INFLUENCE OF PREY ODOR CONCENTRATION ON THE POSTSTRIKE TRAILING BEHAVIOR OF THE NORTHERN PACIFIC RATTLESNAKE

Rattlesnake predatory behavior is defined by a strike and then release of rodent prey. Poststrike, the released envenomated prey dashes off and dies. Therefore, the snake must relocate the prey relying largely upon chemosensory cues emitted by the struck prey. Assessing these poststrike chemosensory cues is important to the snake as these cues may contain significant information about the effectiveness of the preceding strike and hence the likelihood that trailing the odor left by the envenomated prey will allow successful recovery of the prey. One possible cue in this scent trail is concentration of the distinctive odor generated in the prey during envenomation. To test this, we presented snakes with different poststrike choices of low and high prey-odor concentrations. We found that although rattlesnakes could trail each concentration level, they preferred the high odor concentrations. These results imply that rattlesnakes respond to concentration levels, not just to a threshold level of prey odor. This adjustment to different odor concentrations is not accomplished by varying rate of tongue flicks (RTFs). Based on this study and previous work, we propose a behavioral mechanism by which rattlesnakes assess the chemosensory quality of a poststrike prey odor trail.