A year ago life for Cook’s petrel chicks on Little Barrier (Hauturu) was bleak and short lived. Now, less than a year after the operation to rid the island of rats, most chicks have survived to fly from their burrows.
Monitoring this summer has shown that 70 percent of the Cook’s petrel chicks fledged. In previous years as few as five percent survived when up to 95 percent of chicks were killed by kiore or Pacific rat, leaving the sea bird population in a downward spiral.
Department of Conservation island biodiversity manager Richard Griffiths said the turn around for the native seabird was a direct result of the kiore operation.
“It’s one of the first positive signs of the effects of the operation and is concrete evidence of the impact that kiore were having on Cook’s petrel.”
Mr Griffiths said the results were a sign of things to come on the island with an expected increase in native species once preyed on by kiore. However, Hauturu can not be confirmed to be rat free for another 16 months when intensive monitoring will be undertaken.
At the same time as the young petrels head for the sea, an unusually high number have been landing in Rodney townships. The juvenile birds fly over Rodney to the Tasman Sea at night and are thought to be disorientated by lights from urban areas.
Sylvia Durrant of the Rothesay Bay Bird Rescue centre has had more than 80 juvenile birds handed in over the last three weeks, more than double the usual number. The birds have been picked up by people concerned they were injured but are released after being fed and rested. Anyone finding a Cook’s petrel should put the bird in a box and call bird rescue or their local DOC office for advice.
Little Barrier is the stronghold of Cook’s petrel with a population in the tens of thousands. Several hundred of the birds also live on Whenua Hou, near Stewart Island, and there are a small number on Great Barrier.
With kiore gone from Hauturu other seabirds such as diving petrel, fluttering shearwater and grey-faced petrel are likely to return. The future of threatened species such as giant weta, Duvaucel’s gecko and tuatuara will also be more certain.
The operation to eradicate kiore from Little Barrier took place in June and July last year when 55 tonnes of rat bait was spread over the 3083-hectare island in two separate applications.
Biodiversity NZ Media Release