Sex and age-class differences in calls of Siberian wapiti Cervus elaphus sibiricus

Abstract

Stag rutting calls are strongly different among subspecies of red deer Cervus elaphus. Studying sex-, age- and subspecies-related vocal variation may highlight the forces driving the evolution of vocal communication in this species after their expansion from Central Asia to Europe and North America, however, this information was lacking so far for any Asian subspecies of Cervus elaphus. We analysed frequency, temporal and power variables of contact and bugle calls, collected from 63 Siberian wapiti Cervus elaphus sibiricus, the most abundant Asian subspecies of red deer. The open-mouth (oral) and closed-mouth (nasal) contact calls were registered in all sex and age-classes, whereas the open-mouth bugles were found in both stags and hinds but not in the calves. The maximum fundamental frequency (f0max) of contact calls was similar between calves and hinds. Similarly to American subspecies, the small differences of f0 between calls of the young and adults in C. e. sibiricus suggests only a minor ontogenetic decrease of call fundamental frequency compared to European subspecies of red deer. At the same time, the call f0 of all sex and age-classes of C. e. sibiricus was substantially higher compared to those of European subspecies of red deer (C. e. hippelaphus, C. e. corsicanus, C. e. italicus and C. e. hispanicus), although lower than in any studied American subspecies (C. e. roosevelti and C. e. canadensis). These findings provide vocal cues to indicate subspecies of Cervus elaphus, in addition to existing molecular and morphological traits.