148 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



AYTHYA AFFINIS (Eyton): Lesser Scaup; Pato Pechiblanco 



FiGUKE 28 



Ftiligula affinis Eyton, Mon. Anatidae or duck tribe, June, 1838, p. 157. (North 

 America.) 



Of medium size, with white wing speculum ; young males, and fe- 

 males with white in front of eye. 



Description. — Length 380 to 410 mm. Adult male, head and neck 

 black, with faint purplish sheen; upper back, breast, rump, wings, 

 upper and under tail coverts, and tail black, often with a brownish 

 wash; center of back and scapulars lined narrowly with black and 

 white ; wing speculum white, bordered with black. 



Female and immature male, forepart of head, breast, and abdomen 

 white; rest of plumage brownish black, except for the white wing 

 speculum, like that of the male. 



Measurements. — Males (5 from southeastern United States), wing 

 193-200 (197), tail 51.8-54.5 (52.6), culmen 39.6-42.9 (41.1), tarsus 

 33.9-36.0 (35.0) mm. 



Females (5 from the United States), wing 185-191 (187.4), tail 

 48.0-51.0 (49.6), culmen 36.6-40.0 (38.2), tarsus 33.0-34.8 (33.6) 

 mm. 



Regular winter visitor. Tolerably common on larger bodies of 

 fresh water, seen occasionally on salt water; arrives from the north 

 about the middle of November, and remains through March. Re- 

 corded as follows : 



Chiriqui : Lakes near El Volcan. 



Bocas del Toro : Changuinola, Almirante. 



Verag^as: Laguna del Castillo (Salvin, Proc. Zool. Soc. London, 1870, 



p. 219). 

 Canal Zone : Gatun Lake, Gamboa, Juan Mina, Chiva Chiva Lakes. 

 Panama (eastern) : Panama Viejo; Rio La Jagua. 

 Isla Coiba (lagoon at Catival). 



Three records of banded birds include one each from Almirante 

 Bay, Rio Hato, and La Jagua. 



Lesser scaups are diving ducks that frequent ponds and lakes of 

 quiet water and are seldom seen where tidal and other currents are 

 changeable and rapid. They have the sociable habits common to most 

 species of their family, and so it is usual to see them in small flocks. 

 Single individuals may become separated during feeding periods, 

 when the birds dive constantly, but later, when all are at rest, they 

 group again, on open water, or, if in some place where they are not 

 disturbed, at the water's edge. I have found them regularly on the 



