Another member of the Muridae, the field-mouse (Apodemus sylvaticus), is almost as great a nuisance in the trenches as the rat. The field-mouse is very like the house-mouse, with some of its features seen under a lens. The hind feet and ears and eyes are larger than are those of the house-mouse. Perhaps its much longer hind legs help most easily to differentiate the two species. The tail is of about the same length as the body and head added together, and is annulated, presenting some 150 rings. The hands have five-palmar pads, and the feet six pads. There are six mammae in the female, the anterior pair being pectoral.
The general colour of the dorsal surface is described as wood-brown, which pales at the front end and towards the shoulders and flanks, and grows to a more reddish tinge at the posterior end. The whole of the lower surface is of dull, white, silvery colour, and on some well-developed specimens there is a spot of buff, or orange, on the throat, which sometimes lengthens out to form a collar. Moulting seems to be rare—at any rate but a few cases have been recorded.
The field-mouse occurs all over Europe, and extends into parts of Asia. It is found all the way from Iceland, southward to Algiers, and from Ireland to India. In the Himalayas it has been taken at a height of 11,500 feet, and in the mountains of Europe it frequently occurs at a height of 7000 feet. It is certainly the most universally distributed of European animals, and the number of individual specimens probably far exceeds that of any other mammal which occurs in its district.
Fig. 48.—The field-mouse (Apodemus sylvaticus). (From Barrett Hamilton.)
The field-mouse does not hibernate like the dor-mouse, but is active and hardy at all seasons of the year. Although, like other Muridae, it is probably vegetarian by ancestry, it is, in effect, quite omnivorous. It causes considerable loss in cornfields and gardens, especially to early-sown peas; it eagerly eats dandelions and any kind of grain or nut, or berry, or fruit, or bulb, or bud. Even fungi have been found in their winter stores; and one family was discovered which had eaten considerable quantities of putty with apparently no deleterious effect. Their fondness for bulbs is a great nuisance to the Dutch tulip-merchants. As many as 300 have been trapped in a fortnight in a single crocus-bed. They are also a nuisance to bee-keepers, inasmuch as they enter the hive and eat the honeycomb, especially during the winter. Whilst feeding in the hedgerows, or undergrowth, they frequently establish themselves in birds’ nests, and occasionally such nests become their permanent home.
In the hedge-sparrow’s nest he sits,
When the summer brood is fled,
And picks the berries from the bough
Of the hawthorn overhead.