Environment Waikato has undertaken trials of the rabbit haemorrhagic disease (RHD) in the Taupo area and on the Coromandel Peninsula with mixed results.
The most successful results were in Matarangi, where rabbit populations fell by 50 per cent, and in Kuratau-Omori area which showed a 47 per cent positive result. The rabbit control also had some success in Pauanui, where the rabbit population fell by 25 per cent. But the trial was unsuccessful in Kinloch.
“In the Waikato region, it is the responsibility of landowners to control rabbits on their property. However, this can be a real challenge for absentee owners and people in built-up areas where control methods like poisoning, shooting, trapping are not possible or practicable,” says Environment Waikato biosecurity operations manager Peter Russell.
“Environment Waikato therefore maintains an annual, low-level control programme at a few priority sites within the rabbit-prone zones. Given that some of these zones are in built-up areas, such as Pauanui, we have wanted to trial RHD as an alternative way of controlling rabbits.
“However the RHD operation is something new for us, and the results were mixed. This sort of partial success is showing up as a standard response across the country.
“The trial suggests that while RHD has its place, it is not a silver bullet.”
While the RHD operation achieved successful results in Matarangi and Kuratau-Omori, the trial in the Kinloch area showed no noticeable effect on the rabbit population.
“The poor result obtained at Kinloch is probably due to bait shyness from previous extensive poisoning operations last year, and the comparatively high immunity rate to the disease with eight out of the 30 samples showing immunity.”
Environment Waikato is likely to use the RHD virus again at priority sites within the region’s rabbit prone zones.
“We need all the methods that are available to control rabbits in prone areas like around Lake Taupo, which have light sandy pumice soils,” Mr Russell said.
RHD is a highly contagious disease of European rabbits that causes death within 30-40 hours. The virus, which can be used in high density urban areas, was released in June and used as a biocide to target adult rabbits outside the breeding season.
The rabbits were targeted with carrot pieces infected with the RHD virus laid along bait lines in the late afternoon and evening, with uneaten bait recovered the following day. Assessments of rabbit numbers were carried out before and after the operations.