All such species as inhabit the temperate zone migrate with the utmost regularity as winter approaches, and return to their native haunts with such unfailing precision that the day on which they will re-appear may be accurately prognosticated. Those species inhabiting the interior of Africa never actually migrate, but occupy themselves in flying over the face of the country during the wet season. The work of constructing the nest is commenced as soon as the winter journeyings are over, and is always carried on amidst great excitement; the males chasing and fighting each other most furiously during the whole time, and constantly engaging in pitched battles with the birds whose nests they prefer taking rather than undergo the labour of constructing a home for themselves. Unlike the nests of the Swallows, those built by the Swifts seldom consist of more than a few slight materials laid carelessly together, and cemented with saliva from the builder's beak. The eggs are round and white; the female alone broods, but both parents share in the toil of satisfying their hungry progeny. [Illustration: SALANGANES.] * * * * * The TREE SWIFTS (_Dendrochelidon_) constitute a group whose various species form a link between the Swallows and the Swifts Proper. These birds are recognisable by their elongate body, long wings, in which the two first quills are of equal length, their long, deeply-forked tail, and the crest with which their head is adorned: their feet resemble those of the Swallow. THE KLECHO. The KLECHO (_Dendrochelidon klecho_), so called from the sound of its cry, is about seven inches long; the wing measures six, and the tail three inches. Upon the upper part of the body the plumage is of a brilliant metallic steel-green; the wing-covers have a blueish lustre; the quills are blackish on the inner and blue on the outer web, and the shoulder-feathers white. The belly is white, the rest of the under surface and rump of a beautiful deep grey. The male has a reddish brown and the female a black spot near the eye.