Snow has forced the Department of Conservation to postpone the Makarora part of its ''Battle for our Birds'' programme until spring.
Doc has been planning the aerial drop of 1080 poison on 23,000ha of the Mt Aspiring National Park around Makarora since last year.
However, in a statement yesterday, Wanaka conservation services manager Chris Sydney said the operation was now scheduled for spring or early summer, with the exact date to be confirmed near the time.
Snow was given as the reason for the postponement.
''It is not effective to use 1080 on snow.''
The ''Battle for our Birds'' programme was planned by Doc to target an expected population explosion of rodents and stoats following an unusually high level of beech tree seeding late last year. Aerial poisoning of all other areas in the programme has been completed.
Late last month, six helicopters spread 23 tonnes of non-toxic cereal bait on the mountains and valleys around Makarora to prepare rodents for a drop of cereal containing 1080 poison.
Mr Sydney said in his statement the pre-feed would not have to be repeated ''as the effects of last month's pre-feed will last sufficiently until spring''.
Wanaka anti-1080 campaigner Carol Sawyer yesterday disputed that. In the absence of available information about pre-feeds for rodents, Ms Sawyer quoted guidelines from the National Pest Control Agencies on possums and rabbits.
They recommended a pre-feed two to four weeks before a toxic aerial drop but considered a pre-feed could still be effective for eight weeks or longer.
''Four to five months later is not what they had in mind, I am sure,'' Ms Sawyer said.
She also noted the agencies' guidelines stated cereal baits could become rancid and should be stored for ''not longer than three months''.
