Avomic Prairie Rattlesnakes (Crotalus viridis) Fail to Attack Rodent Prey


Department of Zoology and Physiology, University of Wyoming, Laramie WY 82071, U.S.A.

Abstract and Summary

It has been hypothesized, though tested only indirectly, that striking and envenomation of rodent prey by rattlesnakes is guided by thermal and visual senses, vomeronasal senses being employed only after envenomation. To test this hypothesis, prairie rattlesnakes that were reliable hunters/feeders in the laboratory were rendered “avomic” (i.e., their VNOs were sutured closed) or given a control surgery. While all control subjects struck, located, and swallowed prey, avomic rattlesnakes never did so. Avomic subjects exhibited fewer tongue flicks as well. Chemical cues detected by the VNO appear to play a significant role in both pre-strike and post-strike phases of prairie rattlesnake predation. Low rates of tongue flicking observed prior to the strike may be an effect of the cryptic ambush strategy used by rattlesnakes during the pre-strike phase of predation.