Giant carnivorous mice on the British-ruled island of Gough in the south Atlantic are eating seabird chicks alive in mass feeding frenzies, threatening several species' survival.
London, Great Britain -- The house mice, while three times the size of those seen in mainland Britain, are still only one 250th the size of the chicks they attack, the Royal Society for the Protection of Birds (RSPB) said Monday.
The mice, which strike at night in large numbers, are devouring more than one million petrel, shearwater and albatross chicks on Gough Island every year, the charity warned.
The island, a UN World Heritage site in the South Atlantic, is the most important seabird colony on the planet, hosting more than 10 million birds. It is one of the Tristan da Cunha group of islands, a British overseas territory.
"Gough Island hosts an astonishing community of seabirds, and the catastrophe could make many extinct within decades," said Geoff Hilton, a senior research biologist at the RSPB.
"We think there are about 700,000 mice which have somehow learned to eat chicks live, much like blue tits learned to peck milk bottle tops," he said.
"The albatross chicks weigh up to ten kilograms (22 pounds), and ironically albatrosses evolved to nest on Gough because it had no mammal predators -- that is why they are so vulnerable," he said.
"The mice weigh just 35 grams (1.235 ounces). It is like a tabby cat attacking a hippopotamus."
In a pattern only ever seen on Gough Island, one mouse attacks a chick and the resultant blood appears to attract others, who gnaw into the defenceless chick's body, creating a gaping wound until it dies.
The chicks are more or less immobile and unable to defend themselves, Hilton said.
"Without predators this would not be a problem, but for a carnivorous mouse population one of the wettest and windiest places on earth it is an easy meal of almost unimaginable quality," he said.
"The result is carnage."
Scientists suspect that the mice are also eating the eggs and chicks of the rare ground-nesting Gough bunting, a small finch found nowhere else in the world.
Researchers think the finch has been forced from the best nesting sites into less suitable uplands areas.
The Gough mouse is one of 2,900 non-native species damaging native wildlife in the 17 UK Overseas Territories and Crown Dependencies, a review by the Joint Nature Conservation Committee has found.
Gough Island hosts 99 percent of the world's Tristan albatross and Atlantic petrel populations, the birds most often attacked. Just 2,000 Tristan albatross pairs remain.