The Annual Cycle in a Vocalisation Context: a Comparison of the Eastern Yellow RobinEopsaltria australisand Jacky WinterMicroeca leucophaea

Abstract

Vocalisation levels and patterns relative to the annual cycle and breeding stages were explored and quantified in two 'typical', double brooded Australian insectivorous passerines, the Eastern Yellow Robin Eopsaltria australis and Jacky Winter Microeca leucophaea. Highest song levels in both occurred in August during the pre-breeding courtship period. They dropped to 10-12%, respectively, towards hatching; rose to 66 and 47% of original levels prior to the second ovulation, then dropped to 21 and 9% of these with the second brood. Levels rose again (markedly in the robin, to minor degree in the Jacky Winter) post-breeding before going into a steady decline with the approach of the moult. A pre-eminent role of song in courtship is thus confirmed for these Australian species. The persistence of some song throughout the year (in the robin) also suggests that song has a continuing role in temtory maintenance in resident Australian species. A basic diel temporal singing pattern (peak song before, or around, sunrise; low levels through the day) characterised all seasons. The pattern was markedly suppressed at times of low seasonal song activity.