Breeding biology of a migratory Australian passerine, the golden whistler (Pachycephala pectoralis)

Abstract

The breeding biology of Australian passerines is characterised by long breeding seasons and the potential to produce multiple broods within a single season. However, many species undergo a yearly migration from their breeding sites to climatically milder wintering grounds. This migratory behaviour may impose constraints on the breeding biology of these species. We studied a migratory population of golden whistlers (Pachycephala pectoralis) at Toolangi State Forest, Victoria. Individuals typically arrived in early September, attempted to produce a single successful brood over a 3-month period and departed again in late April. Both site- and pair-fidelity were high, with an average of 66% of males returning to the same site, re-pairing with the same female in up to 100% of cases. Nest predation was common, with 45% of nesting attempts failing due to predation. Each pair initiated an average of 1.7 nests per season, resulting in an average of 1.2 fledglings per pair each season. The short breeding season and single-broodedness of the golden whistlers at Toolangi is atypical amongst Australian passerines and suggests that constraints may be imposed on species undergoing annual migration. In this regard, golden whistlers show more similarities to Northern Hemisphere migratory passerines than to the sedentary passerines of the Southern Hemisphere.