Factors Affecting the Movements of Timber Rattlesnakes (Crotalus horridus) From the Mid-Atlantic Coa

Dreslik, Michael J.

Illinois Natural History Survey

University of Illinois Urbana-Champaign

Champaign, IL 61820 USA

Petersen, Christopher E.

Naval Facilities Engineering Command Atlantic

Norfolk, VA 23508 USA

Goetz, Scott M.

Department of Biological Sciences, Auburn University, Auburn, AL 36849

Kleopfer, John (J.D.)

Virginia Department of Game and Inland Fisheries, Charles City, VA 23030 USA

Savitzky, Alan H.

Department of Biology

Utah State University

Logan, UT 84322 USA

Factors governing why or how far an organism moves can reflect local conditions, such as weather and habitat structure, as well as intrinsic biological variables such as age, sex, and reproductive condition. These variables may act synergistically to influence the frequency and distance of movements. We sought to determine whether climatic, behavioral, and or biological factors drive movements in a mid-Atlantic population of Timber Rattlesnakes (Crotalus horridus), using a 17-year radio-telemetric data set. We used mixed-effects binary logistic regression to determine the probability of movement, and general linear mixed-effects regression, coupled with an AIC approach, to determine the best predictive models for distance per movement. Our results indicate that movements are influenced by numerous climatic, behavioral, and biological variables. For example, as mean three-day maximum temperature increased, so did the probability of movement, but the greatest distances moved were at the lower (egress and ingress) and higher temperatures (main activity season). Additionally, the probability of movement was approximately the same throughout the year, whereas the greatest movement distances occurred during the summer months. As the number of days increased since last feeding, the probability of movement decreased, but the distances moved increased. Movements decreased before shedding and increased slightly after shedding. Together, our data suggest that numerous factors affect movements in C. horridus, notably the impact of weather patterns.