Stoats decimating takahe in Fiordland

Takahe foraging at the edge of the Tunnelburn Stream as it leaves Lake Orbell towards Lake Te Anau.
BARRY HARCOURT/Southland Times
Takahe foraging at the edge of the Tunnelburn Stream as it leaves Lake Orbell towards Lake Te Anau.

Stoats have been blamed for a significant decline in takahe numbers in the Murchison Mountains.

At a Southland Conservation Board meeting this week, a report tabled by DOC biodiversity officer Eric Edwards told board members 16 birds were found dead last year.

Stoats were believed to have killed 14 of those.

In 2002 stoat control was set up to determine if low intensity trapping would provide any benefit to the takahe in the Murchison Mountains.

At the time stoats were thought to have little impact on takahe survival.

Less than a third of the area is protected by trapping.

In November, the annual census estimated takahe population in the mountains had declined from a peak of 150 to 92 birds.

"We estimate that the population within the core management area is 94. This is the lowest recorded wild population since takahe were rediscovered in 1948," the report says.

During the census, takahe encounters in the unprotected area were down 58 percent — equating to a 38 percent reduction in the wild population from 2006 to 2007.

However, the population within the trapping area increased by 2 percent.

The results show stoats were a major factor in the decline of the takahe.

It was also a consequence of the 2005/2006 beech mast which fuelled a rat population explosion followed by a stoat plague. Mast seeding occurs every three to five years.

"While these events may not always result in significant levels of predation, the takahe population cannot sustain multiple declines of this magnitude," the report says.

Mr Edwards then asked the board support his recommendation to increase the buffer zone of the stoat trapping programme in the mountains and move some of the remaining takahe to predator free islands.

Board member Ian Buick asked if there was an obsession to keep the birds in the mountains because it was where Geoffrey Orbell rediscovered them. "Is that putting their future at risk?" Mr Edwards said it was an interesting question.

Board member Dr Vivienne Shaw said there was a reason they were found in the Murchison Mountains and that they should remain there. Mr Buick said he wasn't disputing whether they should, he supported the birds remaining on the mainland.

Mr Edwards said protection would have to increase.

Dr Shaw suggested possible community involvement, such as having people adopt a stoat trap line.

The board voted to retain the population in the mountains and increase protection.


The Southland Times