Chemical detection of predators by a lizard, the broad‐headed skink (Eumeces laticeps)

Abstract

AbstractThe scincid lizard Eumeces laticeps is shown experimentally 1) to be capable of detecting integumentary chemical stimuli from two congeneric species of snakes that are sympatric predators of lizards and 2) to discriminate these chemical stimuli from similar ones derived from a sympatric snake that does not eat lizards and from a common insect food species. The experimental technique employed in this study, i.e., presentation of odorants on cotton‐tipped applicators, allows rapid assessment of responses to predator odors and is suitable for a survey of these responses in a wide variety of lizards. The skinks showed significantly higher tongue‐flicking rates in response to odors of snake predators and food odors (cricket) than to odors of a snake that does not eat lizards and an odorless control. Tongue‐flick attack score, a measure of response strength to chemical stimuli from food, was much greater for cricket stimuli than for the predator stimuli. Significantly more lizards bit applicators bearing cricket stimuli than bit applicators bearing any of the other stimuli. After biting applicators bearing predator odors, the lizards quickly released. In contrast, they frequently maintained a grasp after biting applicators bearing cricket odors. A few preliminary speculations are made regarding ecological factors that may affect responsiveness by lizards to predator odors.