Monitoring Amphibian and Reptile Populations on the INL: Indicators of Environmental Health and Change


Many amphibian and reptile species have characteristics that make them sensitive environmental indicators. The main research goal of this project is to provide indicators of environmental health and change by monitoring the distribution and population trends of amphibians and reptiles on the INL Site. This information is important to the DOE for several reasons:

  1. as an indicator of environmental health and change;
  2. for management of specific populations of sensitive species;
  3. meeting NEPA requirements regarding the siting of future developments;
  4. avoiding potentially dangerous snake-human interactions; and
  5. providing a foundation for future research into the ecological importance of these species.

The main objective of this project is to monitor amphibian and reptile distribution on the INL Site.  Specific objectives for 2007 included the following:

  • Continue monitoring snake and lizard populations at the three main den complexes (Figure 9-1);
  •  Expand monitoring program to include a 170 km driving loop to complement the den data (Figure 9-1). This has been added because Denim Jochimsen’s data showed that the proportion of gopher snakes on the roads is higher than at the main den sites;
  • Continue to monitor breeding sites for Great Basin Spadefoot “toads” (Spea intermontana)
  • Continue entering current herpetological information into a geographic information system (GIS) tool database;
  • Provide herpetological expertise, as needed;
  • Provide snake safety workshops; and
  • Provide educational opportunities for undergraduate and graduate students.

Accomplishments Through 2007

Specific accomplishments for 2007 include the following:

  • We continued monitoring of snake populations at three den complexes (Cinder Butte, Crater Butte, and Rattlesnake Cave) allowed us to increase the total number of snakes captured by 481 snakes (Figure 9-2), 332 of which were new marks.

  • We found 51 snakes during eight road cruising trips.

  • We did not confirm spadefoot toad breeding activity at the Big Lost River sinks in 2007.

  • In two man hours of searching we were not able to confirm the presence of Long-nosed Leopard Lizards (Gambelia wislizenii) on the INL Site in 2007.

  • We conducted three snake safety talks in May of 2007 at the INL Site.



The number of marked snakes on the INL Site was increased to 4,400 in 2007, which includes all snakes PIT-tagged since 1994 and marking data collected at Cinder Butte from 1989 to 1994.

  • We found that in 2007, 10 percent of females were gravid at Cinder Butte, 30 percent were gravid at Crater Butte, and 10 percent were gravid at Rattlesnake Cave.

  • No observations of a leopard lizard (Gambelia wislizenii) were made at Circular Butte in 2007. Western skinks (Eumeces skiltonianus) were found in funnel traps at Rattlesnake Cave. Sagebrush lizards (Sceloporus graciosus) were found across the entire INL Site.

  • We found 34 gopher snakes, 16 rattlesnakes, and one unidentifiable snake during our road cruising surveys (Figure 9-3).

  • Spadefoot toad (Spea intermontana) breeding was not observed in the Big Lost River Sinks.

  • We provided herpetological expertise in the form of snake safety talks for the INL Site, as well as, at the Idaho Falls Earth Day celebration and to elementary school children at different schools and libraries.

  • Through the continuation of Scott Cambrin’s masters research he has also started to look at some of the factors affecting body condition and pregnancy rates. Using the results from a laboratory study he has modeled neonate overwinter survival for the three main den sites (Figure 9-4).

Plans for Continuation
Scott Cambrin will complete a thesis and approximately two manuscripts will be submitted to peer reviewed scientific journals.

Investigators and Affiliations

Scott Cambrin, Graduate Student, Herpetology Laboratory, Department of Biological Sciences, Idaho State University (ISU), Pocatello, Idaho

Charles R. Peterson, Professor, Herpetology Laboratory, Department of Biological Sciences, ISU, Pocatello, Idaho

Funding Sources
Idaho State University Graduate Student Research and Scholarship Committee
U.S. Department of Energy Idaho Operations Office

Reports from previous years:


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