Conservation Values and Management of Australian Islands for Non-Volant Mammal Conservation.

At least 16 species of Australian mammals have become extinct over the past 200 years. Without islands, however, this figure would be even worse as nine species that were formerly widespread on mainland Australia were or are restricted to land-bridge islands. In addition, 13 species and subspecies of endangered and vulnerable mainland mammals that still occur on the mainland have island populations, reducing their chance of extinction. In all, 43 islands protect 29 taxa of Australian threatened mammals. Since European settlement some island mammal populations have become extinct, while many new populations, of both Australian and exotic mammals, have been established. The extinction of island native mammal populations is significantly correlated with the introduction of exotic mammals. Management of islands needs to concentrate on four areas: quarantine, monitoring (of both native mammals and possible introduction of exotics), eradication of exotics and translocations of native species. Prevention of introduction and establishment of further exotics to important islands through quarantine procedures is vital, especially for islands with permanent or temporary human habitation. Eradication or control of existing exotics is required for many islands and eradication of further introductions, as soon after detection as possible, should be a high priority action for nature conservation agencies. Past exotic mammal eradications and needs for the future are discussed. Translocations of island mammal populations to the mainland should take place only where the species is extinct on the mainland. Translocation to islands, where translocation to or on the mainland is not feasible, is an important conservation technique. Islands with exotics can be of value for re-introduction of locally extinct mammals or introductions (marooning) of threatened species that are at risk from feral predators on the mainland once the exotics have been eliminated.