Kiwi release results mixed
Endangered great spotted kiwi captured for release in pest protected areas look to have better breeding results in the Flora catchment of Kahurangi National Park than the Rotoiti Nature Recovery Project area at Nelson Lakes.
Department of Conservation recovery project team leader Grant Harper told last week's Tasman biodiversity forum that the sub-alpine climate of Nelson Lakes was probably behind the low egg fertility.
In addition, the Operation Nest Egg (One) programme did not work well for great spotted kiwi. The One project grew from recovery efforts around the North Island brown kiwi. It saw eggs taken from monitored adults in the wild. They were hatched and reared in captivity until chicks which were released back into pest safe areas when they were big enough to defend themselves from predators.
Mr Harper said of the seven One chicks released in the RNRP area in the three years to 2011 only three had survived. One died of misadventure and the other three refused to feed.
"Operation Nest Egg is not that useful for great spotted kiwi. All the eggs survived but not the chicks," he told the forum.
The pest-protected area under the RNRP project now covers around 5000 hectares. Sixteen great spotted kiwi captured at Gouland Downs, near the Heaphy Track, were transferred to the site in 2004 and 2006.
He said the transfers were successful and the birds established well. But the overall breeding success was not good with only one chick being born to the established six pairs of kiwi since their introduction.
Reasons for the poor results could be that mainly older birds were shifted to St Arnaud and the fact the sub-alpine climate made the site infertile for egg production because birds spent much of their energy finding food to maintain body weight, he said.
However, the trial release of two young chicks at 700 gram weight had been a success and both were now 2kg, he said.
Mr Harper said comparison of all the national mainland island sites showed that protected lowland areas were more productive.
However, ecologist Sandy Toy, of the Friends of Flora, said the voluntary body was trying to raise money to transfer more kiwi into the 10,000 hectare pest-protected area in the western ranges of Kahurangi National Park.
Three pairs of the dozen adults transferred from the Clark Valley into the Flora in 2010 were now thought to be nesting, she said. "Twelve is not a sustainable number of birds and we are now planning a second translocation."
Mrs Toy said constant pest control across the whole area was an essential commitment by Friends of Flora, Bush and Beyond, the Friends of the Cobb and DOC.
She said an acoustic survey stemming from reports of kiwi in the Cobb Valley had found low numbers of birds. "We plan to do repeat surveys in the Cobb to test for population growth."
In the meantime volunteers were focussing on raising money in the hope that more kiwi could be moved into the protected area next year.
- © Fairfax NZ News