A Comparative Analysis of Distress Call Structure in Australian Passerine and Non-Passerine Species: Influence of Size and Phylogeny

Abstract

Distress vocalisations were recorded from 65 species of Australian birds, including passerines, parrots and raptors while held in the hand or entangled in mistnets. Distress vocalisations were shown to have similar structural properties in many species: a noisy and/or harmonic structure with a wide frequency range. The finding that distress calls from a range of Australian species have similar physical characteristics that appear to be convergent fits well with Marler's (1955, 1957) classic analyses of mobbing and aerial alarm calls in a variety of European passerines. The spectral structure and high amplitude of distress vocalisations also demonstrate that they are designed for ease of location and effective transmission over long distances. Incidence and rate of calling showed both intraspecific and interspecific variation, with a higher proportion of larger species calling more often. There were significant relationships found between mass and various distress call parameters; larger birds produced louder distress calls which were longer in duration with lower minimum and dominant frequencies.