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 rest- 

 ing 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 



