[Illustration: COMMON WREN _Troglodytes parvulus_ Lower figure St. Kilda variety] THE WREN Troglodytes parvulus, K. L. Koch There must be few people who have not heard a long and clear song sounding almost at their side, when walking along some garden path or along the edge of a wood, and on investigation have found that this song, so disproportionate in volume to the size of the bird that utters it, proceeds from one of the smallest of our birds, the Wren. Skulking as a rule in the thick hedge bottom, among undergrowth in woods, or in a tangle of brambles on a common, he will suddenly hop on to an outstanding spray, rattle off his little song, and then with quick whirring beats of his wings dive into the undergrowth again a few yards off. Always bright and perky as he hops along, with his short tail held up at right angles to the body, he searches for any small seeds or insects which he can find, and as he appears so cheerful, even in the most severe weather, it is not surprising that he has won a way to our hearts, and next to the Robin is the most favoured bird in England. The nest is a beautiful domed structure, very cleverly concealed among the ivy on a wall or tree, or sometimes in a grassy bank or the side of a stack. It is composed of leaves, moss, bents, etc., so arranged and chosen as to harmonise well with its surroundings. The entrance is a narrow round hole, and the interior is warmly lined with hair and feathers. Nest-building seems to be an occupation in which these birds delight, and several nests are generally built by each pair; one only, however, is lined, the others being left quite rough inside. These so-called “cocks’ nests” are used, however, as roosting-places, and if the eggs be destroyed they may be lined and used as their home for a second clutch. The eggs, six to eight in number, are white, sparsely spotted with red. In this country the wren is a resident and seldom wanders far from its home, a habit which has resulted in the birds inhabiting some of our outer islands, like St. Kilda, becoming recognisable as distinct from the mainland form. In winter, however, our native stock receives considerable additions from the Continent, but a return migration in spring has not been noticed. The whole bird is of a uniform reddish brown, rather lighter on the chin and throat, minutely barred with black. There is a dull white streak over each eye. Length 3·5 in.; wing 1·9 in. The female is rather smaller and duller, and the young are less distinctly barred. [Illustration: TREE-CREEPER _Certhia familiaris_] THE TREE-CREEPER Certhia familiaris, Linnæus