Breeding ecology and social behaviour of an antiphonal duetter, the eastern whipbird (Psophodes olivaceus)

Abstract

This 3-year study provides the first detailed information on the ecology and breeding behaviour of a colour-banded population of the duetting eastern whipbird (Psophodes olivaceus). Molecular sexing of banded individuals unambiguously demonstrated that the eastern whipbird duet is male-led. Stable, socially monogamous pair bonds were formed, with a low rate of divorce. Pairs jointly defended a territory year-round, with those inhabiting open tussock grass areas defending significantly larger territories than pairs with a predominantly bracken and Macrozamia spiralis understorey. Territory turnover was low, adult survival was high, and habitat was apparently saturated, suggesting that competition for territories at this site was high. The ratio of unpaired females to unpaired males was 7 : 1, indicating that female competition might be particularly intense. Eastern whipbirds displayed characteristic breeding features of old endemic Australian passerines, with a small clutch size (two eggs), multiple broods in a long breeding-season (5–6 months), a delayed renesting period and an extended period of post-fledging care (~6 weeks). Only the female incubated and brooded young, but both males and females fed offspring. Males provisioned nestlings at a rate almost 1.5 times greater than females and played an equal role in post-fledging care, with each parent caring exclusively for one fledgling. We discuss the value of such ecological information for understanding the function of duets.