Typical of islands, Tristan and Gough have had their fair share of unwelcome guests in the form of mice, rats, pigs, goats, cats and most detrimentally marauding sailors! These alien species have had noticeable impacts on the bird populations, especially breeding seabirds which were targeted for meat and eggs. Most alien species have largely been eradicated; House Mouse Mus musculus is the only remaining alien mammal on Gough. Gough was declared a Wildlife Reserve in 1976 and a World Heritage Site in 1995. In 1997 44% of Tristan’s land area was officially protected (Shirihai, 2002).
19th May 2008: Giant carnivorous mice threaten world's greatest seabird colony
Whalers who visited remote Gough Island in the South Atlantic 150 years ago described a prelapsarian world where millions of birds lived without predators and where a man could barely walk because he would trip over their nests. Today the British-owned island, described as the most important seabird colony in the world, still hosts 22 breeding bird species and is a world heritage site. But Gough is the stage for one of nature's greatest horror shows. One of those whaling boats, probably from Britain, carried a few house mice stowaways who jumped ship on Gough. Now there are 700,000 or more of them on the island, which is the size of Guernsey.
What is horrifying ornithgologists is that the humble house mouse which landed on Gough has somehow evolved to two or even three times the size of an ordinary British house mice, and instead of being a vegetarian, eating insects and seeds, has adapted itself to become a carnivore, eating albatross, petrel and shearwater chicks alive in their nests. They are now believed to be the largest mice found anywhere in the world.
Yesterday, Birdlife International, a global alliance of conservation groups, recognised that the mutant mice, who are without predators themselves, are now completely out of control and are threatening to make extinct several of the world's rarest bird species.
The organisation, which runs the Red List of endangered bird species, raised both the Tristan Albatross, of which only a few remain in the world, and the Gough Bunting, a small finch found nowhere else in the world, on to the list of the world's most critically endangered species, the highest category of threat. Five other bird species on the island are also said to be threatened.
"Things are getting worse on Gough. In the presence of house mice, the albatross and bunting have no chance of survival. The only hope for these threatened birds is the complete eradication of mice", said Dr Geoff Hilton, an RSPB scientist who has been researching conservation problems in UK overseas territories.
"The world's greatest seabird island is being eaten alive, as the mice are likely to be affecting the fortunes of many seabirds on the island. Without help, Gough Island will be likely to lose the majority of seabirds," said Hilton. Studies suggest that about 60% of all Gough's bird chicks die in their nests, probably because of predation by the mice. "It is a catastrophe. The albatross chicks weigh up to 10kgs. Ironically, they evolved on Gough because it had no mammal predators - that is why they are so vulnerable. The mice weigh just 35g; it is like a tabby cat attacking a hippopotamus", said Hilton.