Water voles in Lochalsh and Wester Ross are under threat from a non-native predator, Highland Council has warned.
American mink prey on the small animals and have been blamed for almost wiping out ground-nesting birds on Sandaig and the Sound of Sleat on Skye.
The council and Scottish Natural Heritage (SNH) have secured European funding to survey mink numbers in Skye and Lochalsh.
Volunteers have been sought to carry out the work in August and next April.
Fifty locations will be targeted and evidence gathered will be used to justify a programme of eradiction similar to the Hebridean Mink Project.
Roger Cottis, a member of the Mammal Society, said the plan was to trap and humanely kill mink.
He said: "As a non native invasive species, American mink need to be removed from our environment.
"However, we need to provide good quality scientific evidence of their presence in order to attract sufficient funding to move to the second phase of the project, that of humane eradication."
Rob Raynor, SNH mammals' advisory officer, added: "The distribution of mink in the north west of Scotland is patchy and we welcome this initiative because it will provide a much clearer picture of mink distribution in Skye and Lochalsh, thereby informing any possible future management decisions."
Highland Council said water vole populations in Lochalsh and Wester Ross were threatened by mink that had spread northwards from Argyll.
The mink escaped and were illegally released from fur farms.
The mammal has been blamed for declines in ground-nesting wild birds - such as Arctic tern, common tern, black-throated diver and corncrakes - on the Western Isles.
Started in 2001, the Hebridean Mink Project has entered its final year. So far 1,232 mink have been killed.