Perceptual salience of individually distinctive features in the calls of adult king penguins

In the king penguin, Aptenodytes patagonicus, incubation and brooding dutie s are undertaken alternately;by both partners of a pair. Birds returning fr om foraging at sea find their mate in the crowded colony using acoustic sig nals. Acoustic recognition of the mate maintains and strengthens the mate's fidelity and favors synchronization in the different stages of reproductio n. In this study it was found that the king penguin vocalizes in response t o the mate's playback calls, but not to those of neighbors or unfamiliar co nspecific individuals. To study individual features used by the birds for i ndividual recognition of mates, various experimental signals consisting of synthesized modifications of the mate's call were played back to the incuba ting bird. Results indicated that birds attend to the FM profile of the cal l, in particular its initial inflexion. The frequency modulation shape of t he syllable can be assimilated to a vocal signature repeated though the dif ferent syllables of the call. King penguins pay little attention to the cal l's AM envelope or its absolute frequency. (C) 2000 Acoustical Society of A merica. [S0001-4966(00)05001-3].