Rabbit numbers are ballooning in several regions - particularly Otago, Canterbury and Marlborough - as immunity to the calicivirus spreads.
Ecologist John Parkes, from Landcare Research, says monitoring by regional councils suggests that rabbit populations are rebounding.
He says the calicivirus, now known as Rabbit Haemorrhagic Disease, had kept a lid on number since it was introduced illegally by a group of farmers in Canterbury in 1997.
Mr Parkes says the virus gave farmers 10 years grace to get back into profitability, but landowners will now need to spend more on shooting and poisoning.
"Eventually there'll be some cut-off points where some properties won't be economic, I guess."
He says Landcare Research is exploring ways of reducing the cost per hectare of rabbit control, but the question of who pays for rabbit control on unproductive land has yet to be resolved.
