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

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 103
the pampa they did not appear to breed until December. In Uru-
guay, where the present bird is common, it is an efficient enemy of
the locust hordes that devastate the cultivated lands.
FALCO FUSGO-CAERULESCENS FUSCO-CAERULESCENS Vieillot
Falco fusco-caerulescens Vieillot, Nouv. Diet. Hist. Nat., vol. 11, 1817, p.
90. (Paraguay.)
Near the Riacho Pilaga, Formosa, and from that point eastward
to the Rio Paraguay, aplomado falcons were fairly common during
the middle of August, 1920. They frequented open savannas where
stubs of dead quebrachos offered lookout stations, or failing these,
even rested on the tops of bushes near the ground. Their flight was
swift and direct, performed with strong, quick beats of the wings,
and in general appearance they suggested small duck hawks. At
the Riacho Pilaga the sight of these little falcons brought conster-
nation to the screeching flocks of monk parrakeets that fed in the
open in old sweet-potato fields. A male falcon taken on August 12,
a bird fully grown but in dark immature dress, had the tip of the
bill black, shading posteriorly through gray number 7 to mustard
yellow at base, cere and bare skin about eye mustard yellow; iris
Rood's brown; tarsus and toes primuiine yellow; claws black. The
species was not seen again until April 9, 1921, at Tapia, Tucuman,
when a female was brought down with a broken wing as it passed
me above a wooded slope. This bird ran sw^iftly on the ground to
cover and was captured only after a rapid chase down a brush-grown
slope. On April 10 two were seen, evidently hunting, as one dashed
down into little openings in the woods and then, disappointed in
seeing prey, rose again to continue its direct flight. On April 17 a
male was Idlled from a little tree above a mountain pool at an eleva-
tion of 2,300 meters, in the Sierra San Xavier, above Tafi Viejo,
Tucuman. This was an immature bird of the year, while the female
taken at Tapia is probably in its second year, as it is distinctly gray
above.
The subspecies Falco f. septentrionalis Todd^^ proposed for the
aplomado falcon of North America may be distinguished by slightly
larger bill, longer tail, and bj^ greater average size in all measurements.
In color northern and southern birds appear identical. The
wing measurement in this species seems somewhat variable and in
the series at hand is not of definite value in separation, save w^hen
used in averages. The bill, however, is slightly larger and longer,
and the tail longer in septenti'^ionali^. A single female from La
Raya, in the Andes of Peru, that greatly exceeds any other specimens
in general size (wing, 313 mm.) save that the bill is small, probably
s=Proc. Biol. Soc. Washington, vol. 29, June 6, 1916, p. 98. (Fort Huachuca,
Arizona.)