigned the common name 

‘‘white-sided jackrabbit’’ (Anderson and 

Guant 1962, p. 1). The authors later state 

that they regard each of the previously 

recognized species, Lepus callotis and 

Lepus gaillardi, as conspecific, or 

separate subspecies of the same species 

(that is, Lepus callotis callotis and Lepus 

callotis gaillardi) (Anderson and Guant 

1962, p. 1). There are no recognized 

common names for these subspecies. 

The white-sided jackrabbit, Lepus 

callotis, occurs in New Mexico and in 

Mexico (see Figure 1 below). It is one of 

four species of hares (family Leporidae) 

that occurs in New Mexico (Findley et 

al. 1975), and one of 15 species 

occurring throughout the states of 

Mexico (Lorenzo et al. 2003, p. 11). The 

white-sided jackrabbit can be 

distinguished from other hares by its 

extensive white sides and 

inconspicuous or absent black ear tips, 

as well as differences in features of the 

skull (Findley et al. 1975, pp. 92, 96; 

Best and Henry 1993, p. 1; Anderson 

and Guant 1962, pp. 1-2). The species 

has black on the upper parts of its tail 

and the back and flanks are white 

(Lorenzo et al. 2003, p. 11). 

BILLING CODE 4310–55–S 


hsrobinson on DSK69SOYB1PROD with PROPOSALS
Federal Register / Vol. 75, No. 169 / Wednesday, September 1, 2010 / Proposed Rules 53617 

Figure 1. Map of the range of the white-sided jackrabbit. (Based on Anderson and Gaunt 1962.) 

BILLING CODE 4310–55–C 

There is limited discussion in the 

literature regarding the distinctions 

between the two subspecies, Lepus 

callotis callotis and Lepus callotis 

gaillardi. Anderson and Gaunt (1962, 

pp. 2-5) compared specimens from each 

of the subspecies and recorded the 

following differences: L. c. gaillardi has 

paler and coarser coat, including the 

fringe of hair along the inner margin of 

the ear, the throat patch, and the hue of 

dorsal cover hairs. Specimens of this 

subspecies also have paler rump patches 

that contrast less with the whitish flanks 

and paler patches on the shoulders that 

tend to contrast with (rather than match 

or blend with) the darker middorsal 

pelage (fur). The authors also observed 

differences between the two subspecies 

in skull structure. 

Studies have been conducted to 

determine the genetic relationship 

between species within the genus Lepus 

(Lorenzo et al. 2003); however, we are 

not aware of any information that 

establishes the genetic distinctiveness of 

the two subspecies Lepus callotis 

callotis and Lepus callotis gaillardi. 

Although the literature is inconclusive, 

we have not encountered any 

information which indicates that the 


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53618 Federal Register / Vol. 75, No. 169 / Wednesday, September 1, 2010 / Proposed Rules 

subspecies L. c. callotis and L. c. 

gailllardi are not taxonomically valid. 

Therefore, we consider L. c. callotis and 

L. c. gaillardi to be valid subspecies of 

the species L. callotis. 

Biology 

In the white-sided jackrabbit, females 

are generally larger than males (Bednarz 

1977, pp. 13, 15). In New Mexico, 

white-sided jackrabbits are observed 

almost unvaryingly in pairs (Bednarz 

1977, p. 9), suggesting that mated 

animals remain together on a long-term 

basis. Pair bonds may serve to ensure 

adequate reproduction, in the context of 

generally low population density 

(Bednarz 1977, p. 12). The members of 

the pair are usually near each other and 

run together when approached by 

intruders (Bednarz 1977). Several litters 

are probably produced each year, with 

litter size appearing to average 2.2 

young (Bednarz 1977, p. 12). The young 

tend to have a soft, woolly coat in early 

life and attain sexual maturity at a rapid 

rate. Daytime observations of whitesided jackrabbits are uncommon, as the 

species is primarily nocturnal (Bednarz 

1977, pp. 6-11; Best and Henry 1993, p. 

5). Although many species of jackrabbit 

and hare are considered pests because 

they may damage crops, fields, and 

orchards, the white-sided jackrabbit is 

not known to depredate crops. 

Distribution 

The core distribution of the whitesided jackrabbit lies within Mexico 

(New Mexico Department of Game and 

Fish (NMDGF) 2006a, p. 114). The 

species historically occurred from 

southern New Mexico to northern 

Oaxaca, Mexico, within two distinct 

geographic areas (Best and Henry 1993, 

p. 2). These two distinct geographic 

areas are occupied by each of the two 

subspecies. The historical range of the 

subspecies Lepus callotis gaillardia 

includes the southern Animas and 

Playas valleys of Hidalgo County, New 

Mexico, south into west-central 

Chihuahua and north-central Durango, 

Mexico (Bednarz and Cook 1984, p. 358; 

Reynolds 1988, p. 1), although it is now 

likely extirpated from the Playas Valley 

as no observations of the species have 

been made in this area during more 

recent surveys (Traphagen 2002, p. 5; 

Frey 2004, p. 22; NMDGF 2006a, p. 115; 

Traphagen 2010, p. 1). The other 

subspecies, Lepus callotis callotis, 

ranges from central Durango south 

across the open plains of the Mexican 

Plateau to the State of Oaxaca, Mexico 

(Hall 1981, p. 330). The geographic 

separation of the two areas occurs on 

either side of the Rio Nazas in Durango, 

Mexico. This river has been observed to 

act as a barrier and a catalyst for 

subspeciation in many mammal species, 

isolating one subspecies to the north of 

the river from the other to the south 

(Peterson 1976, pp. 496-498). 

The jackrabbit’s historical range in the 

Animas and Playas Valleys of New 

Mexico occurs entirely within the 

Diamond A Ranch (Traphagen 2010, p. 

3) and was estimated to be about 121 

square kilometers (sq km) (47 square 

miles (sq mi)), or approximately 12,000 

hectares (ha) (30,000 acres (ac)) 

(Bednarz 1977, p. 6; Bednarz and Cook 

1984, p. 359). We are unaware of any 

similar estimates for the jackrabbit’s 

range in Mexico. However, utilizing 

Geographic Information System (GIS) 

techniques and assessing the range 

maps of Anderson and Gaunt (1962, p. 

4) and Hall (1981, p. 330), we estimate 

the range of the jackrabbit in the United 

States to be less than one percent of the 

entire range of the species. 

The white-sided jackrabbit has not 

been confirmed as extant in Arizona 

(Cahalane 1939, p. 436), although in 

1954, Hoffmeister and Goodpaster 

reportedly observed what they believed 

to be white-sided jackrabbits along the 

west base of the Huachuca Mountains, 

Cochise County, Arizona (Hoffmeister 

1986, p. 562). There have been other, 

more recent reported sightings of the 

white-sided jackrabbit in Arizona; 

however, these have been refuted by 

experts on the species (Traphagen 

2009). Therefore, New Mexico is the 

only confirmed state in the United 

States where the species has been 

documented to occur. 

Habitat 

This species is highly elusive. It 

inhabits predominately mature open 

grasslands that have low shrub density 

and level terrain, avoiding hills or 

mountains (Bednarz and Cook 1984, p. 

359; Cook 1986, p. 15; Desmond 2004, 

p. 416). In the United States portion of 

its range, the white-sided jackrabbit 

appears to be found only in association 

with grasslands (Bednarz 1977, p. 6). 

More than 97 percent of all observations 

of this species have been in pure 

grasslands and less than 3 percent in 

grasslands with varying amounts of 

forbs (flowering herbs) and shrubs 

(Bednarz and Cook 1984). In New 

Mexico, white-sided jackrabbits feed 

primarily on Bouteloua gracilis (blue 

grama), Buchloe dactyloides 

(buffalograss), Bouteloua eripoda (black 

grama), and Lycurus phleoides (wolftail) 

(Bednarz 1977, pp. 14, 16). In New 

Mexico, the white-sided jackrabbit was 

historically limited to two valleys, the 

Animas Valley and the Playas Valley, 

that differ in their vegetative 

composition. A detailed description of 

each follows. 

The Animas Valley is a confined 

basin that lies 10 km (6 mi) west of the 

continental divide. The elevation is 

approximately 1,550 meters (m) (5,085 

feet (ft)). It is bounded on the east by the 

Animas Mountains, on the west by the 

Peloncillo Mountains, and on the south 

by the Sierra San Luis Mountains. The 

International Boundary between the 

United States and Sonora, Mexico, lies 

near the southern terminus of the valley. 

Precipitation averages about 381 

millimeters (mm) (15 inches (in)) 

annually, 60 percent of it falling 

between July and October. A large 

portion of the lower Animas Valley lies 

in a dry Pleistocene (the epoch that 

spanned from 2.6 million to 12,000 

years ago) lakebed, parts of which fill 

seasonally to shallow depths of a few 

centimeters. Soil moisture is therefore 

sufficient to support a moderate amount 

of wetland vegetation, namely nutgrass 

(Cyperus rotundus), a plant that is 

thought to be a seasonally important 

food source for the jackrabbit (Bednarz 

1977, p. 14). 

The lower Animas Valley supports a 

variety of grass and forb species, such as 

blue grama; Bouteloua curtipendula 

(sideoats grama); Sporobolus airoides 

(alkali sacaton); Muhlenbergia torreyii 

(ring muhly); Pleuraphis mutica, also 

known as Hilaria mutica (tobosa); 

buffalograss; black grama; wolftail; 

Muhlenbergia repens (creeping muhly); 

Panicum obtusum (vine mesquite); 

Aristida spp. (three-awn), Sphaeralcea 

spp. (globemallow); Gutierrezia 

sarothrae (broom snakeweed); Viguera 

annuum (goldeneye); Eriogonum 

wrightii (Wright buckwheat); and Aster 

spp. The occurrence of this specific 

grassland association, known as plains 

grassland, is uncommon and fairly 

unique in the southwestern United 

States, although it becomes more 

common south into Chihuahua and 

northern Durango, Mexico (Traphagen 

2009, p. 2). The southern Animas Valley 

is largely free of shrubs, probably as a 

function of soil structure, water 

drainage in soils, frequent fires, and 

cold air drainage. The Animas Valley is 

surrounded by several large mountain 

ranges that create winter microclimates 

too cold to support the establishment of 

shrubs such as mesquite (Prosopis spp.), 

cholla (Cylindroopuntia spp.), and 

creosote (Larrea spp.), which are not 

able to tolerate the cold winter nights 

(Traphagen 2009, p. 2). 

McKinney Flats lies 10 km (6 mi) east 

of the Continental Divide in the western 

fork of the southern Playas Valley just 

west of the Whitewater Mountains. This 

4,266-ha (10,240-ac) site is about 1,525 


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m (5,000 ft) above sea level. Bednarz 

(1977) estimated the area of suitable 

habitat for Lepus callotis on McKinney 

Flat to be 1,425 ha (3,520 ac). 

Conditions on McKinney Flat are drier 

than in the Animas Valley, averaging 

about 228 mm (9 in) annual 

precipitation. McKinney Flat is 

characterized as Chihuahuan desert 

grassland (Traphagen 2009, p. 2). Shrub 

invasion in this grassland association 

has occurred on a much larger scale 

than in the plains grassland association 

that exists in the Animas Valley 

(Traphagen 2009, pp. 2-3). 

Graminoid species in the Playas 

Valley include blue grama, sideoats 

grama, Eragrostis intermedia (plains 

lovegrass), tobosa, Bouteloua hirsuta 

(hairy grama), Scleropogon brevifolia 

(burrograss), Setaria machrostachya 

(Plains bristlegrass), black grama, 

wolftail, creeping muhly, vine mesquite, 

Bothrichloa barbinodis (cane 

beardgrass), and three-awn; commonly 

found forbs are Solanum eliaginifolium 

(horse nettle), Wright buckwheat, 

various Croton spp., and Aster spp. are 

commonly found forbs. Shrubs and trees 

such as honey mesquite (Prosopis 

glandulosa), soaptree yucca (Yucca 

elata), catclaw mimosa (Mimosa 

biuncifera), and various prickly pear 

(Opuntia spp.) and cholla 

(Cylindroopuntia spp.) are also present. 

We have little information pertaining 

to the habitat of the white-sided 

jackrabbit in Mexico. The primary biotic 

province in which the jackrabbit occurs 

is termed the Chihuahua-Zacatecas 

biotic province. This province covers 

the northern interior plains in 

Chihuahua, western Coahuila, Durango, 

Zacatecas, San Luis Potosi, and 

Aguascalientes (Goldman and Moore 

1945, p. 354). It is an arid interior desert 

region consisting mainly of grassland 

plains interrupted by areas overgrown 

by various shrub species (Goldman and 

Moore 1945, p. 354). The range of the 

jackrabbit also falls within the biotic 

provinces termed the Transverse 

Volcanic biotic province and the Sierra 

Madre del Sur biotic province. The 

Transverse Volcanic biotic province 

spans parts of 11 States and its diverse 

environmental and geographic features 

cannot be generalized; however, it 

includes areas of grasslands 

interspersed with shrubland (Goldman 

and Moore 1945, pp. 356-357). The 

Sierra Madre del Sur biotic province 

includes high mountain areas ranging 

from west to east through central 

Guerrero and the interior valleys of 

central and western Oaxaca. The climate 

is similar to that of the plateau of the 

northern portion of the country 

(Goldman and Moore 1945, p. 358). 

Although Goldman and Moore describe 

the major habitat types within Mexico, 

we have no information regarding the 

specific habitats occupied by the 

jackrabbit within these broad habitat 

types. 

Population Abundance 

The white-sided jackrabbit has never 

been known to be abundant in the 

United States. The species was first 

discovered in New Mexico by Mearns in 

1892 during surveys of the International 

Border between the United States and 

Mexico (Mearns 1895, p. 552). 

Specimens were not collected again in 

New Mexico until 1931 (Anderson and 

Gaunt 1962), and then again in 1975 

(Bogan and Jones 1975, p. 47; Bednarz 

1977, p. 1). The literature between the 

time of the initial collections and the 

subsequent collections in 1975 show 

argument amongst researchers as to 

whether the white-sided jackrabbit did 

indeed occur in the United States in the 

early 1900s. Multiple survey efforts 

have occurred since the 1975 surveys in 

attempts to document the extent of the 

range of the species in the United States 

and the size and density of the 

populations. 

As discussed above, white-sided 

jackrabbits are elusive and largely 

nocturnal. As such, the most effective 

surveys are completed in the dark by 

driving a vehicle through an area of 

potential habitat with a bright spotlight. 

Bednarz (1977) completed a series of 

such surveys and found a mean of 15 

jackrabbits per survey in the Animas 

Valley. Later, Cook (1981) resurveyed a 

similar area and found a mean of 7.5 

jackrabbits per survey. Mehlhop (1995) 

reported on surveys in the Animas and 

Playas Valleys conducted in 1990, 1994, 

and 1995. The mean number of 

jackrabbits observed during the 1990 

surveys was 3.2, while the mean for the 

1994 and 1995 surveys was 1.1 

(Mehlhop 1995). Traphagen (2010) has 

completed the most recent surveys for 

white-sided jackrabbits, and while the 

author does not report the mean number 

of jackrabbits sighted per survey effort, 

he notes 28 were sighted over the course 

of 9 surveys. Traphagen (2010) also 

notes that surveys were conducted by 

another party between 1997 and 2002, 

but that the results of those studies have 

not been analyzed. On its face, the 

survey information for the white-sided 

jackrabbit would seem to suggest a 

decline in species density in the United 

States over the last 35 years. However, 

each of the surveyors utilized somewhat 

different survey methods and different 

survey routes, thus precluding a 

statistical comparison of their results. 

Based on the historical and current 

survey records, this species was likely 

always rare and appears to continue to 

be rare in the United States. 

Some survey work has been 

completed in Mexico in modern times 

(Desmond 2004; Reynolds 1988); 

however, these surveys have tended to 

be one- or two-summer efforts, and 

without historical information to 

compare their numbers to, it is difficult 

to assess population trends. Reynolds 

(1988) interviewed ‘‘campesinos, 

ranchers, and whenever possible, 

members of a local hunting club’’ about 

their experiences with white-sided 

jackrabbits in the Mexican States of 

Guanajuato, Guerrero, Hidalgo, Jalisco, 

Mochoacan, Morelos, Oaxaca, Puebla, 

Queratoro, San Luis Potosi, Tlaxcala, 

and Zacatecas. The reliability of 

anecdotal reports can also be difficult to 

assess; however, Reynolds (1988) 

reported that the persons interviewed in 

Guanajuato, Guerrero, Hidalgo, and 

Morelos indicated that the white-sided 

jackrabbit may be reduced in numbers 

compared to the previous 20 to 25 years. 

Desmond (2004) reported on surveys of 

white-sided jackrabbits conducted in 

1998 and 1999 in central and 

northwestern Chihuahua, Mexico. He 

reported 0.03 jackrabbits per acre 

surveyed in 1998, and 0.04 jackrabbits 

per acre surveyed in 1999 (Desmond 

2004). When the numbers were adjusted 

to reflect just the area of plains 

grasslands, the preferred habitat of the 

white-sided jackrabbit in this part of its 

range, he reported 0.06 jackrabbits per 

acre in 1998 and 0.08 jackrabbits per 

acre in 1999 (Desmond 2004). Again, the 

importance of these numbers is difficult 

to assess because there is no prior or 

subsequent survey information to which 

to compare them; however, Desmond 

(2004, p. 417) notes, ‘‘It is not clear if 

white-sided jackrabbits have always 

occupied semidesert grasslands at low 

densities or if reduced densities in this 

grassland type are related to habitat 

degradation.’’ 

Summary of Information Pertaining to 

the Five Factors for Lepus callotis 

Section 4 of the Act and 

implementing regulations (50 CFR part 

424) set forth procedures for adding 

species to, removing species from, or 

reclassifying species on the Federal 

Lists of Endangered and Threatened 

Wildlife and Plants. Under section 

4(a)(1) of the Act, a species may be 

determined to be endangered or 

threatened based on any of the 

following five factors: 

(A) The present or threatened 

destruction, modification, or 

curtailment of its habitat or range; 


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(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. 

In making this finding, information 

pertaining to the full species of the 

white-sided jackrabbit, Lepus callotis, in 

relation to the five factors provided in 

section 4(a)(1) of the Act is discussed 

below. In making our 12–month finding 

on a petition to list the full species of 

the white-sided jackrabbit, Lepus 

callotis, we considered and evaluated 

the best available scientific and 

commercial information. 

In considering what factors might 

constitute threats to a species, we must 

look beyond the exposure of the species 

to a factor to evaluate whether the 

species may respond to the factor in a 

way that causes actual impacts to the 

species. If there is exposure to a factor 

and the species responds negatively, the 

factor may be a threat and we attempt 

to determine how significant a threat it 

is. The threat is significant if it drives, 

or contributes to, the risk of extinction 

of the species such that the species 

warrants listing as endangered or 

threatened as those terms are defined in 

the Act. 

Factor A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Livestock grazing and suppression of 

wildfire have been shown to lead to 

shrub encroachment and degradation of 

grasslands, separately and in 

combination (Bureau of Land 

Management (BLM) 2009, p. 2; Malpai 

Borderlands Habitat Conservation Plan 

Technical Working Group 2008, p. 18; 

Traphagen 2002, p. 12). In New Mexico, 

the white-sided jackrabbit is found only 

in association with mature, highelevation (greater than 1,460-m (4,800- 

ft)) plains or Chihuahuan desert 

grasslands, characterized by flat 

topography and few shrubs and forbs 

(Bednarz 1977, p. 6). The bootheel 

region of southwestern New Mexico, 

which contains the range of the whitesided jackrabbit in the United States, 

was dominated by grassland until the 

late 19th century. Historically, the 

presence of shrubs and low growing 

trees was limited to drainages or to 

rocky shallow soil areas; however, 

changes in land use to accommodate 

agricultural practices, including 

livestock grazing and fire suppression, 

have led to the invasion of woody 

shrubs and their establishment into sites 

where they did not previously occur 

(BLM 2009, p. 10). Once invasive shrubs 

become established, they tend to 

increase in density and outcompete 

other native vegetation for soil moisture, 

nutrients, and sunlight and are less 

susceptible to drought than herbaceous 

species, which are green and fleshy as 

opposed to the generally more woody 

shrubs. 

Numerous sources substantiate that 

past range-management practices have 

contributed to the degradation of desert 

grasslands or their conversion to 

shrublands (National Museum of 

Natural History 2008, p. 1; Bednarz and 

Cook 1984, p. 360; Desmond 2004, p. 

417; Forest Service 2007, p. 15; Service 

2008, p. 53). The BLM reports in its 

2009 Environmental Assessment for the 

Bootheel Restoration Initiative that the 

vegetative community in the areas 

affected by shrub encroachment in 

southern New Mexico is far removed 

from the historical climax community 

and no longer supports the historical 

abundance and diversity of flora and 

fauna (BLM 2009, p. 13). Bednarz and 

Cook (1984, p. 360) postulated that 

numbers of white-sided jackrabbit had 

decreased in New Mexico as the density 

and vigor of grasses declined, while 

black-tailed jackrabbits and desert 

cottontail (Sylvilagus audubonii) 

numbers increased in response to an 

increase in woody shrubs. Desmond 

(2004, p. 417) reported a similar pattern 

from Chihuahua, Mexico, where she 

found that increased shrub 

encroachment into grasslands likely has 

negatively affected populations of 

white-sided jackrabbits (Desmond 2004, 

p. 417). 

Traphagen (2009, pp. 1- 4) reports that 

the impacts of livestock grazing and fire 

suppression may differently affect the 

two valleys that compose the species’ 

portion of the range in the United 

States. Traphagen (2009, p. 2) reports 

that the Animas Valley is largely free of 

shrubs, likely due to the soil structure, 

water drainage, frequent fires, and cold 

air drainage. Cold air drainage is a 

process that occurs in valleys as the 

ground cools at night, cooling the air 

and causing denser cold air from higher 

elevations to move down into the valley. 

The Animas Valley is surrounded by 

several large mountain ranges that 

create winter microclimates too cold to 

support the establishment of shrubs on 

the valley floor such as mesquite, 

cholla, and creosote (Traphagen 2009, p. 

2). In contrast, the Playas Valley 

receives less precipitation annually and 

is generally drier than the Animas 

Valley (Traphagen 2009, p. 2). Shrub 

invasion in this grassland association 

has occurred on a much larger scale 

than in the grassland association found 

in the Animas Valley (Traphagen 2009, 

p. 2). 

Livestock Grazing 

Areas where white-sided jackrabbits 

historically or currently occur in the 

United States were continuously grazed 

for over a century (Traphagen 2002, p. 

3). Overgrazed grassland is susceptible 

to invasion by shrubs and forbs, a cover 

type which greatly favors the blacktailed jackrabbit (Baker 1977, pp. 222- 

223; Bednarz and Cook 1984, pp. 359- 

360; Desmond 2004, p. 417; Moore-Craig 

1992, p. 13; NMDGF 2006a, p. 115). 

The Diamond A Ranch in New 

Mexico, which includes the historic 

range of the jackrabbit in both the 

Animas and Playas Valleys, has been 

very lightly grazed since 1994, and there 

have been several periods where grazing 

was deferred on the ranch for 4 years or 

more (Traphagen 2009, p. 3). Prior to 

ownership by the Animas Foundation, 

the ranch was owned by The Nature 

Conservancy, and stocking rates were 

very low (Traphagen 2009, p. 5). During 

the period from 2003 to 2006 there was 

no cattle grazing in the Animas Valley 

where the white-sided jackrabbit occurs 

(Traphagen 2009, p. 5). We have no 

information about current grazing 

practices in historical habitat in the 

Playas Valley beyond the general 

statement that the Diamond A Ranch 

has been lightly grazed since 1994. This 

species appears to be extirpated from 

that portion of its range. The extent to 

which past grazing practices may have 

contributed to that extirpation is 

unknown; however, the Playas Valley 

may have been more susceptible to 

shrub encroachment resulting from past 

overgrazing than the Animas Valley as 

a result of the differences in grassland 

type and cold air drainage patterns 

discussed above. 

Finally, while we know that grazing 

of livestock occurs in Mexico (see, for 

example, Buller et al. 1960), we do not 

have information on the extent or 

intensity of historical or current 

livestock grazing practices throughout 

the range of the species in Mexico. 

Brown (1994) reported that a primary 

cause of loss and degradation of 

grasslands in the Chihuahuan Desert is 

overgrazing by cattle; however, the 

extent of those grassland losses 

throughout the historical range of the 

jackrabbit and the impacts of those 

losses on the jackrabbit are not known. 

Previous research had indicated that 

the jackrabbit required 65 percent grass 

cover of species that included blue and 

black grama, ring muhly, buffalograss, 

wolftail, and bottlebrush squirreltail 

(Elymus elymoides) (Bednarz and Cook 

1984, pp. 359-360). However, in a 


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research project commissioned by the 

NMDGF it was found that presence of 

the white-sided jackrabbit was highly 

correlated with the presence of 

buffalograss (Traphagen 2002, p. 6). No 

other grasses analyzed in the study, 

including blue and black grama, ring 

muhly, wolftail, and bottlebrush 

squirreltail, showed any correlation 

with white-sided jackrabbit habitat. The 

Animas Valley is dominated in many 

areas by buffalograss, but buffalograss is 

no longer present in the Playas Valley 

(Traphagen 2009, p. 3). 

One study found a relationship 

between grazing and the presence of 

buffalograss in two plots in the Animas 

Valley (Traphagen 2009, pp. 3-4). The 

Sacahuiste Grazing Exclosure has been 

ungrazed since 1996. This plot is paired 

with a grazed plot located 50 m (160 ft) 

outside the exclosure. The ungrazed 

exclosure experienced a decline of 300 

percent in cover of buffalograss during 

the 12–year period of no grazing, while 

the grazed plot declined by only 30 

percent (Traphagen 2009, p. 4). If 

grazing does not occur, buffalograss is 

outcompeted because of its lack of 

shade tolerance (Traphagen 2009, p. 5). 

These results indicate that light grazing 

may be an important part of maintaining 

the health of the ecosystem. 

The best available information 

indicates that grazing is not currently 

occurring at a level which may 

constitute a threat to extant populations 

of the species in New Mexico, although 

grazing may have played a role in the 

presumed extirpation of white sidedjackrabbits in the Playas Valley. 

Information about the species’ status in 

Mexico is very limited. As discussed 

above, overgrazing may have caused 

some loss or degradation of grasslands 

in the Chihuahuan Desert, and the 

encroachment of shrubs into grasslands 

may have negatively affected 

populations of white-sided jackrabbits 

there. However, the information 

available concerning grazing practices 

in Mexico does not allow us to assess 

the magnitude or immediacy of these 

impacts on the species, nor the extent of 

the occupied range of the jackrabbit that 

may be subject to overgrazing impacts. 

In the absence of information that 

allows us to make a reasonable 

connection between the impacts of 

livestock grazing and current or future 

declines of white-sided jackrabbits, we 

are unable to conclude that this species 

is threatened by grazing practices. 

Wildfire Suppression 

Wildfire suppression is often a cause 

of grassland degradation. Fire exclusion 

has likely led to encroachment of shrubs 

into the grassland habitat of the whitesided jackrabbit. Humphrey (1958, p. 

245) believed fires were the controlling 

factor that kept shrubs from invading 

the desert grasslands in southeastern 

Arizona and southwestern New Mexico. 

The BLM came to a similar conclusion 

for the region of southwestern New 

Mexico where the white-sided 

jackrabbit historically occurred (BLM 

2009, pp. 1-3). Alternatively, Valone et 

al. (2002, p. 563) reported that two fires 

in 5 years did not result in high levels 

of mortality to woody shrubs such as 

mesquite on the Diamond A Ranch. 

Traphagen (2009, p. 4) reports that 

fire has occurred on a frequent and 

widespread basis across the Diamond A 

Ranch in recent decades, and that fire 

suppression has not occurred on the 

ranch in recent years. He states that 

there have been several major fires in 

the Animas Valley that have burned 

nearly 100 percent of the habitat of the 

jackrabbit (Traphagen 2009, p. 4). He 

provides a partial list of fires and area 

burned on the ranch: in June of 2009 the 

‘‘Pascoe fire’’ burned 23,635 ha (58,404 

ac) in the southern Animas Valley and 

12,304 ha (30,405 ac) in the west fork 

of the Playas Valley. In 1998 the ‘‘Flat 

fire’’ burned over 12,867 ha (31,796 ac) 

of the Animas and Playas Valleys. In 

1999 the ‘‘Garcia fire’’ burned 8,660 ha 

(21,400 ac) in habitat. In 2000 the ‘‘Fitz 

fire’’ burned 2,007 ha (4,961 ac) in the 

heart of white-sided jackrabbit habitat. 

The ‘‘Lang fire’’ burned another 404 ha 

(1,000 ac) adjacent to the Fitz fire. 

From these data, we can conclude that 

fire suppression does not currently 

constitute a threat to the species in New 

Mexico because there is information on 

the dates of fires from the last several 

years as well as the approximate area 

burned. The best available information 

does not indicate that fire suppression 

occurs in New Mexico at a level which 

may impact the status of the species, by 

allowing for the conversion of its 

preferred habitat. We have no 

information about the frequency or 

distribution of wildfires throughout the 

species’ range in Mexico. We have no 

information about the existence of 

wildfire suppression or prescribed burn 

programs throughout the species’ range 

in Mexico. 

It is known that both shrub 

encroachment into grassland fostered by 

current and historical grazing practices, 

as well as fire exclusion, have degraded 

habitat occupied by the species in the 

United States portion of the range. 

However, as stated above, we do not 

find this to be at a level that would 

constitute a threat to extant populations 

of this species in New Mexico. Again, 

there is very little information available 

about the species’ status and its habitat 

in the large portion of its range in 

Mexico. The best available information 

does not describe the historical or 

current trends in grassland health in the 

Mexican portion of the species’ range in 

a way that allows us to assess the 

magnitude or immediacy of the impacts 

on the species. Thus, we cannot 

conclude that habitat degradation due to 

livestock grazing and fire suppression 

leading to shrub encroachment is a 

threat to the species as a whole, either 

now or in the foreseeable future. 

Factor B. Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

The white-sided jackrabbit is not 

believed to be overutilized in the U.S. 

portion of its range, and current 

information on its utilization in Mexico 

is limited (Traphagen 2009, p. 4). 

Hunting of the species is prohibited in 

New Mexico as it is currently protected 

under the New Mexico Wildlife 

Conservation Act (NMDGF 2008, p. 10). 

Further, in New Mexico, the whitesided jackrabbit only occurs on private 

land, thereby limiting hunting 

opportunities (Traphagen 2009, p. 4). 

Literature indicates that the species has 

been commonly hunted in Mexico for 

commercial markets (Leopold 1959, p. 

349; Reynolds 1988). While hunting for 

commercial markets is no longer 

allowed, Reynolds (1988) reports that 

hunting for personal use continues. 

Matson and Baker (1986, p. 41) 

indicated that the species was heavily 

hunted and considered highly edible. 

While there is information that hunting 

of white-sided jackrabbits occurs in 

Mexico, we are unable to assess the 

level of hunting that occurs and whether 

it is having an impact on the population 

levels and overall status of the species. 

The vast majority of the species’ range 

lies in Mexico and the best available 

information does not allow us to assess 

the magnitude and immediacy of this 

impact on the species in that country. 

Additionally, the species does not 

appear to be impacted by such practices 

in the New Mexico portion of its range. 

Therefore, we conclude that hunting is 

not currently a known a threat to the 

species as a whole throughout its range. 

There is some information which 

indicates that the white-sided jackrabbit 

is occasionally subject to impacts from 

animal damage control programs. 

Various rabbit species occasionally feed 

on crop plants and are seen as pests; 

however, the white-sided jackrabbit has 

not been documented as a heavy 

consumer of crop plants. The U.S. 

Department of Agriculture (USDA) 

reported that jackrabbits (Lepus spp.) 

have been taken in New Mexico as part 


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of their animal damage control program 

(USDA Animal and Plant Health 

Inspection Service 1994, Appendix H, 

pp. 18-19). More recent data from 2007 

and 2008 on the numbers and kinds of 

animals killed or euthanized by wildlife 

services in New Mexico report only 

cottontail rabbits as having been lost. 

There is no description of current or 

future plans for lethal control of any 

white-sided jackrabbits, nor is there a 

quantification of the amount that may 

have occurred historically by either the 

USDA or the general public. We have no 

information on the activities of this type 

throughout the species’ range in Mexico. 

Therefore, we find that the best 

available information does not indicate 

that the white-sided jackrabbit is 

currently subject to animal damage 

control programs by methods such as 

trapping or shooting, or is likely to be 

in the future in New Mexico. 

While individual white-sided 

jackrabbits may be subject to 

overutilization or animal damage 

control programs, the available 

information on this impact does not 

allow us to assess whether or not these 

impacts are occurring at a level which 

may affect the status of the species as a 

whole. Therefore, we find that the 

white-sided jackrabbit is not threatened 

due to overutilization for commercial, 

recreational, scientific, or educational 

purposes, either now or in the 

foreseeable future. 

Factor C. Disease or Predation 

We are not aware of any research that 

has been conducted to specifically 

examine the role of disease in the whitesided jackrabbit. Bednarz (1977, p. 19) 

indicated that a lung infection has been 

observed in white-sided jackrabbits in 

New Mexico; however, Moore-Craig 

(1992, p. 11) noted that the infections 

found by Bednarz were all of a minor 

nature, and the overall health of the 

jackrabbit population appeared to be fair 

to good. Tularemia, a common disease 

among black-tailed jackrabbits, has not 

been found in the white-sided jackrabbit 

in New Mexico (Moore-Craig 1992, p. 

11). We do not have any reports of 

disease in the white-sided jackrabbit in 

Mexico. 

A variety of potential predators exists 

throughout the species’ range, including 

coyote (Canus latrans), kit fox (Vulpes 

macrotis), gray fox (Urocyon 

cinereoargenteus), badger (Taxidea 

taxus), spotted skunk (Mephitis 

mephitis), and a number of predatory 

bird species. Of these carnivores, 

probably only the coyote is able to 

successfully prey on adult jackrabbits 

with much frequency, as the jackrabbit 

is nocturnal and generally avoids 

predation by bird species active during 

the day (Bednarz 1977, p. 18). Although 

the jackrabbit is subject to predation, 

there is no data from either country 

which indicates that predation is 

occurring at a level which may 

constitute a threat to the species 

throughout its range. 

Although white-sided jackrabbit 

individuals may be subject to occasional 

infections or predation, there is no 

evidence that either of these is occurring 

at a level which may affect the status of 

the species as a whole. Therefore, we 

find that the white-sided jackrabbit is 

not threatened due to disease or 

predation, either now or in the 

foreseeable future. 

Factor D. The Inadequacy of Existing 

Regulatory Mechanisms 

To determine if existing regulatory 

mechanisms are adequate to protect the 

white-sided jackrabbit, we evaluated 

agreements and laws in effect within the 

range of the species. The white-sided 

jackrabbit was listed as threatened by 

the State of New Mexico on January 24, 

1975. This designation provides the 

protection of the New Mexico Wildlife 

Conservation Act, which prohibits 

direct take of the species except under 

issuance of a scientific collecting 

permit. However, this only conveys 

protection from collection or intentional 

harm. Although the State of New 

Mexico statutes require the NMDGF to 

develop a recovery plan that will restore 

and maintain habitat for threatened 

species, the jackrabbit does not have a 

finalized recovery plan, conservation 

plan, or conservation agreement 

(NMDGF 2006b, p. 430). 

There is some dispute concerning the 

effectiveness of the conservation efforts 

of the Malpai Borderlands Group in 

Hidalgo County, New Mexico. The 

petitioners state that the Malpai 

Borderlands Group does not afford 

protection to the white-sided jackrabbit 

or to its habitat as intended (WildEarth 

Guardians (2008)). The apparent basis of 

this position is that the Service issued 

an incidental take permit under section 

10(a)(1)(B) of the Act on private lands to 

the Malpai Borderlands Group for the 

Malpai Borderlands Habitat 

Conservation Plan (MBHCP). WildEarth 

Gardians (2008) also contends, based 

upon observed degradation of grassland 

habitat and declines in the jackrabbit 

population, that the Malpai Borderlands 

Group is not fulfilling its stated mission 

to restore and maintain natural 

processes that support diverse and 

flourishing animal life in the 

borderlands region, which includes the 

Diamond A Ranch in southern Hidalgo 

County, and constitutes the range of the 

white-sided jackrabbit in the United 

States. However, they provide no 

information that documents the extent, 

magnitude, or immediacy of the 

perceived inadequacies of the MBHCP 

or how they threaten the white-sided 

jackrabbit in New Mexico. Traphagen 

(2009, pp. 4-5) provides information 

indicating that the Animas Foundation 

and the Malpai Borderlands Group have 

supported numerous research, 

monitoring, and restoration projects, 

with nearly all of the projects focusing 

on aspects of rangeland health, shrub 

invasion, and endangered species 

conservation. Traphagen (2009, p. 5) 

states that several major prescribed 

burns have been conducted in the 

Malpai Borderlands Region in the last 

20 years in addition to allowing natural 

fires to run free. Traphagen (2009, p. 5) 

also describes the cooperation of private 

ranchers in deferring grazing in order to 

reduce woody shrub cover and to allow 

pastures with insufficient biomass to 

recover. 

The Mexican Federal agency known 

as the Instituto Nacional de Ecologia ́ is 

responsible for the analysis of the status 

and threats that pertain to species that 

are proposed for listing in the Norma 

Oficial Mexicana NOM-059 (the 

Mexican equivalent to a threatened and 

endangered species list), and if 

appropriate, the nomination of species 

to the list. The Instituto Nacional de 

Ecologia ́ is generally considered the 

Mexican counterpart to the United 

States’ Fish and Wildlife Service. The 

white-sided jackrabbit is not included in 

the NOM-059 (SEDESOL 2008) and is 

therefore not protected by Federal 

regulation in Mexico. 

In NatureServe, the white-sided 

jackrabbit’s global ranking is G3 

(vulnerable) and its National and State 

Status rankings are N1S1 (critically 

imperiled). The species’ status under 

the International Union for 

Conservation of Nature and Natural 

Resources is ‘‘near threatened.’’ 

However, these lists are not regulatory 

mechanisms; they serve only to notify 

the public of the species’ status; no 

conservation or management actions are 

required and no regulatory authority for 

species conservation is established 

through these listings. Additionally, the 

white-sided jackrabbit is on the 

Regional Forester’s Sensitive Species 

List for the Coronado National Forest 

(Forest Service 2007, p. 15); however, 

we found no information to that 

indicates the jackrabbit is present on 

any Forest Service lands in New 

Mexico. 

There is information that indicates 

that the white-sided jackrabbit’s status 

as a State-listed threatened species in 


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New Mexico confers little regulatory 

protection (except against direct take). 

Further, the white-sided jackrabbit is 

not covered by any known regulations 

in Mexico. However, as discussed in the 

other Factors of this section, we have 

not identified any threats to this species 

that are likely to negatively affect the 

status of the species as a whole, such 

that the limited regulatory protection is 

not likely to represent a threat to the 

species. Therefore, we find that the 

white-sided jackrabbit is not threatened 

by inadequacy of regulatory 

mechanisms, either now or in the 

foreseeable future. 

Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence 

The following natural or manmade 

factors may affect the white-sided 

jackrabbit or its habitat, or both, and are 

discussed below: climate change, 

consumption of poisonous plants, 

impacts by vehicles on roads, and fire. 

Climate Change 

The Intergovernmental Panel on 

Climate Change (IPCC) is a scientific 

body set up by the World 

Meteorological Organization and the 

United Nations Environment Program in 

1988. It was established because policy 

makers needed an objective source of 

information about the causes of climate 

change, its potential environmental and 

socio-economic consequences, and the 

adaptation and mitigation options to 

respond to it. The Service considers the 

IPCC an impartial and legitimate source 

of information on climate change. In 

2007, the IPCC published its Fourth 

Assessment Report, which is considered 

the most comprehensive compendium 

of information on actual and projected 

global climate change currently 

available. 

Although the extent of warming likely 

to occur is not known with certainty at 

this time, the IPCC (2007, p. 5) has 

concluded that warming of the climate 

is unequivocal and continued 

greenhouse gas emissions at or above 

current rates would cause further 

warming (IPCC 2007, p. 13). The IPCC 

also projects that there will very likely 

be an increase in the frequency of hot 

extremes, heat waves, and heavy 

precipitation (IPCC 2007, p. 15). 

Warming in the southwestern United 

States is expected to be greatest in the 

summer (IPCC 2007, p. 887). Annual 

mean precipitation is likely to decrease 

in the southwestern United States and 

the length of snow season and snow 

depth are very likely to decrease (IPCC 

2007, p. 887). Further, the IPCC (2007, 

p. 888) concluded that grasslands and 

shrublands appear to be more sensitive 

than previously thought to variability of, 

and changes in, major climate change 

drivers, such as the increase in 

atmospheric carbon dioxide. Several 

climate change models project that the 

southwestern United States will become 

hotter and drier, and indicate that the 

portion of southwestern New Mexico 

currently occupied by the white-sided 

jackrabbit will be characterized by 

shrubland or woodland as a result of 

climate change (The Wildlife Society 

2004, p. 6; Izaurralde et al. 2005, pp. 

110-111). In their Vulnerability 

Assessment for Biodiversity in New 

Mexico, Enquist and Gori (2008, p. 14) 

consider the white-sided jackrabbit to be 

a drought-sensitive conservation target 

based upon the predicted conversion of 

its grassland habitat to shrubland. 

Further, information indicates that 

climate change might contribute to more 

frequent and intense drought within the 

United States and northern Mexico 

portion of the range of the jackrabbit 

(Seager et al. 2007, pp. 1181-1182). 

In consultation with leading scientists 

from the southwestern United States, 

the New Mexico Office of the State 

Engineer prepared a report for the 

Governor (D’Antonio 2006) which made 

the following observations about the 

impact of climate change in New 

Mexico: 

(1) Warming trends in the American 

Southwest exceed global averages by 

about 50 percent (p. 5); 

(2) Models suggest that even moderate 

increases in precipitation would not 

offset the negative impacts to the water 

supply caused by increased temperature 

(p. 5); 

(3) Temperature increases in the 

Southwest are predicted to continue to 

be greater than the global average (p. 5); 

and 

(4) The intensity, frequency, and 

duration of drought may increase (p. 7). 

The best available information 

indicates that the white-sided jackrabbit 

may be vulnerable to climatic changes 

that would decrease suitable habitat in 

New Mexico; however, while it appears 

reasonable to assume that the whitesided jackrabbit may be affected, we 

lack sufficient certainty to know 

specifically how climate change will 

affect the species. Despite large-scale 

conclusions that climate change is 

occurring in New Mexico, we have not 

identified, nor are we aware of, any data 

on an appropriate scale to evaluate 

habitat or population trends for the 

white-sided jackrabbit within its range 

in New Mexico or in Mexico at this 

time, or to make predictions on future 

trends and whether the species will be 

impacted. There are multiple 

hypothetical outcomes associated with 

climate change that could potentially 

affect the white-sided jackrabbit habitat. 

However, we lack predictive local or 

regional models on how climate change 

will specifically affect the habitat in 

either country. Given that reliable, 

predictive models have not been 

developed for use at the local scale in 

New Mexico’s bootheel region or for the 

sites in the many States in Mexico 

within the jackrabbit’s range, currently 

there is little certainty regarding the 

timing, magnitude, and net effect of 

impact. Therefore, we find it is not 

possible at this time to make reliable 

predictions of climate change effects on 

the status of the white-sided jackrabbit, 

due to the current limitations in 

available data and climate models. 

Based on the best available information 

and our current knowledge and 

understanding, we conclude that 

climate change is not a known threat to 

the white-sided jackrabbit or its habitat, 

now or in the foreseeable future. 

Food Poisoning 

A single suspected case of food 

poisoning of white-sided jackrabbits is 

known. Bednarz (1977, p. 18) detailed a 

case in which a New Mexico rancher 

found several dead white-sided 

jackrabbits while eradicating mustard 

plants. Bednarz (1977, p. 18) suggests 

that this mortality may have been 

caused by the jackrabbits’ consumption 

of mustard plants and ensuing nitrate 

poisoning. Consumption of mustard 

plants is known to cause nitrate 

poisoning in cattle, and Bednarz (1977, 

p. 18) states that it likely has the same 

effect on jackrabbits. We are not aware 

of any other similar reports or 

information that indicates that food 

poisoning threatens the jackrabbit. 

There is no evidence that food 

poisoning is occurring at a level which 

may affect the status of the species as a 

whole, now or in the foreseeable future. 

Impacts by Vehicles 

There is information that indicates 

that the white-sided jackrabbit is subject 

to fatal impacts from vehicles on roads 

within the species’ range in New 

Mexico. Moore-Craig (1992, p. 16) and 

Bednarz (1977, p. 18) reported that that 

white-sided jackrabbits were 

occasionally killed by vehicles. 

Rangewide, jackrabbits are likely 

somewhat protected from significant 

impacts due to vehicle collisions 

because they are largely nocturnal 

animals and not active in the day when 

most people are active. However, the 

recent increase in U.S. Border Patrol 

activity may have increased the 

magnitude of this impact on white-sided 


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jackrabbit populations near the 

international border. Due to the nature 

of the U.S. Border Patrol activities, these 

vehicles would be present on roads at 

night more often than vehicles were 

present on roads at night historically. 

Traphagan (2010) notes that U.S. Border 

Patrol agents have reported roadkills at 

night. However, there is no reason to 

extrapoloate these U.S. Border Patrol 

activities and vehicle collision rates to 

other portions of the range of the species 

because U.S. Border Patrol impacts are 

unique to the area near the international 

border. Based on this review of the best 

available information, we find that, 

although individual jackrabbits may be 

subject to impacts as a result of vehicle 

collisions, there is no evidence that this 

is occurring at a level that may affect the 

status of the species as a whole, now or 

in the foreseeable future. 

Fire Management 

The active fire management program 

in the Malpai Borderlands area may 

affect the white-sided jackrabbit. Effects 

to jackrabbits during fire management 

may include mortality or injury of 

individuals as a result of direct 

exposure to fire, smoke inhalation, and 

crushing by the tires or tracks of 

vehicles used in fire management 

activities (Service 2008, pp. 64-65). We 

believe that the jackrabbit is capable of 

surviving such fire effects by running 

away (Service 2008, p. 64). We find 

prescribed burns may also expose 

white-sided jackrabbits to higher rates of 

predation, but may also allow the 

jackrabbits to more easily detect 

terrestrial predators (Service 2008, p. 

65). The effects of a prescribed burn to 

habitats would likely be short term, 

because the fire-adapted grassland 

community usually responds quickly, 

with plant species showing regrowth 

within several days post-fire. 

Nevertheless, a reduction of shrubs 

would benefit the white-sided jackrabbit 

by improving grassland habitat. 

Although the management measures 

employed under the MBHCP will likely 

result in short-term adverse effects to 

the jackrabbit, the long-term effects will 

improve the grassland community used 

by white-sided jackrabbits by reducing 

the shrub component, providing 

additional suitable habitat, and 

improving the area around occupied 

habitat for potential expansion; thus, 

implementation of the MBHCP, 

including the fire management program, 

should promote the conservation of the 

white-sided jackrabbit. Based on this 

review of the best available information, 

we find that although individual 

jackrabbits may be subject to impacts of 

fire management, there is no evidence 

that the short-term impacts of fire 

management are occurring at a level that 

may affect the status of the species as a 

whole now or in the foreseeable future. 

Further, the long-term impacts of fire 

management may serve to improve 

white-sided jackrabbit habitat and thus 

provide a benefit to the species. 

Finding for Lepus callotis 

As required by the Act, we considered 

the five factors in assessing whether the 

full species of the white-sided 

jackrabbit, Lepus callotis, is threatened 

or endangered throughout its range. We 

have carefully examined the best 

scientific and commercial information 

available regarding the past, present, 

and future threats faced by the species. 

We reviewed the petition, information 

available in our files, and other 

available published and unpublished 

information. 

Our review of the best available 

scientific and commercial information 

pertaining to the five factors does not 

indicate that the white-sided jackrabbit 

is in danger of extinction (endangered), 

or likely to become endangered within 

the foreseeable future (threatened), 

throughout its range. This is based on 

our finding in the five-factor analysis 

that stressors in New Mexico do not 

constitute threats to the jackrabbit in its 

current range in New Mexico, and the 

fact that the best available information 

concerning the jackrabbit’s status and its 

habitat in Mexico, limited as it is, does 

not allow us to assess the magnitude or 

immediacy of those potential impacts 

on the species, nor the extent of the 

occupied range of the jackrabbit that 

may be subject to impacts. While we 

have evidence that some impacts may 

be occurring within the range of the 

species (e.g., shrub encroachment, 

grazing, hunting, vehicle collisions, 

changing climate conditions), we do not 

have any specific information that 

allows us to make a reasonable 

connection between these potential 

impacts and current or future declines 

of white-sided jackrabbits. Therefore, 

we find that listing the full species of 

the white-sided jackrabbit as a 

threatened or an endangered species 

throughout its range is not warranted at 

this time. 

Species Information: Lepus callotis 

callotis 

The distribution of the subspecies of 

the white-sided jackrabbit, Lepus 

callotis callotis, is limited to Mexico. 

The northern limit of the subspecies’ 

range is established by the Rio Nazas 

(Peterson 1976, p. 497). The range of the 

subspecies L. c. callotis spans several 

States in the Mexican interior, from 

Durango in the north to Oaxaca in the 

south (Hall 1981, p. 330). The range of 

the subspecies L. c. callotis is fully 

encompassed by the range of the species 

L. callotis. Please see the ‘‘Species 

Information: Lepus callotis’’ section 

above for a full discussion of whitesided jackrabbit taxonomy, species 

description, biology, distribution, 

habitat, and population abundance. 

Summary of Information Pertaining to 

the Five Factors for Lepus callotis 

callotis 

In making this finding, information 

pertaining to the subspecies of the 

white-sided jackrabbit, Lepus callotis 

callotis, in relation to the five factors 

provided in section 4(a)(1) of the Act is 

discussed below. In making our 12– 

month finding on a petition to list the 

subspecies of the white-sided jackrabbit, 

Lepus callotis callotis, we considered 

and evaluated the best available 

scientific and commercial information. 

Factor A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Based on extensive literature 

searches, we find there is no 

information available to us which 

describe threats to the subspecies’ 

habitat or range in a way that allows us 

to assess the magnitude or immediacy of 

these impacts on the subspecies. It is 

likely that many of the same or similar 

anthropogenic activities that occur in 

the United States portion of the full 

species’ range, discussed above, occur 

within the subspecies’ range in Mexico. 

However, there is no information 

available to evaluate whether these 

factors or potential threats have a 

negative effect on the subspecies. We 

are not aware of additional or specific 

activities which may be contributing to 

the present or threatened destruction, 

modification, or curtailment of the 

subspecies’ habitat or range in Mexico. 

Therefore, we find that the best 

available information regarding threats 

to the subspecies’ habitat or range does 

not indicate that listing the subspecies 

throughout all or a portion of its range 

is warranted due to the present or 

threatened destruction, modification, or 

curtailment of its habitat or range, either 

now or in the foreseeable future. 

Factor B. Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

There are reports of the historical 

utilization of white-sided jackrabbits in 

Mexico. As discussed above, we are 

unable to assess the level of utilization 

that occurs and whether it is having an 

impact on the population levels and 


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overall status of the species or either 

subspecies. The best available 

information does not indicate that the 

subspecies is overutilized for 

commercial, recreational, scientific, or 

educational purposes. We have not 

encountered any information that 

indicates the contrary. In the absence of 

evidence that this may constitute a 

threat to the subspecies throughout all 

or a portion of its range, we find that 

listing the subspecies Lepus callotis 

callotis due to overutilization is not 

warranted, now or in the foreseeable 

future. 

Factor C. Disease or Predation 

The full extent of information 

available on the subject of disease and 

predation as threats to the species, and 

therefore this subspecies, is discussed 

above. We have no information 

available to us that indicates that the 

subspecies is subject to disease or 

predation at a level that is affecting the 

status of the subspecies. Since we do 

not have information that this may 

constitute a threat to the subspecies 

throughout all or a portion of its range, 

we find that listing the subspecies Lepus 

callotis callotis due to disease or 

predation is not warranted, either now 

or in the foreseeable future. 

Factor D. The Inadequacy of Existing 

Regulatory Mechanisms 

As discussed above, white-sided 

jackrabbits (including the subspecies 

Lepus callotis callotis) are not covered 

under any known regulations in Mexico. 

We have encountered no information 

that indicates that the status of the 

subspecies is declining due to the 

inadequacy of existing regulatory 

mechanisms. Since we have no 

information that this may constitute a 

threat to the subspecies throughout all 

or a portion of its range, we find that 

listing the subspecies Lepus callotis 

callotis due to the inadequacy of 

existing regulatory mechanisms is not 

warranted, either now or in the 

foreseeable future. 

Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence 

We have no detailed information 

concerning additional natural or 

manmade factors affecting the 

subspecies’ continued existence. Global 

climate change will likely affect the 

subspecies or its habitat; however, the 

effects of climate change on the region 

and their magnitude and imminence are 

unknown. We lack predictive models on 

how climate change will specifically 

affect the subspecies’ habitat in Mexico. 

Given that reliable, predictive models 

have not been developed for use at the 

local scale for the sites in the many 

States in Mexico within the subspecies’ 

range, currently there is little certainty 

regarding the timing, magnitude, and 

net effect of impact of climate change. 

Therefore, we find it is not possible to 

make reliable predictions of climate 

change effects on the status of the whitesided jackrabbit, due to the current 

limitations in available data and climate 

models. Based on the best available 

information and our current knowledge 

and understanding, we conclude that 

climate change is not currently a known 

threat to the subspecies Lepus callotis 

callotis, either now or in the foreseeable 

future. 

Finding for Lepus callotis callotis 

As required by the Act, we considered 

the five factors in assessing whether the 

subspecies of the white-sided jackrabbit, 

Lepus callotis callotis, is threatened or 

endangered throughout all or a 

significant portion of its range. We have 

carefully examined the best scientific 

and commercial information available 

regarding the past, present, and future 

threats faced by the species. We 

reviewed the petition, information 

available in our files, and other 

available published and unpublished 

information. We know very little about 

the status and threats to the subspecies. 

The best available information does not 

indicate that these populations are going 

to experience impacts at a level at that 

would affect the status of the 

subspecies. 

Our review of the best available 

scientific and commercial information 

pertaining to the five factors does not 

indicate that the subspecies of whitesided jackrabbit, Lepus callotis callotis, 

is in danger of extinction (endangered), 

or likely to become endangered within 

the foreseeable future (threatened), 

throughout its range. This is based on 

our finding in the five-factor analysis 

that the best available information 

concerning the jackrabbit’s status and its 

habitat in Mexico, limited as it is, does 

not allow us to assess the magnitude or 

immediacy of those potential impacts 

on the species, nor the extent of the 

occupied range of the jackrabbit that 

may be subject to impacts. While we 

have evidence that some impacts may 

be occurring within the range of the 

species (e.g., shrub encroachment, 

grazing, hunting, changing climate 

conditions), we do not have any specific 

information that allows us to make a 

reasonable connection between these 

potential impacts and current or future 

declines of the subspecies. Therefore, 

we find that listing the subspecies of the 

white-sided jackrabbit, Lepus callotis 

callotis, as a threatened or an 

endangered subspecies throughout its 

range is not warranted at this time. 

Species Information: Lepus callotis 

gaillardi 

The subspecies of the white-sided 

jackrabbit, Lepus callotis gaillardi, 

occurs in both the United States and in 

Mexico. As discussed above, the 

historical range of the subspecies Lepus 

callotis gaillardia includes the southern 

Animas and Playas valleys of Hidalgo 

County, New Mexico, south into westcentral Chihuahua and north-central 

Durango, Mexico (Bednarz and Cook 

1984, p. 358; Reynolds 1988, p. 1), 

although it is now likely extirpated from 

the Playas Valley as no observations of 

the species have been made in this area 

during more recent surveys (Traphagen 

2002, p. 5; Frey 2004, p. 22; NMDGF 

2006a, p. 115; Traphagen 2010, p. 1). 

The range of the subspecies L. c. 

gaillardi is fully encompassed by the 

range of the species L. callotis. Please 

see the ‘‘Species Information: Lepus 

callotis’’section above for a full 

discussion of white-sided jackrabbit 

taxonomy, species description, biology, 

distribution, habitat, and population 

abundance. 

Summary of Information Pertaining to 

the Five Factors for Lepus callotis 

gaillardi 

In making this finding, information 

pertaining to the subspecies of the 

white-sided jackrabbit, Lepus callotis 

gaillardi, in relation to the five factors 

provided in section 4(a)(1) of the Act is 

discussed below. In making our 12– 

month finding on a petition to list the 

subspecies of the white-sided jackrabbit, 

Lepus callotis gaillardi, we considered 

and evaluated the best available 

scientific and commercial information. 

Factor A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

The habitat of the subspecies Lepus 

callotis gaillardi within the United 

States may be threatened by shrub 

encroachment as a result of livestock 

grazing and wildfires. This threat is 

discussed in detail in the threat 

assessment for the full species Lepus 

callotis. There is information that this 

perceived threat may differentially 

affect the subspecies’ separate habitats 

in New Mexico in the Animas and 

Playas Valleys. 

Traphagen (2009, pp. 1-2) indicates 

that the assertion that the current and 

historical grazing practices and 

suppression of wildfire, and the 

subsequent encroachment of shrubs 

threaten the subspecies is not entirely 


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accurate in regard to the habitat of the 

subspecies in the Animas Valley; 

however, it may have been a factor in 

the Playas Valley, where the subspecies 

is presumed to be extirpated. 

As discussed above, Traphagen (2009, 

p. 2) reports that the Animas Valley is 

largely free of shrubs, likely due to the 

soil structure, water drainage, frequent 

fires, and cold air drainage. Cold air 

drainage is a process that occurs in 

valleys as the ground cools at night, 

cooling the air and causing denser cold 

air from higher elevations to move down 

into the valley. The Animas Valley is 

surrounded by several large mountain 

ranges that create winter microclimates 

too cold to support the establishment of 

shrubs on the valley floor such as 

mesquite, cholla, and creosote 

(Traphagen 2009, p. 2). In contrast, the 

Playas Valley receives less precipitation 

annually and is generally drier than the 

Animas Valley (Traphagen 2009, p. 2). 

Shrub invasion in this grassland 

association has occurred on a much 

larger scale than in the grassland 

association found in the Animas Valley 

(Traphagen 2009, p. 2). 

The Diamond A Ranch, which 

incorporates the two valleys, has 

practiced a very light grazing regime 

under ownership by The Nature 

Conservancy, and subsequently, by the 

Animas Foundation (Traphagen 2009, p. 

3). Traphagen (2009, p. 3) reports that 

since 1994, there have been several 

periods during which grazing was 

deferred on the ranch for 4 years or 

more, and from 2003 to 2006, there was 

no cattle grazing in the Animas Valley. 

Traphagen (2009, p. 4) reports that 

fire suppression has not occurred in 

recent years on the Diamond A Ranch, 

and states that there have been several 

major fires in the Animas Valley that 

have nearly burned all of the whitesided jackrabbits’ habitat in that valley. 

These fires are described in further 

detail above. 

We have no information about current 

grazing or fire suppression practices in 

historical habitat in the Playas Valley 

beyond the general statement that the 

Diamond A Ranch has been lightly 

grazed since 1994. This jackrabbit 

appears to be extirpated from that 

portion of its range. The extent to which 

past grazing or fire suppression 

practices may have contributed to that 

extirpation is unknown; however, the 

Playas Valley may have been more 

susceptible to shrub encroachment 

resulting from past overgrazing than the 

Animas Valley as a result of the 

differences in grassland type and cold 

air drainage patterns discussed above. 

Finally, while we know that grazing 

of livestock occurs in Mexico (see, for 

example, Buller et al. 1960), we do not 

have information on the extent or 

intensity of historical or current 

livestock grazing practices throughout 

the range of the species in Mexico. 

Brown (1994) reported that a primary 

cause of loss and degradation of 

grasslands in the Chihuahuan Desert is 

overgrazing by cattle; however, the 

extent of those grassland losses 

throughout the historical range of the 

jackrabbit and the impacts of those 

losses on the jackrabbit are not known. 

The best available information 

indicates that grazing and fire 

suppression are not currently occurring 

at a level which may constitute a threat 

to extant populations of the subspecies 

in New Mexico, although these impacts 

may have played a role in the presumed 

extirpation of white sided-jackrabbits in 

the Playas Valley. Information about the 

subspecies’ status in Mexico is very 

limited. As discussed above, 

overgrazing may have caused some loss 

or degradation of grasslands in the 

Chihuahuan Desert, and the 

encroachment of shrubs into grasslands 

may have negatively affected 

populations of white-sided jackrabbits 

there. However, the information 

available concerning grazing practices 

in Mexico does not allow us to assess 

the magnitude or immediacy of these 

impacts on the subspecies, nor the 

extent of the occupied range of the 

subspecies that may be subject to 

overgrazing impacts. In the absence of 

information that allows us to make a 

reasonable connection between the 

impacts of livestock grazing and fire 

suppression, and current or future 

declines of white-sided jackrabbits, we 

are unable to conclude that this 

subspecies is threatened by grazing 

practices or fire suppression. 

Factor B. Overutilization for 

Commercial, Recreational, Scientific, or 

Educational Purposes 

In New Mexico, the subspecies is 

currently protected under the New 

Mexico Wildlife Conservation Act 

(NMDGF 2008, p. 10). Further, in New 

Mexico, the subspecies only occurs on 

private land, thereby limiting hunting 

opportunities (Traphagen 2009, p. 4). 

Literature indicates that the species was 

commonly hunted in Mexico for 

commercial markets (Leopold 1959, p. 

349; Reynolds 1988). Matson and Baker 

(1986, p. 41) indicated that the species 

was heavily hunted and considered 

highly edible. Thus, it is possible that 

hunting may have played a role in the 

presumed decline of the white-sided 

jackrabbit in Mexico (Moore-Craig, 

1992, p. 13); however, as discussed 

above, we are unable to assess the level 

of hunting that occurs and whether it is 

having an impact on the population 

levels and overall status of the species. 

As the subspecies is legally protected 

from overutilization in New Mexico and 

the best available information does not 

indicate that overutilization constitutes 

a threat to the subspecies in Mexico, we 

find that overutilization does not 

constitute a significant threat to the 

subspecies. We find that listing the 

subspecies Lepus callotis gaillardi due 

to overutilization is not warranted, now 

or in the foreseeable future. 

Factor C. Disease or Predation 

The full extent of information 

available on the subject of disease and 

predation as potential threats to the 

species, and therefore this subspecies, is 

discussed above. We have encountered 

no information which indicates that the 

subspecies is subject to excessive 

disease or predation. We have not 

encountered any information which 

indicates the contrary; however, in the 

absence of evidence that this may 

constitute a threat to the subspecies 

throughout all or a portion of its range, 

we find that listing the subspecies Lepus 

callotis gaillardi due to disease or 

predation is not warranted, now or in 

the foreseeable future. 

Factor D. The Inadequacy of Existing 

Regulatory Mechanisms 

The full extent of information 

available on the subject of existing 

regulatory mechanisms as a threat to the 

species, and therefore this subspecies, is 

discussed above. There is information 

that indicates that the white-sided 

jackrabbit’s status as a State-listed 

threatened species in New Mexico 

confers little regulatory protection 

(except against direct take). Further, the 

white-sided jackrabbit is not covered by 

any known regulations in Mexico. 

However, as discussed in the other 

Factors of this section, we have not 

identified any threats to this species that 

are likely to negatively affect the status 

of the subspecies as a whole, such that 

the limited regulatory protection is not 

likely to represent a threat to the 

subspecies. In the absence of evidence 

that the inadequacy of existing 

regulatory mechanisms may constitute a 

threat to the subspecies throughout all 

or a portion of its range, we find that 

listing the subspecies Lepus callotis 

gaillardi due to the inadequacy of 

existing regulatory mechanisms is not 

warranted, now or in the foreseeable 

future. 


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Factor E. Other Natural or Manmade 

Factors Affecting Its Continued 

Existence 

The possible impacts to the 

subspecies Lepus callotis gaillardi due 

to other natural or manmade factors 

affecting its continued existence do not 

differ from those for the full species, 

discussed above. It is possible that the 

effects of climate change will impact the 

subspecies and its habitat; however, we 

don’t know if the potential habitat 

changes will result in a decline in the 

status of the species. Additionally, there 

has been no research investigating the 

ways in which the effects will impact its 

specific environment. Rather, the 

models of projected change indicate a 

conversion to shrubland over much of 

the region of the southwestern United 

States and northern Mexico and do not 

account for the specific habitat types 

currently occupied by the subspecies. 

Due to the lack of information specific 

to the subspecies’ relatively unique 

grassland association, detailed above in 

the Factor A discussion for this 

subspecies, we find that the best 

available information does not indicate 

that climate change may constitute a 

threat to the subspecies throughout all 

or a portion of its range, now or in the 

foreseeable future. 

The effects of the reported fatal 

impacts of the subspecies by vehicles on 

roads within the subspecies’ range in 

New Mexico are discussed above. 

Although there is potential for this 

factor to affect individuals in the future, 

depending on the activity of the U.S. 

Border Patrol, impacts are currently not 

known to be occurring at a level that 

will affect the status of the subspecies 

throughout all or a significant portion of 

its range. 

Finding for Lepus callotis gaillardi 

As required by the Act, we considered 

the five factors in assessing whether the 

subspecies of the white-sided jackrabbit, 

Lepus callotis gaillardi, is threatened or 

endangered throughout all or a 

significant portion of its range. We have 

carefully examined the best scientific 

and commercial information available 

regarding the past, present, and future 

threats faced by the species. We 

reviewed the petition, information 

available in our files, and other 

available published and unpublished 

information. 

Our review of the best available 

scientific and commercial information 

pertaining to the five factors does not 

indicate that the subspecies of the 

white-sided jackrabbit, Lepus callotis 

gaillardia, is in danger of extinction 

(endangered), or likely to become 

endangered within the foreseeable 

future (threatened), throughout its 

range. This is based on our finding in 

the five-factor analysis that stressors in 

New Mexico do not constitute threats to 

the jackrabbit in its current range in 

New Mexico, and the fact that the best 

available information concerning the 

jackrabbit’s status and its habitat in 

Mexico, limited as it is, does not allow 

us to assess the magnitude or 

immediacy of those potential impacts 

on the subspecies, nor the extent of the 

occupied range of the jackrabbit that 

may be subject to impacts. While we 

have evidence that some impacts may 

be occurring within the range of the 

subspecies (e.g., shrub encroachment, 

grazing, hunting, vehicle collisions, 

changing climate conditions), we do not 

have any specific information that 

allows us to make a reasonable 

connection between these potential 

impacts and current or future declines 

of white-sided jackrabbits. Therefore, 

we find that listing the subspecies of the 

white-sided jackrabbit, Lepus callotis 

gaillardia, as a threatened or an 

endangered species throughout its range 

is not warranted at this time. 

Distinct Vertebrate Population 

Segments 

After assessing whether the species 

and the two subspecies are threatened 

or endangered throughout their range, 

we next consider whether any Distinct 

Vertebrate Population Segment (DPS) of 

the white-sided jackrabbit’s range meets 

the definition of endangered or is likely 

to become endangered in the foreseeable 

future. 

Distinct Vertebrate Population Segment 

Under the Service’s Policy Regarding 

the Recognition of Distinct Vertebrate 

Population Segments Under the 

Endangered Species Act (61 FR 4722, 

February 7, 1996), three elements are 

considered in the decision concerning 

the establishment and classification of a 

possible DPS. These are applied 

similarly for additions to or removal 

from the Federal List of Endangered and 

Threatened Wildlife. These elements 

include: 

(1) The discreteness of a population in 

relation to the remainder of the species 

to which it belongs; 

(2) The significance of the population 

segment to the species to which it 

belongs; and 

(3) The population segment’s 

conservation status in relation to the 

Act’s standards for listing, delisting, or 

reclassification (i.e., is the population 

segment endangered or threatened). 

Discreteness 

Under the DPS policy, a population 

segment of a vertebrate taxon may be 

considered discrete if it satisfies either 

one of the following conditions: 

(1) It is markedly separated from other 

populations of the same taxon as a 

consequence of physical, physiological, 

ecological, or behavioral factors. 

Quantitative measures of genetic or 

morphological discontinuity may 

provide evidence of this separation. 

(2) It is delimited by international 

governmental boundaries within which 

differences in control of exploitation, 

management of habitat, conservation 

status, or regulatory mechanisms exist 

that are significant in light of section 

4(a)(1)(D) of the Act. 

We were asked to list the northern 

populations of the Lepus callotis 

gaillardi subspecies, which includes 

two valleys in Hidalgo County, New 

Mexico, as a DPS. First, we evaluated 

whether the potential DPS met the 

condition of discreteness. Because we 

have so little information about the 

species in Mexico, we are unable to 

thoroughly assess the potential 

separation of the United States 

populations from the Mexico 

populations as a consequence of 

physical, physiological, ecological, or 

behavioral factors. However, as 

discussed in Factor D above, the whitesided jackrabbit is not addressed by the 

regulatory mechanisms available in 

Mexico. Because the white-sided 

jackrabbit is covered by regulatory 

mechanisms in the State of New 

Mexico, there is a difference in 

regulatory mechanisms, and we find 

that the United States populations of the 

white-sided jackrabbit are discrete 

under the DPS Policy. 

Significance 

If we determine that a population 

segment is discrete under one or more 

of the discreteness conditions described 

in the DPS Policy, we then evaluate its 

biological and ecological significance 

based on ‘‘the available scientific 

evidence of the discrete population 

segment’s importance to the taxon to 

which it belongs’’ (61 FR 4725). We 

make this evaluation in light of 

congressional guidance that the 

Service’s authority to list DPSs be used 

‘‘sparingly’’ while encouraging the 

conservation of genetic diversity (61 FR 

4722; February 7, 1996). Since precise 

circumstances are likely to vary 

considerably from case to case, the DPS 

Policy does not describe all the classes 

of information that might be used in 

determining the biological and 

ecological importance of a discrete 


hsrobinson on DSK69SOYB1PROD with PROPOSALS
53628 Federal Register / Vol. 75, No. 169 / Wednesday, September 1, 2010 / Proposed Rules 

population. However, the DPS Policy 

describes four possible classes of 

information that provide evidence of a 

population segment’s biological and 

ecological importance to the taxon to 

which it belongs. As specified in the 

DPS Policy (61 FR 4722), consideration 

of the population segment’s significance 

may include, but is not limited to the 

following: 

(1) Persistence of the population 

segment in an ecological setting that is 

unusual or unique for the taxon; 

(2) evidence that loss of the 

population segment would result in a 

significant gap in the range of the taxon; 

(3) evidence that the population 

segment represents the only surviving 

natural occurrence of a taxon that may 

be more abundant elsewhere as an 

introduced population outside of its 

historical range; and 

(4) evidence that the discrete 

population segment differs markedly 

from other populations of the species in 

its genetic characteristics. 

The following discussion considers 

the significance of the United States 

population of the white-sided jackrabbit 

in light of the above criteria. The 

populations of white-sided jackrabbit 

that occur in the United States occupy 

the plains grassland and Chihuahuan 

Desert grassland vegetation types. These 

vegetation types, especially the plains 

grassland, are somewhat rare in the 

United States, but are more common in 

Mexico, thus the United States 

populations do not occur in a unique 

ecological setting. The populations of 

white-sided jackrabbit that occur in the 

United States represent less than one 

percent of the range of the species. 

While populations which are on the 

edge or periphery of a species’ range 

sometimes have unique characteristics 

which may benefit the survival of a 

species as a whole, or while such areas 

may play an important life-history role 

for a species (such as outlying 

populations composed of juvenile, nonbreeding animals), there is no 

information that indicates this is the 

case with the jackrabbit. Instead, these 

are peripheral populations occurring in 

an area where the species was never 

known to be abundant. The loss of these 

populations is not likely to result in a 

significant gap in the range of the taxon. 

While very little is known about the 

species in Mexico, there is no 

information which suggests that these 

populations are the only surviving 

natural occurances of the taxon. 

Additionally, there is no information 

that indicates that there are any 

introduced populations outside of their 

historical range anywhere. Finally, to 

our knowledge, no genetic studies of 

any kind have been conducted which 

looked at the genetic differences of the 

United States jackrabbits as compared to 

the jackrabbits in Mexico; thus we are 

not able to assess whether the United 

States populations differ markedly from 

populations in Mexico. In summary, 

there is no information that indicates 

the United States population of the 

white-sided jackrabbit can be 

considered significant under our DPS 

Policy. 

DPS Conclusion 

On the basis of the best available 

information, we conclude that the 

United States population of white-sided 

jackrabbits is discrete, but it is not 

significant under the DPS Policy. Since 

we found that the population segment 

did not meet the significance element 

and, therefore, does not qualify as a DPS 

under the Service’s DPS Policy, we will 

not proceed with an evaluation of the 

status of the population segment under 

the Act. 

Significant Portion of the Range 

Having determined that the species 

Lepus callotis does not meet the 

definition of a threatened or endangered 

species, we must next consider whether 

there are any significant portions of the 

range where this species is in danger of 

extinction or is likely to become 

endangered in the foreseeable future. 

On March 16, 2007, a formal opinion 

was issued by the Solicitor of the 

Department of the Interior, ‘‘The 

Meaning of ‘In Danger of Extinction 

Throughout All or a Significant Portion 

of Its Range’’’ (United States Department 

of Interior 2007). We have summarized 

our interpretation of that opinion and 

the underlying statutory language 

below. A portion of a species’ range is 

significant if it is part of the current 

range of the species and it contributes 

substantially to the representation, 

resiliency, or redundancy of the species. 

The contribution must be at a level such 

that its loss would result in a decrease 

in the ability to conserve the species. 

In determining whether a species is 

threatened or endangered in a 

significant portion of its range, we first 

identify any portions of the range of the 

species that warrant further 

consideration. The range of a species 

can theoretically be divided into 

portions an infinite number of ways. 

However, there is no purpose to 

analyzing portions of the range that are 

not reasonably likely to be significant 

and threatened or endangered. To 

identify only those portions that warrant 

further consideration, we determine 

whether there is substantial information 

indicating that: (1) The portions may be 

significant, and (2) the species may be 

in danger of extinction there or likely to 

become so within the foreseeable future. 

In practice, a key part of this analysis is 

whether the threats are geographically 

concentrated in some way. If the threats 

to the species are essentially uniform 

throughout its range, no portion is likely 

to warrant further consideration. 

Moreover, if any concentration of 

threats applies only to portions of the 

species’ range that are not significant, 

such portions will not warrant further 

consideration. 

If we identify portions that warrant 

further consideration, we then 

determine whether the species is 

threatened or endangered in these 

portions of its range. Depending on the 

biology of the species, its range, and the 

threats it faces, the Service may address 

either the significance question or the 

status question first. Thus, if the Service 

considers significance first and 

determines that a portion of the range is 

not significant, the Service need not 

determine whether the species is 

threatened or endangered there. 

Likewise, if the Service considers status 

first and determines that the species is 

not threatened or endangered in a 

portion of its range, the Service need not 

determine if that portion is significant. 

However, if the Service determines that 

both a portion of the range of a species 

is significant and the species is 

threatened or endangered there, the 

Service will specify that portion of the 

range as threatened or endangered 

under section 4(c)(1) of the Act. 

Applying the process described above 

for determining whether a species is 

threatened in a significant portion of its 

range, we next addressed whether any 

portions of the range of the white-sided 

jackrabbit warranted further 

consideration. On the basis of our 

review of the five listing factors above, 

we found no evidence of geographic 

concentration of threats either in New 

Mexico or Mexico such that the full 

species or either of the subspecies may 

be in danger of extinction in that 

portion. The information that is known 

about impacts to the white-sided 

jackrabbit is generally specific to those 

populations in the United States; 

however, a lack of information about 

threats in other portions of the range of 

the species one way or another does not 

mean that threats are concentrated in 

the United States. 

There is no information to suggest 

that any portion of the range of the 

species or either subspecies contributes 

more significantly to the resiliency, 

redundancy, and representation of the 

species or either subspecies than any 

other portion of the range. There is no 


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Federal Register / Vol. 75, No. 169 / Wednesday, September 1, 2010 / Proposed Rules 53629 

information to suggest that any portion 

of the range is particularly of better 

quality than any other portion, or than 

any portion includes an important 

concentration of certain types of habitat 

that are necessary for the species to 

carry out its life-history functions, such 

as breeding, feeding, migration, 

dispersal, or wintering. Further, there is 

no information to suggest than any 

portion of the range provides a greater 

increment of redundancy than any other 

area. Finally, very little genetic 

information is known about white-sided 

jackrabbits. There have been some 

studies that used a variety to taxonomy, 

morphology, and chromosome 

information to differentiate white-sided 

jackrabbits from other species of 

jackrabbits, but no genetic studies have 

been conducted to compare various 

populations of white-sided jackrabbits, 

thus representation cannot be assessed. 

As a result of the above analysis, we 

conclude that there is no indication that 

a particular portion of the white-sided 

jackrabbit’s range warrants further 

consideration as threatened or 

endangered. 

We do not find that the species is in 

danger of extinction now, nor is it likely 

to become endangered within the 

foreseeable future throughout all or a 

significant portion of its range. 

Therefore, listing the full species or 

either subspecies as threatened or 

endangered under the Act is not 

warranted at this time. 

We request that you submit any new 

information concerning the status of, or 

threats to, this subspecies to our 

Southwest Regional Ecological Services 

Fish and Wildlife Office (see ADDRESSES

section) whenever it becomes available. 

New information will help us monitor 

this subspecies and encourage its 

conservation. If an emergency situation 

develops for this subspecies or any 

other species, we will act to provide 

immediate protection. 

References Cited 

A complete list of references cited is 

available on the Internet at http:// 

www.regulations.gov and upon request 

from the Southwest Regional Ecological 

Services Office (see ADDRESSES section). 

Author(s) 

The primary authors of this notice are 

the staff members of the Southwest 

Regional Ecological Services Office (see 

ADDRESSES section) 

Authority 

The authority for this section is 

section 4 of the Endangered Species Act 

of 1973, as amended (16 U.S.C. 1531 et 

seq.). 

Dated: August 19, 2010. 

Wendi Weber, 

Acting Deputy Director, Fish and Wildlife 

Service. 

[FR Doc. 2010–21774 Filed 8–31–10; 8:45 am] 

BILLING CODE 4310–55–S 


hsrobinson on DSK69SOYB1PROD with PROPOSALS