It is still unclear to what extent a massive pest control operation spanning 700,000ha of the South Island and the bottom half of the North Island will need to be carried out.
Called ''Battle for our Birds'' by the Department of Conservation, conservation workers are gearing up for high levels of beech seed this year, which is expected to trigger a population explosion of predators such as stoats and rats.
Director of conservation partnerships Barry Hanson told the Otago Conservation Board in Dunedin last week they were seeing some things ''different to what we expected''.
While it was still likely to be a heavy beech seed year (mast year), predator numbers had not built up to the levels expected yet.
''Whether the seed fall transpires to what we think it will, then the uptake in predators is the next variable. We don't understand completely how it plays out.
''The message is that it is not until late July that we will form a strong view of where we should operate.''
Sites all around Otago are being monitored to get advance warning on the build-up of pests. Poison bait has been ordered and delivered and tenders for aerial drops of 1080 closed two months ago.
Mr Hanson said they had a view on what level of predator numbers would trigger the poisoning operations.
