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Non-native mammals poised to fuel bird extinction crisis

7 July 2010

Grahame Madge
Media Officer

Put together, the UK’s overseas territories are fifth in the world league table of bird extinctions, with at least ten species from the territories going to oblivion since 1500AD, partially or wholly because of the impact of non-native mammals, such as rats, feral cats, mice and pigs.

At an evening reception last night at the Foreign and Commonwealth Office, Sir David Attenborough highlighted the concern surrounding Henderson Island, where non-native rats are threatening several birds with extinction. Sir David Attenborough - an RSPB Vice President - has long been concerned about the unique wildlife of remote islands.  Commenting on importance of Henderson Island for birds, he said: “All of these birds are under threat because of Pacific rats, one of the few human legacies. Rats simply cannot resist eating a fluffy day-old petrel chick. Luckily, technical expertise is advancing in leaps and bounds. We now have an opportunity to rid Henderson forever of the rats and ensure the island remains a natural jewel.”

Continued impact

Across the territories, 33 species of bird are facing extinction on the UK overseas territories and a new report shows that many of these are under threat because of the continued impact of introduced mammals.

The report, published in the journal Ibis, shows that one third of the species facing extinction could be helped by the removal of non-native mammals from just seven island groups in the Atlantic, Caribbean and the Pacific.

The paper’s lead author is Dr Geoff Hilton, of the Wildfowl & Wetlands Trust and formerly of the RSPB. He said: “The territories are jewels of wildlife richness, many with unique species found nowhere else on earth. In addition to this the sheer density of birds on the UK overseas territories are simply staggering. In particular Gough Island and South Georgia contain tens of millions of seabirds, but both of these islands are threatened by non-native mammals.”

The RSPB’s Dr Richard Cuthbert was a co-author on the paper. He added: “Many countries around the world are removing introduced mammals from their islands, improving the fortunes for native species. The UK has ultimate responsibility for the wildlife occurring on our overseas territories and we are urging the government to take urgent action to protect these unique species.”

The paper’s authors have identified 11 islands or territories where urgent action to remove non-native mammals could make a difference to the conservation of birds facing extinction or those that are of global conservation concern.

With five species of bird found nowhere else on earth, Henderson Island – part of the Pitcairn group – is one of the richest wildlife islands in the world. However, non-native Pacific rats are threatening the future of several of these species. In particular, the rats are killing and eating 25,000 seabird chicks each year, including those of the Henderson petrel – a seabird with its only known breeding sites confined to the World Heritage site, which shares its name.

The catastrophic impact of invasive mammalian predators on birds of the UK Overseas Territories: a review and synthesis, GEOFF M. HILTON, RICHARD J. CUTHBERT, Ibis, Vol 152 Iss 3, pg 443-458,DOI: 10.1111/j.1474-919X.2010.01031.x,