Manage

In this section: Management

 Introduction to rabbit management

Pests are animals causing harm or significant disturbance in areas where they are not wanted. They often have the ability to flourish if left unmanaged in suitable environments. Physical, chemical and biological control options are available to variously cull, inhibit breeding or exclude pests from priority areas. It is rare that a single control measure will be completely successful. Even very effective biological controls require support from additional control measures.

Leading questions are:

Which techniques will suit best?

Implementation. Tailor control techniques and strategies to suit.

  • Which method, or combination of the available control methods, will best suit your situation?
  • Is the timing or sequencing of control options important for the best results and best fit with other property management operations?

What to monitor and how?

Follow-up: Monitor outcomes and respond.

  • What will you measure to know if your plan achieved the desired outcome?
  • How and when will you collect information to measure the effectiveness of your plan?

 

Implement selected control options

Rabbit control is best achieved from a well-timed combination of techniques to sequentially knockdown, knockout and mop-up pest populations. In some circumstances fencing rabbits out (rabbit-proof fencing or tree guards) may be an option. Williams & Moore (1995) provide an excellent discussion of the efficiency and effectiveness of different combinations of control options.

The humaneness of alternative rabbit controls has been assessed in accord with the Australian Animal Welfare Strategy. The results are available through pestSmart, along with a Code of Practice for the Humane Control of Rabbits. State based animal welfare and various heritage protection regulations may also be applicable.

In this section:

Knockdown – culling to reduce numbers

  • Biocides. Three sorts of biological control are active in Australian landscapes; the viral myxomatosis and RHDV (calicivirus), and European rabbit fleas (introduced to help spread myxomatosis). RHDV-K5 is the only biocide currently available for active distribution by land managers. Biocontrols are inextricably linked to their hosts – if there are few rabbits around the bio-control agents will be less abundant as well. Yet there is a constant battle (‘arms race’) between rabbits and bio-controls as each evolves to their advantage. The influence of bio-controls therefore fluctuates with seasons, but they are an absolutely crucial foundation to ongoing rabbit control in Australia. See ‘Optimise biological controls’ below for more information.
  • Baiting. The poisons 1080 and Pindone are registered for use against rabbits and the biocide RHDV-K5 is also available for release via ‘baiting’. State regulations and guidelines (e.g. precluding 1080 from use near dwellings or waterways) must be followed in the use of poisons for health and safety reasons and to reduce the risk of ‘off-target’ poisoning. Because rabbits are habitual feeders, it is recommended that a series of ‘free feeds’ are used before baiting, preferably along trails although bait-stations can be used. See ‘How to’ for more information.

Baitlayers are used to cover large areas.

‘How to’ information: Knockdown

Seeding RHDV

RHDV-K5: Rule of Thumb

RHDV bio-controls should not be released following major rainfall or if green grass is present, because protein rich green grass stimulates breeding and rabbits can develop life-long immunity to RHDV if infected when young. In much of Australia young rabbits can be expected to be present during July-December, hence the release of RHDV should only occur in drier months between January and June, if it is not present already.

Baiting; 1080 or Pindone

More information: Optimise Biological controls.

Myxomatosis

Myxomatosis (MYXV or myxomavirus). Myxomatosis is transmitted between rabbits on the mouth-parts of biting insects, such as mosquitoes. The virus was introduced to Australia in 1950. Death rates from myxomatosis vary between 30 – 90% but are often around 50%.

Animals that are infected but survive develop immunity, which is passed to their young for the first six weeks of their life. If exposed to the virus during this time the young rabbits will also develop life-long immunity. It is not unusual for a year with a heavy outbreak of myxomatosis to be followed by a year with little myxomatosis evident, due to the development of immunity. By the third year, natural attrition leaves the population susceptible to myxomatosis once again. For more information see European rabbit. Biological control.

Myxomatosis is no longer produced commercially in Australia and is not available for controlled release.

A dead rabbit showing signs of myxomatosis may be tested to confirm the presence of the disease by submitting a sample to CSIRO. For more information on tissue testing see here.

European rabbit flea

European rabbit flea (Spilopsyllus cuniculi). European rabbit fleas were introduced in 1969 as a vector for myxomatosis to supplement transmission by mosquitoes and to be more effective when and where mosquitoes did not persist. The fleas only breed on pregnant female rabbits. They do not infect domestic rabbits and are rarely found on any other animal species. Arid-adapted Spanish rabbit fleas (Xenopsylla cunicularis) were introduced to Australia in 1996.

European rabbit fleas spread myxomatosis during late winter and early spring (when rabbits are breeding) while mosquitoes tend to be active in summer. The shift in timing due to rabbit fleas coincided with cooler conditions and times when younger rabbits are more prevalent. Both those factors make rabbits more susceptible to myxomatosis.

More information: Cooke BD (2022) ‘Fifty-year review: European rabbit fleas, Spilopsyllus cuniculi (Dale, 1878) (Siphonaptera: Pulicidae), enhanced the efficacy of myxomatosis for controlling Australian rabbits.’ Wildlife Research

RHDV

Rabbit Haemorrhagic Disease Virus (RHDV or calicivirus). RHDV was released in Australia in 1996 with immediate dramatic effect, causing up to 90% mortality in many instances. It is spread by direct contact between rabbits and by some biting insects and flies. It appears that rabbits surviving infection by myxomatosis are more vulnerable to RHDV. For more information see Myxo helps calici virus and Synergistic disease dynamics.

There are now several different strains of RHDV in Australia. A Czech strain of RHDV was released in 1995. A benign endemic form of calicivirus (RCV-A1) also occurs. RHDV2 emerged around 2014 and is now the dominant strain in Australia. RHDV-K5 was introduced in 2017 and is the main strain produced commercially and available for release by land managers. RHDV-K5 does not generally spread far beyond its release site, so it acts as a biocide rather than a free-spreading biocontrol, reducing rabbit numbers at a local scale.

Young rabbits up to about 8 weeks of age are not affected by the Czech strain or RHDV-K5, and develop life-long immunity if infected. If they are not infected their innate immunity begins to wane quite rapidly after about 8 weeks of age, leaving them vulnerable to RHDV-K5. It is therefore important that if RHDV-K5 is used as part of a control program it is only released when rabbits are not breeding, otherwise it can give young rabbits life-long immunity to RHDV and risk that immunity becoming more common in the rabbit population.

Rabbit breeding is induced by high protein (green) feeds so in Southern Australia that generally means not releasing RHDV-K5 in winter, spring or (dependant on season) early summer. For more information on how rabbit breeding is induced by high protein (green) feeds, see About rabbits / Breeding / How seasons and diet stimulate breeding.

Before considering a release of K5 check if RHDV2 is already present. There is no use in releasing RHDV-K5 if it is and doing so could promote immunity. Samples from dead rabbits can be tested for RHDV through RabbitScan or CSIRO or physical examination – see ‘How do I know if a rabbit had RHDV?‘. For more information on tissue testing to determine if RHDV or myxomatosis caused a rabbit death, see here.

RHDV Family tree. Image Amy Iannella

Host-disease dynamics

Host-disease dynamics. Biological controls are living organisms whose populations grow and decline as do those of their target species (hosts). Environmental factors will influence their growth and dispersal, as will their access to hosts. If there are few hosts around the bio-controls may have difficulty encountering them and multiplying. Populations of biocontrol agents may therefore lag behind those of their hosts, all other factors being equal.

The effectiveness of a biocontrol depends on its virulence, the susceptibility of the host, and the ease with which it is spread. Transmission may be direct (e.g. via contact), air-borne, or via a third party (a vector, such as a parasite). Virulence may change over time and target organisms may develop immunity or genetic resistance. These changes are sometimes referred to as an ‘arms race’.  See Rabbit Biology / About viruses for more information.

RHDV-K5: Rule of Thumb

RHDV bio-controls should not be released if green grass is present, because protein rich green grass stimulates breeding and young rabbits can develop life-long immunity to RHDV if infected when less than 8 weeks old . In much of Australia young rabbits can be expected to be present during July-December, hence the release of RHDV should only occur in drier months between January and June, if it is not present already.

Knockout – Inhibit breeding

Warrens or protective harbour (like impenetrable vegetation or debri) provide protection for rabbits from the elements and predators and are crucial for the survival of young rabbits. Removing warrens severely reduces rabbit breeding and the likelihood of rabbits moving back into a cleared area from adjacent lands. Special techniques may be needed in sensitive sites of high social or environmental significance.

A variety of machinery can be used for warren destruction.

Whatever method is used to reduce the number of rabbits, unless efforts are made to destroy their warrens or harbour where they breed,

it will only be a matter of time until their numbers increase once again.

  • Ripping. The aim of ripping is to destroy warrens and ensure they cannot be re-used by subsequent generations of rabbits. See ‘How to’ for more information.
  • Implosion or explosion. Warren blasting may be used in areas inaccessible to ripping machinery. It is generally done by implosion (using ANFO – ammonium nitrate and fuel oil) rather than explosion, with the benefit of less disturbance to the land surface and less risk of subsequent erosion. Implosion uses lower amounts of explosive, so it is also a safer option for operators. See ‘How to’ for more information.
  • Removal of weeds or debri. When rabbits live above ground under the shelter of vegetation or other debri, that cover is crucial to their survival. It provides shelter from predators and can give rabbits time to develop burrows. Removal is encouraged to reduce rabbit numbers and prevent reinfestation. Cleaning up may also serve as an important weed management or fire risk reduction exercise. See ‘How to’ for more information.
Where to find rabbits. Image: Darling Downs - Moreton Rabbit Board

Where to find rabbits. Image: Darling Downs – Moreton Rabbit Board

‘How to’ information: Knockout.

Mop-up – Clean up and monitor.

Rabbit control is rarely completely effective. It is essential to chase ‘that last rabbit’ to reduce the risk of rebounding populations, and to continually monitor for remnant rabbits. A number of control techniques are suited to mop-up operations.

Fumigation can be an effective ‘mop-up’ technique.

  • Fumigation. Rabbits in warrens may be treated by diffusion fumigation (when phosphine gas is released from aluminium phosphide tablets placed in burrows) or pressure fumigation (when noxious gasses are pumped into warrens). Fumigation is often used for ‘mopping up’ residual rabbits. Trained dogs may be used to help herd rabbits into their burrows, but not for catching or killing rabbits. See ‘How to’ for more information.
  • Trapping. Soft nets, padded-jaw leg-hold traps or cages may be used for individual or small isolated pockets of rabbits, subject to any local animal welfare regulations. See ‘How to’ for more information.
  • Shooting. Shooting may be used for residual or isolated rabbits, e.g. during a mop-up phase.
  • Detector dogs. Well trained detector dogs may be used to locate hard to find warrens or isolated rabbits. Dogs are not to be used to chase down and kill rabbits. See ‘How to’ for more information.
  • Ferrets. In difficult to access areas or urban and peri-urban areas when other measures are not feasible, ferrets are sometimes used to chase rabbits out of warrens into nets where they are euthanised. Ferrets that savage rabbits should not be used to flush rabbits from burrows.
  • Quolls. After being declared extinct in the Australian mainland in the 1960’s eastern quolls are now being reintroduced to some reserves and conservation areas in south eastern Australia. One of the benefits of these natural predators is that they are adept at hunting rabbits in their burrows. Predation by quolls is thought to have been one reason for the failure of numerous early attempts to introduce rabbits to mainland Australia.

‘How to’ information: Mop-up.

Fumigation
Trapping
Shooting
Detector dogs
Quolls

A video overview of monitoring techniques is available from Monitoring Pest Animals.

Exclusion – keep rabbits out

In situations where other control options are problematic (small, semi-urban properties or highly valued environments for example), fencing rabbits out may be a practical long-term solution, provided that on-going monitoring and maintenance is kept up to ensure rabbits do not invade the fenced area. If rabbits are found, then ‘Mop-up’ control options could be used within fenced areas.

  • Rabbit proof fencing. An important feature of rabbit-proof fencing is that netting is either laid on the ground or buried to prevent rabbits digging under the fence. A proviso is that rabbit-proof fences must be regularly inspected and repaired. Even then tenacious rabbits may still find a way through, under or over them, so monitoring inside fences for rabbits is also recommended. Rabbit-proof fences are part of regional rabbit control in parts of Queensland. See ‘How to’ for more information.
  • Feral proof fencing. In areas with problems from various feral pests, it may be appropriate to consider fencing that prohibits more than rabbits. Fences to keep predators like cats and foxes out usually have a floppy top that folds back onto any climbing animals. See ‘How to’ for more information.
  • Tree guards. Tree guards can provide a favourable micro-environment for seedlings, e.g. sheltering them from wind, as well as protecting them from grazing by rabbits. However, once the plants grow above the guard, they can be susceptible to nibbling by more adventurous rabbits. Larger, single trees can be protected by wire or steel mesh guards.

Tree-guards are not always effective against rabbits. Note the secateur-like damage to the young callitris by rabbits, far right. Images: Ron Sinclair & Bruce Munday.

‘How to’ information: Exclusion.

Rabbit-proof fencing
Feral-proof fencing

Follow-up: Monitor, Record and Respond

Follow-up, checking on the success of control efforts and responding immediately, should be factored into all control programs as part of monitoring and evaluation.

Monitoring. Information from monitoring should help reflective evaluation once a control program is completed, but it should also be an active part of all operations – checking to see they were effective and remedying any identified problems as soon as possible. Information, like rabbit or active warren numbers, should be available from before and after treatments. Examples include:

  • Checking the effectiveness of a baiting program and relaying baits immediately if there was insufficient original uptake.
  • Checking warrens after ripping to ensure no burrows have been re-opened and closing them immediately if they were.

Recording. Keeping a record of control actions (perhaps including a diary, notes, log-books, RabbitScan, and/or photos) avoids having to rely on memory, and makes review and evaluation much easier. It is the same as recording things like stock movements, fertiliser applications or irrigation on farms.

A number of tools are available to assist in data capture, information gathering and recording.

RabbitScan

RabbitScan app and website is a free rabbit mapping and planning program. It can be used on a mobile phone or desktop computer. It enables:

  • Recording of rabbit activity (which may be set to private or public viewing)
  • Recording photos of rabbits, rabbit damage and rabbit control
  • Sharing data with neighbours to plan joint control programs
  • Recording of your rabbit control activities
  • Access to rabbit sampling kits to see if rabbit viruses are active.

Reporting dead rabbits through RabbitScan provides data for national research and monitoring of rabbits and their diseases, and in return it provides land managers with insight into whether calicivirus is active on their land or not.

Landcarer Community

Landcarer Community offers opportunities to share information, insights and resources with others and to record data on your rabbit control activities.

Monitoring techniques

‘Monitoring techniques for vertebrate pests. Rabbits’ is a guide presenting monitoring options for rabbit abundance (e.g. warren counts, dung counts and spotlight counts) and rabbit impacts (e.g. vegetation, native animals, crop yields, stock returns, and soil erosion), as well as useful background information about rabbits. Data from surveys like these provide useful ‘before and after’ comparisons, and enable assessment of the success or otherwise of control programs.

Handy resources: PestSmart

Handy resources – PestSmart links to resources useful in planning and monitoring rabbit control.

For more information about evaluation at the end of a control program, see Improve.

Useful Resources

Weblinks

Control techniques

Biological controls

Downloads

Comprehensive guides

Control techniques

Baiting

Exclusion fencing

Small & peri-urban properties