Red: uniformly coloured tail Grey: banded coloration giving 'halo' effect
Squirrels are members of the family Sciuridae, a large family of small to medium-size rodents, ranging from chipmunks and marmots to our own red squirrels. Here, we briefly discuss the appearance and ecology of our two resident squirrels, our native red squirrels, Sciurus vulgaris (actually not in the least vulgar) and our non-native american grey squirrel, Sciurus carolinensis.
The important issue here is to be able to tell the difference. Its not always a simple matter of colour and most of us have got it wrong at some time. The key is to look at the tail! The red is of uniform colour, although not necessarily very red; the grey, whilst not particularly saintly, has a distinctive 'halo' caused by banded coloration.
Appearance: Hair colour is uniform, individuals ranging from light brown (even greyish) to almost black, but the underside is always creamy white, they moult twice a year, both in late summer and in early spring. Characteristic ear tufts thin during the summer and then thicken up over autumn (greys have no ear tufts).
Size: Body length 18 to 24cm and body weight 250 to 350gm (much smaller than greys).
Habitat: Either conifer or broadleaf woodland, they achieve their maximum population density of 1.5 per hectare in mixed broadleaf woodland.
Food: seeds, buds, flowers, shoots, nuts, berries and fruit from many trees and shrubs. They also eat fungi and insects, and occasionally birds’ eggs. Food is stored for the winter by burying in the ground or in tree hollows.
Lifecycle: Red squirrels prefer to be in the tree canopy. They live in a ball shaped nest called a drey, built of twigs and lined on the inside with grass and moss. A family group may have several dreys. Mating takes place between January and March, followed by a gestation period of around 40 days. A litter is typically 3 to 4 kittens or 'kits', having no teeth and closed eyes at birth but at 10 weeks they're independent and able to leave the drey. There may be two litters in a year of plentiful food.
They're diurnal and are most active in the morning and to a lesser extent in late afternoon in the summer. They don't hibernate in the winter. They can live for up to six years.
Appearance: hair usually grey but often with a substantial amount of red. Whilst the red squirrel hair is of uniform colour the grey squirrel hair has bands of colour, most evident in the tail where the outer band is white. This gives it a 'halo' effect which, once seen, is a quick and reliable method of recognition, as evident in the above pictures.
Size: Body length 24 to 28.5cm and body weight 400 to 750gms, so can be twice the weight of a red.
Habitat: Preferring deciduous woodland and achieving their maximum population density of 18 per hectare in mixed broadleaf
woodland. Note that this is more than ten times the red squirrel population density.
Food: Similar to that of reds but more dependent on the larger seeds of trees such as hazel, acorn and beech mast. When plentiful, this fuels the very high population densities that can occur. When food is short, typically in early summer, they resort to robbing birds nests of eggs and predating on young birds. Their ability to digest unripe nuts is a significant competitive advantage.
Lifecycle: Grey squirrels are more ground feeders than the arboreal reds and this renders them vulnerable to predators such as fox, stoat and, increasingly, pine marten. They also live in a drey, usually built in a fork between branches. But this tends to be a rather less tidy affair than that of the reds. In every other respect, mating, gestation, size of litter and longevity they are very similar to reds.