More rats on the way out...

Forest and Bird, Issue 265, 1 August 1992, Page 4

More rats on the way out...

Tim Higham

ULVA ISLAND, in the centre of Stewart Island’s Paterson Inlet, is the latest island to be targeted for rat eradication. The poisoning of Norway rats, the only introduced mammals on the island, began in July and will continue over three 25day periods. If the operation is successful, Ulva Island, at 270 hectares, will be the largest island in New Zealand cleared of rats. The project co-ordinator, DoC’s Lindsay Chadderton, said the techniques would differ from those used successfully on Fiordland’s Breaksea Island in 1988. Bait stations would be set further apart, on a 100-m square grid, and | rebaited only every second day. A third of the island will be poisoned at a time — a technique known as a rolling front. Three workers will complete the whole operation.

Scientists Rowley Taylor and Bruce Thomas will use radio tracking equipment to study the home ranges of rats and their behaviour before

and during the poisoning operation. Mr Chadderton said the techniques were being tried out on the island as a possible

forerunner for the important large sanctuary islands of Codfish, Kapiti and Little Barrier. Ulva is renowned for its abundant weka, kakariki and kaka, and is a regular tourist boat stop on cruises of Paterson Inlet. Weka were banded before the operation, to assess any ill effects from the scavenging of dead rats and of baits removed by rats. Weka could be reintroduced from neighbouring islands if their numbers were significantly reduced. Mr Chadderton said South Island saddlebacks would probably be re-introduced to the island when it was predator-free, and kiwi, riflemen and weta may also be considered. Ulva Island will remain an open sanctuary and DoC will run an education campaign among boat owners to help reduce the risk of rodent re-introduction.