Evidence of disarray amongst granivorous bird assemblages in the savannas of northern Australia, a region of sparse human settlement

Abstract

Quantitative evidence of change over the last 150 years amongst granivorous bird assemblages in the tropical and sub-tropical savannas of northern Australia are provided. Twelve of 49 indigenous and mostly resident species have declined, and three have increased. One species is probably extinct, and two taxa are critically endangered. Four introduced species have become established. The northern Australian savannas are for the most part very sparsely settled and subject only to low intensity pastoralism, and the disarray amongst granivorous bird assemblages is perplexing. Even in areas subject to extensive vegetation clearance, decline is shown to coincide with the pastoral era prior to clearing. Grazing and/or changed fire regimes may be responsible. Determining the cause of change and the implementation of management responses is a key issue for the future management of these savannas.