Rabbit hemorrhagic disease virus (also known as rabbit calicivirus disease) RHDV is a virus specific to rabbits. The virus escaped from Wardang Island (off the coast of Yorke Peninsula, South Australia) during trials in 1995 and reached Queensland in the same year.
The virus works by infecting the lining of the throat, lungs, gut and liver. Despite its past success in controlling rabbit numbers, RHDV should not be considered a ‘silver bullet’. Rather, it is simply another tool that can be used to complement other control techniques.
While there are indications that insects may help to spread the disease, RHDV relies primarily on direct rabbit-to-rabbit contact in order to spread. High rabbit numbers are therefore needed before this control method will be effective.
Somehow the virus survives from year to year in an area and revisits rabbit populations (provided there are enough rabbits to support its spread).
After RHDV has infected an area, it is important to use another method for follow-up control to increase the likelihood that the population is eradicated before it is able to develop resistance and increase its numbers again.
Resistance to RHDV depends primarily on the age of the rabbit. Therefore, it is better for RHDV to go through a rabbit population after rabbits have bred and the young are old enough to be affected by the virus. Rabbits that survive RHDV develop antibodies against the virus.
Breeding females can also pass these antibodies on to the young (through antibodies in their milk), conferring temporary protection on rabbits up to 12 weeks old.
Myxomatosis:
Myxomatosis is a virus that was released in Australia in the early 1950s. It is transferred from rabbit to rabbit by mosquitoes and two species of flea—the European rabbit flea and the Spanish rabbit flea.
When the virus was released, Australia’s rabbit population initially decreased dramatically. However, because it was the only control method used, rabbit numbers began to increase again within a few years. Although the virus is no longer produced as a laboratory strain, field strains of myxomatosis still commonly recur and affect rabbit populations.
Trapping:
Trapping alone is not considered an effective method of control as rabbit populations will quickly recover; consequently, trapping will need to be repeated year after year. Trapping is also an extremely labour-intensive control method and requires a skilled operator to set the traps to successfully capture rabbits.
If you do plan to trap rabbits on your property, common sense and respect for animal welfare are essential. While there are currently no strict guidelines for the use of traps in Queensland, it is an area of growing concern for animal welfare advocates.
Cage trap:
A cage trap has a lever that closes the cage when a rabbit steps on it. The rabbits are lured into the cage with bait—usually diced carrot. Traps need to be disabled and left open for two or three nights with bait leading into the cage. This entices rabbits to enter. A trap can be set once a rabbit has consumed a trail of bait all the way into that trap.
Traps should be checked and emptied regularly—usually a couple of times a night. This effective and humane technique is most useful for removing any remaining rabbits from places like hay sheds and after the shed has been fenced to prevent additional rabbits from entering and leaving.
Free-feed then trap, and keep the shed rabbit-proof to prevent rabbits recolonising.
Foothold traps (soft-jaw or padded):
Although foothold traps are not widely used in Queensland, they can sometimes be useful in situations where other control methods can’t be used. They are considered more humane than the serrated, steel-jawed leghold traps that cause pain and suffering, and which should not be used.
Soft-jaw foothold traps have a piece of rubber or cushioning attached to the inner surface of the trap. These traps will hold the animal firmly by the foot without causing unnecessary trauma. Foothold traps are placed on the warren entrance path about 20–30 cm out from an active warren entrance.
The trap should be placed in loose, sandy soil. One trap should be placed at the entrance for each active hole in a warren.
Barrel trap:
A barrel trap is designed specifically for rabbits. It is cylindrical, made of light mesh, and is about 1 m long and 15 cm in diameter. The trap has one open end with two hinged trap doors along its side. The open end is placed in the burrow, and the hinged gates close and trap the rabbit after it enters from the burrow.
The trap can be left in the burrow entrance for a number of days. However, it must be checked at least daily so that if a rabbit has been caught it does not suffer and animal welfare responsibilities are met.
Exclusion fencing:
Rabbit exclusion fences are built with the aim of keeping rabbits out of a particular area. This control method can be very labour intensive and expensive; costs prohibit the construction of new fences over large areas. It is appropriate for small, high-value areas that require protection.
A fully fenced area will only remain rabbit-free in the long term if all rabbits are removed from the enclosed area after fencing and the fence is regularly maintained and checked for holes. A rabbit-proof fence should be made of wire mesh netting (40 mm2 or smaller) and needs to be at least 900 mm high.
The netting should also be buried to depth of at least 150 mm. Gates into the fenced area need to be rabbit-proof as well. Electric fencing is a cheaper alternative, but it is not a complete physical barrier and is also prone to damage from other pest animals and stock.
Shooting:
When used alone, shooting is not considered an effective method of rabbit control as it will only have a small impact on the population. It is impossible to shoot all the rabbits on a property and the population will quickly breed up again to replace those shot.
Shooting is most useful when used to ‘mop up’ after other control methods (such as ripping). To get the best results, shoot at the time of day when rabbits are active. This is usually in the early morning, late afternoon or at night. The best and most economical firearm to use is a .22 calibre rifle.
If your property is within an urban area, you will need to comply with local government regulations and the Police Powers and Responsibilities Act 2000, which restrict the use of firearms.
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