The female is an expert at locating nests. Evidently she watches smaller birds, learns where they are building their nests, and then while they are not watching her, slips in and deposits her egg. Sometimes the egg is laid long before the nest is completed. Occasionally, when an egg is thus deposited before the rightful owner of the nest has laid her eggs, the little birds build another bottom in their nest, sealing the heavy egg beneath the hair and vegetable fiber. Yellow Warbler nests are thus sometimes several stories high, and I have more than once found eggs sealed into the foundation material of the nests of larger birds. I remember one Scarlet Tanager nest which held two eggs of the owner and four of the Cowbird, and there was an additional Cowbird egg sealed in the foundation material.
Cowbird, Male
Being larger than his nest-mates, the young Cowbird claims the most attention. He may actually push the other young and eggs out of the nest.
The Cowbird’s food habits are not objectionable, however, and no ill effects seem to result from this parasitism upon smaller birds.
RED-WINGED BLACKBIRD
Agelaius phœniceus predatorius (Wilson)
Other Names.—Swamp Blackbird; Redwing; in autumn, Reedbird.
Description.—Smaller than Robin. Adult male in spring: Black, with bluish reflections and occasionally narrow rusty edgings; lesser coverts bright scarlet, the outer row of largest feathers buffy or whitish; eyes dark brown; bill and feet black. Males in first breeding plumage: Similar but likely to be more marked with rusty, and some of the feathers of the scarlet patch are streaked with dark brown. Adult males in winter: Upperparts edged with rusty. Adult females: Heavily streaked with dark brown and buffy above, and with blackish and light gray below, a pinkish or orange-buffy suffusion over the face, particularly on the throat. Immature birds are similar to the females. Young birds in the moult in August and September are strangely blotched with black and buffy. Length: Male, about 9½ inches; female, about 8½ inches.
Range in Pennsylvania.—A common though somewhat locally distributed summer resident from mid-March to early November. Found as a nesting bird only where there are cat-tail swamps or low meadows. Sometimes noted in winter.
Nest.—A neatly woven basket of dry grasses suspended, usually, between cat-tail stalks a few feet above the water in a swamp, or in weeds or bushes in a low meadow. Eggs: 3 to 6, pale blue, spotted and scrawled, chiefly at the larger end, with black.
Red-winged Blackbird, Male
At about the time the hilarious tree-frogs set up their evening choruses, the Red-wing returns. His handsome plumage enlivens the stretches of dead cat-tails, and his tuneful, liquid song delights the ear. As he sings, he spreads his blazing wing-patches and fluffs out his glossy plumage. The males come north in a body before the females arrive.