- Rabbits are not native to Australia and affect primary production and native ecosystems.
- Their impact on primary industries includes:
- Lost production (crops, pastures, and revegetation, horticultural or forestry seedlings),
- Control costs, and
- Soil erosion, and associated impacts on infrastructure and waters.
- Their impact on native ecosystems includes:
- Competition for food and shelter,
- Selective grazing of preferred plant species, resulting in low or nil recruitment and subsequent ecological change,
- Maintaining fox and feral cat populations, resulting in increased predation of native animals and contributing to the extinction of some species,
- Soil erosion, and associated impacts on vegetation, wetlands and watercourses, and
- Off-target harm from rabbit control measures such as baiting and fumigation.
European wild rabbits are invasive, feral pests throughout much of Australia. They cause considerable damage to the natural environment and to primary production.
Rabbits were introduced to Australia in the 1800s by European settlers. Free from diseases and facing relatively few predators in a modified environment, the wild populations grew rapidly. They soon became a problem for colonists trying to establish vegetable gardens and, after the 1860s, quickly spread across two thirds of Australia with devastating impact.
History of rabbits in Australia
Domesticated European rabbits arrived in Australia with the First Fleet. They were introduced for food and wild rabbits were later brought in for hunting. A colony of feral rabbits was reported in Tasmania in 1827 and wild European rabbits were released in Victoria in 1859, and in South Australia shortly after. By 1886 they were found throughout that Victoria and New South Wales – even extending to the Northern Territory by the 1900s. By 1910 feral rabbits were found throughout most of their current range.
By 1920 it is thought there were 10 billion rabbits in Australia. The population is currently estimated to be 200 million.
European rabbits are native to southwest Europe and northwest Africa – and have been introduced to every continent on earth except for Antarctica and sub-Saharan Africa. They often cause environmental harm in their new homelands, and their impact has been very pronounced in Australia where seasons permit year-round breeding and there are fewer natural predators.
Prolific breeders, the feral rabbits relatively quickly became established over much of Australia, with the exception of more northerly regions. Their populations rise and ebb with the seasons and, unless controlled, they can reach plague proportions in favourable times. For more information, see ‘Rabbit impacts on agriculture’.
Feral rabbits eat crops and compete with livestock for pasture. As recently as 2004, after more than a century of control programs, rabbits cost Australian primary producers $113 million per year in lost production and control costs. They are also a significant contributor to widespread soil erosion (impacting infrastructure and waters), and the destruction of perennial pasture plants, particularly when their populations are high.
Although rabbits persist in most of their range, control programs have been of tremendous benefit to many agricultural areas. The current impact from feral rabbits on primary production is probably felt most in drier pastoral areas, in revegetation or carbon plantings, and in some forestry and horticultural areas – affecting vegetables, nurseries and tree seedlings.
Environmental damage is now the biggest problem caused by feral rabbits in Australia. Feral rabbits compete for feed and shelter with native animals, but most environmental harm comes from how they graze, and because they help maintain feral predators. Rabbits have clearly contributed to the decline or loss of the greater bilby, yellow-footed rock-wallaby, southern and northern hairy-nosed wombats, the malleefowl and the plains-wanderer.
Rabbits have a small mouth and rodent-like teeth for close grazing, and are selective feeders – they search out tiny seedlings of the most palatable species and remove them before they can grow and reproduce. Rabbits don’t fell ancient, giant trees – but they do seek out and eat every seedling of preferred species within their grazing range before they can grow. Once mature trees die, the species is lost as there are no younger plants to replace them. The immediate impact of rabbits may go un-noticed, but the lack of plant recruitment can change the whole structure of vegetation communities, with flow-on effects for the native birds, reptiles, invertebrates and other animals that live within.
The ability of rabbits to target individual seedlings also makes them a threat to programs regenerating native vegetation or establishing carbon plantings.
If rabbits are present in numbers sufficient to be noticed they are probably already having an impact on native vegetation and the ecology of native fauna. Numerous studies have shown that feral rabbits at very low population densities can prevent the regeneration of favoured plant species; less than one rabbit per hectare in dry regions and around three rabbits per hectare in wetter, more productive, regions. For more information, see ‘Rabbit impacts on native vegetation’.
Compounding the problems is the fact that seeds of some plant species, particularly in dry regions, only germinate after exceptional weather (such as summer storms or localised flooding in very wet years), which may only occur once every couple of decades. If feral rabbits are around at those rare times, then the plants have lost their one in twenty year opportunity to bolster their ranks.
Feral rabbits faced few of their traditional diseases when introduced to Australia, but they did come up against a few predators – some, like them, were recent introductions to the country (e.g. foxes and feral cats). Feral rabbits can be an important part of the diet of cats and foxes, sustaining their populations – which in turn, leads to increased predation on small-to-medium sized native fauna. By maintaining fox and feral cat numbers, rabbits have indirectly contributed to the loss of native species – and Australia has lost more native mammal species than any other country. For more information, see ‘Rabbit impacts on wildlife’.
The startling transformations of islands where rabbits have been removed (such as Phillip Island and Macquarie Island), and the condition of islands which have remained rabbit-free (e.g. Kangaroo Island), are testament to the profound environmental harm caused by rabbits.
Their environmental impact is so great that competition and land degradation by rabbits are listed as a key threatening process under the Environment Protection & Biodiversity Conservation Act. A threat abatement plan for rabbits gives high priority to, amongst other measures, research into bio-controls, raising awareness and rabbit control.