Rabbits do not belong in Australia. They are an invasive pest that damages the Australian environment and costs our primary production millions of dollars each year. They were deliberately introduced to Australia by the early English settlers for hunting, as at home. An initial introduction of 24 wild European rabbits in 1859 produced an astounding 10 billion rabbits by the 1920’s.
Australia has lost more native mammals than any other nation, 22 species in all (as at 2007), and although the extinctions defy simplistic explanations, rabbits, foxes and feral cats are the most culpable for these losses. Rabbits compete with similar-sized native animals for shelter and food. They also have an indirect effect by supporting populations of feral cats and foxes, predators of our native animals. Land clearing and development has also contributed to the decline in the number of native species. In 2007, 17 bird species, 13 mammal species, 4 reptile species, 1 fish species and 1 insect species that are considered to be vulnerable, endangered or critically endangered native species were threatened by rabbits.
Rabbits are also responsible for losses in Australia’s plant biodiversity by removing seedlings and preventing regeneration of native trees and shrubs. As few as 2-3 rabbits per hectare can prevent the regeneration of native trees and shrubs. This deleterious effect of rabbits is particularly important in the arid areas, where good regenerating rains are scarce. Some trees, like mulga, already have very few young trees in the population, and when the old trees die there will be nothing to replace them. In 2007, 121 vulnerable, endangered or critically endangered native plant species were considered to be threatened by rabbits.
Rabbits are an important problem for primary production. Even with the successes of myxomatosis and rabbit haemorrhagic disease in reducing the numbers of rabbits, rabbits still costed primary production at least $113m a year in production losses and control costs in 2004. The level of losses is expected to increase markedly with the emergence of resistance to RHD in rabbits, unless a new biological control agent is found and other rabbit control methods are applied by land managers.
A booklet on assessing rabbit problems to protect biodiversity has been published by the Bureau of Rural Sciences. Titled Rabbits: a threat to conservation and natural resource management, it is designed to be used as a tool to help land managers rapidly assess a rabbit problem and take action. It can be downloaded from the link at left and hard copies are available upon request.