Department of Conservation wins award for rat eradication

The Department of Conservation won an innovation award yesterday (14 October) for the eradication of rats from Campbell Island.

DOC’s win in the Management of Innovation category and commendation in the Central Government category of the BearingPoint Innovation Awards 2003 for the Campbell Is project were announced yesterday (14 October) at a ceremony in Wellington, attended by Prime Minister Helen Clark.

“On the face of it, eradicating rats from a 11,300 ha island, a five-hour helicopter flight south of Invercargill in sub-antarctic winter conditions, was Mission Impossible,” DOC director–general Hugh Logan said today (October 15), on receiving the award.

“Rat eradication had never been done at such an inhospitable site, and a potentially dangerous one for helicopter pilots. We achieved it with careful planning, risk management, engineering and applying technology to an exacting level of detail.”

A world heritage site, Campbell Is had been home to Norway rats for the last 200 years. Their removal in winter 2001 has already benefited conservation of the island’s native plants and animals, in particular endangered albatross and other seabird species. In May this year, a survey confirmed no trace of rats on Campbell Island.

Ensuring an even and lethal spread of baits throughout the island during the optimal winter period - when rats are hungry, not breeding, and seabirds absent – was five years in planning and budgeted at more than $2.5 million.

Prototype rat eradications at Kapiti Island and at Codfish Island made during the planning period, as well as bait design modifications and refinement of bait spreading hoppers, improved the chances of success, Mr Logan said.

World class helicopter work during the operation was a key success factor, Mr Logan said.

“The five pilots risked their lives flying their craft 700km to Campbell Island – we offset the risks as far as we could with detailed monitoring of weather conditions.”

Dyed non-toxic baits laid at half the normal poisoning density of 6kg a hectare confirmed that all rats in a 600 ha test area ate baits. That, and avoiding the normally-undertaken back-up bait laying operation, allowed DOC to ratchet down the bait dosage to 25 per cent of that used at Kapiti Island.

That done, two helicopters shifted 120 tonnes of baits from a ship moored offshore onto the island and the other three flew bait spreading missions during gaps in storms and long periods of low blanketing cloud cover. It took a month, one-third of the time budgeted, thanks to better than expected weather conditions.

Overlapping of bait drops were built into the project, based on likely movement of rats between bait drops.

Until Campbell Island, rodents were regarded as impossible to eradicate from all but relatively small areas because they can learn to avoid baits and traps, develop resistance to poisons and they breed very quickly. It takes only one pregnant female escaping a poisoning operation to repopulate an island.

New Zealanders – internationally-recognised world leaders in pest control - are currently running pest eradication programmes at locations such as Australia, Mauritius, the Seychelles, St Paul, and the Falkland Islands.

Based on the Campbell Is experience, DOC has mounted a multi-species eradication project on Raoul Island in the Kermadec Islands north of New Zealand, now nearing completion.

Mr Logan said the $1000 cheque awarded to DOC would be used for an innovation award within the department.

Helicopter companies participating in the Campbell Is project were: Peter Garden Helicopters Ltd (Gore), Southern Lakes Helicopters Ltd (Te Anau), Helicopters Otago, Wanganui Aeroworks, Heliworks Queenstown.

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