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

BIRDS OF ARGENTINA, PARAGUAY, URUGUAY, AND CHILE 71
nently, making a conspicuous field mark. At no time were they
observed flying at an altitude of more than 80 meters in the air,
while usually they passed barely high enough to clear low trees, from
15 to 30 meters above the ground. In alighting they flapped heavily
to break their momentum as they came down into the grass. Their
tree-perching habit may be the outcome of life in a region where
during the rainy season there is nowhere else to rest save in the
water.
An adult male taken September 7 was completing a molt of the
body plumage and had the sexual organs dormant. No indication of
breeding was noted among them.
To the Anguete Indian the Muscovy duck was known as meh
dik tee.
The immature male (fully grown) secured in Formosa shows
patches of old brown feathers among glossy black plumes that
recently had been renewed. It does not have the broad white
shoulder of the adult; there are scattered black feathers over the
loral region, and the skin behind the eye is closely feathered. The
caruncles of the adult are barely indicated. The adult taken in
Paraguay in life had the soft parts colored as follows: Nail on both
mandible and maxilla dark neutral gray; remainder of tip of bill
pale drab gray, washed with livid brown on margin; spot behind
nostrils, line of culmen between nostrils, as well as central portion of
mandibular rami pale drab gray; band across bill in front of
nostrils extending around on mandible, and base of bill, including
bare skin on side of head, black; caruncles black at base, elsewhere
purplish vinaceous ; iris cream buff ; tarsus and toes black.
DENDROCYGNA BICOLOR BICOLOR (Vieillot)
Anas Mcolor Vieillot, Nouv. Diet. Hist. Nat., vol. 5, 1816, p. 136. (Para-
guay.)
Near Lavalle, Province of Buenos Aires, the fulvous tree duck
was common among the cailadones from October 28 to November 9,
1920. The birds ranged in flocks, frequently 30 or 40 together, that
were found in open ponds where the water was a meter deep. They
were frequently active at dusk. When flushed they rose with the
whistled w^heezy calls that gave them their local name of pato
siiflon and passed on, often flying rather high, to more distant resting
places. In the air they seldom show color, aj^pearing simply as
silhouettes of black against the sky. The birds on the wing differ
in appearance from other ducks and offer a remarkable resemblance
to ibises as they pass with rather slow wing beat and long necks
outstretched, a similarity engendered by the long, bluntly pointed
wing. The flight is only moderately fast. A female taken on