Rakino rats on the way out

Rakino Island’s population of troublesome Norway rats is down and probably out thanks to a successful joint community pest eradication initiative.

For many years the Norway rat has wreaked havoc on the 146 hectare island. Specimens measuring up to 42cm long have been found on Rakino where the high numbers of the rats have habitually posed a nuisance and even a health risk to residents and bach owners.

The Norway rat preys on the eggs and young chicks of seabirds like the blue penguin and this rat was probably responsible for exterminating the grey-faced petrel from Rakino.

The Norway rat is thought to have been accidentally introduced to New Zealand in 1774 from Captain Cook’s ship Resolution. In 1959, Norway rats are believed to have been responsible for the deaths of hundreds of white-faced storm petrels on Maria Island in the Noises. The Norway rat which is an excellent swimmer is thought to have periodically reinvaded the Noises Islands from Rakino frustrating the Department of Conservation’s attempts to keep these high conservation value islands rat free.

But Auckland Regional Council member and Hauraki Gulf conservationist Mike Lee says the ARC, supported by Auckland City Council, (through the efforts of Waiheke Community Board member Nettie Johnstone), and with practical advice from the Department of Conservation and Auckland University School of Biological Sciences, the volunteer labour of the School of Outdoor Studies and the Rakino Ratepayers Association has initiated a programme which appears to have finally cleared the island of rats.

Mike Lee a long term advocate for the eradication of rats from Rakino had been involved in two previous unsuccessful attempts to eliminate rats from the island, and had strongly lobbied for the programme to go ahead.

“The operation worked this time because we had the unanimous support of all the residents and the resources of a coalition of public agencies behind it,“ Cr Lee says.

The programme was directed by ARC Biosecurity manager Steve Hix, who also managed the successful ARC Operation ForestSave possum control programme in the Waitakere ranges.

Mr Hix says that a grid network of approximately 720 bait stations using Talon brodifaum anti-coagulant poison, was laid on the island in early August and three months later, all stations have become inactive indicating that the rat population has been exterminated or is very close to it.

Mr Hix says all parties deserve to be congratulated for their efforts to eradicate the rats.

“Everyone involved has done a great job but I would urge continued vigilance to ensure Rakino does not become re-infested with Norway rats,” he says.

“Rakino residents and anyone travelling to and from the island need to be extremely careful. Boat owners should check their loads to ensure there are no unwanted intruders and residents should keep a sharp look out over the next few months.”

The ARC has provided the island’s residents with tracking tunnels and rat traps enable monitoring and response to any new sightings.

Cr Lee says, “Rat eradication programmes are normally carried our using aerial drops of poison. This was not feasible in the case of Rakino where there is a permanent population and where people collect their water from their roofs. Rakino because it has extensive areas of rank Kikuyu grass, which forms mats sometimes waist deep, can be a difficult place to work,” he says. “If successful, this is one of the larger rodent eradication programmes carried out on an island in New Zealand”.

He says the progressive elimination of pests from islands, especially rats is a vital objective in the restoration of ecosystems on all of the Hauraki Gulf Islands which now form the Hauraki Gulf Marine Park. Cr Lee said the ARC led initiative on Rakino was “walking the talk” - a putting into action the purposes and principles of the Hauraki Gulf Marine Park.

Cr Lee says if the Rakino programme is confirmed to be successful, it raises the question of the eradication of rats from neighbouring Motutapu/Rangitoto Islands. “This should be next big objective on the conservationist agenda. Such an achievement would allow the return of native birds to these islands be the ultimate prize for conservation for Auckland and the inner Hauraki Gulf.”

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