Introduction

The herpetofauna of the Great Basin is dominated by xeric-adapted amphibians and reptiles that can withstand extended periods of drought, extremely hot summers, and, in some cases, below-freezing winters. In western Nevada, the herpetofauna is primarily composed of these xeric-adapted species but also includes, especially in the northwest, several taxa that prefer more mesic environments. The mesic-adapted species tend to be associated with riparian habitats and higher elevations (above 1200 m [4000 ft]) such as those found in the foothills of the Sierra. Unlike the more xeric-adapted species, mesic-adapted amphibians and reptiles tend to be active when ambient temperatures are cooler. Hence, characterizing the herpetofauna of western Nevada requires an understanding of the habitat, microhabitat, and activity cycles of the animals found in the region.

Prior to this study, little was known about the species diversity and population status of the herpetofauna of the Hawthorne Army Depot (hereafter, HWAD), Mineral County. Indeed, no comprehensive survey of amphibians and reptiles had been conducted on the property. Surveys conducted previously from adjacent regions in Nevada and California (e.g., Nevada Test Site Survey, Macey and Papenfuss 1991a,b) suggest that the herpetofauna on the HWAD is likely to be diverse. This expectation is further supported by the geological and floristic diversity of the region. Moreover, unlike much of Nevada, which has recently been subjected to commercial harvesting of its herpetofauna (Albert et al. 1999), the amphibians and reptiles of the HWAD have not been collected for either commercial or scientific purposes. Therefore, the herpetofauna of the depot is expected to be both diverse and abundant relative to populations outside of the military property. Here we describe the results of a single season-long survey aimed at characterizing the herpetofauna of the HWAD.

Habitats

The distribution and abundance of amphibians and reptiles in space and time is strongly influenced by latitude and elevation which, in turn, affect abiotic factors such as climate and the timing of seasonal cycles (Pianka 1986). In addition, a suite of biotic factors including the distribution and abundance of vegetation, prey, predators, and parasites also influence the distribution and abundance of amphibian and reptile populations (Pianka 1986). Thus it is important to characterize the geographic, climatic, and biotic environment prior to developing predictions regarding the species and distributions of amphibians and reptiles in a given region.

We visited the HWAD in early May 1999 to conduct a preliminary assessment of the geology, climate, and vegetation of the region. The depot's 58,680 ha (145,000 acres) spans over wide range of elevational, climatic, and biotic regions. The elevation of the HWAD ranges from 1220-3445 m (4000-11,303 ft). The base's major phytogeographic regions (expressed as the dominant vegetation of each locality) are discussed in more detail below.

South Magazine Area.This region is characterized by two predominant shrubs, blackbrush (Coleogyne ramosissima) and hopsage (Atriplex spinosa), as well as several perennial grasses including Indian ricegrass (Achnatherum hymenoides) and western bunchgrass (Hilaria jamesii), and introduced annual brome grasses (Bromus spp.). The soil composition of this area ranges from fine to coarse gravel. This region has numerous roads which connect groups of magazines and lead to individual storage bunkers. Most of these roads are asphalt which warm during the day and thus provide a heated surface sought by nocturnal reptiles for thermoregulation. Generally, there is little rubbish in the area, but old cottonwood logs and some debris can be found near Cory Creek on the southwestern portion of the base. The topography is primarily flat, with a few small, rolling hillsides. In the region south of Magazine 33, there are washes with an abundance of cobble and smooth larger boulders.

Central Magazine Area.This region is predominantly composed of four shrubs: blackbrush (Coleogyne ramosissima), four-wing saltbush (Atriplex canescens), shadscale (Atriplex confertifolia), and hopsage (Atriplex spinosa). The perennial grass Indian ricegrass (Achnatherum hymenoides) is the most abundant perennial grass. The major soil type is sandy. Like the South Magazine Area, the Central Magazine Area has many roads transecting the region.

North Magazine Area.Winterfat (Ceratoides lanata) and four-wing saltbush (Atriplex canescens), are the major shrubs found in this region. The perennial grasses, Indian ricegrass (Achnatherum hymenoides) and saltgrass (Distichlis spicata) were also found accompanying these shrubs. Consolidated sand dunes occur from the southeast shore of Walker Lake to the northern section of this area. The two major soil types in this region were sand and coarse gravel. Like the magazine areas to the south, there are numerous asphalt roads transecting this region. Rubbish-especially lumber-is common in this area

Southwestern Shore of Walker Lake.-This region is characterized by two major plant communities. The area within 200 m (655 ft) of the lakeshore is occupied primarily by cottonwood (Populus fremontii) and cattails (Typha latifolia) and the soil is a boggy, wet peat. Several freshwater springs feed into the lake. The riparian area just beyond this point consists of cottonwood (Populus fremontii), tamarisk (Tamarix chinensis), coyote willow (Salix exigua), Russian olive (Elaeagnus angustifolia), and saltgrass (Distichlis spicata). The soil type in this second area is almost entirely sand. Numerous boulders and tufa formations line the ancient lake shore and provide an abundance of habitat for herps. These formations are most abundant along the depot's dirt road between Highway 95 and the shore of the lake. Rubbish is common in this area and includes various construction debris, fencing, abandoned corrals, and concrete and asphalt slabs.

Slopes of Mt. Grant.-The surveyed area in this region is immense with an elevation gradient ranging from 1370-2440 m (4500-8000 ft). This elevational range translates into notable floral diversity within the area. Riparian zones found along the various creeks support wild rose (Rosa woodsii), Russian olive (Elaeagnus angustifolia), singleleaf pinyon (Pinus monophylla), cottonwood (Populus fremontii), coyote willow (Salix exigua), big sagebrush (Artemisia tridentata), and, at higher elevations, aspen (Populus anguifolia). Beyond these riparian zones, there are transitional changes in the vegetation which follow the changes in elevation. At the base of the mountain slopes 1370-1525 m (4500-5000 ft), the vegetation consists mostly of big sagebrush (Artemisia tridentata), winterfat (Ceratoides lanata), blackbrush (Coleogyne ramosissima), and Indian ricegrass (Achnatherum hymenoides). At elevations ranging from 1525-2135 m (5000-7000 ft), the dominant shrubs are big sagebrush (Artemisia tridentata), winterfat (Ceratoides lanata), Mormon tea (Ephedra spp.), and singleleaf pinyon (Pinus monophylla). Above this point, big sagebrush (Artemisia tridentata), aspen (Populus anguifolia), singleleaf pinyon (Pinus monophylla), and Utah juniper (Juniperus osteosperma) constitute the dominant floral components. The soil structure in these areas consists of gravel and rocky areas ranging in size from cobble to extensive outcrops of large boulders and talus slopes. Many of the canyons are lined by steep rocky slopes. There are numerous fallen logs and abundant leaf litter in many areas. Most areas of Mt. Grant (including the creeks) are accessible only by narrow dirt roads.

Human-made 'Habitats'

In addition to the vegetation, various natural and human-made structures provided habitat for the local fauna. Within the magazine areas, lizards were commonly found on and around the magazines and towers which served as elevated perches for basking and performing territorial displays. These structures may have even allowed one species to extend its range into the magazine areas despite the lack of otherwise suitable habitat. A single desert spiny lizard (Sceloporus magister) was found inhabiting Magazine 10-AT-1. This species is generally found in areas associated with rocky outcrops, and this type of habitat is not found within 0.4 km (0.25 mi).

Materials and Methods

Preliminary Species List

To date, no single source of biological information exists for the more than 70 species and subspecies of amphibians and reptiles inhabiting Nevada. We relied on a combination of sources of information to compile a list of species which we suspected might live within the borders of the HWAD. First, we have more than 60 years of collective field experience observing, collecting, and studying amphibians and reptiles in western North America-primarily in desert environments. This experience was supplemented with information from the primary literature, species accounts (Catalogue of the American Amphibians and Reptiles), regional surveys (Tanner and Jorgensen 1963, Macey and Papenfuss 1991a,b, Tracy and Espinoza 1998), field guides (Basey 1976, Stebbins 1985, Brown 1997), and records from natural history museums (primarily the University of Nevada, Reno and the Museum of Vertebrate Zoology, University of California, Berkeley). A tour of the HWAD in early May 1999 (discussed above) allowed us to examine the diversity of habitats found on the HWAD. This helped us to modify our initial list of species based on the absence or paucity of critical microhabitats required by some of the taxa on our preliminary list.

A total of 30 species and subspecies of amphibians (n = 6) and reptiles (n = 24) have ranges that overlap the HWAD boundaries (Table 1). Several are considered to be rare or unlikely to be encountered (designated with a "?" in the list below), and two are considered to be species of concern because of recent population declines (i.e., northern leopard frog and Panamint rattlesnake). Even if present, these "?" species may not be encountered because they (1) are at the edge of their distributional range; (2) are generally uncommon; (3) have highly secretive (e.g., subterranean) habits; and/or (4) have seasonally short periods of activity. To this end, special efforts were made to identify and thoroughly survey (in both space and time) the areas that might support these species.

General Summary

A total of two species of amphibians and 16 species of reptiles were encountered (Table 3). Among the reptiles, eight species were lizards and eight were snakes. Each taxon is treated in a separate species account (below) which describes its status (= estimated abundance; see below), phenology (temporal occurrence during our surveys), distribution, and natural history based from observations of populations from the HWAD and on information from the literature. Each species was categorized into one of the following abundance classes based on frequency of observation and relative density (see box on page 12 for definitions of these categories).

Unknown: rarely encountered, but population size and density unknown because of the secretive nature of the species or limited habitat availability

Frogs and Toads

Western toad, Bufo boreas (Figure 1)

Status: Common. Approximately 75 western toads were observed over the course of the survey.

Distribution: Toads were found along the southwestern shore of Walker Lake and in two canyons on the east side of Mt. Grant. In Cat Creek Canyon, toads were found within 10-50 m of the base of the dam within the bed of a small creek/seepage. In House Creek Canyon, toads were found at the weir and slightly downstream of the pool formed by the weir. A single road-killed toad was found in the Industrial Area near the housing developments (Map 1).

Phenology: Western toads were first seen in late spring (4 May) and remained active through late summer (13 August). Toads were found active by day in the canyons which are well shaded and much cooler than the riparian areas near the lake. Near the southwestern shore of Walker Lake, these amphibians were most commonly encountered at night.

Description and Natural History:Western toads are frequently the most abundant and commonly encountered amphibians in northern Nevada. They can be distinguished from other frogs by the distinct yellow mid-dorsal stripe and warty skin (Figure 1). In contrast to most frogs, these toads can withstand extended periods of drought and are often seen far from permanent water sources. However, like most frogs, western toads must return to water to reproduce. Males do not produce a mating call, but do produce a characteristic chirping cry (release call) when gripped from behind the forelimbs (as occurs during courtship among rival males). Females extrude from 2000-6000 eggs in distinctive strings which males inseminate externally. The characteristic black tadpoles feed on algae and detritus and take approximately one month to complete metamorphosis. Toads on the HWAD were usually within a 100 m (330 ft) of a source of water (e.g., a spring, creek, sprinkler system).

Great Basin spadefoot, Spea intermontana (Figure 2)

Status:Common. Approximately 26 spadefoots were observed; however, many more were heard calling during night surveys.

Distribution: Spadefoots were found only along the southwest shore of Walker Lake (Map 2).

Phenology: The first spadefoots were encountered rather late in the season (10 July), and the last were seen on 12 August.

Description and Natural History:Unlike toads, spadefoots lack the prominent mid-dorsal stripe and have less warty, more glandular skin (Figure 2). They also have vertical pupils (in toads the pupils are horizontal) and a black "spade" of cornified skin on the base of each hind foot which enables them to burrow quickly in the substratum. These amphibians spend most of their adult lives underground in burrows which they construct when summer rains loosen the soil. Adults appear on the surface briefly (2-3 weeks) in summer to feed and breed en masse on only a few, usually rainy, nights. Juveniles and the occasional adult can be found throughout the summer, especially on rainy nights. We did not locate pools of calling and/or breeding spadefoots. We also did not encounter tadpoles of this species, but this is not surprising because the larval stage is very brief, and fully metamorphosed froglets can emerge from small bodies of water in fewer than 14 days (Hall 1998).

Lizards

Western whiptail, Cnemidophorus tigris (Figure 3)

Status:Abundant. A total of 408 individuals was observed which suggests that whiptails are the second-most abundant lizard on the HWAD.

Distribution: Whiptails were found in virtually all habitats with relatively flat topography (Map 3). They were also found along Cottonwood Road to elevations approaching 1830 m (6000 ft).

Phenology: Whiptails were observed from 5 June through 9 August, and numerous individuals were encountered during every survey where suitable habitat and favorable thermal conditions were available (see below).

Description and Natural History:Western whiptails are long-tailed, pointy nosed lizards that move in a jerky fashion as they race from shrub to shrub in search of insects and other invertebrate prey. The speed, agility, and vigilance of whiptails make them difficult to approach and almost impossible to capture. As a result, our encounter rates undoubtedly underestimate their prevalence in the area (which we still estimate to be quite high). Moreover, relative to other lizards, whiptails have fairly short activity periods on both a daily and seasonal basis (see Vitt and Wright 1992). At the HWAD, whiptails were active during midsummer, and on very hot days (air temperatures over 35 °C [95 °F]). They were also commonly encountered crossing or basking on asphalt roads in the magazine areas. These lizards feed on the abundant insects (especially grasshoppers) in the area and, in turn, are preyed upon by leopard lizards, and diurnal snakes.

Great Basin collared lizard, Crotaphytus bicintores (Figure 4)

Status:Common. A total of 73 individuals was observed over the course of the survey including adults, subadults, and juveniles.

Distribution: Collared lizards were found on the north and eastern slopes of Mt. Grant, northeast of the North Magazine Area (just northeast of the railroad), and east and south of the South Magazine Area. They were common along the boulders of Cottonwood Road (to 2286 m [7500 ft]), just east of Highway 95 within 1000 m (0.6 mi) of Walker Lake, and near the Rifle Range near the foot of Mt. Grant (Map 4).

Phenology: Collard lizards were active during the entire survey period. They were first encountered on our introductory tour in early May, and regularly observed until the last day of our survey on 13 August.

Description and Natural History:Collards are large, robust, large-headed lizards that live exclusively on large boulders and rock outcrops. From these elevated vantage points, they aggressively perform territorial displays (e.g., head bobbing and "push-ups") and chase off neighboring conspecifics. At night and when threatened, they seek refuge under boulders or in rodent burrows beneath large rocks. Like their relative the leopard lizard, collards are thermophilic (heat-loving) lizards that were active during even the hottest part of the day. They are well known for their habit of eating other smaller lizards (e.g., side-blotched lizards, juvenile desert spinys, and whiptails) but they also eat insects such as grasshoppers (McGuire 1996).

Long-nosed leopard lizard, Gambelia wislizenii (Figure 5)

Status:Abundant. Leopard lizards of all age classes were encountered on most survey days so long as ambient temperatures were high (see below). In total, we observed 160 individuals.

Distribution: Leopard lizards were found in virtually all habitats with a relatively flat topography. They were encountered at elevations up to 1675 m (5500 ft) near the historic outflows of Dutch and Squaw Creek (Map 5).

Phenology: Leopard lizards were observed on most days of our survey. They were first seen during our initial tour of the HWAD on 5 May and last seen on 13 August (the last day of our study).

Description and Natural History:Leopard lizards are aptly named for the pattern of spots on their body (Figure 5). These large, robust carnivores are the ground-dwelling relatives of the collard lizards. On the HWAD, leopard lizards were most abundant in the eastern portion of the South Magazine Area, but were commonly encountered in most lowland habitats. Leopard lizards are also thermophilic (heat loving) and were active on warm days (air temperatures above 30 °C [86 °F]) and even midday during midsummer. They were most frequently encountered basking on gravel or sandy soils between shrubs. This is the same habitat used by other small lizards (zebra-tailed, horned, and side-blotched lizards; see below) which are prey items of adult leopard lizards (Smith 1946, Stebbins 1985). Leopard lizards were also frequently seen basking on or along the edges of roads in the magazine areas. By late summer (August), recently hatched leopard lizards were observed throughout much of the South Magazine Area.

Zebra-tailed lizard, Callisaurus draconoides (Figure 6)

Status:Abundant. Zebra-tailed lizards are another abundant lizard-especially in the eastern portion of the depot. In total we observed 168 individuals representing all age classes.

Distribution: Zebra-tailed lizards were found in virtually all habitats with a relatively flat topography (Map 6). They were encountered at elevations up to 1525 m (5000 ft).

Phenology: Zebra-tailed lizards were first encountered in our preliminary visit in early May and last seen on 9 August. Hatchlings first appeared in late July.

Description and Natural History:Zebra-tailed lizards are thermophilic (heat-loving) lizards, swift moving lizards that are found almost exclusively on sandy or gravelly soils. Their relatively flat bodies, long limbs, countersunk jaws, and banded tail (Figure 6) distinguish them from other terrestrial lizards in the area. When approached, zebra-tails wag, then curl their tails over their backs and swiftly retreat-often 10-20 m before seeking shelter in a shrub or plunging head first into the sand. They feed on insects and other small invertebrates and are preyed upon by diurnal lizards and snakes, and nocturnal mammals (e.g., skunks, badgers, kit foxes, coyotes) which dig them out of the sand.

Desert horned lizard, Phrynosoma platyrhinos (Figure 7)

Status:Abundant. A total of 82 adult, subadult, and hatchling horned lizards was encountered throughout our survey.

Distribution: Horned lizards were found in virtually all habitats with a relatively flat topography. They were encountered at elevations up to 1675 m (5500 ft) near the historic outflow of Squaw Creek (Map 7).

Phenology: Horned lizards were found throughout the survey period. They were first observed on 5 May and last seen on 7 August. Hatchlings first appeared in mid-July.

Description and Natural History:These distinctly shaped lizards are remarkably cryptic (Figure 7) and, therefore, often readily overlooked in the field. Paradoxically, individuals can be easy to detect because they have small home ranges, very specific microhabitat and diet preferences, and large, distinctive feces. Specifically, horned lizards are found on gravel or sandy soils usually sparsely vegetated areas. When active, they are usually near nests of harvester ants (Pogonomrymex spp.) which can make up approximately 90% of their diet (Tanner and Krough 1973; Pianka and Parker 1975; Rissing 1981).

Desert spiny lizard, Sceloporus magister (Figure 8)

Status:Common. Forty-one desert spinys of all age classes were observed over the course of the study.

Distribution: Desert spinys were found almost exclusively along the eastern slope of Mt. Grant extending eastward to just east of Highway 95. A single individual was also found in the South Magazine Area atop bunker 10-AT-1 (Map 8).

Phenology: We observed desert spinys throughout the entire survey period (5 May through 13 August). Hatchlings appeared in mid-July.

Description and Natural History:Desert spinys are large, robust lizards with extraordinarily spiny scales (Figure 8). They are further distinguished from their relatives the western fence lizard by their distinctive black neck collar which is apparent in all age classes (Figure 8). Like the western fence lizard, desert spinys prefer elevated basking sites such as large logs or rocks from which they perch and interact with their neighboring conspecifics. They tend to be somewhat more thermophilic (heat loving) than fence lizards and feed on insects and the occasional flower. These are weary lizards that usually retreat under large boulders or similar refugia before a person can approach within 5-10 m.

Western fence lizard, Sceloporus occidentalis (Figure 9)

Status: Abundant. A total of 172 fence lizards was encountered over the course of the survey period.

Distribution: Fence lizards were found almost exclusively on Mt. Grant at elevations from 1340-2255 m (4400-7400 ft; Map 9). Thus, this species has the highest elevational distribution of any amphibian or reptile on the base. Fence lizards were particularly common in the riparian areas of Cat Creek, House Creek, Rose Creek, and along the dirt road of Cottonwood Creek. Interestingly, a single specimen was observed in the extreme eastern portion of the South Magazine Area near the depot boundary (1525 m [5000 ft]).

Phenology: Fence lizards were active during the entire survey period (5 May through 13 August). Hatchlings were first encountered in late July.

Description and Natural History:Fence lizards (AKA: "blue-bellies") are well named for their propensity to perch on elevated structures in their environment (e.g., fence posts, construction debris, trees and logs, rocks, etc.). From these vantage points, they communicate status, territorial boundaries, and reproductive readiness to one another through displays including head bobs and "push-ups." They feed on insects and spiders and are, in turn, fed upon by other lizards (e.g., leopard and collared lizards), as well as snakes, birds, and mammals. In the morning, and when they are cool, they are black dorsally-the only black lizards in this region. As they warm, their color lightens to gray-brown (Figure 9). Like the desert spiny lizard, their scales are rough and pointed at the tip. But unlike desert spinys, fence lizards lack a black neck collar, are darker in color, and never achieve as large a body size (5.5-8.5 cm [2-3 in] vs. 8-14 cm [3-5 in] in the desert spiny).

Species not Encountered but with Overlapping Ranges

Four species of herps (Table 4) have ranges that overlap the HWAD, but were not expected to be found because (1) they are rare in the state (leopard frog), (2) they are at the edge of their distributional limit (rubber boa), or (3) after intensive searching suitable habitat was not found in the region (leopard frog and garter snakes).

Expected, but not Encountered

Among the species on our preliminary list, several species we expected to find were not encountered in our surveys. These include two species of frogs, two species of lizards, and three species of snakes (Table 5). Among these, the fact that we did not find Pacific chorus frogs on the HWAD was most surprising. Suitable habitat was found in several areas on Mt. Grant-especially Cory Creek, Cat Creek, House Creek, Rose Creek, and Cottonwood Creek. However, at least in Nevada, chorus frogs and western toads are rarely found in sympatry (E. Simandle, pers. comm.). Currently, it is not known why this should be the case, given that the two species commonly occur in sympatry in southern California (R. Espinoza, unpubl. data).

Frogs

Pacific chorus frog (Pseudacris regilla)

bullfrog (Rana catesbeiana)

Lizards

sagebrush lizard (Sceloporus graciosus)

Snakes

western racer (Coluber constrictor)

western patch-nosed snake

(Salvadora hexalepis)

ground snake (Sonora semiannulata)

Bullfrogs also were not recorded in our survey. Bullfrogs were introduced to the western U.S. (west of the Rocky Mountains) in the mid-1800s by settlers. Since that time, they have successfully invaded habitats occupied previously by native frogs. Bullfrogs are voracious predators and commonly eat other frogs-even their own species. As a consequence, they have caused local extirpations of numerous species of frogs in Nevada (determined by historic records in UNR Herpetology Collection). Initially, we were somewhat surprised not to find bullfrogs given that they are common throughout northern Nevada (and at the north end of Walker Lake), but the chief habitat of these frogs-deep ponds or slow moving water courses with sun-exposed banks-was not found on the HWAD.

Among the lizards, we encountered every species we expected to find except sagebrush lizards. But this was not surprising given that both side-blotched lizards and fence lizards were found in the habitats where sagebrush lizards might be encountered, and the latter two species are known to compete with sagebrush lizards in nature.

Among the snakes, three species which likely live on the HWAD were not encountered. Two (yellow-bellied racer and patch-nosed snake) may be in low densities and were, therefore, not found. The final species, the ground snake, is a highly secretive species that has a relatively short above-ground activity season.

Conservation of the HWAD Herpetofauna

Many of the herps (especially the lizards) we encountered on the HWAD were found in densities that were high relative to populations outside of the base. However, a few snakes were encountered too infrequently to provide information on their status on the base. Hence, at this time we are only able to provide information that could prove useful for protecting one species in particular, and all snakes in general.

Only one 'species of concern' was encountered in our surveys. The Panamint rattlesnake (Crotalus mitchellii stephensi) is considered a "sensitive" species by the Nevada Division of Wildlife. This species was found only in the southeastern portion of the South Magazine Area where it was most commonly encountered on roads at night. Interestingly, this is also the northernmost limit of distribution for this species. As such, this presumably small population of rattlesnakes is vulnerable to local extirpation.

Perhaps the greatest threat to this species, as well as most other nocturnally active snakes on the HWAD, is being run over by a vehicle. We recorded approximately 20 road-killed snakes, and at least an equal number of lizards in the short time we surveyed the HWAD. Our records are certainly underestimates of the actual number of herps killed on HWAD roads for two reasons. First, we did not make an effort to drive all the roads on the base on a regular basis to check for roadkills. Second, scavengers-particularly ravens-have learned to survey roads for roadkills. Hence, the vast majority of roadkill herps was likely devoured before they could be recorded by our surveyors. Most of these animals were likely overlooked rather than deliberately run over. Indeed, most of the security officers who were assigned to patrol the magazine areas told us that they avoided running over snakes and other reptiles in their vehicles. Many guards even alerted us to sightings of snakes as we passed through the gates on our nighttime surveys. However, a small number of security officers expressed an interest in deliberately killing the snakes they encountered. This kind of attitude is not uncommon among people who have not been exposed to the importance of these animals in ecological communities. Because we feel that automobile fatalities likely account for a significant portion of the mortality of snakes on the base, we suggest a snake awareness program be offered to stress an appreciation for the importance of these creatures to the ecological communities of the base (e.g., pest control). We have provided a similar program to a local utility company which resulted in improved awareness and responsible action when snakes were encountered in the field by workers.

We thank the following students for their long hours, tireless efforts, and master observational skills in the field: Greg Fuerst, Jessica Hay, and Kevin Murphy. In addition, the following researchers spent one or more days helping to gather data: Renee Aldrich, Carrie Carreño, Mike Hansen, Becky Niell, Heather Powell, and Eric Simandle. Soil types and plant communities were characterized by Greg Fuerst. Eric Simandle and John Walker produced the GIS-based maps based on distributional data compiled by Greg Fuerst and Jessica Hay. Larry Hillerman (Biological Resources Research Center) provided invaluable administrative support throughout the duration of the study. Finally, we thank the staff at HWAD, especially Jim Purrell (Government Staff), Carol Silva (Housing), Tony Lessard (Security), Jim Holt (Safety), and Greg Coppola (Contracts/Purchasing) for providing us with the opportunity to experience the beautiful and relatively unspoiled environments of the HWAD, and for their support and assistance during our stay.