Antipredator Behavior of California Ground Squirrels (Otospermophilus Beecheyi) PDF Download

Author: Margaret A Mantor
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ISBN: 9781267760791
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Languages : en
Pages :

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Book Description
Antipredator behavioral can give insight into the evolution of animal communication and the processes that shape it. California ground squirrels are a model species for studying how natural behavioral systems have been shaped by known sources of selection acting through millennia of evolution. The natural history and biology of California ground squirrels have been well studied making them an ideal species for studying the development and maintenance of antipredator behavior. This dissertation focuses on the differences in California ground squirrel antipredator alarm call behavior toward humans and domesticated dogs: two categories of mammalian predator that differ in the level of threat they pose. This study found that squirrel antipredator behavior varies by age class, predator type, and location. Chapter two focuses on differences in antipredator behavior between adults and juveniles. Results indicate that adult and juvenile antipredator behavioral patterns differ in the proportion of time spent in antipredator behaviors and that many of the behavioral differences may aid juveniles in appearing larger and more adult-like which could deter predators, a hypothesis first described in this dissertation and termed size bluffing. Adult behavior patterns varied with the threat level posed by the stimulus but juvenile behavior patterns did not. Results also indicate behavioral differences varied on a geographic basis between our two study sites, likely influenced by experience with different predator environments. Chapter 3 focuses specifically on alarm calls — vocalizations produced when squirrels are threatened or startled by a predator or some other disturbance. This chapter examines the degree of situational specificity of alarm calls by analyzing the temporal and acoustic structures of the vocalizations. Results indicate that alarm calls have a degree of situational specificity and that the first call of a call bout was different than subsequent calls, which may indicate that the first call has a different function than subsequent calls. Squirrels may vary alarm call parameters to communicate about the type of predator or the threat level posed by the predator, or about the internal state of the signaler. Chapter 1 focuses on trapping and handling methods to reduce stress and injuries to the animal. During this dissertation study trap modifications and a refined handling method using a handling bag rather than chemical immobilants were used. This paper reports injury rates caused by trapping and handling from this dissertation study and other squirrel studies using similar trapping and handling modifications. This dataset on multiple species provides values for comparison with other studies and can be used to compare and choose appropriate methods, and thereby improve the welfare of animals captured for research.