PhD research with DEEP

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Drivers of bird community structure on temperate land-bridge islands: a case study on a shifting strait​

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Supervisors: Prof Barry Brook, Dr Jessie Buettel, Dr Matthew McDowell

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Land-bridge islands are often overlooked in conservation research. However, these unique environments are home to some of Australia’s most endangered avian fauna. The Bass Strait Islands were once part of a land bridge that connected Tasmania to the Australian Mainland before sea level rise flooded the basin. Isolation had several effects on the local avian fauna, most notably, the diversification of several populations that are now identified as separate subspecies. Sea level rise also triggered significant shifts in the distributional range of birds in the area, possibly leading to anomalies in the current distribution of several species. Bird communities on the islands were further impacted following European occupation and subsequent large-scale habitat modification.

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For some generalist species, like the Forest Raven (Corvus tasmanicus), land-use change on King Island seems to have been beneficial due to increased food availability from roadkill and hunting of macropodids. This has potentially led to the modification of raven behaviour to forage on roadsides more frequently, as they provide a reliable source of carrion. Increases in raven abundance have reportedly led to the competitive exclusion of the vulnerable King Island Black Currawong (Strepera fuliginosa colei). In contrast, habitat modification has resulted in the global extinction of some birds, such as the King Island (Dromaius novaehollandiae minor) and the Tasmanian (D. n. diemenensis) subspecies of Emu. As emus are important seed dispersal agents, this function may now be absent from these regions, a particularly pressing concern given projected climate change.

My PhD project will study the woodland birds of the Bass Strait Islands, focusing on distributional anomalies, current threats to species and past avian extinctions, which will allow us to predict future shifts in bird communities of the region. The principal aim of this project is to understand how drivers, such as isolation, climate change and habitat modification, have shaped woodland bird communities on land-bridge islands and resulted in the extinction and endangered status of several endemic subspecies. To do this, I require a contemporary snapshot of the bird communities of the islands which will be achieved through the collection of field data in the Bass Strait region.

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