The behaviours of eastern chipmunks (Tamias striatus) in response to aerial predators were studied in the field using trained kestrels (Falco sparverius) flying over a food patch where animals of known gender, age and burrow location categories were foraging. Their typical response was to flee toward a nearby refuge while producing a trill. After a few seconds, chipmunks usually emerged and started to produce long (but sometimes interrupted) series of chucks while facing the predator. Acoustical analysis showed that the trill consisted of a rapid series of usually high pitched and variable notes while most chucks consisted of two partially overlapping components differing mainly in frequency range. No differences were observed between individuals of different categories for most antipredator responses. Various observations suggest that the trill functions to startle the predator and that the chuck deters the predator from hunting in the area.

Chipmunk antipredator calls were examined during the summers of 1990 and 1991. The structural characteristics of the three calls, chipping, chucking and the trill, were obtained through taped recordings and sonagraphic analysis. Behavioural observations indicated that chucking by choruses of individuals occurs in the presence of aerial predators, chipping by choruses of individuals occurs in the presence of terrestrial predators and the trill is given by single individuals when fleeing from predators. / Experiments were carried out to determine the function of the trill and chipping. Demographic and contextual effects indicate that the trill is in part a call which functions to warn kin but may also indicate to conspecifics that the caller has escaped into a refuge. An experiment with a tethered cat concluded that chipping is likely to function to deter predators from hunting in the area. This is done through vocal mobbing by several individuals whose home ranges overlap.

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