Bunny boom means return of calicivirus

The controversial calicivirus is about to be released throughout the country to control rapidly rising rabbit numbers.

Ten of the country's 13 regional councils from Northland to Southland - including the Auckland Regional Council - have confirmed they will release the virus this winter after an explosion in rabbit numbers following ideal summer breeding conditions.

The virus works by causing the rapid development of blood clots in major organs. The clots block a rabbit's blood vessels and cause death from heart and respiratory failure within 30 to 40 hours.

Although legal here since 1998, the calicivirus still remains a highly controversial form of pest control with questions about its effectiveness, because over time rabbits reportedly build up immunity.

Auckland Regional Council biosecurity manager Jack Craw said thousands of rabbits were devastating market gardens in Karaka and Pukekohe. Farmers reporting high rabbit numbers had experienced dramatic losses in production as six rabbits were able to eat as much grass as one sheep.

Mr Craw said rabbit numbers were high in Awhitu and Helensville, as well as in sand dune areas such as Muriwai Beach and the Omaha sandspit, where they were creating coastal erosion.

"This is why we will be releasing the virus in a controlled programme in 10 to 30 spots throughout the region from July."

This would include "rabbit plagued" Great Barrier Island, despite it being the only likely calicivirus-free site in the country.

Full community consultation was scheduled before the release.

"We want to assure people this is a very safe virus, it is not a new strain and tests have shown it does not threaten other wildlife."

Mr Craw said though farmers and environmentalists on the island were supportive of the release, he was unsure how other residents would feel about it.

"Some people just don't like the idea of a virus being released no matter what, but we're happy to explain why the risks are few."

- HERALD ON SUNDAY