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Cowbird

eggs, species, nests, nest and habit

COWBIRD, a bird (Molothrus ater) of the family Icteridce (q.v.), abundant throughout North America except in the far north, and notorious because of its habit of escaping the drudgery of domestic cares after the fashion of the European cuckoo. Closely related to the bobolink or reed-bird, the cowbird lacks the acute tail feathers and rich spring plumage of that species, while its general build, and par ticularly its stout beak, are even more finch-like. The male is from seven and a half to eight inches long and iridescent black with a brown head and the female slightly smaller and nearly uniform dull brown. The cowbird takes its name from the habit of associating in flocks with cattle in the fields, apparently for the pur pose of securing the flies which frequent the cattle or the other insects which are disturbed by their movements. They are migratory and gregarious, never separating in pairs, but appar ently quite promiscuous in their sexual rela tions. Nests are never built, but, like the Euro pean cuckoo, the eggs are stealthily introduced into the nests of other birds, preferably those of smaller size, such as warblers, finches and vireos, of which a great many species are vic timized. Apparently the cowbird exercises lit tle choice, but drops its eggs into any suitable nest .that happens to be convenient; and, owing to its abundance, an astonishingly large number of nests are thus invaded. Some of the smaller warblers, notably the yellow warbler (Dendroica cestiva) and the redstart (Setophaga ruticilla), endeavor to circumvent the intruder by building a second story to the nest, enclosing between the two floors the egg of the cowbird and even sacrificing one or more of their own. Nests

with three cowbird's eggs thus enclosed in as many compartments have been found. Although but a single egg is deposited at a time, as many as three or four will sometimes be found in a single nest, in which cases they have probably been dropped by different females. The alien eggs, which are white or grayish and speckled with brown, and are about .84 by .65 of an inch, hatch before those rightfully belonging to the nest, and, once the young cowbird has hatched, its demands for food so claim the attention of its foster-parents that the latter's own eggs or young arc neglected and usually perish. Al though chiefly insectivorous, berries and seeds are sometimes eaten by the cowbird.

In the warm parts of America a number of related species occur, which, having similar hab its, are also known as cowbirds. A most re markable relation exists between two South American species.

Molothrus badius, one of those in question, has the unusual habit of seizing and utilizing for the purpose of incubating its own eggs the nests of weaker birds, whose eggs arc destroyed. The second species (M. rufoaxillaris) is regu larly and perhaps exclusively parasitic on the former. Consult Bendire, (The Cowbirds,) (in Report of the National for 1893, Washington 1895).