Diet of the Noisy Scrub-birdAtrichornis clamosusat Two Peoples Bay, South-western Western Australia

Abstract

The Noisv Scrub-bird Atrichornis clamosus is a small semi-flightless inhabitant of dense scrubs and low forests on the south coast of Western Australia. Between 1961, when the species was rediscovered (Webster 1962) and 1976, A. clamosus was largely confined to the Mt. Gardner area of the Two Peoples Bay Nature Reserve 40 km east of Albany (Smith 1985a). As a result of habitat management (fire exclusion) and translocation of birds to new sites the population index of the species (determined as the number of singing males) had increased from 45 in 1970 to 290 in 1990, and the range spread over about 30 km of coastal and near coastal land (Danks 1991). The population remains vulnerable to wildfire however, and the species is still classified as endangered (Garnett 1992). Knowledge of the dietary requirements of A. clamosus is important in developing a-better understanding of its ecological needs, for managing its habitat and in selecting release areas for the translocation program. John Gilbert, who discovered A. clamosus in 1842 recorded that the stomach contents of specimens he collected consisted of 'Coleoptera and seeds' (quoted in Whittell 1951). The naturalist William Webb. who also took specimens of A. clamosus in the Albany area between 1875 and 1889, considered the bird's food to consist of 'small beetles and other small insects' (Whittell 1943, quoting Webb 1895). Field observations in the Mt. Gardner area in the 1970s showed that A. clamosus is a predominantly terrestrial insectivore foraging in leaf litter, decayed wood and among shrubs and sedges (Smith 1985b). Observations of prey fed to nestlings and analysis of faecal sacs removed from the nest by the female provided information on the diet of nestlings (Smith & Robinson 1976; Smith & Calver 1984). In the latter study, it was found that nestlings were fed a variety of invertebrates from 19 orders plus a few small vertebrates. The most common prey were Araneida (35%), Orthoptera (27%), larvae (15%) and Blattodea (7%) (Smith & Calver 1984). While this information provided a good guide to A. clamosus diet, it was possible that the nestling was being fed a different diet to that taken by adults. The results of a limited study of the diet of adult A. clamosus based on analysis of faecal samples from birds captured during the translocation program are reported here.