Behavioral variation in prey odor responses in northern pine snake neonates and adults

Squamate reptiles (snakes, lizards, amphisbaenians) rely heavily on chemosensory cues to identify, locate and choose between suitable prey items, but comparatively little research has focused on the chemical ecology of threatened squamate species. Such knowledge highlights ecologically important aspects of their survival. Due to gape limitations, squamates often demonstrate ontogenetic shifts in their diet where they consume larger prey as they grow older and their gape size increases. This shift enables squamates-especially snakes-to exploit new resources in their environments, usually mammalian prey. To test for ontogenetic variation in prey odor responses of a threatened snake species, the Northern pine snake (Pituophis melanoleucus melanoleucus), we presented food-na < ve neonates and food-experienced adults with potential prey and non-prey animal scents and quantified their behavioral responses. Our data indicate a strong response to rodent scents from both neonates and adults. Further, neonates showed more frequent investigative probing and retreating behaviors from scented swabs and a higher rate of tongue-flicking than adults. We also developed a new metric for measuring snake responses to prey odor, a tongue-flick reaction score (TFRS), that incorporates investigative behaviors that may be unique to constrictor-type snakes. The TFRS did not differ between age classes and was highest when rodent odors were tested. A canonical discriminant analysis confirmed the relationship between TFRS behavioral components and tested chemical signal reactions. Based on our data, P. melanoleucus may fall into a category of snakes that exhibit an ontogenetic telescope rather than a general ontogenetic shift in their prey odor responses.