Social organisation and breeding biology of the Western Grasswren (Amytornis textilis textilis)

ABSTRACT Grasswrens (Amytornis) lack behavioural ecological studies despite many species having a declining population and threatened status. The Western Grasswren (Amytornis textilis) is a semi-arid passerine endemic to Western Australia (WA) and South Australia. This study aims to provide further knowledge about the social organisation and breeding biology of the WA subspecies (A. t. textilis) based on a colour-banded population over three years of monitoring. Western Grasswrens maintained territories in pairs, with occasional cooperative breeding facilitated by adult offspring of either sex who delayed dispersal. There was no evidence of divorce between breeding pairs. However, resighting of banded grasswrens was infrequent which may have biased this conclusion. Nest predation and abandonment events were lower than previously documented for this species. Offspring productivity was high, with >70% of the monitored groups producing at least one fledgling per year. Grasswrens used a range of substrates for nesting, but all had common structural features that likely aided in the concealment or thermoregulation of the nest. Social organisation and breeding biology were similar to what had been observed in two other grasswren species. This study has increased our understanding of a poorly understood cryptic species, and understudied genus, that can later be incorporated into future management strategies, population viability models and comparative analysis.