Rattlesnakes Create a Context for Localizing Their Search for Potential Prey

Abstract

Abstract This paper presents systematically collected field data on what transpires between free‐living rattlesnakes ( Crotalus viridis oreganus ) and individuals of an important prey species, California ground squirrels ( Spermophilus beecheyi ). In the course of two field seasons we discovered that rattlesnakes and California ground squirrels can engage in at least six different episode classes: snake watching, snake following, inspecting/probing coiled snakes, interaction, rattlesnake approaching squirrel and envenomation. If a rattlesnake is moving directly toward a squirrel and is within 3 m of its burrow an interaction may develop, but more commonly it does not. Instead of engaging the snake, the squirrels seemed to try to remain stationary in the face of the snake's advance, as if to minimize affording the snake information about the nursery burrow location. The rattlesnakes in turn behaved as though they were using the location of the squirrels that resisted moving away from their advance as the hub of a radial search pattern. We argue that if the squirrel engages the snake before it discovers the burrow, the location of the nursery burrow may be revealed and the pups' vulnerability actually increased.