Pine martens: The red squirrel’s friend

Good news and red squirrels don't often mix, but recent events in Ireland suggest that they might confound the pessimism of conservationists and make a comeback. Colin Lawton of the National University of Ireland (NUI) Galway reports that the red's enemy, the grey squirrel, has declined substantially in Ireland's midland counties and the red, absent from much of the area for 30 years, is once again widespread.

NUI Galway scientists believe that a resurgent pine-marten population is the cause; these cat-sized, tree-climbing predators can kill greys, but perhaps the agility and lighter weight of the reds enable them to get away on to smaller branches that heavier pine martens can't access. Grey-squirrel remains-but not those of the red-have been found in pine-marten scats. Dr Lawton also thinks there may be more subtle impacts, such as martens causing stress in greys, which deters them from breeding.

The year 2011 was the centenary of the fateful introduction of greys when six pairs were released in Co Longford; as in the UK, it was the start of the native red squirrels' retreat. It remains to be seen whether pine martens could now become the salvation of the UK's reds.