Most Unwanted | Invasive Species Ireland

Most Unwanted: Grey squirrel

Sciurus carolinensis
Habitat: Terrestrial
Threat: Threatens red squirrel and woodlands
Status: Established

The grey squirrel is a larger tree squirrel than the native red squirrel. It has a distinctive long bushy tail and characteristic short front legs. Colouration is known to vary with some specimens displaying ‘chestnut’ markings on paws, hips and face which can lead to misidentification. In winter the species displays a thick winter grey/silver coat on the upper side of the body with a white under side. The total length of these squirrels ranges from 430-500 mm, tail length ranges from tail 210-240 mm, and generally is 400-710 g. in weight. The maximum known lifespan in the wild is 12.5 years.

What is it

The species preferred habitat is mature woodlands with a diverse understory however; in Ireland the species is common in agricultural lands, planted forests, scrub or shrublands, and urban areas. Sciurus carolinensis feeds on nuts, buds, flowers, seeds, fruits, fungi, some insects and occasionally bird eggs. When food is scarces, grey squirrels are known to damage trees by stripping the bark to get to material contained within the soft inner layers of the tree.

Impact

Grey squirrel is considered the main threat to the endangered and protected red squirrel. They out compete the red for space and food and are also a known vector for the Parapox virus which can be fatal to red squirrels.
Grey squirrels also cause economic loss to forestry plantations by stripping the bark of trees which can lead to tree die off.

Where is it from

Originated from North America but was introduced to Europe to ‘improve’ diversity of estates in the late 19th centaury and early 20th centaury.

Where are they in Ireland

Grey squirrel was first released in Ireland at Castle Forbes, County Longford and has since spread and is now widespread in the east, south and north of the island.