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

BIEDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 109
of the lower abdomen and under tail coverts are marked or tipped
obscurely with white. The second specimen is an immature bird
in process of molt from the first year plumage : On the dorsal sur-
face new, nearly black feathers are appearing. Below, the breast
and abdomen are dirty white, with more or less streaking of fus-
cous. It appears that three years at least may be required to gain
the full adult plumage, since the new feathers growing in on the
back in this individual are obscurely margined with rusty, a character
absent in the fully adult bird. The plumages and plumage
change in this hawk are of considerable interest, but can be studied
successfully only with a considerable series. Apparently the species
is dimorphic since light or dark individuals are found in the young
stages.
This beautiful hawk inhabited the open savannas of the Chaco,
or the extensive marshes of the pampas. Almost invariablj^ it was
seen skimming in true harrier style along the borders of channels
or lagoons where it might hope to encounter prey, its large size
serving to distinguish it from C. cinereus found in the same regions.
The dark plumaged adults were especially handsome, their colora-
tion being frequently visible at a considerable distance.
The species was found at a number of points, but was more
common in the Chaco than elsewhere, as will be observed in the
folloAving records: Las Palmas, Chaco, July 26 and 31, 1920;
Eiacho Pilaga, Formosa, August 15 and 17; Kilometer 182 to Formosa,
Formosa, August 21, several; 200 Idlometers west of Puerto
Pinasco, Paraguay, September 25, one; Lavalle, Buenos Aires,
November 2 and 4; San Vicente, Uruguay, January 31, 1921, and
at the Paso Alamo, Arroyo Sarandi, February 2, one; Lazcano,
Urugua3% February 3, one.
The adult male taken had the distal half of the bill black; base
gray number seven ; cere vetiver gray ; iris ochraceous tawny ; tarsus
and toes light orange-yellow; claws black.
URUBITINGA URUBITINGA URUBITINGA (Gmelin)
Falco uriiUtinga Gmelin, Syst. Nat., vol. 1, pt. 1, 17SS, p. 265. (Eastern
Brazil.'")
Near Las Palmas, Chaco, on July 14, 1920, I Idlled a male in immature
plumage from a tree above a pool of water in heavy forest.
This bird was only recently from the nest, as, though in complete
plumage, down filaments still clung to some of the rectrices and
secondaries. Above it is dark brown, with markings of sayal brown
^Gmelin writes that the bird was found in Brazil, but Berlepsch and Hartert (Nov.
Zool., vol. 9, 1902, p. 113) from the original sources of Gmelin's information have
given the type locality as "Bras, or.", eastern Brazil.)