Bulletin - United States National Museum - si-pddr - Smithsonian ...

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 remainder
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 extreme
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, December
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