KEY POINTS:
More tracking stations have been set off by a rat, or rats, on what was thought to be predator-free Motuihe Island in the Hauraki Gulf.
A Department of Conservation ranger found evidence of rat activity on the island on Monday when rat pawprints were picked up in a tracking station on the northern end of the island.
DoC spokesman Bill Trusewich said five more tracking stations spread across the 179ha island had yesterday shown evidence of rat activity.
He said that could indicate the island had one "very ambitious rat" or more than one rat.
It was a concern because of the planned release next month of kakariki, a native parrot, on Motuihe which had been been free of rats and mice since 1996.
The reserve became pest free in 2004 when 20,000 rabbits were eradicated.
The island was being ecologically restored with volunteer reafforestation and the establishment of other native bird species, such as saddlebacks which had doubled in numbers since they were introduced a couple of years ago.
Mr Trusewich said if the rat was a ship rat, which was likely, it would be omnivorous and eat eggs.
It might even attack shore nesting birds, including the protected variable oyster catcher and the critically endangered New Zealand dotterel.
A sniffer dog was to be taken to the island yesterday but that would not now happen until today when a trained terrier could be brought up from the Coromandel Peninsula.
DoC workers were already laying out a grid of 250 rat traps which were being baited with peanut butter. It could take a few weeks to catch the rat.
