October 20, 2005

Rat outsmarts scientists for four months

LONDON (Reuters) - A cunning rat released on a deserted
island off New Zealand outsmarted scientists and evaded traps,
baits and sniffer dogs before being captured four months later
on a neighboring island, researchers said Wednesday.

Scientists from the University of Auckland in New Zealand
released the Norway rat on the 9.5-hectare (23.5-acre) island
of Motuhoropapa to find out why rats are so difficult to

They got more than they bargained for.

"Our findings confirm that eliminating a single invading
rat is disproportionately difficult," James Russell and his
colleagues said in a report in the science journal Nature.

Despite all their efforts, including fitting the rat with a
radio collar, they couldn't catch the crafty creature.

After 10 weeks on the island the rodent decided it had had
enough. It swam 400 meters, the longest distance recorded for a
rat across open sea, to another rat-free island where it was
eventually captured in a trap baited with penguin meat several
weeks later.

The Norway rat, which is also called the brown or sewer
rat, is a husky rodent that weighs about 11 ounces (312 gram)
and has a long tail.

Invading rats on remote islands off the coast of New
Zealand have been a recurring problem. Norway rats have invaded
the uninhabited Noises Islands at least six times between 1981
and 2002.

"Our results may help in the design of conservation
strategies to keep islands free of invasive rodents," Russell
and team added.