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Monitoring Amphibian and Reptile Populations on the Idaho National Laboratory: Indicators of Environmental Health and Change

Investigators and Affiliations

Scott Cambrin, Graduate Student, Herpetology Laboratory, Department of Biological Sciences, Idaho State University, Pocatello, ID

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

Funding Sources

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

Background

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. 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.
5. Providing a foundation for future research into the ecological importance of these species.

Objectives

The main objective of this project is to monitor amphibian and reptile distribution on the INL. Specific objectives for 2006 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) database;
• Provide herpetological expertise, as needed;
• Provide snake safety workshops; and
• Provide educational opportunities for undergraduate and graduate students.

Accomplishments Through 2006

Specific accomplishments for 2006 include the following:

• 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 463 snakes, 241, of which were new marks (Figure 9-2) . Calculated population estimates for Rattlesnake Cave (Figure 9-3).

• Determined body condition for the rattlesnakes at the three den sites for 2006 (Figure 9-4) and cumulatively for rattlesnakes from 1994 through 2006 (Figure 9-5). Looked at the spatial and temporal variation and estimate what environmental characteristics might play a role in determining snake body condition and ultimately survival.
• Found 27 snakes during 10 road cruising trips.

• Confirmed spadefoot toad breeding activity at the Big Lost River sinks in 2006.

Results

• The number of marked snakes on the INL was increased to 3919 in 2006, which includes all snakes PIT-tagged since 1994 and marking data collected at Cinder Butte from 1989 to 1994 (Table 9-1).

• We found that in 2006, 54 percent of females were gravid at Cinder Butte, 37 percent were gravid at Crater Butte, and 23 percent were gravid at Rattlesnake Cave (Figure 9-6).

• Two observations of a leopard lizard (Gambelia wislizenii) were made at Circular Butte in 2006. Western skinks (Eumeces skiltonianus) were found in funnel traps at Rattlesnake Cave. Sagebrush lizards (Sceloporus graciosus) were found across the entire INL.
• We found 20 gopher snakes (one alive), four rattlesnakes, and three garter snakes during our road cruising surveys (Figure 9-7).
• Spadefoot toad (Spea intermontana) breeding was observed in the Big Lost River sinks, and tadpole, adults and recently metamorphosed spadefoots were located.
• Provided herpetological expertise in the form of snake safety talks for the INL, as well as, at the Idaho Falls Earth Day celebration and to elementary school children at different schools and libraries. This monitoring program was the subject of a talk at the Idaho Herpetological Society in November 2006.
• Through the continuation of Scott Cambrin’s Masters Degree research he has also started to look at some of the factors affecting body condition and pregnancy rates. He found there was a positive correlation with yearly precipitation and body condition with an R2 value of 0.37 and a p-value of 0.035 (Figure 9-8). He also found a significant relationship between body condition and percent gravid females with an R2 value of 0.36 and a p-value of 0.039 (Figure 9-9).

Plans for Continuation

A M.S. thesis is expected to be completed in 2007 by S. Cambrin based on this work. Monitoring herpetofauna is one part of the wildlife monitoring task in the ESER program and is expected to continue.

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