602 REPORT OF NATIONAL MUSEUM, 1S93. 



their own, and some of these are usually punctured. In none of these 

 nests were eggs of the Dwarf Cowbird found in addition to those of the 

 GallothruH robustus. The former appears to confine itself to the smaller 

 Orioles only. 



The eggs of the Bronzed Cowbird are rather glossy ; the shell is finely 

 granulated and strong. Their shape varies from ovate to short and 

 rounded ovate. They are pale bluish green in color and unspotted, 

 resembling the eggs of the Black-throated Sparrow and Blue Grosbeak 

 in this respect, but are much larger. 



The average measurement of 38 specimens in the U. S. National 

 Museum collection is 23,11 by 18.29 millimeters, or 0.91 by 0.72 inch. 

 The largest egg of the series measures 24.(54 by 18.80 millimeters, or 

 0.97 by 0.74 inch; the smallest, 21.84 by 10.76 millimeters, or 0.86 by 

 0.66 inch. 



MOLOTHKUS BONARIENSIS (Gm.). Argentiue Cowbird. 



Molothrus honariensis, ScL. et, Salv., NomencL, p. 37; Hudson, P. Z. S., 1872, p. 809, 

 1874, p. 153 (Buenos Ayres); Duknford, Ihis, 1877, pp. 33, 174 (Cliupat) ; 

 White, P. Z. S., 1882, p. 601 (Buenos Ayres) ; Dohing, Exp. al Rio Negro, Zooh, 

 p. 41 (Carhue); Barrows, liull. Ntiit. Orn. Cl.viu, p. 133 (Eutrerios); Sol., 

 Cat. B., XI, p. 335. — Molothrus sericeus, BuRM., La Plata Beise, n, p. 494. 



Description. — Uniform shining purplish black; less lustrous on wings 

 and tail; bill and feet black; total length, 7.5 inches; wing, 4.5; tail, 

 3. Female, dark ashy brown; beneath paler; slightly smaller in size. 



Hah. — Argentina, Paraguay, Bolivia, and Brazil. This species is 

 the Tordo Gomun of Azara, and is usually called '■^ Tordo^^ or '■'•Pajuro 

 Kegro'''' by the Spanish, and ^'- Blacl-bird''^ by the English-speaking- 

 Argentines. A more suitable name, I think, is the Argentine Cowbird, 

 which has been given to it by some writers on ornithology, Cowbird 

 being the name of the closely allied North American species, Molothrus 

 pecoris. 



This Cowbird is widely distributed in South America, and is common 

 throughout the Argentine country, including Patagonia, as far south 

 as Chupat. In Buenos Ayres it is very numerous, especially in culti- 

 vated districts where there are i)lantations of trees. The male is 

 clothed in a glossy plumage of deep violaceous purple, the wings and 

 tail being dark metallic green; but seen at a distance or in the shade 

 the bird looks black. The female is inferior in size and has a dull, 

 mouse-colored i)luniage and black beak and legs. The males are much 

 more numerous than the females. Azara says that nine birds in ten are 

 males, but I am not sure that the disparity is so great as that. It 

 seems strange and contrary to nature's usual rule that the smaller, 

 shyer, inconspicuous individuals should be in such a minority; but the 

 reason is perhaps that the male eggs of the Cowbird are harder shelled 

 than the female eggs, and escape destruction oftener when the i)arent 

 bird exercises its disorderlj^ and destructive habit of pecking holes in 

 all the eggs it finds in the nests into which it intrudes. 



