BIRDS OF ARGENTHSTA, PARAGUAY, URUGUAY, AND CHILE 75 



m Dafila acuta in the United States, males desert their mates as soon 

 as the eggs are deposited, and then band together to spend the re- 

 mainder of the summer in company. Pintails nested commonly 

 through the pampas in this immediate region and were breeding at 

 this time. It was my opinion, however, that many of the birds 

 observed, patently in migration, had come from more southern 

 regions in Patagonia, where the species nests commonly. The ex- 

 treme eastern part of the Province of Buenos Aires, behind the Bay 

 of Samborombon and Cape San Antonio, is divided into great 

 estancias, with small rural population. Broad marshes, sAvamps, 

 and wet meadows, loiown as canadones and baiiadones extend for 

 miles and furnish feeding and loafing grounds suitable for these 

 birds where they may pass the hot weather and molt in lazy idleness. 

 After November 9 these ducks remained abundant, but, although 

 they roamed over the country in search of feeding grounds, there 

 was no concerted movement among them, as the great migration 

 from the south seemed at an end. On November 15 I found many 

 (nearly all males) along the Rio Ajo below Lavalle, where few had 

 been observed on October 25. 



The breeding season, as in many other birds of this region, may 

 be irregular. A paired female taken November 4 was not yet in 

 condition to lay. On November 16 in traveling from Lavalle to 

 Santo Domingo, Buenos Aires, I observed what seemed to be a 

 mating flight of this bird. As a pair circled over a caiiadon, high in 

 air, the male at short intervals swung under and slightly in front 

 of the female, while she at each approach swerved to one side or the 

 other leaving him again behind. 



At General Roca, in the Territory of Rio Negro, from November 

 23 to December 3, pintails were common along the Rio Negro. A 

 female, in company wuth eight young 3 or 4 days old, was found on 

 November 27, and four of the young birds were taken. On December 

 3 a female was seen with a brood of immature birds at least three- 

 quarters grown. In both instances the females (who were not 

 accompanied by males) were very solicitous and thrashed about in 

 the water to attract my attention or flew back and forth overhead. 

 A single bird was seen on a salt lagoon at Ingeniero White, the 

 port of Bahia Blanca, on December 13, while from December 15 to 

 18 the species Avas common at Carhue, in western Buenos Aires. 

 The fresh skull of an adult male Avas secured from the camp of a 

 hunter. One was seen at a small pool near Victorica, Pampa, De- 

 cember 29. 



In Uruguay tAvo were noted January 9, 1921, on an arroyo beloAV 

 Carrasco, a bathing resort near Montevideo, while on January 31 a 

 fcAv were found on the Laguna Castillos near San Vicente, in the 



