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

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 133
board from ships at anchor in the harbor. The species was recorded
near Montevideo and Carrasco, Uruguay, on January 9 and
16, 1921. At nightfall I observed them passing along the coast
to some resting place to the eastward. A few were observed at La
Paloma, Rocha, on January 23. Near Guamini, Buenos Aires, on
March 5 I was rather surprised to observe three in company with
flocks of Larus maculipennis about the large lake near town. Larus
doviinicamis was more usual in occurrence near the coast, j^t came
here about 120 miles inland.
The species is similar in habits and notes to large gulls of the
North' rn Hemisphere.
LARUS MACULIPENNIS Lichtenstein
Larus maculipennis Lichtenstein, Verz. Doubl. Zool. Mus. Berlin, 1823,
p. 83. (Montevideo.)
The brown-hooded gull is the most common of the lariform birds
found on the open pampas. An adult male taken at Lavalle, Bue-
nos Aires, on October 29, 1920, was in full plumage and about to
breed. In this bird when freshly killed the bill was Vandyke red;
margin of eye-lids dull Brazil red; iris Vandyke brown; tarsus
and toes Vandyke red; and nails dull black. The colors of bill and
legs have become somewhat duller in the dried skin. One of two
females secured on the coast 15 miles below Cape San Antonio
on November 3 is in winter plumage with brown feathers of the
Juvenal plumage present on the lesser wing-coverts. In the other
the dark hood is indistinctly outlined on the crown and sides of the
head, with scattering dark feathers on the throat. In both specimens
the ends of the inner secondaries are grayish brown and the
tail is tipped with dull black. Both have the feathers of wings
and tail considerably worn. An adult female secured at the Laguna
Castillos, near San Vicente, Department of Rocha, Uruguay, on
January 31, 1921, is in full winter plumage except that the outer
primaries are being renewed. The plumage of the breast has a faint
rosy tint. Two adult males in full winter plumage (one prepared
as a skeleton) were secured at Guamini, Buenos Aires, on March 5,
and a skull was taken from a dead individual on the same date.
The skin preserved shows a few pin feathers on the ventral surface.
From other specimens at hand it appears that the post-breeding
molt is completed about the end of March.
The genus Chroicocephalus that has been used for the hooded
gulls (including L. cirrocephalus and L. maculi'pennis) is seemingly
based entirely on differences in color and color pattern. Several
years ago I examined the skeleton of Larus franklini, 'Philadelphia,
and atricilla, and several species considered to represent typical
Larus, but after careful study was unable to make out structural
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