Department of Conservation rangers have temporarily removed 11 kiwi chicks from two West Coast sanctuaries this breeding season as part of the Bank of New Zealand Kiwi Recovery's Operation Nest Egg programme.

West Coast Conservator, Mike Slater, said the risk to new born chicks escalated in December when stoat numbers climbed dramatically in both the Haast Tokoeka Sanctuary and the Okarito Sanctuary near Franz Josef.

The high stoat numbers were a consequence of a forest fruiting phenomenon which created perfect conditions for rodents in both sanctuaries. High numbers of rats provided an abundant source of protein for female stoats to maximise their full breeding potential and create a population explosion. Stoats can travel tens of kilometres a day and a plague of juveniles began an invasion into both sanctuaries in December.

For Okarito this is the second consecutive stoat plague. Last breeding season rangers managed to rescue two chicks at Okarito after 13 of 14 monitored chicks in the sanctuary were killed by stoats at less than 11-weeks old. The Haast Tokoeka Sanctuary did not suffer from a stoat plague last season and 40 percent of the monitored chicks reached the 1000gram stoat-safe weight.

Mr Slater said trapping networks in both sanctuaries have a record of providing a significant boost to kiwi breeding success and recruitment rates in years when stoat numbers do not reach plague proportions.

Stoats are unable to kill adult kiwi and therefore the long-term breeding capacity at both the Haast Tokoeka Sanctuary and the Okarito Sanctuary is not under direct threat.

However, Mr Slater said the current stoat plague is the largest experienced in either sanctuary since monitoring began in 2000.

In Okarito, 268 stoats were trapped last month compared to 136 the previous December. In Haast, 123 stoats were trapped last month compared to 69 the previous December.

To counter the threat, the department has temporarily removed chicks from both locations. Seven rowi chicks have been removed from Okaritio for rearing on Motuara Island in the Marlborough Sounds, including one which made the 500km trip yesterday. Four tokoeka chicks have been removed from Haast for rearing behind the predator fence at the Burwood Reserve near Te Anau. These include two chicks hatched from eggs for the Department by the Kiwi and Birdlife Park in Queenstown.

Mr Slater said stoats are known to have killed four chicks in Haast and one in Okarito. "We will continue to monitor nests in both sanctuaries and any chicks that emerge will be transferred," he said.  Mr Slater said plans to control rats at Okarito with an aerial 1080 operation were shelved after rat numbers began a dramatic decline in November.

"At the time that rat numbers began to drop we had very low stoat numbers inside the sanctuary. This meant that a 1080 operation would have provided only a very brief beneficial bykill of stoats, possibly lasting only a matter of weeks. This could not have dealt with the massive reinvasion of stoats from outside the sanctuary.

"We also discovered through our monitoring that rats are not clogging the stoat trapping network to any significant degree.

"In the circumstances, our most effective option to counter a stoat plague of this intensity has been the temporary removal of chicks as part of the Bank of New Zealand Kiwi Recovery's Operation Nest Egg programme," Mr Slater said.

"We have also enhanced the trapping programme to bring stoat numbers down again inside the sanctuary's core, this will prevent the invading stoats from establishing a large resident population," Mr Slater said.

The Okarito Kiwi Sanctuary covers 10,000 hectares just north of Franz Josef in South Westland. The sanctuary is home to an estimated 100 breeding pairs of rowi (Okarito Brown Kiwi).

The Haast Tokoeka Sanctuary covers 11,400 hectares and is 25kms South of  Haast Township. It is home to an estimated 200-300 tokoeka.

For further information please contact:

DOC West Coast: Ian Gill
03 755-5524 (wk) or 03 755-4013 (hm)

Bank of New Zealand Kiwi Recovery Trust: Kieron Goodwin
ph: 09 375 1084, or 029 478 4610

The Bank of New Zealand Kiwi Recovery Trust was established in November 2002 by the Bank of New Zealand and the Department of Conservation, building on an 12-year sponsorship relationship. The Bank of New Zealand Kiwi Recovery Trust is responsible for public awareness and education, fundraising, sponsorship and grant allocations for kiwi recovery nationally.