Diet of Roadkilled Western Rattlesnakes (Crotalus oreganus) and Gophersnakes (Pituophis catenifer) in Southern British Columbia

Abstract

Abstract A critical 1st step in understanding the basic ecology of any predator is to delineate their suite of prey species. In this paper we provide data on the diet of 2 threatened snake species in British Columbia, the Western Rattlesnake (Crotalus oreganus) and the Gophersnake (Pituophis catenifer). By dissecting the gastrointestinal tracts of roadkilled specimens, we identified a total of 11 different prey types. Unlike what has been previously reported elsewhere for the 2 species, we found a strikingly high degree of overlap between the diets, as shown through Morisita's similarity index (Ĉ = 0.98). The Deer Mouse (Peromyscus maniculatus) was the most frequently identified prey type for both species, followed by shrews (Sorex spp.). Other prey species consumed by Western Rattlesnakes were approximately even in abundance and in low numbers. Gophersnakes had a wider range of prey consumed at moderate frequencies, including voles (Microtus spp.) and birds. We also detected prey in a relatively high per...