Elusive Rangitoto rat finally caught

Rangitoto Island in the Hauraki Gulf is now pest-free after a major search and trapping operation caught an elusive rat. File photo / Martin Sykes

A rat which managed to dodge 213 traps, a ranger searching round the clock and a team of rodent-sniffing dogs is thought to have finally been killed.

The major search and trapping operation was launched last month after rat tracks were found on the island, which the Department of Conservation (DOC) planned to turn into one of the country's largest sanctuaries for endangered species.

DOC Auckland area manager Brett Butland said the rat had entered rodent-detecting tunnels which ring the island at least 24 times -- it had nibbled on the peanut butter placed in the middle of ink pads used to detect paw prints -- but had refused to enter adjacent traps.

"We suspect it may have survived an encounter with a trap in the past and become trap-shy."

The ranger cunningly replaced the peanut butter with a generous dose of rat poison, which was all gone the next day.

"We haven't found its body but we're confident the rat is dead as it's eaten six pellets of poison bait and two pellets are a lethal dose," Mr Butland said.

DOC Auckland area biodiversity manager Phil Brown said trappers had tried no less than 30 different tactics to try to find the marauding rodent.

"We had all sorts of different types of traps and all sorts of different baits -- we tried many, many things in combination of baiting, tracking and trapping."

DOC had set 231 traps for the rat and a ranger had been hunting it for about four weeks.

Auckland Council had also provided two specialist rat-sniffing dogs and dog handlers, who worked for about 10 days.

"We were quietly confident that we would win the battle, it was just a matter of time. That's not to say I didn't lose a bit of sleep over it by about the second week when it still hadn't gone into a trap," Mr Brown said.

Some of the rat's hairs were found in the tunnel and DNA tested, which established that it was a Norway rat, not a ship rat, as was previously thought.

DOC has been treating Rangitoto and neighbouring Motutapu Island as pest free after conducting an eradication programme to remove rats, mice, stoats, feral cats, hedgehogs and rabbits from the islands in 2009. Possums and wallabies were removed in the 1990s.

DOC said the pest eradication would enable the islands to become one of the country's largest sanctuaries for endangered wildlife.

- NZPA