Vocal communication in two lemming species (Lagurus lagurus and Eolagurus luteus)

The vocal repertoire of steppe (Lagurus lagurus Pallas, 1773) and yellow steppe (Eolagurus luteus Eversmann, 1840) lemmings consists of only one type of signal, namely, a squeak. The signal does, however, have considerable variability. The DFA standard procedure shows the significant differences in the parameters of squeaks between species and significant differences in squeak parameters between the sexes in steppe lemming but not in the yellow steppe lemming. The fundamental frequency of the smaller steppe lemming’s squeak is higher than that of the larger yellow steppe lemming, although the peak frequencies have comparable values. In addition, the steppe lemming displays a pronounced sexual dimorphism in vocalization parameters; the frequency characteristics of the signals of the smaller females have lower values, which are contrary to scaling laws, stating that smaller individuals tend to have higher fundamental and peak frequencies. The age-related variability in the signals of yellow steppe lemmings was also described. The fundamental frequency of their squeaks is higher than that of the adults, but the peak frequency of signals in young and adults is not distinguished, and its value is higher than theoretically calculated. Such deviation in signal frequency parameters from the optimum may be result of directed selection, indicating the high value of such signals in the acoustic communication of lemmings.