European Rabbits as Invasive Species in Australia and New Zealand

Invasive species are any non-native species introduced into an environment. The introduced species are normally transported to different countries through human activities. This transportation has been both accidental and by design. Human travel across the globe has resulted in a negative impact in many countries throughout the world. ‘Australia is home to many plants and animals that have been introduced since European settlement. Some of these have become invasive — they have spread and multiplied to the point where they damage the environment, threaten the continued existence of native plants and animals, or create significant problems for agriculture’. One of the most invasive animals introduced to Australia and New Zealand is the European rabbit.

European rabbits:

European rabbits are small mammals that typically have grey-brown black fur and a white underbelly, they have a lifespan of up to 6 years in the wild. They are native to the Iberian Peninsula, France, Gibraltar, and north-western Africa. Rabbits are herbivores and their diet mainly consists of plants (including crops), roots, pastures, young trees, and vines. Often when they are not feeding, they spend time digging networks of burrows (warrens). The burrows play a major part in the rabbit’s reproduction cycle, as they are used for shelter when the rabbits' young are born to protect them from predators.

Environmental impact on Australia:

European rabbits were first introduced into Australia in 1859 when they arrived on the first fleet. They were originally transported to Australia to be a companion animals for early settlers, but in later years they were deliberately sent to Victoria to provide game for wealthy settlers to shoot. The rabbit’s population grew rapidly, due to the fact that they had no natural predators because they had been introduced to a new environment and food chain. Although the rabbits were first introduced as companions, they soon became a pest throughout Australia. Their diet consists of native plants and introduced vegetation such as grasses, leaves, bub, tree bark, and roots. Because of their diet rabbits damage native plants, preventing seedlings from restoring and reducing crop yields which all results in native species and livestock having to compete for their own source of food. The burrows that the rabbits dig also negatively impact the environment because the digging can often lead to a loss of vegetation cover, which eventually results to soil erosion and slope instability.

Strategies used by Australia Government

European rabbit control:

‘Current techniques available for controlling rabbits can be categorized broadly as biological, chemical, and mechanical. Biological control for rabbits has been particularly effective.’.

The earliest form of biological control was the myxoma virus first released in the early 1950s. This virus was spread by fleas and mosquitos and achieved a 90 percent morbidity in the feral rabbit population. The surviving population did develop a resistance to the virus. Continued modifications to the virus by the CSIRO helped overcome this resistance ensuring that the virus remains successful. This resulted in present times keeping the rabbit population to an average of 5 percent of previous population sizes in damper areas, and 25 percent in dry areas. Another effective biological control [image: ]used is rabbit calicivirus disease (rabbit hemorrhagic disease virus) which was released in 1996, it’s used for rabbit population control in wetter parts of the country then drier as it is more effective in damper conditions. The most commonly used chemical technique for controlling the rabbit population is fumigation. Fumigation is often applied after other mechanical techniques are used. It is only used if the landscape is too steep or rocky for warrens to be mechanically destroyed. Some Mechanical methods used in Australia include warren destruction (by ripping or explosives), poisoning/baiting, vermin-proof fencing, and shooting or trapping. The most widely used mechanical method however is warren destruction and ripping. This is cost-effective in decreasing the rabbit population and prevents reinfestation by destroying habitat. Results before and after methods used for rabbit control by the Australian government. Show an increase of land vegetation.

European rabbits in New Zealand

Environmental impact on New Zealand:

European rabbits were introduced into New Zealand in 1830 some 20 years earlier than in Australia. They were introduced for similar reasons to their introduction in Australia, namely as a food source and for sport. Similar problems arose due to the rabbit’s rapid rate of breeding, causing negative environmental impacts similar to Australia’s. Some of the like impacts New Zealand faced were damage to native plant communities, livestock competing for food, and degradation of agricultural land. These impacts were mainly caused from the rabbits overgrazing or digging networks of warrens. The rabbits digging and overgrazing can cause extensive damage on erosion-prone soils, so much so that agricultural land can be rendered useless. Native species of fern grown in New Zealand, are commonly eaten by European rabbits.

Strategies used by the New Zealand Government

The same three categories as Australia (biological, chemical, and mechanical) have been applied in new Zealand’s methods for rabbit control. Mechanical forms of control were mainly used when European rabbits first became a problem in New Zealand. Some of these methods include destroying warrens (ripping or explosives), hunting rabbits with dogs, guns and traps, and rabbit-proof fencing. Biological and chemical forms of control were later introduced in the early 1950s after New Zealand followed Australia’s government's methods for rabbit control. Fumigation was introduced and rabbit viruses that were designed to be spread by flies, fleas, and other rabbits. One of the most effective diseases spread is the RHDV disease. ‘RHDV – also known as rabbit calicivirus – is a virus used as a pest control tool to reduce the number of wild rabbits. It affects the European rabbit (Oryctolagus cuniculus). Rabbits are infected with the virus which then spreads through the population. Once a rabbit shows symptoms, it dies quickly’.

Evaluation of strategies used by Australia and New Zealand

The strategies biological, chemical, and mechanical are each in their own way very effective for decreasing the European rabbit species and keeping their numbers within control. New Zealand and Australia used mechanical methods when the rabbit population first became a problem. These methods were very effective at the time and still are used in the present time, as they have decreased the rabbit population significantly, more than other biological or chemical methods used. However biological, and chemical methods still contribute to keeping the rabbit’s population within control, as they can be combined with mechanical methods and overall have more effective when used collectively. Overall these methods have proved effective to help keep the European rabbit population within control, as their numbers have continuedly decreased over the years since they were first introduced.

My solution for Australia’s invasive species the European rabbit

My solutions would be very similar to the methods already put in place by the Australian government. The methods used in Australia (biological, chemical, mechanical) have all proved to be effective in keeping the rabbit number under control. My solution would be to continue using the methods of the Australian government, to collectively use all three categories. As spreading diseases through the rabbits, destroying their habitat, or flushing them out using chemicals are already successful methods used, I would continue to use them as they would still steadily decrease the European rabbit population.

Bibliography:

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