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How much does it cost to save an endangered species? For the dark herald
petrel the price is a modest £47 500.

Most of the world’s dark herald petrels live on the Pitcairn Islands,
a British dependent territory in the middle of the Pacific, 5000 kilometres
from New Zealand. They are being eaten by the islands’ colonies of introduced
Polynesian rats faster than they can reproduce.

Britain has designated the petrel’s main stronghold, the rat-infested
Henderson Island, as a World Heritage Site. ‘The obvious solution would
be to eradicate rats from Henderson,’ says Michael Brooke, a zoologist at
the University of Cambridge. ‘But this is impractical given its size, 37
square kilometres.’

The next best option, says Brooke, is to provide a safe haven for the
birds on a smaller island, ‘and trust that the birds have the wit to utilise
it’. He proposes eradicating the rats from Oeno, a nearby coral island that
covers just 65 hectares.

The proposal is contained in a draft management plan for Henderson
Island, written by Brooke and his colleagues following a government-sponsored
expedition to the island two years ago. But that plan is still being shuffled
between Whitehall departments. The Foreign Office, the Department of the
Environment, the Joint Nature Conservation Committee, the British High Commission
in New Zealand and Pitcairn’s Island Council, which represents the fifty
local residents, all have a say.

Last month, Foreign Office minister Alastair Goodlad told Tam Dalyell
MP that the government would not do anything about the rat problem until
it was sure that any solution would not be prohibitively expensive. Now
he has his answer: a £47 500 proposal to lay poisoned bait to kill
the rats of Oeno, prepared by Wildlife Management International, a company
in Wellington which specialises in removing rats from islands around New
Zealand.

The company says that it will require 2 tonnes of pellets containing
the anticoagulant brodifacoum to clear Oeno of its rats. There are, it
says, some ‘non-target species to be considered’. The most important of
these are crabs. While crabs are not directly affected by the poison, they
accumulate it in their bodies, which could be a problem if birds eat the
crabs.