A Polynesian rat approaches a Laysan albatross's nest on Hawaii's Kure Atoll. Such boldness has helped rats around the world prey on about a quarter of all seabird species, a new study says.
Some birds are more vulnerable to rats than others.
"Rats can have a larger impact on entire seabird populations in species with adults that are small enough to prey on," said Yale University's Holly Jones, lead author of the study released in February 2008.
"Burrow-and crevice-nesting seabirds share the same underground habitat [as rats], which makes a predation encounter more likely," Jones said.