Rabbit numbers have been higher than usual across the region this year. This is most likely the result of a combination of factors – poor control carried out last season, an extended breeding season caused by the early break and a less effective rabbit calicivirus disease (RCD) season. This trend has been common right across the state, with reports of crop damage for the first time in many years and unusually high requests for bait during winter.
Experts are currently investigating the reasons for RCD being less effective this year. It is too early to give a definitive answer but it could be a simple case of unsuitable seasonal conditions for build up and spread of the disease or a more sinister development of developing genetic resistance to the virus. A national project is currently researching the issue to see if we need to change our tactics in the battle against rabbits.
A trial is currently underway in the Upper South East to test the effectiveness of distributing RCD on oat baits. While RCD remains present throughout the state following its release in the 1990’s, its effect has often been patchy in the South East region. Distributing the virus on bait material may serve a useful purpose in filling in the gaps or delivering the virus at the right seasonal time to be most effective. The trial has so far showed a 40% reduction in rabbit numbers on the property during the month following baiting.
While that is helpful, it is clearly inadequate for effective control of rabbit damage and highlights the importance of maintaining traditional rabbit control activities regardless of how low rabbit numbers are. Rabbits will never be immune to 1080 so baiting during summer is still the best bet for reducing rabbit numbers. Follow up control activities such as ripping and fumigating warrens are critical in preventing re-establishment.
Many landholders have become complacent about the need for conventional rabbit management due to the biological controls now available. These techniques were not designed to replace traditional control methods but to complement them. RCD is not a magic wand and will not get rid of all rabbits, but it offers a great opportunity for land managers to obtain more cost-effective and longer-lasting control with conventional methods. The challenge is still to take maximum advantage of lowered rabbit numbers and achieve local eradication.
RabbitScan is an initiative of the national Rabbit Management Advisory Group. Currently the community is being invited to gather data to create an evidence base of rabbits, their density, distribution and impacts across Australia. Already this campaign has resulted in increased community interest in pest management programs.
Community members are encouraged to visit www.rabbitscan.net.au and add known data about rabbit distribution in the South East to the database.