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 is to provide indicators of environmental health and change by monitoring the distribution and population trends of amphibians and reptiles on the INL.

Information from this project 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) for meeting NEPA requirements regarding the siting of future developments, (4) for avoiding potentially dangerous snake-human interactions, and (5) for providing a basis for future research into the ecological importance of these species. Additionally, this project provides venomous snake safety training to INL employees and summer assistants. This training provides key information on how to avoid and treat bites from venomous snakes. It also helps workers place the relatively low risk of snakebite in perspective and fosters an appreciation of the ecological role of snakes on the INL. Finally, this project assists in the training and support of undergraduate and graduate students in environmental research.

The overall goal of this project is to determine amphibian and reptile distribution on the INL and monitor populations in select areas. Specific objectives include the following:

  • Continue monitoring snake and lizard populations;
  • Continue entering current herpetological information into a geographic information system (GIS) database;
  • Provide herpetological expertise, as needed;.
  • Provide snake safety workshops; and
  • Provide educational opportunities for undergraduate and graduate students.


Specific accomplishments include the following:
  • Continued monitoring efforts at three den sites allowed more accurate estimates of reptile abundances on the INL (Figure 9-1). These estimates will allow examination of population trends over time. Currently, the team is working on new ways to monitor the health of rattlesnake populations on the INL. It is believed that calculating condition indices may be an additional method for assessing population health in western rattlesnakes. Western rattlesnakes are relatively long lived, active for short periods of the year, and require multiple years of foraging to have one successful reproduction. Because of these factors, environmental characteristics such as habitat degradation or weather patterns could indirectly influence the condition indices by altering prey resources. For example, spatial variation in body condition may indicate spatial patterns of habitat degradation or weather (Figure 9-2). Trends in body condition over time may indicate how patterns in habitat or weather are changing temporally (Figure 9-3). Overall, the team is still evaluating how to incorporate these condition indices into the monitoring program; however, it is agreed that this information will be an effective complementary method for monitoring snake health.
  • Updated the INL Herpetological database using the observations gained from the team's research.
  • Provided herpetological expertise to numerous groups on the INL in 2003 including snake safety training sessions and field safety consultations.


Important results included confirming the continued presence of leopard lizards (Gambelia wislizenii) at Circular Butte, continuing radiotelemetry studies, beginning small mammal trapping, and providing specific herpetological expertise to several groups on the INL.

  • The number of marked snakes on the INL increased in 2003 to 3390, including all snakes PIT-tagged since 1994 and marking data collected at Cinder Butte from 1989 to 1994.
  • Two observations of a leopard lizard (Gambelia wislizenii) were made at Circular Butte in 2003. Many western skinks (Eumeces skiltonianus) and sagebrush lizards (Sceloporus graciosus) were sited across the entire INL, and two short-horned lizards (Phrynosoma douglassii) were found close to the Rattlesnake Cave snake den location.
  • The team did not observe breeding activity by spadefoot toads (Scaphiopus intermontanus) on the INL in 2003.
  • As part of Chris Jenkins' Ph. D research, radiotelemetry work continued and small mammal trapping began in the southeastern portion of the INL to look at the effects of landscape characteristics on rattlesnake populations.
  • Provided herpetological expertise in the form of presenting five snake safety training sessions and outreach to the public through programs for children both onsite and at the INL Science Expo. In addition, herpetological data for the site was disseminated, and conducted field safety consultations. The snake safety sessions have generated positive feedback from the employees, and many yield invitations for additional presentations, both on the INL and in local communities.

Click to enlarge

Investigators and Affiliations
Charles R. Peterson, Professor, Herpetology Laboratory, Department of Biological Sciences, Idaho State University, Pocatello, ID

Christopher L. Jenkins, Graduate Student, Herpetology Laboratory, Department of Biological Sciences, Idaho State University, Pocatello, ID

Chris Jenkins received  the Ted Trueblood Communications Award for best student presentation for his lecture entitled, Life History Variation Among Western Rattlesnake Populations on the INL, presented at the Idaho Chapter of the Wildlife Society in Boise on March 7, 2003.  

Funding Sources
U.S. Department of Energy Idaho Operations Office

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