ROSY-BILLED DUCK 115 



Adult Female: A plain brown-colored duck, much darker on the back. The top of the head is very 

 dark brown which shades into lighter tones on the sides of the head and to white on chin and throat. 

 Speculum white as in male, breast much darker than abdomen, under tail-coverts white. 



Iris hazel. Bill bluish slate-color with the tip black. Legs and feet dull orange-yellow to grayish 

 with the webs dusky. 



Wing 220-240 mm.; bill 54-59; tarsus 41-44. 



Male in First (Juvenal) Plumage : Apparently like the female but the lower parts brown, lacking 

 the silvery-white appearance of the old female. Bill without pronounced knob. The young males 

 appear to be in transition plumages in April or May, that is, at six or seven months of age, and show 

 the adult black feathers mixed with the worn brown ones. 



Male after the Breeding Season: I have seen no specimen which might be called a true eclipse 

 plumage. The knob decreases in size. 



Young in Down: Not examined. 



DISTRIBUTION 



The Rosy-bill is one of the co mm on and characteristic ducks of the Argentine Republic, where it is 

 found throughout the year. Its seasonal movements are very irregular and limited. Its range, how- 

 ever, is a restricted one, comprising only the northern half of the Argentine and the adjacent territory. 

 Wace (1921) states that it has been recorded from the Falkland Islands by Bennett. So far as I 

 know there is no definite record of its occurrence on the mainland south of the Rio Negro, except 

 the specimens seen and taken by J. L. Peters near Huanuluan, Rio Negro Province, and at Neluan 

 some sixty miles southeast. Wetmore (MS.) saw several early in December on the Rio Negro just 

 below General Roca. Farther north, in the Province of Buenos Aires, is its real home, and there it is 

 said to be the commonest duck and one of the most abundant birds, especially in the breeding season 

 (P. L. Sclater and Hudson, 1889; A. H. Holland, 1892; Hartert and Venturi, 1909; C. H. B. Grant, 

 1911; D. Rodriguez, 1918; E. Gibson, 1920; Beck, MS.; Wetmore, MS.). C. H. C. Burmeister (1861) 

 found the species common on the Rio Parana, and C. S. Reed (1916) states that it is common about 

 La Paz, Mendoza Province. Farther north and especially west it becomes a much rarer bird, though 

 specimens have been taken in Cordoba (Frenzel, 1891), Rioja (Giacomelli, 1907), Tucuman (Lillo, 

 1902) and in the Chaco (Lynch-Arribalzaga, 1920). 



As to its status in Chile very little is known beyond the fact that it is a resident (James, 1892) and 

 is most common in the central parts (Quijada, 1910). Schalow (1898) has recorded a specimen taken 

 near Concepcion and I doubt whether the range extends farther south than that. 



There is no record of the Rosy-bill's occurrence in Bolivia, but it is found in Paraguay (H. von 

 Ibering, 1904; Bertoni, 1913). Kerr (1901) states that he saw a few late in January in the Gran Chaco 

 and was told by Mr. Pride that the species was more common several days' journey to the west. The 

 U.S. National Museum also has specimens from Paraguay. 



In Brazil this duck occurs only in the extreme southeast, Province of Rio Grande do Sul (H. and R. 

 von Daering, 1907), but in Uruguay it is abundant, especially during the freshets. A few may breed 

 near Concepcion (Barrows, 1884), but the species has been recorded also from Montevideo, Cane- 

 lones, Maldonado, Rocha, Cerro Largo and the Rio Negro (Aplin, 1894; Alvarez, 1913; Tremoleras, 

 1920; Wetmore, MS.). 



Migration 



Seasonal movements do occur and as little has been written about these I think it is worth while to 

 quote from Mr. Peters' notes. He says: "Upon my arrival at 'Las Yngleses' (Mr. Gibson's old estate) 



