Previous studies have shown that snakes can use groundborne vibrations for localizing prey, and some have proposed that such vibrations provide important cues for cottonmouth snakes while foraging on fish that fall from island bird rookeries. The latter hypothesis was tested by using fish and fish models to study the behavioral response of insular Agkistrodon piscivorus conanti to groundborne vibrations and olfactory cues. Diving and wading birds that nest on Seahorse Key, a small island adjacent to the northern Florida peninsula in the Gulf of Mexico, regularly drop fish in the vicinity of resident A. piscivorus during the colonial nesting period. Here we report that presentation of an equivalent groundborne vibration, without associated chemosensory or visual stimuli, failed to induce overt foraging behavior in these snakes. However, presentation of a fish-based olfactory stimulus, without associated groundborne vibration or motion, triggered a foraging response in A. piscivorus. Snakes from two study sites reacted differently to the olfactory stimulus; those from the site with less ground cover, more rats, and fewer snakes exhibited a weaker foraging response.