Concerted action will be needed in order to protect Ireland's population of red squirrels, authors of the Irish Squirrel Survey 2007 announced yesterday.
Undertaken in January by the National Council for Forest Research & Development, the survey concluded that the native red squirrel has disappeared from counties Meath and Westmeath and is under threat in many others, largely due to the spread of the more aggressive North American grey squirrel.
"The grey is chasing the red west," said Minister of State for Forestry Mary Wallace in introducing the survey results. "The grey is literally the tree rat," she added, noting the importance of educating people on the difference between the two species.
Greys pose a threat to the broadleaf trees which serve as the habitat for both species, the survey said, as greys regularly strip trees of their bark. Additionally, greys have a significant advantage with regard to the food supply - they can more readily digest acorns that are not yet ripe enough for red squirrels to eat.
Grey squirrels have also been found to carry squirrel pox virus antibodies, outbreaks of which can cause rapid losses in red squirrel populations.
Since its 1911 introduction to Ireland at Castleforbes, Co Longford, the grey squirrel has expanded its territory rapidly. The most dramatic gains in the last 10 years have been in Wexford and Wicklow; during the time period, greys have colonised an additional 50km in the region. Forestry consultant and project leader Dr Michael Carey said the results serve as a "wake-up call. The survey has also made me much more aware of the complex issues surrounding biodiversity and the fine balance in nature between one species and another . . . and the absolute need for reliable scientific data before any action is taken," he said.
A possible link between increases in pine marten populations and that of red squirrels gave survey authors reason to be cautiously optimistic. Pine martens are the only potential major predator of squirrels in Ireland. Some evidence exists that in areas of the country where pine martens have spread, likely as a result of legislative protection and tree planting initiatives, grey squirrels have also declined, though a direct link cannot yet be claimed.