PERCEPTUAL TUNING TO FREQUENCY-CHARACTERISTICS OF TERRITORIAL SIGNALSIN COLLARED DOVES

Frequency modulations in the perch coos of collared doves, Streptopeli a decaocto, affected the responses of territorial males. In this study we used playback experiments to reveal the impact of absolute and rel ative aspects of the frequency modulations on this responsiveness; Mod ulated coos always led to stronger responses compared with unmodulated coos, irrespective of the size of the frequency modulation, except wh en they contained frequencies outside the natural range. We found an o ptimum for the size of the frequency modulation, with the strongest re sponses to coos containing frequency modulations of 75-108 Hz, even th ough higher modulations are still within the species-specific range. T he selective responsiveness shows that territorial males are perceptua lly tuned to the species-specific frequency range and to the species-s pecific frequency modulation size. This allows a delineation of the op timal acoustic design of the territorial signal, based on the responsi veness of the receiver. (C) 1998 The Association for the Study of Anim al Behaviour