Foraging decisions by eavesdropping bats
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Animals forage in complex environments in which they must constantly make decisions about which resources to approach and which to avoid. Many factors can influence these foraging decisions including perception and cognition. Predators that locate prey by eavesdropping on prey mating calls face a challenging foraging task because they must be able to identify which species-specific prey signals indicate palatable prey. My thesis investigates such foraging decisions in eavesdropping bats. The Neotropical fringe-lipped bat, Trachops cirrhosus, locates its frog and katydid prey by eavesdropping on the prey's calls. One of the prey of T. cirrhosus in Panamá is the túngara frog, Physalaemus pustulosus, that can make simple calls consisting of a "whine" alone, or complex calls which are a whine followed by 1-7 "chucks". In my first chapter I examine what components of frog calls bats use to identify and localize them. I assess how bats respond to the two components of the complex calls of P. pustulosus, and report that, unlike female frogs, bats respond to the chuck component alone but preferentially approach the whine. Next, I examine how response to prey cues is affected by prey availability by assessing the response of T. cirrhosus to geographically and seasonally variable prey. I find population and seasonal differences in response to some prey cues but not to other cues. Trachops cirrhosus can also learn novel prey cues from exposure to a conspecific tutor (social learning). My third chapter examines the conditions that influence when bats socially learn novel prey cues. I discover that bats are more likely to use social information to learn novel prey cues when the cue they are currently using to find food is unreliable. In my fourth and final chapter I address how eavesdropping can contribute to the evolution and diversification of bats by investigating the potential of eavesdropping on katydid calls for niche partitioning in two closely related bat species, the European greater and lesser mouse-eared bats, Myotis myotis and Myotis blythii oxygnathus. Together these studies highlight the role of cognition in foraging decisions and consider the consequences of eavesdropping for niche partitioning.