Nevada Mountain Kingsnake Survey

        The Great Basin is North America’s largest desert, spanning an area of 190,000 square miles (Figure 1). Located in the rain shadow of the Sierra Nevada, the region is arid, mountainous, and cold, with most precipitation falling as snow. Climate varies dramatically, and higher elevations are cooler and wetter than lower elevations. Such climactic variability produces vegetative complexity. Plant communities from valley floor to mountain peak include salt desert, sagebrush, piñon and juniper, mountain mahogany, mixed conifer, riparian, and alpine vegetation. As the most remote region of the contiguous United States, only three cities in the Great Basin have populations over 100,000. These cities, Salt Lake, Reno, and Provo are located on the region’s eastern and western fringes. Due to the vast area, vegetative and topographic complexity, and extreme remoteness, Great Basin reptile communities have historically received little attention. Voucher specimens are sparsely distributed throughout the Great Basin and entire mountain ranges and valleys lack collection data. As a consequence, reptilian distributions, natural history and ecology are poorly understood. This is especially true of secretive species such as the Utah Mountain Kingsnake (Lampropeltis pyromelana infralabialis; Figure 2).

First documented from the central Great Basin in eastern Nevada in 1932, L. p. infralabialis has since been considered rare due to the low frequency of observations, isolated populations, and the location of Nevada on the extreme northwestern limit of species’ distribution. Great Basin populations are isolated on mesic mountain ranges separated by xeric valleys (Figure 3). These montane habitats are relicts of cooler and wetter Pleistocene climates, which allowed the expansion of woodlands and forests across Great Basin valleys. Populations expanded under these favorable conditions. As climates became warmer and drier during the Holocene, suitable habitat contracted, isolating L. pyromelana to its present mountain chain distribution. Research needs for L. pyromelana in Nevada include basic natural history information such as distribution, abundance, and habitat requirements.

Since 2006 Great Basin National Park and the Nevada Department of Wildlife have hosted annual spring surveys for L. pyromelana. These surveys have been attended by a diverse array of surveyors including graduate students, professional state and federal biologists, hobbyists, and most importantly volunteers. The North American Field Herping Association (NAFHA) has played an important role in making these surveys possible. Over a dozen NAFHA members have participated in the surveys and located several specimens of L. pyromelana. The forum boards have been a very important media for recruiting volunteers and coordinating survey efforts.

So far the surveyors have logged 839 search hours and 14 individuals of L. pyromelana infralabialis at five sites. On average it has required 60 search hours to locate a mountain kingsnake. An additional 1034 observations of reptiles were made and 111 voucher specimens were cataloged into Brigham Young University’s reptile and amphibian collections. Based on museum records, survey data and anecdotal observations spring appears to be the best time to survey for L. p. infralabialis in eastern Nevada (Figure 4).

We’ve learned a lot about mountain kingsnakes in the Great Basin from these surveys. One of the more interesting findings has been that the snakes do not require surface water. We’ve found them at two extremely dry sites which are completely lacking in surface water (Figure 5). Other sites however have lots of surface water and riparian vegetation. Lampropeltis pyromelana appears to be more abundant in these areas.

Lampropeltis pyromelana prefers cloudy or shady conditions for surface activity. They tend to occur in areas with high reptile diversity and are most active in the spring and are slightly larger than conspecifics in the south. Males are encountered much more frequently than females. Mark Hazel’s finding in 2007 of two males engaged in combat has been a survey highlight (Figure 6).

Surveys for L. pyromelana will continue this year (2010) during the week of May 24th. Our goal is to locate six kingsnakes and implant them with radio transmitters. Radio telemetry will provide much information about this species including habitat utilization, activity and movement patterns, and home range size. We also hope that radio telemetry will lead to the discovery of additional snakes.

If you are interested in surveying, contact Bryan Hamilton at:

100 Great Basin National Park

Baker, Nevada 89311

(775) 234-7331 ext. 255 (phone)

(775) 234-7210 (fax)

 

bryan_ hamilton@nps.gov

 

 

  

Figure 1. The Great Basin is the region bounded by the Sierra Nevada to the west, the Wasatch to the east, the Mohave desert to the south and the Columbia plateau to the North. The region is traditionally defined hydrologically as an area of internal drainage where water does not reach the oceans.

 

 

 




Figure 2. Lampropeltis pyromelana infralabialis is distinguished from other subspecies by a reduced number of infralabial scales and white annuli which extend across the ventral scales. Although several authors have suggested that infralabials is not a valid subspecies, no data have been published refuting its validity.


 

Figure 3. The range of Lampropeltis pyromelana is highly fragmented in the Great Basin. Figure from Stebbins, R. C. 2003. A Field Guide to Western Reptiles and Amphibians. 3rd edition. Houghton Mifflin Company, Boston, New York.

Figure 4. Monthly observations of Lampropeltis pyromelana infralabialis in the Great Basin. Data are from voucher specimens and sight records from Nevada, Utah, and Northern Arizona from 1932 to 2007.



 

Figure 5. Documentation of L. pyromelana from three xeric sites such as this limestone hillside suggests a large amount of unsurveyed habitat is suitable for this species.



Figure 6. In May of 2007 two male L. pyromelana were found in combat. Very little is known about the reproduction of this species in the wild. This observation suggests that mating occurs in the spring. Photo by Mark Hazel.

 

Article written by:

Bryan Hamilton - Biologist

Education Specialist - NAFHA Rocky Mountain Chapter