COWBIRD. A small North American black bird (Holuthrus titer) closely related to the red wing, remarkable for its parasitic habits, and frequenting in small flocks fields where cattle pasture, often alighting upon them to eat para sites, or clustering about their feet to snap up the insects disturbed by their movements: to this habit it owes its names, cow-blackbird, cow pen-bird or bunting, buffalo-bird, etc. This common species (see Plate of BLACKBIRDS) is about S inches long: the adult male is rich glossy black, with greenish reflections, except the head, which is chocolate-brown : the female and young are simply brownish-gray, paler beneath, The cowbird is found throughout the United States, from Texas northward nearly to Hudson Bay. In the north it is migratory, but south of the Ohio it is a permanent resident. It is to be seen in small hands frequenting fields and pas tures, where its principal food is vegetable (mainly seeds of weeds).with insects caught upon the ground and about cattle. There are usually several more males than females in each band. for these birds do not pair; and the antics and spluttering and guttural squeaks with which the males try to attract the females are most queer and amusing. In the autumn they gather in large flocks and associate with other blackbirds. Two other species are found in the southwestern United States, a third and fourth in Mexico and Central America (of the allied genus ranrn aims), and several in various parts of South America.
The parasitism of the cowbirds is their most striking characteristic, their behavior resembling that of the European cuckoo. None, except one, takes a mate, or makes a nest, or incubates its eggs. • Instead of this, when the breeding season (May and June) is at hand, the female ready to lay an egg quietly leaves the flock and stealth ily seeks the home of some bird, from which the mother is temporarily absent, incubation not hav ing begun. There she deposits her egg (see Col ored Plate of EGGS OF SONG-Bums), to which she pays no more attention. It matters not whether the nest she visits has already its full supply of eggs, or even whether it already contains one or several eggs of her own species; she will some times throw out eggs of the owner to make room for her own. The egg of the cowbird usu
ally hatches in less time than do the eggs of the bird on which it is imposed, whereupon the rightful eggs, may be abandoned or thrown out; or, if some of them hatch, the young are speedily starved or smothered or elbowed out of the nest, while the foster-parents devote themselves to the care of the greedy stranger. He remains in the nest until it is really outgrown, but even after he has left it he is eared for, for a time, by the birds that brought him up. But at last, when w ell able to tly, lie seeks out others of his own kind, and the birds that have devoted themselves to him so assiduously have nothing to reward their pains. Over 100 species of birds are thus burdened with more or less frequency; but some will desert the nest rather than incubate the strange egg; others build a second story on the nest, leaving the cowbird's egg to perish below, while they raise their own brood in the super structure.
The egg of the cowbird is a rather blunt oval, measuring, on the average. .S4 by .65 of an inch, and is white or grayish, profusely speckled with browns, the general effect of which is indis tinct and pale; it is not easily mistaken for any other bird's of its size. Several species of cowbirds inhabit Central and South America, and have similar habits, except in one instance, the bay-winged eowbird (.11oluthrus bodies) of Argentina and Bolivia, which differs from the ordinary type in several ways, among others in having a low and pleasing song, which it delivers more or less all the year around. It does not abandon its eggs to the care of other nurses, but forms conjugal ties and occasionally makes a nest of its own; more often, however, it seizes upon the nests of other birds, and in their de spoiled property lays its eggs and rears its own young. A circumstantial history of this inter esting group and a discussion of bird-parasitism may he found in Selater and Hudson. A rgentine ftreithologp (London, 1SSS-S9) largely re printed by Bendire, in "The Cowbirds," in Re port of time National Museum, for 1893 (illus trated, Washington, 1895).