Page:The Zoologist, 4th series, vol 4 (1900).djvu/461

Rh shrouded in obscurity. I have found and critically examined many scores of Sparrow-Hawks' nests, and have taken hundreds of their eggs, and in the whole of my experience I cannot recall to mind a single case in which the parent birds had not resorted to the old and discarded nests of some other species. These same nests, erstwhile the possessions of Ring-Doves, Carrion-Crows, and Magpies, generally presented a very ragged appearance previously to adaptation, being tattered and torn by the storms and gales of winter. "Long ere the leaf is out—sometimes, indeed, as early as the end of March—mental selection is unquestionably made of the nest that is eventually to be used as a breeding-site." At dawn, and again at the approach of dusk, the birds are frequently to be found in its vicinity, either soaring high in the air, and occasionally uttering sharp screams as they wheel to and fro, or else perched in the trees beneath. "With the advance of spring they will be found busy at the nest itself, apparently cleaning and patching it up, while in course of time there is superimposed a shallow and very extended structure of twigs and sticks, in which receptacle the eggs are laid." The substructure or basis is entirely the handiwork of some other species, the superstructure that of the Sparrow-Hawks themselves. The birds gather the supplementary materials chiefly from beneath the tree, flying up and down in turn, as I have repeatedly proved by watching them from an ambush. The eggs are laid on alternate days, six being the largest clutch I have taken, though I have secured as many as fifteen and sixteen from single nests, the first egg of the latter number having been laid on May 1st, and the last on May 31st; so that, by judicious manipulation of the nest and its contents, I had induced the bird into laying an egg on every other day throughout that traditionally merry month. It will generally be found that one egg in a clutch differs appreciably in the markings from the remainder; sometimes it is altogether devoid of colouring matter, while at others a considerable portion of its bluish-white ground is blushed over with brown of a much paler shade than that with which the rest of the eggs in the clutch are usually so handsomely clouded and blotched. Sparrow-Hawks begin to sit about May 10th, in Leicestershire, or about six weeks after the first overtures have been made to the nest that has been selected. So far as I have been enabled to test the point, the eggs—which are exceedingly thick-shelled—are seldom hatched before the expiration of five weeks. The ultra-extended platform built by the Sparrow-Hawks themselves, and superadded to the relics of the nest of some other species, is assuredly a beautiful expression of the instinct when considered in relation to its use at a subsequent stage. Nevertheless, the fact that this roomy plateau not only does duty as a repository for freshly-killed prey, but as a family banqueting-table, whither the young periodically return for many days after they are fledged and gone out into the world,