Variability in the alarm call of golden-mantled ground squirrels (spermophilus lateralis and S. saturatus)

Abstract

Many animals have geographic variation or dialect differences in their vocalizations. These differences combined with social behavior and isolation can contribute to speciation. We compared the acoustic vocalizations of 3 subspecies of Spermophilus lateralis and those of S. saturatus using wild-caught animals in the presence of a predator, Canis lupus familiarus. Variation was examined using 9 sonogram variables. We found both local dialect differences and geographic variation in alarm calls. S. saturatus could be distinguished 100% of the time from S. lateralis using discriminant analysis. Widespread use of ultrasonic vocalizations was found in both S. lateralis and S. saturatus. Dialect differences showed a pattern of character displacement between adjacent subspecies. Vocalization parameters changed within local sites and between years, suggesting alarm calling is at least partially a learned behavior. Species share more uniquely defining vocalization variables than either subspecies or local populations.