Geographic Variation in Vocalizations of California Chipmunks Tamias obscurus and T. merriami

Vocalizations of chipmunks were analyzed from isolated mountain ranges of California to determine the extent of interspecific and intraspecific variation in chip calls. For calls recorded, based on five measurements per emission, the two species showed significant differences in vocal parameters measured from sonagrams. Significant intraspecific variation in chip calls suggests that populations of chipmunks have achieved a level of divergence in chip calls in some cases equivalent to differences between populations belonging to different species. The terminal pulse is first described for Tamias merriami, along with a presentation of the previously undescribed T. obscurus vocalization pattern.