Trophic rewilding of native extirpated predators on Bass Strait Islands could benefit woodland birds

Abstract

Woodland birds are increasingly threatened by the impacts of environmental change. As the global population and economy grow, we continue to modify habitat for human use, reducing available nesting and foraging opportunities for birds. In addition, post-European occupation has led to the introduction of alien species, like cats (Felis catus), and the expansion of generalist species, like corvids, resulting in increased predation and competition for vulnerable bird species. To successfully preserve habitats, manage invasive species and conserve both endangered and common-but-declining bird species we need pre-emptive and innovative management strategies that can be implemented now.

These issues are particularly relevant to the avifauna on two of Australia’s large offshore islands, King Island and Flinders Island, in the Bass Strait. Birds on the islands include the critically endangered King Island Brown Thornbill (Acanthiza pusilla archibaldi) and King Island Scrubtit (Acanthornis magna greeniana) and the endangered Forty-spotted Pardalote (Pardalotus quadragintus) (Webb et al. Citation2016). They are currently threatened by reduced habitat availability, widespread invasive predator populations and altered corvid behaviour. Trophic rewilding, involving the reintroduction of extirpated native predators, could provide a novel alternative to traditional conservation interventions, via the suppression of invasive species and overabundant herbivores, thus re-engineering the ecosystem (Sweeney et al. Citation2019). The original native predators on the islands, including Spotted-tailed Quolls (Dasyurus maculatus), Eastern Quolls (D. viverrinus), and Wedge-tailed Eagles (Aquila audax), likely went extinct due to over-hunting by Europeans shortly after their arrival and the Tasmanian Devil (Sarcophilus harrisii) has been documented in recent fossil evidence on Flinders Island (Peacock et al. Citation2018). These islands provide ideal case studies to demonstrate how trophic rewilding might be a useful tool for the conservation and rehabilitation of threatened avian species, providing lessons not only for other islands but also mainland settings.