The Status and Ecology of the White-throated Grasswren Amytornis woodwardi

Abstract

The White-throated Grasswren Amytornis woodwardi is endemic to the sandstone plateaux and escarpments of western Arnhem Land and surrounding areas of the Northern Territory. Recent surveys extend the known range 100 km east and 80 km south. This grasswren appears to be neither rare nor endangered. Based on estimates of the area of suitable habitat, its total population is probably over 14 000, possibly over 50 000. Optimum habitat appeared to be flat, often sparsely vegetated, high plateaux; heavily dissected escarpments and outliers supported less dense populations. The most consistent components of the habitat were bare rock and spinifex, which together constituted almost three-quarters of the sub-stratum. Fire is important in the ecology of the species but information at present is inconclusive as to its effects. Regular burning may indirectly benefit these birds by maintaining a high density of spinifex and low density of more fire-sensitive plant species. The diet of A. woodwardi is not specialised, and includes plant stems, seeds and insects. The breeding season is long (December to May or June) and allows two or more broods to be produced. Territories averaging 10 ha were held by pairs and larger groups during the breeding season, providing evidence of cooperative breeding.