Strike‐induced Chemosensory Searching in the Colubrid Snakes Elaphe g. guttata and Thamnophis sirtalis

Abstract

AbstractStrike‐induced chemosensory searching (SICS) occurs in numerous venomous snakes. SICS also occurs in the nonvenomous snakes Elaphe g. guttata and Thamnophis sirtalis. These species elevated tongue‐flicking rates more after striking than after exposure to experimental control conditions. Controlled effects were disturbance, visual cues (and possibly noncontact chemical cues), and handling. In another experiment with T. sirtalis, degree of disturbance was controlled. Some snakes received tactile stimulation of the oral mucosa and others similar tactile stimulation plus chemical prey cues. The much greater tongue‐flick rate in the condition including prey odors indicates that 1) disturbance alone cannot account for SICS, 2) tactile stimulation of the mouth is unlikely to elicit the full SICS response, and 3) chemical cues may be of paramount importance. SICS may be widespread in nonvenomous snakes and was presumably a preadaptation favoring the strike‐release‐trail strategy used by many venomous species. The highest tongue‐flicking rates in both species occurred after striking. In E. g. guttata an equally high rate followed swallowing. Tongue‐flicking rate in T. s. sirtalis decreased after swallowing. Interspecific differences in post‐swallowing response by snakes may be related to feeding mode and prey aggregation.