icterid.e — agel.eiNjE: marsh blackbirds. 467 



feathers have dusky centres ; and most of those of the under parts have dark shaft-liues, giving 

 a somewhat streaky appearance. Some gloss on upper parts, particularly on wings and tail, 

 where a slight greenish lustre is usually evident. Bill blackish -brown, paler below; feet 

 blackish-brown. Smaller than $: Length 7.00-7.50: wing about 3.75; tail 2.75. Young 

 ^ 9 '• Similar to 9 adult; still duller, and more variegated; upper parts dusky brown, the 

 feathers skirted with gray, producing a set of semicircles on back ; below, pale grayish, or even 

 ochrey-brown, everywhere streaked with dusky. Sexual difference in size is soon appreciable, 

 and black of $ soon begins to appear in patches. Temperate N. Am., S. in winter through 

 Mexico ; migratory, abundant, gregarious, polygynous, polyandrous, parasitic. The singular 

 habits of this bird, shared by others of the genus, form one of the most interesting chapters in 

 ornithology. Like the European Cuckoo, it builds no nest, laying its eggs by stealth in nests 

 of various 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 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 incubate the strange egg (their devices to avoid the duty are 

 sometimes astonishing), become assiduous in their care of the foundling, even to the neglect of 

 their own young, which usually perish in consequence. The Cowbird's egg hatches in 10 or 

 11 days, and thus sooner than that of most birds; this obviously confers additional advantage. 

 The list of birds in whose nests Cowbirds' eggs have been found is now about 100, and includes 

 a large number of Finches, Warblers, Chats, Greenlets, Wrens, Larks, Thrushes, Guatcatchers, 

 Flycatchers, etc.; there seems to be really little choice. While small species are usually vic- 

 timized, this is not always the case ; we have found eggs in nests of the Kingbird, Towhee, 

 Robin, Bobolink, Marsh Blackbird, Brewer's Blackbird, Yellow-headed Blackbird, various 

 Orioles, Red-headed Woodpecker, Yellow-billed Cuckoo, and Carolina Dove. In the West, 

 where Cowbirds swarm about the ranches and settlements, it is the rule, I had almost said, to 

 find their eggs in nests of the prairie FringilUdce, etc. Egg usually single ; sometimes 2, 3, 

 and even 4 are found in a nest ; they range 0.75-1.00 X 0.60-0.70, averaging 0.85 X 0.65, and 

 are white or whitish, fully speckled and dashed with browns and neutral tints, in very variable 

 details of pattern. The number which may be laid by any one 9 is unknown, supposed to be 

 8 or more ; the laying season is from middle of May to end of July. 



M. a. obscu'rus. (L,a,t. obscurus, dark.) Dwarf Cowbird. Similar; smaller; j;^ the size 

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

 parently constant. Southwestern U. S., Texas toS. Arizona, and S. into Mexico; the resident 

 form, breeding there, while ater passes on, though the two are associated during the migration 

 of the latter. Swarming like ater; eggs as in that species, but smaller; only up to about 0.80 

 X 0.60, laid from middle of April to end of July in the nests of such birds as the Common 

 Cowbird usually selects ; the ascertained list of species victimized is now 25. 

 CAL'LOTIIKUS. (A word apparently formed to agree in termination with Blolothnis, from 

 Gr. KdXXoi, beauty, + {Mol-)othnts : Cassin, Pr. Acad. Nat. Sci. Phila. 1866, j). 18.) Brazkn 

 Cowbirds. Generic characters nearly those of Molothrits; but feathers of neck of $ elon- 

 gated, forming an erectile ruff, like the pile of velvet, and inner webs of 4 outer primaries sinu- 

 ated and emarginated in a peculiar manner. Sexual difi'ereuces in coloration less marked than 

 in Molothrus. Eggs whole-colored. Our single species has been given in 2d-4th eds. of Key 

 as 31. (fneus; but the Mexican birds have proven to be of two species, to one of which, from 

 western Mexico, the original Psarocoliits ceneus of Wagler has been restricted, while for the 

 other, M. robustus of Cabanis, Mus. Hein. i, 1851, p. 11)3, has been adopted, this being the 

 bird of eastern Mexico, with which ours is identical. See Ridgw. Man. 1887, p. 589; Coues, 

 Key, 4th ed. 1890, p. 900; A. O. U. List, 2d ed. 1895, p. 203, No. 49t). 



