Distress call in six species of African Poicephalus parrots

We report here a description of the bioacoustic structure of distress calls of a number of African parrots, namely six species pertaining to the genus Poicephalus. The description is based on an analysis of 1523 distress voca lizations, totalling 8.54 min of record. The Poicephalus distress calls sound like a threatening growl that is compo sed of a series of short harmonic, scarcely modulated pulses, one following another in a short time. To be efficient over long distances and to be eas ily located by all possible receivers, the basic acoustic shape of this cal l showed a complex carrier frequency, numerous harmonics, low frequency mod ulation and wide frequency range. The highest frequencies of distress call emitted by African Poicephalus parrots exceeded 10 kHz; high frequencies ar e greatly attenuated with distance so that the distress call may efficientl y provide information on both long distances and also on short ones. The de gradation of high frequencies may be used by the receiver to determine the emitter distance or to startle mam mal predators into releasing the distres sed parrot. The distress call of African Poicephalus parrots is also a sexu ally dimorphic vocalization, with significant differences in the main physi cal parameters of the two sexes of all the species studied. Finally we foun d significantly differences between species and super-species even though t he vocalization is extremely conservative.