Rats were brought to the islands by sailors 100 years ago

About 10,000 rodents on Canna, which lies south of Skye, pose a serious threat to colonies of rare seabirds.

Over the past three decades their numbers have dropped dramatically, with Manx Shearwaters hit hardest.

However, before the rats can be destroyed scientists must catch and remove several hundred rare wood mice.

A team from Edinburgh Zoo will catch the mice and take them to the mainland for safekeeping.

They will be re-introduced when the rats have been eradicated.

The common brown rat was accidentally introduced to Canna by sailors more than 100 years ago.

Over the next nine months experts from New Zealand will lay bait every 50 metres, even abseiling over cliffs to ensure that every rat is dead.