Facts about grey squirrels
Originally from North America, grey squirrels were introduced into parks in a number of locations during Victorian times. They have spread and bred rapidly, and have displaced the red squirrel through England and Wales and in central and southeast Scotland.
In the wild the grey squirrel is diurnal and most active at dawn and dusk, searching for available food. It spends more time foraging and feeding on the ground than in the trees. It is, however, very agile in the trees and can run along slender twigs, leaping from tree to tree. The long, muscular hind legs and short front legs help it to leap. The hind feet, longer than the front, are double-jointed to help the squirrel scramble head first up and down the tree trunk. Sharp claws are useful for gripping bark and the tail helps the squirrel to balance. If a squirrel should fall, it can land safely from heights of about 9m (30 ft). They grey squirrel can leap more than 6m.
Squirrels have good eyesight and often sit upright on a vantage point to look around them. They have a keen sense of smell too. They are clever and adaptable which make a squirrel infestation hard to treat.
Although grey squirrels have a wide range of calls, they communicate mainly through their tails, using them as a signalling device; they twitch their tails if they are uneasy or suspicious. Regular routes are scent-marked with urine and glandular secretions. Squirrels identify each other, and food, by smell.
Nests
The grey squirrel builds itself a nest, or drey, about the size of a football, made of twigs, often with the leaves still attached. It is built fairly high in a tree and lined with dry grass, shredded bark, moss and feathers. A summer drey is usually quite flimsy and lodged among small branches. Sometimes the squirrel may make its nest in a hollow trunk or take over a rook’s nest, constructing a roof for it. A squirrel often builds several dreys.
The grey squirrel does not hibernate and it cannot store enough energy to survive for long periods without food. A larger, thicker winter drey is built, usually on a strong branch close to the trunk, and a squirrel will lie up in this in very cold weather, coming out now and then to search out hidden stores of food. These stores of single nuts and other items are buried in the ground in autumn, well spread out. They are found by smell, rather than memory. As well as nuts they will eat young birds and eggs. Winter dreys are often shared for warmth. As it sleeps, the squirrel curls its tail around its body to act as a blanket.
Breeding
In late winter, squirrels may be seen courting with one or more chattering males chasing a female. Females only mate twice a year, but males may mate at any time. After mating, the male plays no part in the rearing of his young. Squirrels breed for the first time at one year old.
The female uses a winter drey as a maternity nest and gives birth after a six week gestation period (time between mating and birth), in March/April and perhaps again in June/July. An average litter has 3 babies but as many as 9 may be born. The mother suckles the naked, blind young every three or four hours for several weeks. They gradually grow fur, their eyes open and at about seven weeks old they follow their mother out on to the branches. Gradually they start to eat solid food and when their teeth are fully grown, at 10 weeks, they give up suckling. A month or so later they move away from the nest to build dreys of their own. If there are not too many squirrels in the area, the young stay nearby; if it is crowded they will be chased away to look for less crowded feeding areas.
