Island arks: the need for an Australian national island biosecurity initiative

Abstract

Threats to island biotas from non-indigenous species have been extensively documented and remain among the most powerful drivers of biotic extinction. Despite this, Australia does not have a national, comprehensive plan of action for island biosecurity. Recent initiatives by Australian governments could provide the basis for the first systematic and comprehensive approach to securing the future of Australia’s continental and oceanic islands. A National Island Biosecurity Initiative would lay the foundations for effective island biosecurity. It would protect globally significant populations of migratory species and play a major role in preventing the extinction of hundreds of threatened species and ecosystems. Australian islands need a more comprehensive and strategic biosecurity regime. This is evidenced by ongoing expensive efforts to control non-indigenous species on islands in Australia and the progressive loss of native species on those islands. Most islands have not suffered the same range of disturbances as has mainland Australia. However, for some islands, the arrival of nonindigenous species because of the lack of quarantine has led to extinctions (e.g. Burbidge & Manly 2002), the most recent example of which is the loss of the Christmas Island Pipistrelle (Pipistrellus murrayi) in 2009. However, these islands are a minority; many Australian islands are largely in a natural condition, and effective biosecurity will be critical if they are to remain so. Biosecurity is defined by the ‘Beale report’ (Commonwealth of Australia 2008) as ‘the protection of the economy, environment and human health from the negative impacts associated with entry, establishment or spread of exotic pests (including weeds) and diseases’. We propose that implementation of this report’s recommendations should include a new and comprehensive strategic framework specifically for island biosecurity. This would be based on an assessment of island biodiversity values and a risk assessment approach. Furthermore, the use of systematic conservation planning (e.g. Pressey & Bottrill 2009) would provide a more rigorous and transparent basis for allocating resources efficiently to different strategies. The importance of maintaining the natural condition of Australian islands is underlined by their unique biodiversity values. Oceanic islands are home to many endemic species. Both oceanic and continental islands provide the sole or major breeding and roosting habitats for many species of seabirds, marine mammals and reptiles. Continental islands are also refugia for species that have disappeared or declined on the mainland. Most of Australia’s breeding seabirds nest only on islands. Of those nesting on both islands and mainland beaches, island populations fare best (e.g. Fairy Tern (Sterna nereis), BirdLife International 2010). The situation is similar for sea turtles: mainland rookeries are subjected to human disturbance and nest predation by pigs, dogs and foxes. ‘Marooning’, or translocating mainland species at high risk to