RESPONSES TO PREY CHEMICALS BY A LACERTID LIZARD, PODARCIS-MURALIS - PREY CHEMICAL-DISCRIMINATION AND POSTSTRIKE ELEVATION IN TONGUE-FLICK RATE

The ability to discriminate prey chemicals from control substances and the presence of a poststrike elevation in tongue-flicking (PETF) rate are experimentally demonstrated in the lacertid lizard, Podarcis muralis. The tongue-flick attack score, a composite index of response strength, was significantly higher in response to integumental chemicals from cricket than to cologne or distilled water. The cricket chemicals additionally elicited a significantly greater rate of tongue-flicking and higher proportion of attacks by the lizards than did control stimuli. PETF combined with apparent searching movements strongly suggest the presence of strike-induced chemosensory searching (SICS). Experimental evidence indicates that both PETF and SICS occur in insectivorous representatives of three families of actively foraging autarchoglossan lizards, suggesting their widespread occurrence in such lizards. The adaptive roles of chemosensory behavior in the foraging behavior of P. muralis are discussed. It is proposed that these lizards may form chemical search images and the PETF and SICS may have been present in the lacertilian ancestors of snakes.