The All Ireland Squirrel Survey 2012 has found that only red squirrels can be found in counties Donegal, Tyrone, Fermanagh, Leitrim and Sligo.
The findings are in dramatic contrast with the rest of the country where the grey squirrel is ousting the red squirrel.
According to Dr Michael Carey, who helped conduct the survey, there has been a dramatic increase in grey squirrels since 2007 but not in Donegal.
“The grey squirrel is a major threat to the survival of the native red squirrel and to the future of broadleaf trees. Recently there have been reports of two cases of the pox virus in Co Wicklow and another in Antrim. The disease is lethal to the native reds and carried by grey squirrels.
“With the increased planting of broadleaf trees over the last two decades, woodland owners and the public need to be vigilant with regard to the threat posed by grey squirrels and on the extent to which they can destroy vigorous healthy trees through bark stripping and eliminate red squirrels.
“The new survey aims to pin point the most vulnerable areas in the country and ensure strategies are in place to minimize further tree damage and spread of the pest,” he said.
Sightings can be easily recorded on a form on www.woodlandmammals.com. Hard copies of the form are also available from Ms Margaret Flaherty, Mammal Ecology Group, Martin Ryan Institute, NUI, Galway.