Meeting Abstract

45.5  Jan. 6  Frequency of Rattle Use by Free-ranging Western Diamondback Rattlesnakes PLACE, AJ; Northwestern Oklahoma State University ajplace@nwosu.edu

The rattle system of rattlesnakes (Genera Crotalus and Sistrurus) is an adaptive suite of morphological, physiological, and behavioral characters. Previous studies have addressed the morphology and physiology of the rattle system. While previous studies have addressed proximate factors influencing rattle use, a more complete understanding of the adaptive value of the rattlesnake rattle requires a better understanding of the context and frequency in which the rattle in employed by free-ranging rattlesnakes. Data were collected from randomly encountered and radio-telemetered western diamondback rattlesnakes to assess the frequency and context in which the rattle was used. Twenty-five of 45 randomly encountered snakes rattled when approached. Coiled snakes were more likely to rattle than snakes moving. There was no association between rattling and sex. Seven radio�tagged snakes were observed 140 times, five of which resulted in a rattle response. Moving radio-tagged snakes were more likely to rattle than coiled snakes. The results reported here are compared to previous reports for other species. A behavioral threshold model for the origin of the crotaline rattle is also introduced.