A visible increase in rabbit (Oryctolagus cuniculus) numbers across south east Victoria has prompted Landcare groups along with the South Gippsland Community Weeds Taskforce to raise the issue. As were all well aware, rabbits are nothing new to mainland Australia. Since the late 18th century they have hopped about the landscape digging warrens, decimating native vegetation, devouring pastures, sustaining fox populations and so on. Rabbits are that common these days that one doesn't bat an eyelid at the sight of bug's bunny peacefully nibbling grass on the roadside edge.
Is it rabbits 'commonness' that has management efforts falling by the way side? Or is the effort to control rabbits by land managers undermined by the sheer magnitude of the problem? Or rather are we stepping back from the problem and depending on the release of a new biological control agent to save the day? The likely answer is yes to all of these factors.
It's a given that control programs cost money, as a result land managers often rely on once a year poisoning programs. Typically only on their own properties and when rabbit populations are high with no integration/follow up with other control methods. To achieve effective rabbit control effort must be continuous. Therefore it's not the effort that is undermining the result but rather the ineffective methods that are generally used. One needs to be able to; adopt and use integrated rabbit control, kill rabbits at a faster rate than they can replace themselves at all densities, ensure rabbit immigration into your control site is zero, monitor rabbits at low densities and take immediate action if the population increases and maintain a social environment with your neighbours and community that supports the goal of aiming for rabbit free.
The success of the myxomatosis virus released in 1952 was poignant, reportedly wiping out 99.8% of rabbits. However by the 1990's rabbits showed resistance to the virus and their numbers once again climbed back into the millions. From 1996-1998 the Rabbit Calicivirus Disease (RCD) reduced rabbits by >50% in arid areas however once again, as with the myxo virus, numbers have bounced back. If the history of biological control agents is anything to go by then we shouldn't depend on it to keep rabbit numbers under control, at least not in the long run.
If we stop tolerating the 'commonness' of rabbits and start to adequately control numbers we stand to win big time. A dairy farmer in Colac, Victoria (similar growing conditions to parts of South Gippsland) increased his milk production by 300% and doubled his fodder harvest over 5 years simply by tackling his rabbit problem. A sheep farmer in Colac, who also managed his rabbits effectively, increased his dry sheep equivalent from 1.75 to 7.75 over a 5 year period.
Whilst researching the topic of the impact on native vegetation from rabbits I came across this insightful quote; 'What's the difference between chainsaws, bulldozers and rabbits? Not much really. Though chainsaws and bulldozers are the preferred tool for clearing land, rabbits are just as effective. They eat tree seedlings so that when the mature trees die there are no young ones to replace them. The net effect is identical, only the time scale differs' (Pickard 1995, Managing Vertebrate Pests; Bureau of Resource Sciences and CSIRO). Adequate control would give native vegetation a chance to regenerate and ultimately lend itself to providing habitat and food for native wildlife that was previously displaced by rabbits.
It's important to recognise that rabbits do impact us economically, socially and environmentally. We must not wait for the next biological control agent but rather act now to control their numbers using a variety of techniques, continuously and in coordination with our neighbours, (including public land managers) and local community. For further information on rabbit control visit the Department of Primary Industries (DPI) website at www.dpi.vic.gov.au or contact the South Gippsland Landcare Network Project Officer Kate Williams on 5662 5759 or email katew@wgcma.vic.gov.au. To record rabbit sightings in your area visit www.feralscan.org.au. Feral Scan is a citizen science website where you help map feral animals and the damage they cause.
Reference
Bloomfield, T., Paroz, G. Rabbits and Their Impact October 2010, LC0298 Department of Primary Industries, Attwood.
Photo caption: A single pair of rabbits (Oryctolagus cuniculus) can produce 30-40 young a year.
