THE ROLE OF AIRBORNE AND SUBSTRATE CUES FROM NON-ENVENOMATED MICE DURING RATTLESNAKE (CROTALUS OREGANUS) POST-STRIKE TRAILING

Abstract

Rattlesnakes are highly adept at following substrate chemosensory trails left by struck (envenomated) prey. However, there are other sources of chemical information that may be present in the post-strike environment, such as odors from unstruck mice, that could either confound or aid predatory success. Rattlesnakes can follow airborne chemosensory trails of a struck prey, but the ability of rattlesnakes to use airborne chemosensory cues of unstruck prey has not been examined. Therefore, our purpose was to examine the abilities of rattlesnakes to locate prey using substrate and airborne cues from unstruck mice and compare this with their success with airborne odors from struck mice. We used a Plexiglas Y-maze through which paired airborne and/or substrate odor choices were presented to northern Pacific rattlesnakes (Crotalus oreganus). In one treatment, snakes given a choice of odor from an unstruck mouse (substrate) versus a control (unscented air) showed a significant preference for the unstruck, substrate odor trail. In a second treatment, snakes given a choice of unstruck mouse odor (airborne) versus a control (unscented air) showed no significant preference for the airborne odor. In a third treatment, snakes given a choice of unstruck mouse (airborne) versus struck mouse odor (airborne) again showed no preference for either odor. This last result suggests that one cue used during airborne trailing is a general chemical cue and is most likely not associated with a distinct post-strike searching image (as is the case in substrate trailing). Snakes also exhibited certain behaviors within the maze (i.e., turning behavior, emergences) more often when exposed to airborne cues than when exposed to substrate cues. These observations indicate that a different system of behaviors is used when rattlesnakes follow airborne compared to substrate odor cues during post-strike trailing.