Killer mice hit seabird chicks

Science News,  April 28, 2007  

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Gangs of mice have been caught on surveillance video nibbling to death rare seabird chicks on a remote island.

Conservation biologists haven't worried much about mice, according to Ross Wanless of the University of Cape Town in South Africa. Programs to wipe out the rats on islands get far more attention and money.

Ordinary house mice are the only non-native mammals on Gough Island in the south Atlantic. That's the breeding site for what may be the last self-sustaining populations of the Tristan albatross (Diomedea dabbenena) and the Atlantic petrel (Pterodroma incerta). In 2000-2001, year-round monitoring found unusually high chick losses.

Researchers returned to the island in 2003 with video cameras. They recorded mice poking around petrel burrows and killing six chicks. The researchers also recorded fatal attacks on two albatross chicks (for a sometimes-disturbing video, see www. sciencenews.org/20070428/mouse.wmv).

The albatross chicks weigh several hundred times as much as a mouse and can fend off attacks by big predatory birds. Yet the chicks don't fight off the tiny mice. The raids didn't kill albatross chicks immediately, but repeated feeding by up to 10 mice at a time finally did in the birds.

It's rare for mice to be the only invasive mammals on an island, so their menace may have been overlooked, Wanless and his colleagues note in a paper now online and in an upcoming Biology Letters. They caution that ridding islands of cats or other predators of native wildlife may be ineffective unless the mice go too.--S.M.

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