Neuroethological Studies on Intraspecific Call Discrimination in the Grass Frog

Abstract

The vocal repertoire of the grass frog, Rana temporaria, includes at least five different calls: the mating call (MC), a short territorial call, a long territorial call (TC), the release call of the male (RC-m), and the release call of the female (RC-f). These calls may be distinguished by differences in spectral composition, pulse repetition rate, duration, and overall amplitude modulation (Schneider, 1973; Brzoska et al., 1977; van Gelder et al., 1978). The dominant frequencies of mating calls and territorial calls are distributed around 400Hz, while the energy maxima of the release calls of the males extend between 150Hz and 250Hz and between 800Hz and 1400HZ. The low frequency peak is absent in the release calls of the females. On average, the pulse repetition rate of the mating call and the territorial calls is between 31 and 35 pulses/s at a temperature of above 15°C, that of the male release call is about 60 pulses/s, and that of the release call of the female is around 270 pulses/s. The short territorial call and the release calls are uttered in a series of calls at a repetition rate of 2–3 calls/s. Furthermore, a series of short territorial calls may be followed by the long territorial call which in turn is often followed by further short calls.