Squirrels appear to be strictly monogamous, pairing for life, and constantly inhabiting the same dwelling. The young, three or four in number, are produced in June, and for their reception the parents prepare a very beautifully constructed nest, formed of interlaced moss, leaves, and vegetable fibres, which is placed either in the hole of a tree, or in the fork between two branches. The young Squirrels are very carefully attended by both parents, and the family remains united until the following spring, when the young go out to find partners, and settle themselves in the world.
The Common Squirrel may serve as an example of the whole genus Sciurus, which includes the ordinary Tree Squirrels, the species of which are very numerous, probably more than one hundred, and distributed over nearly all parts of the world. The species are most numerous in the warm Oriental regions, in India, and the countries and islands lying to the east of it, from which nearly fifty species have been recorded. The northern parts of the Old World only possess half a dozen species, but North America has about eighteen, many of which are considerably larger than the European Squirrel. The most striking of the North American species are the GREY SQUIRREL (Sciurus carolinensis) and the FOX SQUIRREL (Sciurus niger), both of which are abundant in the Atlantic States, and vary considerably in colour, presenting both grey and black individuals.
BLACK FOX SQUIRREL.
Besides the ordinary Squirrels, a considerable number of other species are arboreal in their habits, and, indeed, even more strictly so than the true Squirrels. These are the Flying Squirrels, as they are called, which may be at once distinguished from the others by the presence of a large fold of skin, extending along the sides of the body, and including the limbs as far as the wrists and heels (see figure on next page). In the case of the Common Squirrels, it is observed that in performing leaps of any considerable extent the limbs are stretched out, and the long, bushy tail extended, so as to give the animal as large a surface as possible; but in the Flying Squirrels, as in the Flying Lemur (Vol. I., p. 344), when the limbs are extended laterally the folds of skin (patagia) become tightly stretched, and form a regular parachute, which seems to give the animal essential support in its most extensive leaps. The extent of this membrane is increased by means of a sort of bony spur, which articulates with the wrist.
The TAGUAN (Pteromys petaurista) is a large species, indeed, the largest of the whole family Sciuridæ. It measures about two feet long, and has a bushy tail of nearly equal length. Its ears are pointed, but not tufted, and its eyes are large and prominent. Its colour above is greyish-black, produced by a mixture of entirely black hairs with others having the tips greyish-white; beneath it is greyish-white. About the head and on the limbs the fur is tinged with brown or chestnut brown, and the lateral folds are sometimes of the latter colour, sometimes blackish-brown above and grey beneath. The tail is rounded in its form.
This species inhabits the peninsula of India and Ceylon, Malacca and Siam, where it is found only in the forests, living in trees, either singly or in pairs. Its activity is chiefly nocturnal, in which respect it differs from the ordinary Squirrels. During the day it sleeps in the holes of trees, but at night it comes forth, climbing and leaping with the greatest rapidity about the trees on which it lives. While thus engaged the lateral membranes are loosely folded at the sides of the body; but from time to time the Squirrel wishes to pass from one tree to another at some distance, and then it ascends to a considerable elevation and springs off, at the same time extending all four limbs as much as possible, when the tightly-stretched folds of skin lend the body a support, which enables it to glide through the air to some distance, although it seems always to alight at a lower level than that from which it started. During these aerial excursions the long bushy tail serves as a sort of rudder, and enables the animal even to change its course during flight. Of the habits of the Taguan very little is known. It appears to feed upon fruits, and is exceedingly shy and fearful. Of a nearly-allied species which he observed in China, Mr. Swinhoe says that the nest, which was placed high up in a large tree, measured about three feet in diameter, and was composed of interlaced twigs, and lined with dry grass. It contained only a single young Squirrel; but this might be exceptional.
TAGUAN.