Conservationists believe Wales may have its own "pure" race of red squirrels.
The red squirrel exists in some isolated areas in Wales
A project to find out more about the elusive mammal has started in the coniferous forests of mid Wales.
Researchers say that, because the population is so isolated, the bloodline could be one of the purest in the UK.
Numbers are in serious decline. In Wales, there are just a few sites where red squirrel live - in Gwynedd, Clwyd, and central Wales.
A two-year study is being carried out by the Mid Wales Red Squirrel Project - a partnership which includes the Wildlife Trust of South and West Wales, the Countryside Council for Wales (CCW), the Forestry Commission, private woodland managers, and Carmarthenshire, Powys, and Ceredigion councils.
The work will concentrate on the squirrels known to live in the Tywi, Irfon and Crychan Forests.
Richard Dodd, senior conservation officer with the Wildlife Trust of South and West Wales, said funding had been received from CCW to employ a surveyor to carry out the work.
"The isolated nature of the squirrels in central Wales may mean they are a very pure race of 'Welsh' red squirrels," he said.
"Any opportunity to increase our knowledge of the animal is important.
The grey squirrel competes with the red for food
"This may our last chance to save this population of red squirrels, so the success of this project is very important."
Recent research has showed that the majority of the red squirrels in the UK have Scandinavian ancestry.
The mammal is widespread in many parts of europe, but has largely been replaced by the grey squirrel in England and Wales.
There are around 2.5m greys in the UK, but only about 160,000 reds.
Posters, explaining the plight of the reds, are being put up in the survey areas to raise awareness of the project and to ask people to let the Wildlife Trust know if they see any red squirrels.
Project officer Anna Hobbs will set traps baited with the squirrels' favourite food, in the hope of catching some of these rare animals, starting in the forests above Llyn Brianne Reservoir in Carmarthenshire.
She aims to record as much information as possible about them before releasing them back into the forest.
Two red squirrels were caught during a recent trapping session carried out in privately-owned forests at nearby Bryn Arau Duon..
Any grey squirrels that are trapped during the survey work will be humanely destroyed.