Document ID: chunk:federal_register_of_legislation:F2009L02536:reg:2:p2
Version: federal_register_of_legislation:F2009L02536
Segment Type: reg
Provision Reference: reg 2 (pt 2/3)
Character Range: 7665–10615

of the islands are entirely or substantially managed under various reserved tenures, about 34% are privately owned or leased, and about 9% are owned by indigenous people. Many islands that are important for biodiversity have permanent residents. Thus governments, private citizens and indigenous groups have generic and island-specific interests in this plan. Islands themselves are often iconic sites and many harbour iconic species, so wider stakeholders include groups with a conservation focus, to private companies promoting ecotourism, as well as the wider Australian public – and for some islands the international community.

2.3                   Impacts on biodiversity
The contribution of islands to Australia's biodiversity assets is out of proportion to their area. This is due to continental islands often representing less-disturbed examples of mainland ecosystems and offering refuges for species threatened on the mainland. In addition, oceanic islands have high degrees of endemism and are thus unique evolutionary units in their own right. Both types of islands are key places for breeding marine birds, turtles and seals.

Seven lines of evidence prove that exotic rodents have and continue to adversely affect native biodiversity on Australian islands, prevent some restoration options and are a potential threat to island ecosystems currently free of exotic rodents. Exotic rodents:
    * eat native species and compete for food
    * carry diseases that may affect native animals
    * drive some species endemic to the island to extinction
    * extirpate some species from particular islands
    * continue to threaten native species on many islands
    * change ecosystems by more complex indirect effects by causing changes in species that 'engineer' the ecosystem – such as seabirds
    * act as the primary prey for other exotic predators such as feral cats or foxes, which then threaten native species.

Of the two common rodents on Australian islands, ship rats are the most obvious threat judging by their known impacts to biodiversity on both Australian and other islands. For example, five birds endemic to Lord Howe Island had survived decades with mice but became extinct after the rats arrived in 1918. The effect of mice has been more subtle as they have not had such catastrophic effects on avian species. However, recent evidence from Gough Island (a British island in the Atlantic Ocean) shows that under some circumstances mice can kill large naïve prey such as albatross chicks. Mice are efficient predators of invertebrates (particularly spiders) but their impacts on these prey species at population levels remains unknown.

Exotic rodents are also social and economic pest on islands inhabited by people. For example, the palm seed horticultural industry on Lord Howe Island would benefit by over $5 million over 30 years if ship rats could be eradicated.

2.4                   Managing the threat
The