An epic 16,700 mile voyage of conservation has set sail, with the objective of removing all rats from a remote Pacific island bird sanctuary to save the lives of thousands of chicks which are eaten alive by the human-introduced predators. Britain's Royal Society for the Protection of Birds (RSPB) in partnership with the US Fish & Wildlife Service and other nature conservancy projects is funding a world-leading mission to Henderson Island in the Pitcairn Islands. The project will cost £1.5 million ($2.4 million), of which the UK government has put up £400,000 ($645,000) and the rest is coming from other conservation groups and public donations.

Ground nesting petrels on Henderson Island by Richard Cuthbert/RSPB

The M.V. Aquila, which is expected to arrive at Henderson in August, has two helicopters and extensive equipment intended to eradicate all the rats and restore one of the world's most pristine islands, is part of a unique international partnership which will see a single ship complete three island restoration projects in turn on Palmyra Atoll (USA), in the Phoenix Islands Protected Area (PIPA, Kiribati) and on Henderson Island (UK), meaning the project will benefit from shared costs, equipment and technical expertise. Introduced Pacific rats are eating 25,000 petrel chicks on Henderson Island every year, and driving a unique seabird, the Henderson Petrel, which nests only on this one island, to extinction. By the time it returns to Seattle in September, the Aquila will have covered 16,700 miles (27,000 km).

Petrel chick being eaten on Henderson Island by Alve Henricson/RSPB

Tim Stowe, the RSPB's International Director, said: "This massive voyage right around the Pacific is a huge milestone. Given the very high costs and logistical complexities of getting aerial eradication equipment to remote island locations, such a multi-island restoration has been mooted in the Pacific for at least a decade. This partnership has allowed us to share the costs, and made it possible for these three important eradications to go ahead. On top of the financial benefits, being able to share expertise is priceless. It must also be said that this project would not have been possible without the generous contribution and support received from the UK Government, for which we are extremely grateful."

Rats were introduced to the Pacific islands by seafarers in the past. They have no predators and can multiply enormously. If only one pregnant female rat survives, the operation will have been a failure. However rats have successfully been eradicated from over 287 islands. No eradication using the aerial baiting methods has ever failed against this species of rats, so the RSPB consider it very unlikely that any will survive the poisoning. As an example, Campbell Island is the biggest island that has been successfully cleared, and one that had the highest population density of brown rats ever recorded in the world. Earthtimes reported previously on the Rodent Eradication Success in South Georgia.

M.V. Aquila by Kale Garcia/RSPB

Henderson Island: a remote idyll

Uninhabited, and with almost no human influence at all, this remote paradise is home to over 55 species found nowhere else on earth, including four unique land-birds, nine plant species, eight species of snail and dozens of invertebrates. The island's beaches, meanwhile, provide crucial nesting habitat for endangered marine turtles. All of which will benefit from the eradication which will restore the ecosystem of the whole island.

Pitcairn Islands location

Part of the UK's Pitcairn Overseas Territory and over 3,000 miles from the nearest continent, the island was declared a UN World Heritage Site in 1988, due to being the world's only forested atoll with its ecology virtually intact. In August last year, the UN warned that a rat eradication scheme was of 'critical importance to maintaining... the integrity of the property', and urged rapid action to protect the outstanding natural qualities for which the island was listed.

Richard Cuthbert is a conservation scientist with the RSPB and will be on Henderson Island during the eradication. He said: "Our research has shown that it's possible to get rid of these rats and reverse the seabird decline on Henderson. Without a full-scale eradication, the wildlife on this island faces a very bleak future, with the Henderson petrel sliding towards extinction". Highly experienced eradication experts will use two GPS-guided helicopters to methodically drop poison bait across the island. It will take two to three days for the entire island to be treated, with the whole operation being repeated one week later, so as to ensure no rats survive.

The endangered Henderson Petrel by Alve Henricson/RSPB

Rats were introduced by Polynesian settlers who once lived there and the rats have gone on to decimate the four species of petrel that live there. The Henderson petrel is the most vulnerable because the island is its only known breeding site. Research showed that around 95% of petrel chicks are eaten alive by rats within the first week of hatching and numbers of petrels have dropped from millions of pairs 800 years ago, to an estimated 40,000 now. The RSPB believes the ecosystem on the island will rapidly recover following the rat eradication, which will benefit wildlife across the island.

The project still needs donations so click below to contribute.

Top image: Henderson Island by Dave Williamson/RSPB

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Donations to Henderson Island Project