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Along to alarm calls, Eurasian ground squirrels of the genus Spermophilus also produce other call types toward potential predators and rival conspecifics. Individually identified 50 speckled (Spermophilus suslicus), 18 European (S. citellus) and 59 yellow (S. fulvus) ground squirrels were examined for interspecies differences in their vocal repertoires. A separate sample of 116 (90 adult and 26 juvenile) S. suslicus was examined for presence of ultrasound in their alarm calls. In addition, all tonal calls in all the three species were checked for presence of nonlinear phenomena. Calls were elicited by approaching animals in live-traps or near burrows; some types of vocalizations were also recorded during handling. Eight call types, three tonal and five wideband ones, were described. Vocal repertoires were remarkably similar between species, excluding the alarm calls, which were species-specific. Alarm calls with ultrasonic components were found in two individuals of S. suslicus. Concerning nonlinear phenomena, biphonation in alarm calls of S. suslicus, frequency jumps and sidebands in screams of S. citellus, frequency jumps and subharmonics in screams of S. fulvus were found. Results are discussed with literature evidence on audible and ultrasonic vocalizations in ground squirrels.

The Anatolian ground squirrel Spermophilus xanthoprymnus like other ground-dwelling sciurids, emits alarm calls in the presence of predators. In this study, we provide a description of the acoustic structure of alarm call of this species and compare it to those of two closely related species, the Taurus ground squirrel Spermophilus taurensis and the European ground squirrel Spermophilus citellus. The alarm call of S. xanthoprymnus is a tonal sound mostly consisting of two different elements-the first element has low frequency modulation while the second element is highly frequency modulated. A similar basic structure can be found in the alarm calls of some other old world ground squirrel species of the genus Spermophilus, including S. taurensis and S. citellus. Despite this similarity, we found that these three species can be clearly distinguished on the basis of their alarm calls. Differences in the acoustic structure of S. xanthoprymnus and S. taurensis calls are especially remarkable, as these two species were considered to be conspecific until 2007. S. xanthoprymnus and S. taurensis were also demonstrated to have closer acoustic similarity, which is in contrast to results based on molecular data indicating that S. taurensis is most closely related to S. citellus.

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