402 SYSTEMATIC SYNOPSIS. —PASSEEES— OSCINES. 



lias lately been added ; there are several others in the wanner parts of America, all of the 

 irregular and objectionable tendencies. 



Analysis of Species and Varieties. 



(f , steely black witli brown head. 



Larger: cf, wing over 4.00; tail over 3.00 ; $, wing about 3.75; tail about 2.75 ater 313 



Smaller: cf, sizeof $ of the foregoing obscurus 314 



cf, brassy black, including head; eyes red; wing near 5.00; tail nearly 4.00 ceneus 316 



.313. M. a'ter. (Lat. w^^er, black. Fig. 258.) Common Cowbird. Cuckold. jJ, adult: Lus- 

 trous green-black, with steel-blue, purple, and violet iridescence. Head and neck deep wood- 

 brown, with some purplish lustre. Bill and feet black. Length 7.50-8.00; extent 13.50; 

 wing about 4.50, at least over 4.00 ; tail about 3.25 ; bill 0.70 ; tarsus 1.00-1.10. 9 , adult : 

 An obscure-looking bird, dusky gi-ayish-browu, nearly uniform, but paler below than above, 

 where most of the feathers have dusky centres, and most of those of the under parts with dark 

 shaft lines ; giving a somewhat streaky apjiearance. There is some gloss on the upper parts, 

 particularly on the wings and tail, where a slight greenish lustre is usually evident. Bill 

 blackish-brown, paler below ; feet blacldsh-brown. Smaller than the ^. Length 7.00-7.50 ; 

 wing about 3.75; tail 2.75. Young ^ 9 : Similar to the 9 adult; still duller, and more 



variegated ; upper parts dusky brown, the 



feathers skirted with gray, producing a set 



^^^^*jms^m ^^ semicircles on the back; below, pale 



grayish, or even ochrey-brown, everywhere 



streaked with dusky. The sexual difference 



in size soon appreciable, and the black of 



the ^ soon begins to appear in pat<'hes. 



K. An:i. at large ; migratory, abundant, 



gregarious, polygamous, parasitic. The 



singular habits of this bird, shared by others 



_^ _ of the genus, form one of the most inter- 



"^- ^^* esting chapters in ornithology. Like the 



European cuckoo, it builds no nest, laying 

 Fig. 258. — Cowbird, reduced. (Sheppard del. its eggs by stealth in the nests of various 

 Nichols sc. ) other birds, especially warblers, vireos, and 



sparrows ; and it appears to constitute, furthermore, a remarkable exception to the rule of 

 conjugal affection and fidelity among birds. A wonderful provision for the perpetuation of the 

 sjiecies is seen in its instinctive selection of smaller birds as the foster-parents of its offspring ; 

 for the larger egg receives the greater share of warmth during incubation, and the lustier young 

 cowbird asserts its precedence in the nest ; while the foster-birds, however reluctant to incu- 

 bate the strange egg (their devices to avoid the duty are sometimes astonishing), become assid- 

 uous in their care of the foundling, even to the neglect of their own young. The cowbird's 

 egg is said to hatch sooner than that of most birds : this would obviously confer additional 

 advantage. The list of birds in whose nests cowbirds' eggs have been found includes a large 

 number of finches, warblers, greenlets, flycatchers, etc. ; there seems to be really little choice. 

 While small species are usually victimized, this is not always the case. I have found eggs in 

 nests of the kingbird and towhee bunting. In the West, where cowbirds swarm about the ranches 

 and settlements, it is the rule, I almost said, to find their eggs in nests of the prairie Frin- 

 gilUdcB, etc. The egg is usually single; sometimes 2, 3, even 4 are found in a nest; they 

 range from 0.80-1.00 in length, by 0.65-0.70 in breadth, and are white, fully speckled and 

 dashed with browns and neutral tints. 

 314. M. a. obscu'rus. (Lat. obscurus, dark.) DwAKF Cowbird. Similar ; smaller ; ^ the size 

 of 9 M. ater; 9 under 7.00; wing 3.33; tail 2.33. The difference is strongly marked, and 



