Species specificity and geographical variation of Eurasian marmots' alarm call (Marmota, Sciuridae, Rodentia)
The alarm call species specificity of Eurasian marmots is based on a combination of three key features: characteristics of the frequency modulation of the low- and high-frequency components and the amplitude modulation. In general, the results of the cluster analysis do not contradict to the traditional classification of marmots and at most coincide with the results of the latest molecular-genetic methods. Aberration of the alarm call of Marmota bobak is a special case of geographical variation. The variability of the signal in the areas of secondary contact collaterally confirms the hybridization between M. bobak and M. baibacina and between M. baibacina and M. sibirica. The preliminary results of the New World marmots' alarm call analysis showed significant differences between Eurasian and North American species. Alarm call of North American species is different from Eurasian species' call with wide variety of duration, low probability of the low-frequency component and the absence of amplitude modulation (it exists in alarm call of M. vancouverensis only). It is advisable to extend the study of the geographical variation of marmot alarm call and to study alarm call of North American species in detail. It allows one to analyze the variability of alarm call of Eurasian and North American species of marmots combined.