Mousiraptor!

A report (http://www.guardian.co.uk/environment/2008/may/20/wildlife.endangeredspecies) suggests that House mice introduced about 150 years ago from whaling boats to Gough island (a British-owned, World Heritage site) in the South Atlantic have become a major predator of the chicks of endangered seabird species including petrel, shearwater and the Gough albatross. The mice (there are estimated to be more than 0.5m on this small island of about 6500 hectares) can reportedly reach about three times the size of their commensal cousins (circa 100g) and have switched their diet from seeds, spiders and insects (presumably in short supply on Gough) to eating the defenseless chicks of ground nesting birds. Although the fat-rich chicks are much larger than their 'predators' (they are more than 300 times their size), the parent birds cannot defend them when the mice 'attack' the nests at night (mice are generally nocturnal whereas the birds depend on vision). It has been estimated that currently the mortality of chicks on the island has reached 60%. The birds essentially nest on the island because it was free of terrestrial mammal predators. This lack has apparently also benefited the mice (normally limited by cats, owls and birds of prey) allowing them to increase in size without becoming more prone to being attacked. The RSPB are horrified by this development but one can't help being impressed by how the highly adaptable House mouse has evolved to exploit this niche! Of course, if unchecked, the situation is likely to be unsustainable (once the birds stop breeding in numbers, the mice will have little to eat and their numbers are likely to crash). Looks like another job for the removers of inadvertently introduced species!