Perceptual tuning to frequency characteristics of territorial signals in collared doves.

Frequency modulations in the perch coos of collared doves, Streptopelia decaocto, affected the responses of territorial males. In this study we used playback experiments to reveal the impact of absolute and relative aspects of the frequency modulations on this responsiveness. Modulated coos always led to stronger responses compared with unmodulated coos, irrespective of the size of the frequency modulation, except when they contained frequencies outside the natural range. We found an optimum for the size of the frequency modulation, with the strongest responses to coos containing frequency modulations of 75-108 Hz, even though higher modulations are still within the species-specific range. The selective responsiveness shows that territorial males are perceptually tuned to the species-specific frequency range and to the species-specific frequency modulation size. This allows a delineation of the optimal acoustic design of the territorial signal, based on the responsiveness of the receiver. Copyright 1998 The Association for the Study of Animal Behaviour.