More rabbits immune to RHD

The rabbit is skilled at adapting for its survival, as is shown by building an immunity to RHD ,after this disease was effective in decimating numbers for many years. With an efficent reproductive system that allows it to maximise its opportunities to recover from disease outbreaks, numbers are building again and landowners are being urged to return to conventional controls.

There will be some who will say this build up of immunity to RHD proves its illegal release was a failure, but the land has had  seven years to recover and landowners a period of reduced costs. With pastoral farming now more economic due to the upturn in prices, the ability to invest in these costs is now much more sustainable than it was. Farmers need a unified district pest control plan to keep this vermin from reaching plague proportions again.

Landowners must continue to use conventional rabbit-control methods to keep a lid on populations as young rabbit immunity to rabbit haemorrhagic disease [RHD] increases, Marlborough District Council biosecurity co-ordinator Dave Grueber says. The disease had a "horrendous" effect on the region's rabbit population for about seven years, but was not the silver bullet many thought it would be, Mr Grueber said. Many rabbits have developed immunity reports The Marlborough Express.

Council biosecurity officers presented results of this year's tests at regular sites at Muller and Middlehurst Stations in the Awatere Valley and new sites at Upcott Station, two farms in the Avon Valley and about five in the Wairau Valley. The results showed 45 per cent of young rabbits – those born last spring and most likely to breed – captured at Muller Station were immune to RHD, compared with 52 per cent last year, while 59 per cent captured at Middlehurst Station were immune, down from almost 70 per cent in 2010. Both stations had 100 per cent immunity in the adult population.

Although the number of immune rabbits at the control sites had fallen, that was because control programmes had reduced overall rabbit numbers, Mr Grueber said. RHD immunity was generally rising."Those rabbits that survive [control] – their immunity has increased. That is of concern."Landowners were urged to use the information given to them by the council to continue with conventional rabbit control, such as poisoning and shooting, rather than rely on RHD to do the job. "Carry on with conventional control. When RHD came in, it was considered by some to be a silver bullet, but it's not."