European rabbits (Oryctolagus cuniculus) originated in Spain, but they are now found throughout most temperate regions of Europe, North Africa, Chile, and Australasia.
Most Australian rabbits are descended from 24 wild rabbits released near Geelong in 1859. By the 1920s, rabbits had colonised most of the southern half of Australia and were present in extremely high numbers over most of that area. Rabbits were established on at least one island off the coast of Western Australia (WA) in 1827 and may have been present earlier on other islands. It was common practice for early mariners to leave live rabbits on small islands as a food supply in case of shipwreck or future visits.
Until the successful release of the myxoma virus, and the introduction of 1080 (sodium fluoroacetate) poisoning programs in the 1950s, rabbit numbers remained essentially unchecked. During this period, they had a profound effect on Australia’s environment and economy. In 1996, rabbits were estimated to cost the nation at least $600 million annually in lost agricultural production. Since the release of the rabbit haemorrhagic disease virus (RHDV), the estimated agricultural production loss is about $206 million each year, with an additional $25 million spent annually on management and research costs. The accumulative benefit to Australia's pastoral industries of 60 years of myxoma and RHDV biocontrol is estimated at $70 billion.
Rabbits have a well-documented history for causing severe environmental damage. In WA, they are declared pests of agriculture in both their domestic and feral forms under the Biosecurity and Agriculture Management (BAM) Act 2007. Landholders are required to control rabbits on their properties.
Biosecurity and Agriculture Management ActMore information
Identification
The typical European rabbit is grey-brown with a pale belly. Black or ginger forms are not uncommon, but they represent a small proportion of the population; white rabbits are rarely seen in the wild. In WA, adult wild rabbits weigh from around 1200 g to 2250 g.
Behaviour
Rabbits are largely nocturnal animals, emerging from shelter in the late afternoon and retreating early in the morning. They avoid high temperatures and predators by living in burrows, or in the shelter of dense scrub or fallen timber.
During the winter breeding season, rabbits live in small social groups that tend to break down in summer, when breeding ceases. A large warren may contain several groups. Each social group has its own territory, which it actively defends against intruders. Members mark their territory on logs, grass, or other objects with faeces, urine, and secretions from a gland beneath their chins. Dominant males (bucks) also use dung piles to mark their territories. There is a strict social hierarchy in each group. High-ranking females (does) breed more successfully than lower ranking animals. Dominant male rabbits father more offspring than subordinate animals.
Reproduction
The main breeding season of rabbits in south-west WA extends from about May to November, depending on availability of suitable green feed. The breeding season is usually shorter in other areas of the state. The percentage of pregnant adult females rises steadily through the breeding season to nearly 100% in July and August. Later, the pregnancy rate and average litter size falls. While breeding virtually ceases when pastures dry off, in the south-west, a small proportion of females can be pregnant in most months. Where favourable conditions for breeding persist, a single doe may produce up to 30 kittens in 6 or 7 litters a year.
Female rabbits usually conceive their first litters shortly after the first autumn rain, ensuring the maximum number of litters are born while green feed is available. Gestation lasts about 30 days.
In many rabbit populations, the high reproductive rate can be offset by a 60 to 70% death rate among kittens up to a month old. The mortality of kittens born late in the year may rise to nearly 100%, due mainly to lack of suitable feed. Climatic factors, predators, and diseases are the main causes of natural mortality. As kittens become older, their survival rate improves and their chance of survival is good, once they reach adult weight. Adult rabbits have an average life expectancy of 2 to 5 years.
Rabbits evolved in the western Mediterranean region, which has a cool wet winter and hot dry summer. This is like the climate of the south-west of WA. Rabbits can produce a relatively large number of offspring, which allows them to take advantage of favourable conditions and quickly colonise or recolonise areas.
Rabbits are best suited to regions with a long winter, which allows a lengthy breeding season. The biggest populations occur where areas of uncleared scrub, or other suitable cover, are interspersed with improved pastures. These conditions combine the advantages of both high-quality refuge areas and food resources. Remnant vegetation in the south-west of WA offers considerable complexity and protection so rabbits from these areas have less reliance on warrens than in other parts of Australia. Warrens and/or short breeding burrows (stops) are required for successful reproduction.
Rabbits compete directly with livestock and many native animals for food. Eight rabbits are estimated to eat as much as one sheep. However, unlike sheep, which graze over the entire paddock, rabbit grazing tends to be concentrated near refuge areas. This can result in very severe localised degradation of pasture and bush reserves, and significant soil erosion.
Rabbits graze plants closer to the ground than livestock, often killing germinating clover seedlings, which prevents good clover establishment. Rabbits may overgraze perennial grasses during summer, even eliminating them from a paddock. The pasture is then more likely to be invaded by weeds and can become more prone to erosion.
Rabbits do considerable harm to the natural environment, and the detrimental impact of rabbits on the regeneration of native plants is well recognised. In many rangeland areas, as few as 4 rabbits per hectare (ha) can prevent the regeneration of native plants (for example, some Acacia species). During drought, rabbits can strip bark from shrubs and trees. This increased grazing pressure often results in the loss of vegetation cover, which leads to soil erosion and exacerbates predation on native fauna by introduced predators. Digging by rabbits to make warrens can also cause soil erosion and tree losses.
Landholders are legally required to control rabbits on their land, even landholders not growing crops or livestock, to protect their neighbours’ land from the impact of rabbits.
Check for rabbit activity
Before carrying out control activities for rabbits, ensure there is rabbit activity. Areas intended for seeding, planting, or conservation efforts, especially near rabbit harbourage, should be thoroughly checked. This is particularly important in areas where rabbits have previously been a problem. Rabbit activity is usually indicated by scratchings, dung heaps, and active burrows or warrens. More revealing checks can be made late in the day or at night, when rabbits are active and more observable, by spotlighting.
Control issues
- The key to success is persistence and choosing the best control method for the situation. One-off efforts produce only short-term results as rabbits may produce many offspring and populations can quickly recover after successful control programs.
- The best outcome is achieved by integrating appropriate control methods. Effective control is achieved in late summer when rabbit numbers are decreasing, and feed is limited.
- District-wide campaigns can reduce the problem of re-infestation by covering a large area.
- Sometimes it will not be possible to use poison.
- Biological controls (myxoma virus and RHD virus) are not silver bullets. Every rabbit population will consist of a mix of ‘susceptible’ and ‘immune’ individuals. Individuals immune to biological control must be controlled by alternate methods.
Chemical, mechanical, physical, and cultural rabbit control methods include:
- baiting
- warren fumigation and ripping
- harbourage destruction
- rabbit-proof fencing
- shooting and trapping.
The department can provide help and advice.
Baiting
Baiting is the most cost-effective way to reduce rabbit populations, particularly over large areas, but restrictions apply.
1080 baits
Several types of 1080 (sodium fluoroacetate) rabbit bait is available. Trained landholders can purchase bait products after they have obtained a Registered pesticide permit from the department (refer to the Registered pesticide permit page, linked on this page under Related content). 1080 is quickly broken down in the environment. In Western Australia, many native animals have developed a high degree of tolerance to 1080. Domestic stock and pets are very sensitive to 1080 baits and poisoned rabbits and are at risk from accidental poisoning. Humans are also sensitive to sodium fluoroacetate.
Pindone baits
Pindone is an anticoagulant with a similar effect to products used in some rat poisons. While pindone rabbit bait can be used in urban areas where 1080 cannot be used, pindone (and pindone poisoned rabbit carcasses) are toxic to all animals that receive repeated doses over 2 to 3 consecutive days. Unlike 1080, an antidote (Vitamin K) is available for pindone poisoning.
Pindone poses a risk to native animals including kangaroos, birds of prey, and bandicoots. Pindone must not be used in the presence of these animals. Access to pindone bait by non-target animals can be minimised by appropriate use of bait stations.
Warren fumigation
Rabbits use warrens as a refuge and for breeding. Fumigation is the best method to use when a few rabbits live in widely scattered warrens or inaccessible areas. Warrens are treated with aluminium phosphide tablets which liberate phosphine gas on exposure to atmospheric or soil moisture.
The Health (Pesticides) Regulations 2011 (Pesticide Regulations), (Reg 63), require that risk assessment, fumigation plan, and emergency management plan be completed and implement prior to using fumigants in WA. Refer to the WA Department of Health website (health.wa.gov.au) for public health requirements and approval for fumigation.
For more information, refer to Rabbit control: fumigation – Factsheet, linked on this page under Documents.
Warren ripping
Areas where warrens have been destroyed by cross ripping the soil are much less likely to be recolonised by rabbits. Cross-ripping is achieved when a tractor-mounted ripper is used to penetrate the soil to a depth of at least 60 cm.
Harbourage destruction
Areas that rabbits use for harbourage/refuge include rock piles, deadfall timber and stumps, old buildings, and abandoned farm machinery. Such material should be removed, buried, or surrounded with rabbit-proof fences. Permission is required from local government before remnant or roadside vegetation can be cleared.
For more information about warren ripping and harbour destruction, refer to the Rabbit control: warren and harbourage destruction – Factsheet, linked on this page under Documents.
Rabbit-proof fencing
Rabbit-proof fences can be effective in preventing animals moving into or re-infesting an area. Well-maintained fences can provide a permanent solution to rabbit problems. Fencing can also be used to contain rabbits in an area where they can be more efficiently poisoned.
Two viral biological control agents, myxomatosis and rabbit haemorrhagic disease virus (RHDV) or calicivirus, have been introduced to Australia to help reduce the impact of rabbits on agricultural production and the natural environment.
Myxomatosis
The myxoma virus was introduced to eastern Australia in 1950 and Western Australia in 1951. Despite some less virulent strains evolving, outbreaks (epizootics) of myxomatosis (the disease caused by the myxoma virus) remain important in helping to manage rabbit abundance.
The virus is transmitted on the mouthparts of biting insects, particularly mosquitoes and fleas. Mosquitoes were the only efficient spreaders of the myxoma virus in Australia until the European rabbit flea and the Spanish rabbit flea were introduced in 1969 and 1996. Outbreaks of myxomatosis during winter are mainly spread by European rabbit fleas and often tend to kill more rabbits due to the added stress imposed by lower temperatures at this time. Mosquito-borne outbreaks generally occur in summer.
Studies by the department have shown that myxomatosis alone will often not reduce rabbit numbers to an acceptable level. Death rates for this disease can vary from 30% to 90% but are typically around 50%. In some years, high mortality may occur, but the rabbit population can quickly recover the following year because most surviving rabbits are immune.
Following an outbreak of myxomatosis, infected rabbits that survive acquire lifelong immunity. As well, young born to immune mothers are protected from the disease during the first 6 weeks of their lives by maternal antibodies. Exposure to the virus during this period will convert the temporary immunity into life-long immunity.
Because of this, an outbreak of myxomatosis does not usually occur in 2 consecutive years because there are too few susceptible rabbits. By the third year, natural attrition, and the birth of new susceptible rabbits, reduces the proportion of immune individuals, and the population again becomes susceptible to the disease.
Rabbit Haemorrhagic Disease Virus
RHDV was first introduced to Australia in October 1996. This virus, which is specific to rabbits, was accepted in Australia as a biological control agent against rabbits after undergoing rigorous testing on livestock and native species. The virus was deliberately released into selected rabbit populations at about the same time it began to arrive in WA from other parts of the country.
The initial impact of RHDV was dramatic, causing a drop of up to 90% in some rabbit populations, but there were other areas where little or no apparent effect was seen. The greatest impact occurred in the drier parts of the country, with less than 300 mm annual rainfall.
RHDV is spread by direct contact between rabbits, some biting insect vectors, and contaminated clothing and equipment. It is also transmitted by some blowfly species. The virus can persist in the environment for several weeks under mild conditions, but its survival is shorter at higher temperatures.
For reasons not well understood, young rabbits up to about 8 weeks of age are less susceptible to RHDV than older rabbits. In addition, maternal antibodies temporarily protect rabbits born to immune mothers. If exposed to the RHDV virus during this time, the kittens are likely to survive and develop antibodies that give them life-long immunity to the disease.
The timing of RHDV outbreaks is therefore important in the long-term impact of RHDV on rabbit populations. If outbreaks occur, either by deliberate release or naturally, when there are many young rabbits present, sufficient rabbits are likely to survive, allowing the population to recover.
The interaction between myxomatosis and RHDV, and their combined impact on rabbit populations, requires further study. To date, RHDV does not appear to have lessened the occurrence or impact of myxomatosis on Australian rabbits. Outbreaks of both diseases continue to cycle through many rabbit populations, occasionally simultaneously at some sites.
It is not possible to control outbreaks or the impact of biological control agents such as the myxoma virus and RHDV. The susceptibility of rabbit populations to these diseases will depend on several factors, including the number of susceptible rabbits (for example, those without antibodies), and the availability of suitable vectors for transmitting each disease. These diseases should be viewed as an aid in controlling rabbit numbers and be supported with other control methods, such as poisoning, refuge removal, ripping, fencing, and shooting, to ensure greater long-term effect. The addition of follow-up control is vital to maximise the benefits from these diseases.
RHDV1 K5
In March 2017, there was a national release of a Korean strain of rabbit haemorrhagic disease virus, known as RHDV1 K5. This was the first time in 20 years that a new rabbit biocontrol agent had been released into Australia and was part of a 20-year national biocontrol plan for rabbits. As above, RHDV1 K5 should not be released into rabbit populations that have a high proportion of very young kittens (<6 to 8 weeks old). Exposing very young rabbits to RHD viruses will increase the resistance of rabbit populations to this form of biological control, reducing the efficacy of this tool over time.
RHDV1 K5 is available as a commercial product to authorised users. The supply and use of RHDV1 K5 in WA to authorised users is enabled under the Biosecurity and Agriculture Management Regulations Amendment 2017 (linked on this page under Related content). Under regulation 45 C, anyone who will be handling and mixing the liquid suspension virus must complete online training to become an authorised user of RHDV. RHDV1-K5 Authorisation Training is available from our Progi online training website (linked on this page under Related content).
Coordinated, landscape scale release of rabbit biological control viruses will maximise effectiveness and produce greater results than patchy, individual landholder releases.
The department recommends land managers contact their local biosecurity group before applying for the virus to coordinate a release or to determine if a release has already occurred within their area. Biosecurity group contact details are available in the online RHDV1 K5 training package.
It is legal to keep domestic breeds of rabbits in WA without permits or conditions, but the keeping of wild-type rabbits is prohibited. Pet rabbits should be kept in insect-proof hutches to reduce their chances of contracting RHDV and myxomatosis. Good animal hygiene will also help reduce the number of vectors available for transmitting myxomatosis.
Rabbits should be kept humanely, and commercial breeders are advised to abide by the Code of Practice for the Keeping of Rabbits in Western Australia, 2003, linked on this page under Documents.
Pet and commercial meat rabbits can be protected from RHDV by vaccination. The vaccine used is a killed vaccine and is unable to reproduce in the rabbit, so annual boosters are recommended. There are no suitable vaccines for use against myxomatosis in Australia. Vaccinating domestic rabbits against myxomatosis is prohibited as the current vaccines are based on live viruses, which could spread to wild rabbit populations, resulting in their immunisation against the disease. This would have serious implications for agricultural production and the environment.
Related content
- Registered pesticide permits
- Progi online training website (dpird.wa.gov.au)
- Recognised biosecurity groups
- Biosecurity and Agriculture Management Act 2007
- Biosecurity and Agriculture Management Regulations Amendment 2017 | WA Legislation (legislation.wa.gov.au)
- Health (Pesticides) Regulations 2011 (Reg 63) | WA Legislation (legislation.wa.gov.au)