Pattern Analysis of Acoustical Behavior in Four Species of Ground Squirrels

Acoustical behaviors of Spermophilus armatus, S. columbianus, S. elegans, S. richardsonii, and S. elegans × S. richardsonii hybrids were studied in an area of sympatry in southwestern Montana. Calls, categorized as chirps, churrs, squeals, growls, and teeth-clatters, were described in detail; further distinctions were noted for some taxa. Audiospectrograms were coded into two-dimensional arrays for correlation, and subsequent cluster analysis of call syllable patterns determined both within-call structure, and phenetic relationships between species. Tests to determine whether chirp, churr, and preface syllables paralleled systematic relationships were inconclusive but chirp calls seemed to be convergent where species were sympatric while churr calls seemed unaffected.