The Song Warblers principally frequent the woodland districts of the more northerly portions of the Eastern Hemisphere, and usually prefer tracts covered with low trees and underwood to lofty forests. They almost entirely avoid mountainous regions, even should these be thickly overgrown with their favourite shrubs and bushes. Unlike the Thrushes, they rarely descend to seek for food upon the surface of the ground, nor are they apparently more at their ease when on the wing, for they frequently undertake lengthy journeys during their winter migrations, and their flight is in most instances fluttering and heavy; some few species, however, prove exceptions to this rule, as they are not only capable of careering with a rapid undulating course through the realms of air, but frequently, when about to pour forth their song, soar to a considerable altitude. It is in the depths of the thicket, however, that the members of this family best display the wonderful agility with which they have been endowed. No tangled brake, no mass of foliage, however dense, is impervious to these little birds. With lowered head, and wings and feet drawn in, they creep through the smallest apertures with astonishing dexterity, and make their way with an ease and rapidity that is almost unequalled in the whole feathered creation. Unlike the Thrush or Shrike, they never agitate their tail and pinions when in motion; but, if angry or excited, display the crest that decks their head, and slightly raise their wings above the back. As regards their vocal powers, they are, for the most part, highly gifted. Their senses are keen, their intelligence remarkable, and their dispositions shy and cautious. Although usually peaceable during the breeding season, they frequently exhibit considerable fury and violence towards any suspected rival or enemy, that contrasts strangely with the tenderness and devotion they display while endeavouring to win the attention of their mates, or ministering to the wants of their little family. More than one brood is usually produced in the year, each of which consists of from four to six eggs, of a white hue, spotted with grey or brown. The flat and prettily-formed nest is placed amongst the bushes, or on a branch, and constructed of stalks, cottony wool, spiders' webs, green moss, and fibres, lined with horsehair, the whole being woven together so lightly that the eye can penetrate its interior. In some instances these fragile little structures are fastened so insecurely on their foundations as to be liable to be dislodged by the wind. During the summer months the Song Warblers subsist almost entirely upon insects, larvæ, caterpillars, and similar fare, and in autumn devour large quantities of berries and fruit. They are often very destructive to cherry-trees, and in Southern Europe do great damage to the crops of ripe figs.
The TRUE SONG WARBLERS (Curruca) are distinguished from their congeners by the comparative length of their pointed wings, in which the third quill is longer than the rest, also by their moderately-sized and almost or quite straight tail.
THE SPARROW-HAWK WARBLER.
The SPARROW-HAWK WARBLER (Curruca nisoria), the largest European member of this group, is seven inches long and eleven broad; the wing measures three and a half, and the tail three inches. Upon the upper part of the body the feathers are deep grey, usually shaded with rust-red; the under side is greyish white, decorated with dark grey crescent-shaped spots, which are most clearly defined in the plumage of the male bird; the quills are brownish grey, edged with a paler shade; the tail-feathers deep grey, with light borders. The eye is bright gold colour, the beak brownish black, and yellowish pink at its base; the foot is light grey. In the young, the crescent-shaped spots on the breast are but slightly indicated.
This species is numerously met with in most European countries that lie between Southern Sweden and Central Asia; it is, however, unknown in England, and is extremely rare both in Spain and Greece. Pasture lands, abounding in shrubs and bushes, on the banks of large rivers, are the localities it almost exclusively frequents; it never occupies lofty trees, except as temporary resting-places during its winter migrations. In its general habits and movements the Sparrow-hawk Warbler closely resembles most other members of its family; it flies with difficulty, and comes but seldom to the ground, but displays the utmost agility in creeping through the densest bushes, or in hopping from branch to branch. Its song is rich, varied, and uttered constantly, almost throughout the entire day. The period of incubation commences as soon as the birds have returned to their usual spring haunts, and is accompanied by repeated outbursts of jealousy and violence on the part of the male, who not only frequently engages in fierce conflicts with his actual rivals, but flies assiduously round his mate while she carries on the work of building their little dwelling, in order to keep the coast clear from even a distant intruder on her privacy. The nest is usually placed in a hedge or bush, at from two to four feet above the ground, and is in every respect similar to that above described; the eggs, from four to six in number, are oval, with thin greyish shells, spotted with grey or olive brown. Both parents exhibit great timidity whilst occupied in the care of their young, and quit the nest at the first alarm of danger, the female frequently endeavouring to divert attention from her brood by feigning to be lame or suffering. If disturbed while occupied in building, it is not uncommon for a pair to leave the spot and re-commence their preparations elsewhere; indeed, in some instances, an unusually timid couple have been known to desert their brood when terrified by the approach and investigations of a stranger.
THE SPARROW HAWK WARBLER (Curruca nisoria).
THE ORPHEUS WARBLER.