590 REPORT OF NATIONAL MUSEUM, 1893. 



On tlie whole, our Cowbirds present a far wider and more interesting 

 field for careful observation and studj* than does the European Cuckoo, 

 as their habits differ greatly in many respects; for instance, they are 

 among the few, if they are not the only birds, which practice polyan- 

 dry, which is probably caused for the reason that the males generally 

 outnumber the females about 3 to 1. 



In order to give the reader some idea of these disreputable but never- 

 theless interesting birds, my articles written for Life Histories of North 

 American Birds, Part ii, are printed from advance sheets without alter- 

 ation, excepting the addition of a concise description of each species, 

 taken from Mr. 11. Kidgway's Manual of North American Birds. 



Fgures of an adult male and female Cowbird, Molothrus ater, are 

 here given (pis. 2 and 3) as well as a nest of the Yellow Warbler, Ben- 

 (Jroica aestiva, (pi. 1) containing three eggs of its own and one of this 

 parasite. 



The articles on the Cowbirds found in the Argentine Eepublic are 

 copied from Messrs. P. L. Sclater and W. H. Hudson's work on Argen- 

 tine ornithology, the notes on their habits being based on observations 

 made by the latter gentleman. The two series of articles combined 

 will enable the reader to arrive at a better understanding of the gen- 

 eral habits of some of the members of this interesting genus. 



MOLOTHRUS ATEE (Boddaert) Cowbird. (Plates 2 aud 3). 



Oriolus ater, Boddaert, Tables des jilaiiches eulumiuoes d'liistoire uaturelle, 

 1783. 37. 



Molothrus ater, Gray, Hand List of Birds, ii, 1870,36. 

 (B 400, C 211, R 258, C 313, U 495.) 



Description. — Adult males: Head, neck, and chest uniform brownish 

 (varying greatly in tint); rest of plumage glossy black, with a green- 

 ish reflection, changing to purplish next to the brown of the neck, 

 especially on the upper back. Adult females : Plain brownish gray, 

 darker on upper parts, jialer on chin and throat; the feathers, especially 

 on back and breast, with indistinct darker shaft streaks. Young: 

 Above dull brownish gray, the feathers bordered with i>ale buffy; 

 lower parts dull light buffy, broadly but rather indistinctly streaked 

 with dull l)rownish gray. 



Length (male), about 7.75-8.25 ; wing, 4-4.60 (4.31) ; tail, 2.90-3.35 (3.08) ; 

 culmen, 0.61-0.72 (0.66); tarsus, 08-1.12 (1.05): female considerably 

 smaller. 



Geographical raiuje. — United States and the southern parts of the 

 Dominion of Canada, in the eastern portions to about latitude 49-' north ; 

 in the interior to Little Slave Lake, southern Athabasca, latitude 

 55° 30', and probably still farther north; west to British Columbia, 

 eastern Washington, eastern Oregon, Nevada, and southeastern Cali- 

 fornia ; south in winter to southern Mexico. 



The breeding range of the Cowbird, also known as Cow Bunting, 



