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The native red squirrel population had declined significantly by the early 2000s, and there was a large gap in the midland counties where few or no red squirrels could be found. The grey squirrel, a species originally from North America, was introduced into Ireland in 1911. As the grey squirrel population in Ireland spread, particularly in the east of the country, the red squirrel population began to decrease.
A grey squirrel is larger than a red squirrel. The size difference between the species gives the grey squirrel an advantage over the red squirrel when competing for food such as seeds and nuts. Another reason that the arrival of the grey squirrel into Ireland was detrimental to the red squirrel population was a disease that grey squirrels carried. The squirrel pox virus is carried by grey squirrels, but rarely kills them.
Red squirrels are also susceptible to the disease, but unlike the grey squirrels, it is often deadly for them. Both of these factors contributed to the spread of the grey squirrel and decline of the red squirrel.
Within the last 15 years however, the red squirrel population has started to recover and even repopulate woodland areas that the species had previously disappeared from. The rise in numbers of another native Irish mammal has been instrumental in the reversal of the red squirrel’s fortunes. The pine marten is a native predator to Ireland and a member of the Mustelidae or weasel family. Pine martens had become a rare sight in Ireland and mainly inhabited small areas in the west of the country.
The pine marten population in Ireland declined because of hunting and habitat loss. Like squirrels, pine martens live in woods and forests, and hunt and climb in the trees. This animal has mostly dark brown fur and a creamy patch under its chin. A pine marten’s body is long and slender and it has a long tail to balance while climbing trees. As the pine marten population began to recover, it slowly returned to areas which it had not inhabited for decades.
Pine martens are also becoming more widespread in Ireland, including the midlands and east of Ireland
As the pine marten’s range has increased into areas with grey squirrel populations, the grey squirrel numbers have begun to drop. As pine martens and red squirrels are both native to Ireland, they have evolved with each other. Red squirrels know to avoid pine martens to escape being preyed upon. Grey squirrels do not recognise pine martens as a danger to them however, and pine martens use this fact for their benefit.
Woodland areas where pine martens have re-established themselves in large numbers are now emptying of grey squirrels. Red squirrels have begun to return to these areas and because they try to avoid pine martens, their populations are less affected by the predators. Grey squirrels are now absent from several counties that the species was found in during the 1990s.
The grey squirrel’s ability to adapt, however, has allowed it to maintain large populations in urban areas such as Dublin. Pine martens are also becoming more widespread in Ireland, including the midlands and east of Ireland.
The ongoing recovery of the pine marten in Ireland has helped red squirrel numbers to increase and hopefully the populations of both species will continue to rise.
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