Flexible Defense: Context-Dependent Antipredator Responses of Two Species of Australian Elapid Snakes

Abstract

Abstract Snakes exhibit a complex repertoire of defensive responses, shifting from one tactic to another depending upon conditions at the time of encounter with a potential predator. Standardized laboratory trials, controlling factors such as time of day, temperature, and type of encounter, can be used to test predictions about the form of this context dependency. We studied two sympatric species of elapid snakes from southeastern Australia. Although similar in body sizes, habitat use, and nocturnality, small-eyed snakes (Cryptophis nigrescens) are wide foragers (and hence, encounter predators under cool conditions at night in relatively open areas), whereas broad-headed snakes (Hoplocephalus bungaroides) lie in ambush for long periods within sun-warmed rocky retreat sites (and hence, encounter predators mostly when the snake is warm, and within its retreat). Based on those differences, we predicted that small-eyed snakes would be thermal generalists; that is, temperature would exert relatively little eff...