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

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 77
small flocks, at times as many as 50 together, near the mouths of
fresh-water arroyos draining into the strongly saline Lago Epiquen,
or in small ponds common here in slight depressions through the
undulating pampa. The birds rose with a high-pitched call, and on
the wing in flight and form resembled Daflla spinicauda, a species
from which they were easily distinguished by the buffy-brown tail
(in color distinctly lighter than the back) and by the sharply defined
lines of their bicolored heads.
As no specimens were taken these notes are allocated under the
subspecies ruhrirostris on the basis of Bangs's recent review of the
group.^^
NETTION FLAVIROSTRE (Vieillot)
Anas flavirostris Vieillot, Nouv. Diet. Hist. Nat., vol. 5, 1816, p. 107.
(Buenos Aires.)
The curious nesting habits of the tree or yellow-billed teal have
been well described by the late Ernest Gibson in his notes on birds of
the Cape San Antonio region, Province of Buenos Aires.^^ While
working at Mr, Gibson's estancia, Los Yngleses, near Lavalle, from
October 30 to November 9, 1920, I found the birds fairly common.
The breeding season had begun and the teal were nesting in huge
stick nests of the monk parrakeet {Myioj)sitta monachus) placed in
the tall eucalyptus trees lining the driveways near the estancia house.
The birds themselves spent much of their time resting 40 or 50 feet
from the ground on open horizontal limbs in the eucalyptus, where
they stood on one leg asleep with the bill in the feathers of the back
as calmly as though they rested on some mud bar in a lagoon.
Though six or eight frequently congregated in these situations,
when flushed the birds separated in pairs that circled swiftly over
the open fields to return to some safer haven among the trees. The
males gave a low whistle and the females a high-pitched kack hack
ka-ack^ notes that in both cases resembled those of the similar sex
in the green-winged teal {Nettion carolinense) . In fact, the re-
semblance to the call of the northern bird was so close that I never
overcame a feeling of surprise when I heard the present species call
from the treetops.
After heavy rains the tree teal descended to shallow pools in the
grassy fields near at hand, but at other times flew out to feed in the
marshes and swamps in company with other ducks. Males taken
were in full breeding condition. On October 31 I observed a male
on the wing in pursuit of a female, giving his musical whistled note.
The two circled and swimg swiftly through the tops of the trees in a
^^ Proc. New England Zool. Club, vol. 6, Oct. 31, 1918, p. 89.
"Ibis, 1919, pp. 20-21.