Turning the tide – what it takes to take out rats

Kate Evans visits a passionate team as they carpet a remote volcanic island in Tonga with poisoned bait, hoping to eradicate rats. What does it take to complete this kind of project, what are the chances of success, and what will it mean for the island's ecosystems if they manage to remove the rats once and for all?

Rat eradication from islands is a team sport. It's not a competition - but if it were, New Zealand would surely be up there. That's why on most pest removal teams around the world you can probably find one or two Kiwis right in the thick of things.

It takes a village

A team lined up to complete the rat eradication project for the island of Late in the kingdom of Tonga is no different. The New Zealand Department of Conservation is supporting the operation and have provided some skilled staff. The helicopter team (pilot, engineer, ground crew) are all Kiwi too.

They're joined by a project manager from the NGO Island Conservation, and Tongan conservationists from the national environment department.

Years of feasibility studies, finding funding, planning and logistics have come down to this - a second, and final, aerial application of poisoned bait across the island.

Island paradise

It may not be what you picture when you think of a tropical island, but its jagged basalt cliffs and remoteness has made volcanic Late a potential wildlife haven.

Here you can find the Tongan whistler and ground dove, two rare birds on the IUCN red list of threatened species. And it has the habitat needed for the malau - the Tongan megapode - to breed. Malau don't incubate eggs by sitting on them, instead they bury them in warm volcanic soils and sands, and Late's smoking surface is perfect.

Rat eradications elsewhere have allowed forests to rejuvenate, land birds to rebound and seabirds to return. The bird guano ripples the effect out further - feeding the coral reefs and allowing nearby ocean ecosystems to flourish.

Science journalist Kate Evans joins the team on the last day of bait spreading, in what they hope will be the first day of a bright future for the island and its inhabitants. …

Go to this episode on rnz.co.nz for more details