Sex Accent and Biphonation in the Sound Signal of Ground Squirrels (Mammalia, Rodentia).

The alarm call of the little ground squirrel (Spermophilus pygmaeus), like those of six other Eurasian ground squirrels, contains a high-frequency component. In males, the peak and maximum frequencies of the high-frequency component are higher than in females. Biphonation of the alarm calls of Sp. pygmaeus, Sp. musicus, Sp. xanthoprymnus, and Sp. alaschanicus has been demonstrated, with the low- and high-frequency components generated by different sources in the vocal tract. The material was collected in the field.