152 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



Recorded as follows : 



Veraguas: Pacific slope (specimen in British Museum collected by Arce). 



Herrera : Cienaga Macana. 



Canal Zone: Rio Chagres between Gamboa, Juan Mina, and Santa Rosa; 



Miraflores lakes. 

 Panama (eastern) : Rio La Jagua. 

 Darien: Laguna de Pita (Salvadori and Festa, Boll. Mus. Zool. Anat. Comp. 



Univ. Torino, vol. 14, no. 339, 1899, p. 13). 



The masked duck is an inhabitant of fresh-water ponds and the 

 quiet waters of the larger streams, where there are extensive growths 

 of aquatic plants that make suitable shelter. Usually two to a dozen 

 or more are found together in small pools or in open stands of floating 

 vegetation where they remain quiet or seek cover. If they have not 

 been disturbed by shooting often they are tame and allow fairly close 

 approach. At such times they remain quiet, with neck drawn in, 

 even when boats pass close at hand, as they are camouflaged against 

 their background, if indeed they are not actually hidden. Their flight 

 is swift and strong, with the white patch in the wing showing 

 prominently. As they rise from open water they may splatter along 

 for 4 or 5 meters to gain momentum, but they also go straight up 

 as readily as teal. In alighting they come in a few feet above the 

 surface, bank, back stroke into the wind, and then drop with a 

 plump into the water, where they bob up and down for a few sec- 

 onds, often without moving forward appreciably. Both methods — 

 that of arising and that of alighting — ^are practical adaptations to a 

 water surface covered with floating or submerged vegetation. On 

 the wing masked ducks suggest their relative, the ruddy duck 

 {Oxyura jamaicensis) , as they have the same bulky head, thickened 

 neck, and short, rounded form. Flight in the two is equally strong, 

 but masked ducks rise more easily from the surface of the water. 

 While they are active on the wing they hide regularly among standing 

 water plants. Sometimes when approached they submerge quietly, 

 and then usually disappear completely, even where the plant cover 

 appears too sparse to give them protection. 



Little is known as yet concerning their nesting. The egg in the 

 Barnes collection described by Bent (U. S. Nat. Mus. Bull. 130, 1925, 

 p. 162) may be of doubtful identity since, with a measurement of 

 63.0 by 45.8 mm., it appears to be too large. Schonwetter (Handb. 

 Ool., pt. 2, 1960, p. 116) describes the eggs as cream-colored, with a 

 roughened shell, and (pt. 3, 1961, p. 133) gives the measurements of 

 9 specimens as 59-63 X 44-47.4 mm. which also seems over large. 

 Bond (Checkl. Birds West Indies, Third Suppl., 1958, p. 3, fig. 1) 



