Rabbits are an enormous problem for Australian ecosystems – they’re a major threat to 322 species of plants and animals already at risk of extinction. This is more than double the number of species threatened by cats and foxes.
The Conversation investigation
To keep rabbit numbers down, many land managers roll out rabbit haemorrhagic disease virus, a powerful biocontrol. Land managers play a crucial role in conserving the environment and managing pest species – their involvement is essential to the success of many conservation programs.
But our new research finds around three quarters of land managers who reported releasing the biocontrol don’t follow the recommended guidelines, and release it during the peak rabbit breeding period. This potentially leads to the population actually increasing as young rabbits build an immunity to the virus.
It’s highly likely this widespread inappropriate use has substantial environmental and economic consequences. Rabbit haemorrhagic disease virus must be released strategically with caution, or the good intentions of land managers may have terrible outcomes.
Good intentions but bad outcomes
Two major viral rabbit biocontrols have been introduced to Australia: myxomatosis (introduced in 1950) and rabbit haemorrhagic disease virus (introduced in 1995). Both viruses have proven to be highly effective in reducing Australia’s rabbit numbers.
They now circulate naturally in Australia and continue to reduce rabbit numbers across the entire country, resulting in enormous environmental and economic benefits. Land managers can intentionally release rabbit haemorrhagic disease to help reduce rabbit numbers at more local scales, such as on a farm. But it’s crucial the biocontrol is released at the right time.
In young rabbits, less than 10 weeks old or so, rabbit haemorrhagic disease virus is not lethal. Instead, infection in this cohort primes their immune system and leaves them with life-long immunity to the virus.
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