Evidence for an innate basis of prey preference in a desert ambush predator.

Chemical eavesdropping is a critical tool used by organisms to gain information about their environment and mediate interactions with other organisms within it, such as prey gaining information about predators and vice versa. However, most chemical eavesdropping studies focus on information used by prey species, not predators. The goal of this study was to assess whether or not a desert ambush predator, Crotalus ornatus (Eastern Black-tailed Rattlesnake), differentiates among chemical cues from nonnative familiar and novel native prey items when choosing ambush spots. Naive neonate C. ornatus were obtained from wild mothers, born and raised in captivity, and placed in an arena where they were presented with aquatic extracts from the integument from 9 known and suspected prey items, a familiar non-native prey item, and a tap water control. Their reactions to the chemical extracts were recorded under diurnal and nocturnal conditions, and they were given a tongue-flick ambush (TFAM) score based on their predatory behavior towards the chemical cue. Ten naive neonate C. ornatus were put through each of the 11 trials under diurnal and nocturnal conditions, and based on TFAM scores, snakes differentiated among the chemical cues, but there were no detectable differences based on photoperiod. Post hoc pairwise tests revealed that snakes preferred native small mammal and lizard prey. The snakes used in this study had never been exposed to wild prey stimuli in their native ecosystem and had fed exclusively on non-native mammalian prey in captivity, thus their preference for native small mammals and lizards indicates an innate basis for prey preference in C. ornatus. [ABSTRACT FROM AUTHOR]