12.D.3 Measuring threats of invasive animals to biodiversity in New South Wales

Collaboration between the IA CRC and NSW Department of Environment and Climate Change (DECC) has produced a report measuring environmental impacts of invasive animals. The Threat Posed by Pest Animals to Biodiversity in New South Wales (see ‘Documents’) attempts to quantify, for the first time in Australia, the impact of invasive animals on biodiversity and shows that they are a major cause of biodiversity decline in New South Wales. It illustrates the problem’s scale in terms of the number and range of native species at risk.

The report assessed threats to 972 species, populations and ecological communities listed under New South Wales legislation for threatened species. About half of these threatened species are also listed under the Commonwealth’sEnvironment Protection and Biodiversity Conservation Act 1999. The threatened species list spans a broad range of mammals, birds, fish, insects, plants, fungi and algae.

The report shows that alien pest animals pose a threat to 40% of the biodiversity examined. The threat posed to biodiversity by invasive animals (as a single factor) was ranked fourth: land clearing, altered fire regimes and weeds are the top three threats. Pest animals also ranked highly when compared with broader processes threatening biodiversity, such as the destruction and modification of native vegetation.

Feral cats, foxes and wild dogs are the alien predators that pose the highest risk to threatened biodiversity in New South Wales. Feral goats, rabbits and pigs were found to be the most threatening alien herbivores. The worst of the alien freshwater fishes were gambusia, redfin perch and European carp.

Impacts of pest animals were also spatially analysed using three broad geographic zones in New South Wales: coastal, central and western. The report shows the impact of alien pest animals on biodiversity increases from east to west (ie from coastal to arid western New South Wales).

This report provides a long-overdue baseline on invasive animals that can be used to make informed management and policy decisions into the future. It should also help stimulate discussion on the description of threats, which is currently not standardised. The novel approach used to assess impacts on threatened species could be used in other jurisdictions, to give a national picture of biodiversity threats posed by invasive animals.

Addressing the impacts of species such as the feral cat, fox, feral pig and European carp are high on the list of priorities for the IA CRC. This report gives further weight to the urgent need to reduce the threats posed by alien pest species.