THE COWBIRDS. 615 



of birds of other genera. Certainly in this way the parasitic instinct 

 may liave originated in M. honariensis withont that species ever having 

 acquired the habit of breeding in the covered dark nests of other birds. 

 I have supposed that they once possessed it only to account for the 

 strange attraction such nests have for them, which seems like a recur- 

 rence to an ancestral habit. 



MOLOTHRUS RUFOAXILLARIS, Cassiii. Screaniinjj Cowbird. 



Molothrus rtifoaxiUarifi, SCL. et Salv., Nomencl. p. 37; Hudson, F. Z. S. 1874, p. 

 161 (Buenos Ayres); Durnford, Ibis, 1877, p. 174 (Bueuos Ayres) ; White, 

 /'. Z. S. 1882, p. 601 (Catamarca) ; Barrows, Bull. Nutf. Orn. CI. viii, p. 

 134 (Entrerios); ScL Cat. B. xi. p. 338. 



Description. — Silky black, washed with purple; wings and tail with 

 a slight greenish gloss; a chestnut spot on the axillaries; bill and feet 

 black; whole length 8 inches, wing 4.5, tail 3.3. Female similar, but 

 somewhat smaller. 



Habitat. — Argentina and Uruguay. 



This bird has no vulgar name, not being distinguished from the 

 common Cowbird by the country people. The English name of Scream- 

 ing Cowbird, which I have bestowed on it, will, I think, commend 

 itself as appropriate to those who observe this bird, for they will always 

 and at any distance be able to distinguish it from the species it resem- 

 bles so nearly by listening to its impetuous screaming notes, so unlike 

 anything in the language of the common Cowbird. 



The Screaming Cowbird is larger than the allied species. The female 

 is less than the male in size, but in color they are alike, the entire 

 plumage being deep blue-black, glossy, and with purple reflections; 

 and under the wing at the joint there is a small rufous spot. The beak 

 is very stout, the plumage loose, and with a strong, musky smell; the 

 oesophagus remarkably wide. 



It is far less common than the other species of ^[olothrus, but is not 

 rare, and ranges south to the Buenos- Ayrean pampas, where a few 

 individuals are usually found in every large plantation; and, like the 

 3f. badius, it remains with us the whole year. It is not strictly grega- 

 rious, but in winter goes in parties, never exceeding five or six indi- 

 viduals, and in the breeding season in i^airs. One of its most note- 

 worthy traits is an exaggerated hurry and bustle thrown into all its 

 movements. When passing from one branch to another, it goes by a 

 series of violent jerks, smiting its wings loudly together, and when 

 a party of them return from the fields they rush wildly and loudly 

 screaming to the trees, as if pursued by a bird of prey. They are not 

 singing birds, but the male sometimes, though rarely, attempts a song, 

 and utters, with considerable effort, a series of chattering uumelodious 

 notes. The chirp with which he invites his mate to fly has the sound 

 of a loud and smartly-given kiss. His warning or alarm note when 

 approached in the breeding season has a soft and pleasing sound; it 



