Biology Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2749
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Item ADAPTIVE FLIGHT AND ECHOLOCATION BEHAVIOR IN BATS(2015) Falk, Ben; Moss, Cynthia F; Neuroscience and Cognitive Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bats use sonar to identify and localize objects as they fly and navigate in the dark. They actively adjust the timing, intensity, and frequency content of their sonar signals in response to task demands. They also control the directional characteristics of their sonar vocalizations with respect to objects in the environment. Bats demonstrate highly maneuverable and agile flight, producing high turn rates and abrupt changes in speed, as they travel through the air to capture insects and avoid obstacles. Bats face the challenge of coordinating flight kinematics with sonar behavior, as they adapt to meet the varied demands of their environment. This thesis includes three studies, one on the comparison of flight and echolocation behavior between an open space and a complex environment, one on the coordination of flight and echolocation behavior during climbing and turning, and one on the flight kinematic changes that occur under wind gust conditions. In the first study, we found that bats adapt the structure of the sonar signals, temporal patterning, and flight speed in response to a change in their environment. We also found that flight stereotypy developed over time in the more complex environment, but not to the extent expected from previous studies of non-foraging bats. We found that the sonar beam aim of the bats predicted flight turn rate, and that the relationship changed as the bats reacted to the obstacles. In the second study, we characterized the coordination of flight and sonar behavior as bats made a steep climb and sharp turns while they navigated a net obstacle. We found the coordinated production of sonar pulses with the wingbeat phase became altered during navigation of tight turns. In the third study, we found that bats adapt wing kinematics to perform under wind gust conditions. By characterizing flight and sonar behaviors in an insectivorous bat species, we find evidence for tight coordination of sensory and motor systems for obstacle navigation and insect capture. Through these studies, we learn about the mechanisms by which mammals and other organisms process sensory information to adapt their behaviors.Item Communication and Social Influences on Foraging in Bats(2012) Wright, Genevieve Spanjer; Wilkinson, Gerald S; Moss, Cynthia F; Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Using social information can be an efficient way to respond to changing situations or to learn skills. Other benefits of foraging in a group, such as social facilitation, have also been reported. Furthermore, individuals foraging near conspecifics may use acoustic communication to mediate interactions. Many bat species (Order Chiroptera) are gregarious, and many tropical frugivorous bats rely on seasonally-abundant foods such that following conspecifics to a food source could benefit "followers" without harming "leaders." Animal-eating bats do not typically share food, but information obtained from experienced foragers could help facilitate development of prey acquisition skills in young bats. Additionally, communicative vocalizations serving various social functions have been reported in diverse bat species. Despite the opportunities for social learning and information transfer that many bats experience, few studies have attempted to determine if these phenomena occur in bats. Similarly, despite research on echolocation and some communicative calls, the context and function of social calls emitted by flying, foraging bats have received relatively little study. In this dissertation, I examine interactions between individuals in a foraging context and the impact of these interactions on the individuals' behavior. Specifically, I used pairs of big brown bats (Eptesicus fuscus) to test whether insectivorous bats can acquire a new foraging skill via social learning and what social cues might facilitate learning. I then describe the context of and attribute function to social calls emitted by bats in pairs. Finally, I examine the effects of social context on the foraging behavior of the frugivorous short-tailed fruit bat (Carollia perspicillata) presented with a food-finding task. My results provide the first evidence of the role of social learning (via attention to feeding buzzes and interaction with experienced individuals) in the development of foraging skills in young insectivorous bats. I also report a repertoire of social calls produced by foraging big brown bats and present evidence that males use social calls to defend food and increase their foraging success. Finally, I present evidence that social facilitation increases foraging performance in short-tailed fruit bats. These findings contribute to our knowledge of the social aspects of foraging in group-living animals.