On the other side to Sir Ed is the scene of one of our greatest conservation triumphs. Allison Hess explains.

Stuffed into your wallet or passed across the till, the New Zealand $5 note circulates largely unobserved. But if you were to take a closer look at the ubiquitous burnt orange bill, you would see clues from one of the world’s monumental conservation triumphs. 

Most would recognise Sir Edmund Hillary, whose craggy face graces one side of the note. But how many of us know the story on the other side? Four clues feature: a tall penguin with yellow goggles, an island view, a tuft of funny-looking yellow flowers, and a bouquet of purple daisies.

It’s a scene from Motu Ihupuku (Campbell Island), the southernmost of our subantarctic islands and a UNESCO World Heritage Area. Hoiho (yellow-eyed penguin) live and breed there, Ross lilies produce spectacular yellow flower heads and Campbell Island daisies are megaherbs that only grow in the region. When the bill was first designed in the 1990s, the reality of life on the island was far less idyllic than pictured.

For nearly 200 years, rats ruled the 11,300-hectare island, decimating the endemic wildlife and earning Campbell Island the dreadful reputation of having the highest Norway rat population density known anywhere in the world.

A rich and extensive smorgasbord greeted Norway rats as they scampered unimpeded off whaling and sealing ships in the early 1800s. Rats have an extraordinary ability to colonise new habitats and food sources. On their menu were albatross eggs and chicks from seacliff nests, available in six species flavours every spring. Snipe and flightless teal made for easy meals as they fossicked along waterways and in the vegetation – that is, until the last few were forced to take refuge on rocky outlying islets. Parakeets and bellbirds disappeared completely down the throats of rats. Endemic insects and plants served as succulent side dishes, including ground wētā, giant slugs, weevils and megaherbs found nowhere else on earth.

By the early 2000s, the island’s rat population swelled to an estimated 200,000. They were the only introduced pests left on the island after feral sheep (the remains of a farming attempt gone awry) were removed, and feral cats had died out.

But the sheer size of the island, its consistently wet and windy weather, along with its isolation (700km south of Bluff through stormy seas) meant eradicating rats seemed like an impossible dream. But turns out New Zealand was up for the challenge.

In the world’s largest and most ambitious rat eradication operation at the time, Motu Ihupuku was blitzed with rat poison in the winter of 2001. 

The pros: a winter operation meant the penguins, albatross and skua would be at sea, away from the harmful helicopter blades and toxic bait. 

The cons: winter conditions in an already inclement region. The Department of Conservation (DOC) team tasked with the monumental mission would need 60 hours of relatively calm, clear weather to do the job. However, three out of four days on Campbell Island the wind blows 63 km/h, gusting up to 90 km/h. There’s an average of 12 hours of total sunshine in June. Rain falls 325 days a year. Temperatures barely rise above 6 degrees Celsius. 

In an unbelievable window of uncharacteristically good weather, the 19-strong eradication team spent only a month on the island spreading 120 tonnes of poison bait.

The advancement of technology like GPS-equipped helicopters (hot new tech in the early 2000s) was vital for covering the rugged terrain of Campbell Island. The helicopter pilots were carefully selected; not even the smallest gap in bait spread was permissible. Just a few missed rats would doom the operation to failure. GPS allowed pilots to see where they needed to fly with special bait-spreading buckets and recorded their routes to revisit any missed areas. 

In his account published by New Zealand Geographic, project leader Pete McClelland described the exceptional care and precision needed for sowing the bait – nowhere moreso than along the island’s seacliffs: “Not only was there the danger of vicious updrafts, but especial thoroughness was required to land sufficient bait on ledges and clefts likely to be frequented by rats.” 

Miraculously, the operation went without a hitch. 

In 2003 the island was officially declared rat-free. DOC was on a high: “If we can do Campbell, we can do almost anywhere in the world.”  With rats gone, teal and snipe returned from exile. Albatross could nest in peace. Storm petrels re-established themselves, and plants and insects bounced back. Humans also returned to the island – as tourists with special permits and under rigorous biosecurity procedures. Intrepid tour companies like Heritage Expeditions bring people to the captivating island to see the wildlife and megaherbs.

Campbell Island’s success set a new standard for island restoration projects and opened the possibility of further projects both at home and internationally.

The techniques and experience developed inspired predator eradication projects on other subantarctic islands. Macquarie Island (Australia) was cleared of rabbits, mice and rats in 2010. South Georgia Island (Britain) gained the title of the world’s largest island eradication project when rodents were removed from 100,000 hectares between 2011-2015.

Auckland Island is the only remaining island in the NZ subantarctic region where pigs, cats and goats roam free. The eradication project plan is ready, but funding woes have pushed the plan into hibernation.

It would be our biggest and most complex eradication job undertaken yet. Sound familiar?