October 2013 NUI Galway Study Finds Recovery in Numbers of Pine Marten, Ireland’s Most Elusive Mammal

NUI Galway and WIT study finds healthy numbers of Pine Marten in the Midlands, but rare in the East

An NUI Galway study on Ireland’s most elusive mammal, the native pine marten, is to be published in the European Journal of Wildlife Research. The study, which was collaboration between NUI Galway and Waterford Institute of Technology, was funded by The Irish Research Council and the European Squirrel Initiative, and led by Dr Emma Sheehy and Dr Colin Lawton of the Ryan Institute’s Mammal Ecology Group in NUI Galway. 

The study, which involved the use of DNA analysis to assess pine marten population abundance in the midlands and the east of Ireland, found that the pine marten has recovered to healthy numbers in the Irish midlands. “Pine marten numbers in the midlands appear to be slightly higher than other parts of Europe” says Dr Sheehy. “This is likely to be a result of both a lack of competition with other terrestrial mammal species, and the relatively warm winters and lack of seasonality we experience in Ireland, compared with much of the pine marten’s natural range. However, it is important to note that we actually know very little about the true potential of contemporary pine marten numbers in much of Europe, as pine marten populations have been decimated by human impacts historically as a result of hunting, persecution and deforestation.” 

The pine marten is a slow breeding species, very sensitive to loss of habitat and persecution and a population can take a very long time to recover from such impacts. In Ireland, the pine marten has been protected by law since the late seventies, and this has helped the population to recover. “However, while we have recorded healthy numbers in the midlands they are still quite rare in the east and still absent altogether from some parts of the country” says Dr Sheehy.  

DNA analysis was also used to determine which mammals Irish pine martens were feeding on and where. The woodmouse was found to be the most frequently consumed mammal in the pine marten’s diet, and the first evidence of the pine marten preying upon the invasive North American grey squirrel was also recorded by the group.

“We were particularly interested in how often squirrels feature in the diet of the Irish pine marten population” says Dr Sheehy. The study reveals that the native red squirrel has an extremely low frequency of occurrence in the diet, but in areas that the invasive grey squirrel is still present, it features significantly more frequently than the native red.

“This is likely to be a result of differences in ecology between the red and grey squirrel. Red squirrels are suitably adapted to living with a tree-climbing predator such as the pine marten and indeed they have co-existed successfully in Ireland and Europe over many millennia. In contrast, the grey squirrel, which originates in America, lives in much higher numbers and is less agile than the red squirrel, making it both an easier prey item to catch, and also much more numerically available too” says Dr Sheehy. 

An interesting element of the study was that where pine marten numbers were found to be high, such as the midlands, the grey squirrel was either absent or rare, even in sites where they had previously been very well established. “So much so that we eventually had to use a specially trained scent detection dog from the UK to help us find evidence of pine marten in the east where the grey squirrel was available to eat” says Dr Sheehy.   

Dr Sheehy and Dr Lawton expect to have further insights from their research into the relationship between red and grey squirrel distribution and pine marten abundance published later this year.

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