PERSISTENCE OF TRAILING BEHAVIOR: CUES INVOLVED IN POSTSTRIKE BEHAVIOR BY THE RATTLESNAKE (CROTALUS VIRIDIS OREGANUS)

Abstract

Following the release of envenomated prey, a rattlesnake exhibits a series of poststrike behaviors, involving largely chemosensory cues that lead to recovery and swallowing of the dead prey. Unlike prestrike chemosensory activity that may help the snake place itself generally in the vicinity of prey, this poststrike trailing is more specific and selective. The rattlesnake discriminates the particular poststrike trail of the envenomated mouse from odor trails of other unstruck mice. But an envenomated prey may dash significant distances over complicated terrain. Consequently, poststrike trailing by the rattlesnake may take hours during which it is exposed to its own predators. If the odor trail ages significantly, losing its perceptibility, then poststrike trailing eventually becomes futile. To examine this, each rattlesnake was permitted to strike prey, but allowed to follow the placed scent trails only at six fixed intervals poststrike, t = 0, 2, 4, 6, 12, and 24 hours. Our results indicate that in the absence of an envenomating strike, rattlesnakes did not exhibit successful trailing of prey odors, whether those scent trails were from an unstruck mouse or a mouse struck independently by another snake. However, allowed to strike, snakes maintained an interest in selective trailing up to 24 hours from the time of envenomation, although with decreasing frequency. Therefore, the strike must precede the specific and selective poststrike trailing behavior, characterized by an ability to discriminate and track the scent of the particular mouse envenomated. These results imply that the strike itself is a releaser of selective chemosensory trailing and that snakes can retain for extended periods of time a 'memory′ of the unique chemical cues of the particular mouse struck.