A project aimed at protecting internationally important seabird populations on two of the Isles of Scilly by killing more than 3,000 brown rats, is under way.
The islands, which are located off Cornwall, are home to breeding populations of 14 seabird species and approximately 20,000 birds.
Eradication experts from New Zealand and the UK have been contracted to carry out the work.
"Among many challenges our seabirds face, the greatest threat on land is predation of eggs and chicks by brown rats," said Jaclyn Pearson from the Isles of Scilly Seabird Recovery Project.
"The brown rats were accidently introduced to islands from shipwrecks in the 18th Century," she added.
The project is part of a 25-year programme to protect "internationally important" seabird numbers, including those of Manx shearwaters and storm petrels, and is costing more than £755,000.
The rodents will be poisoned on St Agnes and Gugh by Wildlife Management International Limited (WMIL).