BIRDS, OF PENNSYLVANIA. 209 



GENUS MOLOTHRUS SWAINSON. 

 Molothrus ater (BODD.). 



Cowbird ; Cow Bunting ; Cow Blackbird. 



DESCRIPTION (Plate 57). 



Bill short, stout, about two-thirds as long as head ; tail nearly even or very slightly 

 rounded ; bill and feet black ; iris brown. 



Male with the head, neck and anterior half of breast deep brown, with slight pur- 

 plish gloss ; rest of body lustrous black, with a violet-purple gloss, next to the 

 brown, of steel-blue on the back, and of green elsewhere. 



Female. Plain grayish-brown, lighter on the under parts. 



Young. Dull dusky-brown above, feathers edged with grayish, lower parts light 

 brownish-gray more or less streaked or spotted with darker markings. In the late 

 summer and early autumn the young male can often be distinguished by the con- 

 spicuous black patches on the body. The female is smaller than the male. An 

 adult male measures about 8 inches in length and 13| inches in extent. 



Habitat. United States, from the Atlantic to the Pacific, north into southern 

 British America, south, in winter, into Mexico. 



This well-known bird is a common summer resident in Pennsylvania. 

 It arrives here late in March or early in April, and migrates southward 

 about the middle of October. These polygamous birds, at all times, are 

 gregarious. In the autumn these birds, frequently in company with the 

 Crow Blackbirds and robins, collect in large flocks in thickets, where 

 they roost during the night. When " coming in " to these roosting 

 places the flocks of Cowbirds do not scatter and alight in the surround- 

 ing trees and bushes, as the Crow Blackbirds are accustomed to do, but 

 they fly in a compact body directly to the thick bushy covert, where 

 they remain, and unless disturbed are seldom heard to utter their harsh, 

 rattling chuckle. The Cowbird builds no nest, nor does she attempt to 

 rear her young ; when desirous of laying, she quietly slips away from 

 her companions, arid finding a nest deposits her egg, and flies off to 

 join her comrades feeding in the fields, or, perhaps, assembled in a tree- 

 top. Although the Cowbird generally selects the nests of small birds, 

 she never gains access to the same by force, but pays her visit when the 

 owners are absent. Sometimes birds whose homes have been invaded 

 by these feathered parasites abandon their nests, mostly, however (par- 

 ticularly if one or more of their own eggs have been deposited), they 

 submit to the imposition and rear the young Cowbirds. The Yellow 

 Warbler, occasionally, will build a new nest above that in which the un- 

 welcome egg is deposited. I have twice found broken eggs of Cowbirds 

 on the ground near nests of the Yellow-breasted Chat, and on three oc- 

 casions have discovered the shattered remains of these eggs directly be- 

 neath the pendant nests of Baltimore Orioles. It may be that these two 

 species, sometimes at least, toss out the alien eggs. While it is mostly 

 observed that the Cowbird lays in the nests of birds much smaller than 

 14 BIRDS. 



