Up to 8000ha of Otago could have poisoned bait spread for rabbits this winter, twice the area covered in each of the past two years.
A bumper breeding season and a lowering by the Otago Regional Council of the maximum allowed levels of rabbits, particularly in Central Otago, mean more farmers are required to reduce numbers this winter.
The operation's manager, Peter Preston, of council-owned Regional Services, said the final area to be poisoned this year was still to be finalised.
He expected it to be more than 6000ha but it could be up to 8000ha.
Last year, about 4000ha was poisoned.
Rabbit numbers were not back to pre-RHD levels, he said, and the population explosion was not universal across farms, but tended to be in pockets on properties and in some areas were at level seven on the McLean scale.
The biggest contract confirmed so far was for 1700ha, but because of the excellent breeding season operations could be run in areas not poisoned for many years including, possibly, on several farms on the Otago Peninsula.
Mr Preston said farmers in the Lindis Pass were planning their largest poisoning operation since before the arrival in 1997 of rabbit haemorrhagic disease (RHD).
Programmes were also planned for the first time in many years at Roxburgh and in the Wakatipu Basin, along with the historically rabbit-infested areas of Cromwell and the Upper Clutha.
The council has amended its policies to allow a maximum level throughout Otago of three.
In parts of Central Otago it was up to five.
"It has resulted in a quantum change in thinking," he said.
Some of the programmes were required because farms did not comply with the new maximum level and farmers had been told to address the issue, but others were because farmers realised they had to control the population.
An excellent breeding season had accentuated a gradual increase in numbers, he said, with the 23,000 rabbits killed at the Great Easter Bunny Hunt in Central Otago significantly up on the 15,000 killed a year earlier.
Although that was not an accurate measure, the total number killed was back at pre-RHD numbers, he said.
A mix of 1080 and pindone poison will be used, with pindone favoured in lifestyle blocks and built-up areas.
Mr Preston said plenty of carrots were available and with winter frosts burning off vegetation cover, pre-feeding to introduce rabbits to the bait could start later this month.
Blocks were typically closed to livestock for 10 to 12 weeks and Mr Preston said farmers were keen to get operations under way so they could have access to them for lambing.