13 Feb 2019

Momentous mission: first successful invasive species removal in Marquesas

Conservationists leaped from boats onto sheer rock faces and braved “10,000 dive-bombing Sooty Terns” to achieve the first successful eradication of invasive rodents on Teuaua Island, French Polynesia. This success paves the way for larger island restorations across the Marquesas Archipelago.

Teuaua is home to 90,000 Sooty Terns - one of the nation's largest colonies © Island Conservation
Teuaua is home to 90,000 Sooty Terns - one of the nation's largest colonies © Island Conservation
By Jessica Law

As your boat nears the island, you brace yourself, knowing you can’t lose your nerve now – you don’t have much time. At the very last minute, you leap off the hull and scramble onto the narrow, metre-wide ledge. But you can’t relax yet. You gaze up at the ten-metre vertical cliff face looming above you, with nothing but ropes to get yourself to the top. And it isn’t until you’ve hauled yourself and your equipment onto the island that the real challenge begins. That’s when the sky fills with Sooty Terns swooping down upon you to defend their nests – the very birds that you’re trying to help.

Such was the everyday challenge for field scientists like Jason Zito, restoration specialist from BirdLife’s partner in the operation, Island Conservation. “Once on the island’s plateau, there is no respite from the elements and the tens of thousands of dive-bombing and screeching Sooty Terns make it hard to hear yourself think,” he recalls.

BirdLife joined forces with local conservation groups to restore the island © Island Conservation

Nonetheless, everyone involved in the project would tell you that it’s worth it. Teuaua, a small, uninhabited island in the Marquesas Archipelago, French Polynesia, is home to 90,000 Sooty Terns Onychoprion fuscatus – one of the nation’s largest colonies. These stylish black-and-white seabirds rub shoulders with nationally significant populations of Bulwer’s Petrel Bulweria bulwerii and many others.

“This island is a critical habitat for breeding and roosting seabirds and offers a glimpse into the once-rich coastal ecosystems that existed across the Marquesas archipelago,” explains SOP Manu project manager Tehani Withers – a winner of BirdLife’s Young Conservation Leadership Awards 2018, who has continued to lead the island restoration work.

The Sooty Tern can now raise its young in safety © Island Conservation

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However, for decades non-native rats had been devouring hundreds of seabirds’ eggs and chicks, even munching up the island’s native vegetation as a side salad. If allowed to continue, these populations could eventually have been lost altogether. And so BirdLife and SOP Manu (BirdLife in French Polynesia) joined forces with Island Conservation and Association Vai ku’a i te manu o Ua Huka to launch a large-scale restoration of this unique ecosystem.

It wasn’t easy. Despite its diminutive size, Teuaua Island is difficult to access and offers little shelter from the buffeting wind and scorching sun. But after months of courage, skill and pure stubbornness, the team could finally proclaim the island to be predator-free.

Teuaua island is uninhabited and difficult to access © Island Conservation

The future now looks bright for the island’s resident birds, who can watch their chicks grow up sheltered by verdant natural plant life. The team also hopes that the restoration of the island may persuade species that had been driven out to make their home there once again.

“We are optimistic seabirds once present on the island may return, increasing the diversity of the island’s seabird community and security of threatened species like the Polynesian Storm-petrel [Nesofregetta fuliginosa – Endangered]” says Steve Cranwell, BirdLife International Pacific Seabird Programme Manager.

And it’s not just the birds on this island – the lessons learned from this success can be used to tackle the restoration of other Marquesan islands.

The techniques learned on this project can be scaled up to other islands © Island Conservation

“Teuaua demonstrates what can be achieved in the Marquesas. It is seen as an important stepping stone to much larger, more complex restoration projects such as Hatuta’a and Mohotani. Restoration of these islands would improve the fortune of two Endangered terrestrial bird species and two Endangered seabird species that call the Marquesas home.”

The local community are also keen to continue working with the partnership. They offered invaluable support to the team throughout the project, providing food and accommodation, and without their sailing expertise, the restoration may not have been possible.

"We would like to continue to work with you on these type of projects in the future: it is great to have people from outside visiting our island and helping us protect our environment," says Florida Brown, president of the local environmental NGO Vai ku’a i te manu o Ua Huka (which means protecting birds of Ua Huka).

Local people's boating expertise made the project possible © Island Conservation

The benefits of healthy seabird populations stretch far further than the islands on which they live. Seabirds travel far out to sea, eating the fish they find there, and when they get back, they recycle these nutrients into the soil in the form of phosphate-rich droppings, known as guano. An island that might otherwise just have been barren rock can suddenly support plants and the land animals that depend on them. These nutrients also wash off into the nearby ocean, enriching the waters. In fact, studies have shown that on islands free of invasive seabird predators, coral reefs thrive, with fish growing larger and faster for their age compared to islands where these predators still thrive.

With Teuaua now free of rats, the Marquesan community and other project stakeholders can focus on planning the restoration of the six other uninhabited islands within the Archipelago. However, to do this, they will need to find the estimated $3M USD needed to implement this ambitious conservation project, which will require a support ship and helicopter. Once properly equipped, they will be able to spring into action straight away, armed with the tried-and-tested skills and knowledge gained from this successful pilot scheme.

Help us to restore paradise: support the Marquesas restoration project here.

We are grateful for the support of the David and Lucile Packard Foundation, without which this successful operation would not have been possible.