313. 
314. 
402 SYSTEMATIC SYNOPSIS. —PASSERES— OSCINES. 
has lately been added; there are several others in the warmer parts of America, all of the same 
irregular and objectionable tendencies. 
Analysis of Seiten: and Varieties. 
d, steely black with brown head. 
Larger: ¢', wing over 4.00; tail over 3.00; 9, wing about 3.75; tail about 2.75 ee +. Ater 313 
Smaller: ¢, size of 9 of the foregoing . . . z - . obscurus 314 
d, brassy black, including head; eyes red; wing near 6 00; ‘tail nearly 4. 00. a ee KR eM AS @neus 315 
M. alter. (Lat. ater, black. Fig. 258.) Common Cowsirp. CucKoxp. é&, 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 grayish-brown, 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 appearance. 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 blackish-brown. Smaller than the g. Length 7.00-7.50; 
wing about 3.75; tail 2.75. Young g @: Similar to the ? adult; still duller, and more 
variegated ; upper parts dusky brown, the 
feathers skirted with gray, producing a set 
of 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 patches. 
XN. Am. 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 
Fic. 258. — Cowbird, reduced. (Sheppard del. its eggs by stealth in the nests of various 
Nichols 60.) 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 
species 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 smail species are usually victimized, this is not always the case. Ihave found eggs in 
nests of the kingbird and towhee bunting. Inthe 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- 
gillide, 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. 
M. a. obscu’rus. (Lat. obscurus, dark.) DWwarr Cowsirp. Similar; smaller; ¢ the size 
of 9 M. ater; Q under 7.00; wing 3.33; tail 2.338. The difference is strongly marked, and 
as 
