The Yellow Shepherdess (_Budytes flava_) is another species of Wagtail. The male is olive-green on the back, and yellow on the lower part of the body, but the breast of the female is nearly white. These birds do not frequent the banks of rivers, but are generally found walking among the grass of meadows, and following sheep. They are summer visitors to England. White says, that “while the cows are feeding in the moist, low pastures, broods of Wagtails, white and grey, run round them, close up to their noses, and under their very bellies, availing themselves of the flies that settle on their legs, and probably finding worms and larvæ that are roused by the trampling of their feet. Nature is such an economist that the most incongruous animals can avail themselves of each other.” “Interest makes strange friendships!” [Illustration: THE SWALLOW. (_Hirundo rustica._)] “From the low-roof’d cottage ridge See the chattering Swallow spring; Darting through the one-arch’d bridge, Quick she dips her dappled wing.” CUNNINGHAM. SWALLOWS are easily distinguished from all other birds, not only by their general structure, but by their twittering note and mode of flying, or rather darting from place to place. They appear in Britain in April, and build in some outhouse, or, in part of a human dwelling, where they lay their eggs and hatch their young. About August they disappear, and do not return till the following spring. Swallows kept in a cage moult about Christmas, and seldom live till spring. There are several species of the Swallow: the general characters of which are a small beak, but large, wide mouth, for the purpose of swallowing flying insects, their natural food; and long forked tail and extensive wings, to enable them to pursue their prey. The common Swallow builds under the eaves of houses, or in chimneys, near their top; it is frequently called the Chimney Swallow from its preference for the last-mentioned rather singular situation; the Martin also builds under eaves, and most commonly against the upper corner or side of our very windows, and seems not afraid at the sight of man, yet it cannot be tamed, or even kept long in a cage. The nature of the Swallow’s nest is worthy of close observation: how the mud is extracted from the sea-shores, rivers, or other watery places; how masoned and formed into a solid building, strong enough to support a whole family, and to face the “pelting storm,” are wonders which ought to raise our mind to Him who bestowed that instinct upon them.