Habitat selection and prey odor in the foraging behavior of western rattlesnakes (Crotalus viridis)

We tested the roles of prey odor and other habitat cues in the pre-strike m ovement patterns of two, ecologically distinct sub-species of the western r attlesnake in naturalistic arenas. In the first experiment, rattlesnakes pr eferred habitat containing prey odor and cover comprised of rocks, sticks a nd plants. While searching, rattlesnakes methodically investigated the edge s and crevices within rock, areas rodents might frequent in nature. In the second experiment, rattlesnakes investigated sticks more than rocks arrange d topographically similar to sticks. In the third experiment, rattlesnakes preferred habitat that included brush foliage and used chemical prey trails in pre-strike behavior via (i) trail-following, (ii) casting search patter ns and (iii) scanning search patterns. Several snakes coiled in stereotyped ambush postures that allowed them to face chemical trails while resting ag ainst rocks and foliage. These results suggest that rattlesnake foraging ex hibits qualities advantageous for hunting rodent prey in addition to provid ing protection from predators and perhaps promoting thermoregulation. Sub-s pecies did not exhibit geographic variation in foraging behavior despite di fferences in natural history and morphology. Hence, the microevolutionary p attern suggests that generalized foraging repertoires are successful in num erous environments when coupled with locally specialized body patterns.