Rabbit Control Methods

Pindone

Pindone is a first-generation anticoagulant poison (similar to some rat poisons), used to control rabbits in Australia since the 1980’s.

In Tasmania, Pindone is the preferred poison for rabbits rather than 1080 because of the risk of 1080 to other animals such as domestic cats and dogs. Because there is a delayed onset with pindone poisoning (6 to 14 days) an effective antidote for anticoagulant poisoning (vitamin K1) can be used if required, which is not the case for 1080.

It is extremely difficult for a dog to eat enough poisoned rabbits to take a toxic dose of pindone. However, a dog that eats the bait may be poisoned. A cat would need to eat most of a dead rabbit each day for several days to be poisoned. Commercially produced pindone products contain a green dye to reduce its attractiveness to birds.

All 1080 poison operations in Tasmania must be performed under the supervision of NRE Tas Wildlife Management officers.

Permits

Landholders who wish to lay their own bait must be instructed in the use of pindone and must hold an Agricultural Spray Permit. An NRE Tas Authorised Officer may issue a permit to use pindone, for a prescribed fee. The permit may be issued for a period of up to five years.

Method of use

Landholders must notify their neighbours and post signs when pindone baits are laid.

Pindone is a liquid, which is issued for field use as a 2.5 per cent concentration of active ingredient (a.i.) and mixed with bait by an authorised person to give a final concentration of 0.025 per cent (a.i.). The most common baits used are carrots and oats. Oats are not as effective in some circumstances, particularly when there is abundant green feed available.

Preparation and planning for baiting

When planning your control program, you must know:

density and distribution of rabbits on your property and adjoining properties
if rabbits are moving across your boundaries
the types of harbour rabbits are using
where the rabbits are feeding
what non-target animals are present (native/domestic) and whether they may eat poison bait or poisoned rabbit carcasses.

When to bait

Rabbits can be poisoned whenever they will readily take oat or carrot bait. As such, most rabbit poisoning occurs in the late summer and early autumn period because:

myxomatosis, RHDV and natural mortality have reduced rabbit numbers
feed is at a minimum and rabbits are foraging for food
rabbits are old to enough to emerge from the burrow (21 to 25 days) and be exposed to the bait
breeding is usually over so rabbits begin to forage over larger areas.

Where to bait

Place the bait in the feeding areas.

Most rabbits feed within 25 m of the burrow. Rabbit feeding areas are characterised by:

short grazed vegetation
dung heaps
scratching’s.

It is important that all rabbits have access to poison baits, to maximise program effectiveness.

Free feeding

Offering free feed (non-poisoned baits) before toxic baiting at least one week prior to poison baiting is essential. Free feeding will habituate the rabbits to eating the carrot. Following the steps below will lead to a more successful baiting operation.

Determine where rabbits are actively feeding and place untreated baits in these areas in the early evening.
Use good quality carrots as bait so they are attractive to the rabbits.
Every 1-2 days, check and replace baits, adjusting amounts according to how much is being eaten.
In areas where all baits are taken, put down more.
If some areas show minimal signs of activity for multiple feeds, then concentrate your baiting operation on areas where the feed is being taken instead.
Calculate the amount of poison bait required.
Identify whether non-target species may be at risk.

Baiting safety

Safety is your responsibility, and you must keep children, livestock, dogs and other animals away from baits and poisoned carcasses to reduce the chance of off-target poisoning. You may also consider muzzling your dogs to further protect them in poisoning programs.

The symptoms of pindone poisoning include:

excess salivation
vomiting
bloody fluid in the mouth
progressive general weakening

Always adhere to the product label and the directions for use of Pindone bait products for all transport, storage, usage, safety directions and disposal procedures.

Cleaning up

The baited area, and surrounding areas, must be thoroughly searched for dead rabbits during baiting. Carcasses and uneaten baits must be disposed of according to the product label.

Biological Controls

Points to note about biocontrol:

Calicivirus releases are restricted to trained NRE Tas staff only.
Calicivirus will not be released when there is evidence of young rabbits under 10 weeks old and is only considered where there has been no evidence of calicivirus for over 12 months.
To reduce the risk of increasing immunity levels to calicivirus in rabbit populations, calicivrus is only released in drier months (usually autumn), when grass has dried off and consequently rabbits have stopped breeding.
Calicivirus alone will not provide effective rabbit control.
Biocontrol options must be used in conjunction with traditional control methods to be effective - integrated pest management.
Susceptible rabbits exposed to RHDV and myxomatosis are likely to die. However, some exposed rabbits will live a full life and breed as normal increasing the likelihood of resistance in that rabbit population.

Myxoma virus

Myxoma virus causes myxomatosis which is a natural viral disease that kills European rabbits. Spread by biting insects, myxomatosis causes florid skin lesions, acute blepharo-conjunctivitis and oedematous swelling of the genital area. Myxomatosis ultimately compromises the rabbit’s immune system leading to respiratory infections that often lead to death. Myxoma Virus was released into the feral rabbit population in the 1950s. Within months of its release, myxoma virus had knocked over 90 per cent of some rabbit populations in Australia. However, as with most viruses, it became less effective over time due to rabbits developing genetic resistance. Today Myxoma Virus continues to exist in the environment and periodically affects rabbit populations in Tasmania when conditions allow. It is no-longer released to manage wild rabbits.

RHDV1 (calicivirus)

RHDV1, previously known as rabbit calicivirus, is a highly contagious, naturally occurring disease of European rabbits, that is spread by insects and close contact with other infected rabbits. Rabbits infected with RHDV1 become feverish and display flu-like symptoms. RHDV1, has been used as a biocontrol for rabbits in Tasmania since 1997. The first strain came from the Czech Republic (RHDV1 Czech v351) and was extremely effective, knocking down 90 per cent of the pest rabbit population in some parts of Australia. However, rabbits began to develop a resistance to this strain and its effectiveness has declined since. A benign endemic form of RHDV, RCV-A1, was also formally identified in 2009. Found in cooler wetter regions of Australia, RCV-A1 was providing rabbits in these areas with protection from RHDV1 Czech v351. A strain from Korea (RHDV1 K5) was found as part of the RHD Boost project to identify a new strain of RHDV with superior performance in wetter and cooler areas and that could overcome the genetic resistance.

The national release of RHDV1 K5 occurred in 2017, but not before it was rigorously tested, assessed and registered. Upon its release, RHDV1 K5 produced an average rabbit population knockdown of 34 per cent, although the results were highly variable. It was also discovered that RHDV1 K5 worked more as a biocide, rather than a biocontrol agent, meaning it generally did not spread beyond the original release site. When rabbit numbers increase and cause significant impact, Biosecurity Tasmania actively releases (when conditions permit) RHDV1 K5 to achieve localised rabbit control.

RHDV1-K5 only affects European rabbits and poses no risk to human health or other non-target species. A vaccine is available for domestic rabbits against RHDV1 and RHDV2. Your veterinarian can provide you with more information.

For more information visit the website PestSmart - Boosting Rabbit Control

RHDV2

In 2016, a rogue virus called RHDV2 was detected in wild rabbits in Tasmania. RHDV2 is a different type of rabbit haemorrhagic disease virus to the current strain used in Tasmania for wild rabbit control – RHDV1-K5. RHDV2 is able to cause the death of rabbit kittens as young as 3-4 weeks, while RHDV1 strains tend not to kill rabbits younger than 12 weeks, giving them the ability to develop immunity once infected. RHDV2 has also been reported to infect hares, unlike the RHDV1 strains. This virus has now spread throughout most of Australia and is currently the dominant RHDV strain. RHDV2 will occur naturally when conditions are suitable resulting in localised rabbit deaths showing no outward signs of cause of death.

If you notice rabbits dying suddenly,you can support the spread of biological control agents by leaving infected rabbit carcasses where they died. It is important to report all rabbit deaths to Biosecurity Tasmania to enable testing which maintains our knowledge of rabbit viruses in Tasmania. Contact 03 6165 3777 or invasivespecies@nre.tas.gov.au

Ripping to destroy warrens

Some areas are more suitable for rabbit warrens than others, while some rabbit populations do not require a warren if there is adequate vegetation providing cover from predators and the weather.

Ripping is essential as it destroys the warrens where rabbits live and shelter from the weather elements and predators. A rabbit control program will fail unless all burrows and other harbour are destroyed.

Before you begin:

Make sure all rabbits are underground by running dogs over the area, or by making enough noise to flush rabbits into their warren.
You should have located, mapped and marked all warrens in your planning phase.
Employ a spotter to direct the machine to each warren and ensure all warrens are destroyed.
Mechanical equipment including bulldozers, excavators, backhoes and tractor-mounted rippers are highly efficient methods to destroy warren systems.
A tined ripper mounted on a bulldozer, or an appropriate tractor, is commonly used to rip burrows in open areas.
Where minimal disturbance is important, excavators and backhoes are more appropriate. They can be used successfully on rocky sites, along fence-lines and where removal of woody weeds is necessary. They can also be successfully used to minimise disturbance to areas of native vegetation where warrens are interspersed with remnant vegetation.
Digging warrens out with a shovel, mattock or pick can be an option if warrens are hard to get to or access is an issue.

Ripping:

You must rip at least four metres out from the outermost warren opening.
Rip lines should be no more than 50 cm apart.
Interline ripping between the rip lines after the first pass, will help destroy the warren structure.
You must cross rip by ripping in one direction and then ripping again at an angle of 90 degrees to the original rip lines.
Rip to a depth of at least 70 cm or deeper if possible - The deeper the ripping the better the result.

Warren ripping examples
Photo: Rabbit Free - Australia

Ripped warrens should be back bladed and track rolled to leave a flat and compacted site, which decreases its attractiveness to re-invading rabbits. It also helps compact the soil surface and reduce the risk of erosion. The site should be revegetated with appropriate vegetation as soon as possible.

Above-ground harbour removal

Rabbits use a variety of above ground shelter such as heaps of debris, patches of weeds, buildings and some forms of native vegetation. Above-ground harbour aids rabbit survival by protecting them from the elements or predators.

To limit the use of above-ground harbour:

Trim under all hedges and thickets of scrub to remove low branches and destroy possible shelter.
Remove prickly and woody weeds (such as gorse, boxthorn and blackberries), rubbish piles and old machinery.
Fence off rock piles, building materials, hay bales and woodpiles or store them in a manner that does not create a hiding place for rabbits.
Fence off the underneath of buildings, water tanks and other areas rabbits may hide or burrow.
Remember fallen timber may provide harbour for rabbits and habitat for native wildlife. If you are planning to remove fallen timber, you must ensure that you do not affect native wildlife.

Remember, these techniques are best employed as complimentary to baiting and ripping as part of an integrated pest management program. Using these techniques on their own will rarely achieve long term outcomes.

Shooting

Shooting is rarely effective unless it is implemented at very low rabbit densities or to remove a small number of individuals.
Shooting is labour intensive, requires appropriate licences and warrens remain open for re-infestation.
Shooting doesn't provide any level of long-term control.

Note: In Tasmania, a licenced person must not discharge a firearm within 250 metres of a dwelling house unless they have the consent of the occupier.

Exclusion

Fencing

Exclusion fencing involves constructing a fence around a rabbit-prone area to exclude rabbits. When making enquiries, ask for 'rabbit-proof fencing' as this is fencing material specifically designed for the purpose of excluding rabbits.

A minimum of 17 cm of the fencing wire netting is buried in the ground, or the lower section of the wire netting is angled to lie on the ground facing in the direction of possible rabbit entry. The wire must be held down securely with pegs, rocks, or timber. The remainder of the mesh must be securely fixed to a suitable support fence so that it reaches a minimum of 88 cm above ground.

Fences are expensive and require regular maintenance to ensure there are no gaps. With proper maintenance fences should last up to 20 years.

Baiting and ripping works need to be completed before or after you have 'rabbit-proofed' your area. Well-built and well-maintained fences can keep properties free of rabbits once successfully treated.

One consequence of such fences is that the movement of some native animals may be limited by rabbit-proof fencing.

Minimum specifications:

Use of '105 × 4 × 1.4' standard rabbit netting. That is 105 cm width 4 cm mesh diameter 1.4 mm wire diameter.
The support fence should be able to withstand stock or native animal forces.
Rabbit netting should be fixed so that it reaches at least 88 cm above the ground.
Where netting is buried, it is buried to a minimum of 170 mm.
Where netting is bent to lay on the ground surface it must be held down with pegs, rocks or timber.
Suitable rabbit-proof gates should be placed at all breaks in the fence.

Rabbit proof fence design

General support fencing needs:

Use sturdy posts driven at least 45 cm into the ground (either rammed, or dug in).
Spacing between posts and star pickets should be determined by soil type, topography and required strength of the fence.
It is best to have fences erected by experienced or professional fencers.

Tree guards

Tree guards are essential in some rabbit prone areas. It may be more cost-effective when planting large areas to rabbit-proof fence the whole site and remove all rabbits inside the fenced area prior to planting.

Repellents and deterrents

There are repellents and deterrents available that may provide some level of protection to gardens, crops and pasture. Repellents and deterrents do not provide any rabbit population reduction.

Spreading blood and bone fertiliser (non-pelletised) has been successfully used to protect garden areas and when placed on recently ripped warrens can deter rabbits from recolonising.