BIOACOUSTIC CHARACTERISTICS OF THE POPULATIONS OF RUSSET GROUND SQUIRRELS (SPERMOPHILUS MAJOR) IN THE VOLGA REGION AND ANY BORDERING TERRITORIES

Relevance and goals. The existence of a population is unthinkable if there is absence of informational links between individuals. For ground squirrels whose settlements are confined to open landscapes, sound signaling performs two important population functions: the scream by an individual is an identification mark of its spatial presence and it warns the population of the imminent danger. Studies of the intraspecies variability of this important population feature at the level of the structured habitat area allows us to take a fresh look at the mechanisms of adaptation of the species to rapidly changing modern living conditions. Since the 50s of the last century, the russet ground squirrel, which until then was considered the vicariate of the speckled ground squirrel (Citellus suslicus) along the Volga river bed, has been stably living on the right bank of the Volga, continuing its resettlement to the west. As a result of this expansion of new habitats, an extensive sympatry zone of the russet ground squirrel with the indigenous speckled ground squirrel was formed, where both their contact settlements and cases of interspecies hybridization were revealed. The aim of the study was to study the individual and population variability of sound signals of russet ground squirrels in the Volga right-bank regions and adjacent territories, taking into account the fragmentation of its range and the nature of intraspecies relations with speckled ground squirrels. Materials and methods. We analayzed 1230 signals warning of danger and made by russet ground squirrels (n = 269) from 46 populations, which form 14 geographical groups (metapopulations). The signals were recorded using a Marantz PMD 670 tape recorder and a SONY ECM737 microphone directly from live traps. Frequency (initial - Fstart, maximum - Fmax, minimum (final) frequency - Fmin, modulation depth - Hmod, kHz) and time (duration D1, D2, D3, Dtotal, ms) signal characteristics were obtained using programs Avisoft-Sonograph and Adobe© Audition ver. 1.0. Statistical data processing was made with the help of Microsoft Office Excel 2010 and STATISTICA 10.0. packages. Results. Analysis of the sound signal indicators made by russet ground squirrels with the help of standard procedures of multiple comparison revealed their rather varied directions of variability and population specifics. The performed multivariate analysis allows us to identify some features of the population and environmental variability of bioacou