THE EFFECT OF LANDSCAPE CHANGE ON THE LIFE HISTORY OF WESTERN RATTLESNAKES (CROTALUS OREGANUS)

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Background

This project was designed to assess the impact of landscape disturbance on western rattlesnakes by examining trophic interactions among habitat, small mammals, and snakes. The synergistic effect of livestock grazing, invasive plants and fire is changing sagebrush steppe ecosystems in the Upper Snake River Plain. It is hypothesized that this phenomenon is affecting the prey base of top-level predators in the system. The main research goal is to determine if changes in habitat are altering prey availability and subsequently life history characteristics of western rattlesnakes. Information from this project is important to the Department of Energy for several reasons: (1) as an indicator of how habitat change is influencing small mammal biomass; (2) as an indicator of how trophic interactions affect western rattlesnakes; (3) providing recommendations for the management and conservation of predators on the INL; (4) for utilizing a long term mark recapture data set gathered by the Idaho State University Herpetology Laboratory to further an understanding of community ecology on the INL; (5) assisting in the training of graduate and undergraduate students in environmental research.

Objectives

The overall goal of this project is to determine if current landscape patterns in habitat and prey on the INL are influencing rattlesnake life histories. Specific objectives for 2003 included the following:

Quantifying spatial variation in rattlesnake life histories.
Determining if rattlesnakes are selecting habitats with greater small-mammal biomass.
Determining if disturbance to sagebrush steppe systems affects small-mammal biomass.

Accomplishments Through 2003

Specific accomplishments for 2003 include the following:

Found significant variation in life history characteristics among three den complexes on the INEEL. More specifically, it was found that snakes at one den complex had life history characteristics that would indicate lower fitness.
Found that small-mammal biomass was greater in snake core activity areas than in either migration corridors or random locations.
Found that small-mammal biomass was highest in habitats characterized by relatively tall shrub cover, low grass cover, and high biological crust cover.

Investigators and Affiliations

Christopher L. Jenkins , 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 Department of Fish and Game
Bureau of Land Management
Idaho State University (ISU) Department of Biological Sciences
ISU Graduate Student Research Committee
INL – ISU Education Outreach Program

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