Conservationists from the charity Trees for Life are planning to reintroduce the endangered species in up to eight forests after the success of similar work in other areas of north-west Scotland.
Now they have launched the Reds Return appeal to raise £22,000 to fund the work, which involves capturing red squirrels from thriving colonies in the north-east of Scotland and relocating them to suitable habitats on the other side of the country.
The latest sites have not yet been finalised, but are likely to be located on the Morvern peninsula and north of the Dornoch Firth.
The team is planning the latest move after releasing 140 of the animals in locations including Plockton, Shieldaig, Kinlochewe and Poolewe over the past three years.
Estimates suggest there are only 120,000 red squirrels left in Scotland, which is the UK stronghold for the species.
The main threat to their survival comes from the alien grey squirrel, which was introduced from north America in the 1800s.
Larger greys can out-compete their native counterparts for food and nest sites, while also spreading diseases such as squirrel pox – this causes no harm to invasive greys but is deadly to reds. Loss of pine forests has also contributed to declines.
Grey numbers have rocketed over the years, with the United Kingdom-wide population now standing at around three million compared to a total of 160,000 reds.
Work, including culls, is ongoing to try to limit their spread northward.
Experts say the west Highlands has ideal territory for establishing new colonies of reds because woodlands there are cut off from places with established grey populations and so provide a natural safe haven for native squirrels.
They says the presence of red squirrels will also help regenerate and expand native pine forests in the region, as any uneaten winter stores of nuts and seeds left buried will eventually grow into trees.
“Although one of our best-loved wild animals, red squirrels are sadly missing from suitable woodlands across the Highlands,” said Steve Micklewright, Trees for Life’s chief executive.
“They cannot reach these isolated havens on their own because they avoid crossing large open spaces. Every donation will help us reintroduce red squirrels to ideal forest habitats. Returning them to forests safe from grey squirrels will help conserve this charismatic species for ever.”