The grey squirrel is a common sight in most areas of the UK but is not a native animal. Its name is derived from its grey colour (although variations due occur) and in the United States where it is a native species it is also known as the Eastern Grey Squirrel having the name carolinensis as the Carolinas is the area in which the species was first identified. White and black coloured examples are found more often in urban areas (such distinct animals are prone to predators in rural settings). The Black coloured (melanistic) can become dominate in some populations especially in areas of Canada and more recently in southern UK (2008). The animal is larger and heaver than the native British red Squirrel being about 30cm long in body with a tail of up to 25cm, an adult weighing up to 600grams. They are one of the few mammals that descend a tree head first as they are able to turn their back feet so that the claws are able to grip backwards.
The nest they build is normally in the fork of a tree made of dry leaves and twigs, this is known as a drey, dreys have been found in lofts and outside walls of houses. Grey Squirrels do not hibernate and are normally active at dawn and dusk to help avoid predators. Greys can breed twice a year, normally December to February and then again in May to June although the later breeding season can be later in colder areas or years. Litters are normally up to 6 but can be higher, with the first litter being born around late February and the second in late June. The young are born blind but are weaned at 7 weeks and leave the drey after 10 weeks. Adults become sexually active by 5 ½ months old but are normally 1 year old before they produce their first litter. An adult can live to 20 years old but general life expectancy is about 12 years.
Grey Squirrels favour large woodlands with dense tree cover but are adaptable and can be found in the trees of urban parks and other urban areas. In the USA they can be found in the Eastern US and also in south east Canada in the north to Florida in the south. They can also be found in North West USA as far south as California.
In South Africa they are an introduced species but are not a threat to local species as they have a very limited range being found only in a small part of the Western Cape where they feed on introduced pine trees and some commercial fruit but are unable to eat indigenous flora which has prevented spread.
In the UK (introduced from America at the end of 19th century) the grey spread rapidly becoming the dominant species in England and Wales with some pockets in Scotland. They have spread to Ireland but spread has been slow as introduction was in a single area and containment projects have been successful. Elsewhere in Europe the grey squirrel has been introduced to Italy raising concerns that it will displace red squirrels in mainland Europe.
The main impact has been displacement of the indigenous red squirrel population. This is due to a wide variety of factors with the greys generally being a much more robust species, being stronger, larger and able to store more fat for winter, being able to feed on acorns earlier than red squirrels and being able to feed on a wider range of foods. The greys also often carry a pox virus which they are somewhat resistant to while the red squirrel population has a high mortality rate from this virus. Finally the red squirrel is more vulnerable to the destruction of their habitat than the more adaptable grey.
In the UK it is illegal (Wildlife and Countryside Act 1981) to release or allow any grey squirrel that is trapped, it is required the animal should be humanly destroyed.
In the UK the grey squirrel has few natural predators as they are generally too fast for domestic dogs to catch although some domestic cats have been known to catch and kill them. Most squirrels seen dead in the UK have died of old age or been killed in traffic collisions while crossing busy roads. Common wild predators include hawks, snakes, large owls and mustelids.
Their population has grown rapidly and they have been classified as a pest with efforts to reduce their numbers especially in areas where native Red squirrels remain. They eat a wide range of food such as seeds, acorns (and can digest green acorns which are too unripe for Red Squirrels to eat), nuts and some fungi. They have proven very adaptable to urban areas with parks and are common raiders of bird feeders showing impressive ingenuity in getting inside the feeders to eat sunflower seeds and millet. I have also seen them travelling along washing lines to take socks or parts of clothing presumably to line nests. In rare occasions when food is rare they have been recorded feeding on insects, frogs, bird’s eggs and even small birds and rodents.
Like many members of the squirrel family, Grey Squirrels will also hide food in small caches. Theses are recovered within days at the most if near a site of abundant food but can then be reburied in safer caches for use months later. A single squirrel can make hundreds if not thousands of these caches a year and they have excellent spatial memory which aids in retrieval but the caches that are forgotten do aid in the spreading of certain plant and tree species.
Squirrels can be eaten tasting like a cross between lamb and duck, the best meat is in the large back legs although they are hard to skin so it is best to cut in half and skin only the rear even then they provide little meat. Most recipes recormmned using the meat of several animals in a stew boiled for 45 minutes with herbs and potatoes
Please note the Red Squirrel is a protected species under UK law