The Red Squirrel (Sciurus vulgaris) is a species of the tree squirrels. Red squirrels are tree-dwelling omnivorous rodents that are frequently found throughout Eurasia. In Britain, however, numbers have decreased drastically due to the introduction of the eastern Grey Squirrel from North America. Red squirrels have a head to body length of 19 to 23 centimetres and a tail length of 15 to 20 centimetres.
Red squirrels are not sexually dimorphic as male Red squirrels and female Red squirrels are the same size. The red squirrel is slightly smaller than the eastern grey squirrel which has a head to body length of 25 to 30 centimetres and weighs between 400 and 800 grams. It is thought that the long tail helps the squirrel to balance and steer when jumping from tree to tree and running along branches and may keep the animal warm during sleep. The coat of the red squirrel varies in colour according to the time of year and location.
There are several different coat colour morphs ranging from black to red. Red coats are most common in Great Britain. The underside of the squirrel is always white-cream in colour. Red squirrels shed their coats twice a year, switching from a thinner summer coat to a thicker, darker winter coat with noticeably larger ear-tufts between August and November. A lighter, redder overall coat colour, along with the larger ear-tufts, helps to distinguish the European red squirrel from either of the Eastern Grey Squirrel or the American Red Squirrel.
The red squirrel, like most tree squirrels, has sharp, curved claws to enable the climbing of trees, even when branches are overhanging.
Mating can occur in late winter during February and March and in summer between June and July. Up to two litters a year per female are possible. Each litter usually contains three or four young although as many as six may be born. Gestation is about 38 to 39 days. The young are looked after by the mother alone, and are born helpless, blind and deaf and weigh between 10 to 15 grams. Their body is covered by hair at 21 days, their eyes and ears open after 3 to 4 weeks, and they develop all their teeth by 42 days. The juvenile red squirrel can eat solids around 40 days following birth and from that point can leave the nest on their own to find food, however they still suckle from their mother until weaning occurs at eight to 10 weeks.
The lifespan of the red squirrel is on average 3 years, although individuals may reach 7 years of age and 10 years in captivity.
Red squirrels eat mostly the seeds of trees, neatly stripping conifer cones to get at the seeds inside. Fungi, birds eggs, berries and young shoots are also eaten. Often the bark of trees is removed to allow access to sap. Most of their active period is spent foraging and feeding. Excess food is put into caches, either buried or in nooks or holes in trees and eaten when food is scarce.
Although red squirrels do remember where they created caches, their spatial memory is substantially less accurate than that of grey squirrels. They will often have to search for them when in need, and many caches are never found again. No territories are maintained and the feeding areas of individuals overlap considerably.
The red squirrel is protected in most of Europe, however in some areas it is abundant and hunted for its fur. The red squirrel has drastically reduced in numbers in the United Kingdom. Under 140,000 individuals are thought to be left, approximately 85% of which are in Scotland. This population decrease is likely to be due to the introduction of the eastern grey squirrel from North America as well as the loss and fragmentation of its native woodland habitat.
In order to conserve remaining numbers of red squirrels, the UK Government in January 2006 announced a mass culling program for grey squirrels. This was welcomed by many conservation groups. The UK has established a local program known as the North East Scotland Biodiversity Partnership, an element of the national Biodiversity Action Plan. This program is administered by the Grampian Squirrel Society, with an aim of protecting the Red squirrel.
The eastern grey squirrel population appears to be able to out-compete the red squirrel for various reasons: The eastern grey squirrel can easily digest acorns, while the red squirrel cannot. The eastern grey squirrel carries a disease, the squirrel parapoxvirus, that does not appear to affect their health, though will kill most red squirrels.
When red squirrels are put under pressure, they will not breed as often. It is worth noting that eastern grey squirrels do not usually attack red squirrels, and direct violent conflict between these species is not a factor in the decline in red squirrel populations.