KEY POINTS:
The call of the kokako will not be heard in a Waikato forest this year because of the wetter-than-normal winter.
Parts of the region received about 150 per cent of the normal rainfall.
This caused problems for farmers and landowners, but it also means 10 pairs of kokako will have to wait until next year to be moved from Pureora Forest Park to Maungatautari Ecological Island Trust, near Cambridge.
Maungatautari Trust chief executive Jim Mylchreest said it was "incredibly disappointing" but the wet weather had delayed the trust's final planned aerial pest eradication of mice for the year.
"We didn't want to risk translocating the kokako until we were sure the residual bait was gone, and with the weather the way it has been it doesn't give us time to do the transfer."
The kokako, which start breeding at the end of October, were to be moved at a cost of about $70,000.
"That's if we can catch them - they're pretty tricky and live high up in the canopy," said Mr Mylchreest.
Other "interesting challenges" in relocating the birds included differences in dialect and a possible generation gap.
"It appears that the birds' dialects change not only through location but over time, and a recording taken 20 years ago might not be the tunes they're singing now.
"We're still not sure whether over a period of time they mix it up and learn each other's vocabulary. It's certainly one of the exciting things about the project."
Renowned for their ethereal and haunting call, the kokako are critically endangered. Fewer than 800 breeding pairs are left.
But Mr Mylchreest says that when they are established on Maungatautari, about 20km south of Cambridge, numbers could increase by up to 40 per cent, making it the largest remaining population.
"I would imagine several hundred pairs would be able to survive on the mountain and be fully self-sustaining."
Other birds to be shifted to the 3400ha reserve include robins, whiteheads, stitchbirds, saddlebacks and riflemen.
