Few havens for threatened Australian animal taxa that are highly susceptible to introduced and problematic native species

Many Australian animal species are threatened by introduced species, and some by problematic native species. Conservation programs resulting in a network of havens (islands and fenced mainland areas free of introduced predators) have successfully reduced extinction risks for many threatened mammal taxa susceptible to introduced predators. However, less strategic assessment and conservation investment has occurred for other groups of Australian threatened animal species susceptible to introduced and problematic native species. Here, we report that 122 threatened Australian animal taxa, additional to the previously recognised 63 predator-susceptible threatened mammals, are extremely or highly susceptible to introduced species or problematic native species. Most of these threatening interactions involve predation, but there are also cases of competition, disease, habitat degradation, hybridisation, parasitism and poisoning. The introduced species affecting the largest number of these threatened taxa are two trout species Oncorhynchus mykiss and Salmo trutta (affecting 25 threatened taxa), chytrid fungus (23 taxa, all frogs), black rat Rattus rattus (23 taxa), cat (13 taxa additional to the 61 previously recognised threatened mammal taxa) and red fox (eight taxa, additional to the 43 previously recognised threatened mammal taxa). Havens provide a potential foundation for the conservation of these susceptible species. However, 55 of these 122 threatened taxa lack havens that exclude the relevant introduced or problematic native species. Thirty-one of the 122 threatened taxa are present in some island havens; however, the total area of these is only 3,910 km². Currently, only five of the threatened taxa on the Australian mainland occur in havens that fence out the introduced or problematic native species that threaten them, mostly in very small exclosures. Other susceptible taxa, notably several freshwater fish, persist only in small, precarious natural havens.