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

380 BULLETIN 133, UNITED STATES NATIONAL MUSEUM
recognition of two races under this species as I have done here. The
earliest name apparent for the eastern race is Agelaius chrysopterus
Vieillot from the reference cited above. The male of Vieillot's de-
scription is a hopeless composite drawn apparently from Agelaius
xantho7nus of Porto Rico, and whatever species of Icterus is indi-
cated by Latham's Oriolus cayanensis. The female, however, is
taken from Azara's account of the Tordo negro cohijas amanllos
and refers to the present bird. The name may thus be identified
definitely with the eastern form of the yellow-shouldered blackbird.
An adult male taken at Berazategui, Buenos Aires, on June 29,
1920, is in full black plumage save for a few faint, paler margins
that remain on the lower breast, abdomen, and lower tail coverts
(where they are most pronounced) and on the dorsal surface. A
pair in breeding plumage, somewhat worn, were taken at Lavalle,
Buenos Aires, November 6 (female) and November 15 (male). At
the Laguna Castillos, near San Vicente, Uruguay, I killed a pair in
very worn breeding plumage and an immature female not quite
fully grown. The adult female is very dark, and both of the older
birds are smaller than others I have seen, as the wing in the male
measures 80 mm. and in the female 75.4 mm., a condition due perhaps
in part to wear. The juvenile female is dark in tone and much
browner than others slightly older from other regions. At Tunuyan,
Mendoza, on March 23 I secured an adult male, a female of equal
age, and an immature female. The male has just completed the postnuptial
molt and has the black obscured in a peculiar way. The
crown is bone brown with a central streak of deep olive buff and a
superciliary streak of pale olive buff. The hind neck is darker than
buffy brown, the back feathers are margined with deep olive buff
and natal brown, the greater and median wing coveyts tipped with
pale olive buff, and' the feathers of rump and upper tail coverts
bordered with deep olive buff. The entire undersurface has the
feathers margined with pale olive buff. These lighter markings are
lost through wear, so that by spring the bird is black save for the
yellow shoulders. Pale markings persist on the under tail coverts
longer than elsewhere.
The adult female from Tunuyan has about completed the body
molt, but has all of the rectrices and a few wing feathers growing in
anew. Females from Mendoza are distinctly paler than birds from
Buenos Aires, and it is probable that they represent a pale form
with a range covering marshes in the arid western regions of Ar-
gentina. Present material is not sufficient to demonstrate this satis-
factorily.
The yellow-shouldered blackbird is an inhabitant of rush-grown
fresh-water marshes, though ranging near the coast where salt water
is tempered by springs or streams. At Berazategui, Buenos Aires,