LIFE HISTORIES OF NORTH AMERICAN WILD FOWL 163 



breeds somewhere near them — very possibly amonj^ the dense thickets of red 

 mangrove (Rliizophora) , by wliich they are mostly surrounded. Anyone who 

 has ever been among rod mangroves will appreciate the diflicwlty of finding the 

 nest of a diving bird among them — except by a fortunate chance, which never 

 came to the writer. 



Most of the resident birds of Grand Cayman are remarkably fearless of 

 man, very niuch as robins are in Europe, but these ducks are more wary, and 

 when their pond is approached generally make their first appearance in the 

 middle of it, having dived at the sight or sound of the intruder and, if near 

 the shore, found their way under water to what they think is a safer place. 

 When at rest they float very much as most waterfowl do, the water line being 

 in about its usual place, but when swimming they are almost always deeply 

 submerged, and if approaching or receding from the observer, seem to have 

 a relatively enormous "beam." Of course this effect may be only due to the 

 very low elevation of the bird's back above the water. Their method of diving 

 is interesting. It has the appearance of being done without the movement of 

 a muscle, just as if the bird were a leaking vessel which was going down on 

 an even keel. This downward progress is (jften interrupted, when just the 

 head, the neck, and the upper part of the upstanding tail are showing above 

 the surface, or a little later, when only the head and part of the neck, which 

 is habitually kept stiffly upright (as is the tail), are visible. In either of 

 these positions the bird seems able to rest as well as to swim at some speed. 



Nomonijx dominicus has at least two calls, one of them very like the clucking 

 of a hen to her chickens and the other more reminiscent of a short note from 

 a motor horn. 



H. B. Conover writes to me, of the habits of this species in Vene 

 ziiela, as follows: 



We lir^t s:iw the masked duck in ;; suiuU pond on the edge of the savannah 

 about 60 miles south of Maracaibo. Here one day I ran into a pair of males 

 in the hen plumage. They were sitting a short way offshore and allowed us 

 to walk up within 15 or 20 yards. The native with me shot at them, killing 

 one, and the other bird jumped. This pair were probably stragglers ; I was 

 around there for a week and never saw any more. At Lagunillas in May these 

 birds were abundant in the same marsh as the tree ducks. They sat around 

 in open patches of water among the aquatic plants in small lots of about 5 to 

 15. They seemed to stay almost entirely in these open patches of water and 

 rarely, if ever, were seen to alight among the floating aquatic plants. They 

 would start to flush at about 75 yards and would rarely let one get within 50 

 yards of them in a boat. As a general rule, when the flock was approached, 

 they would go off one or two at a time, not rising in a body. They would 

 again alight within 200 or 300 yards. They rose fairly easily from the water, 

 which was a great surprise to me, as they got off the surface very quickly and 

 were not anywhere nearly as clumsy as the ruddy duck. A few birds were 

 seen at this time which showed the red plumage, but the greater majority were 

 in the brown stage. I tried my best to get an adult male, but the birds were 

 so wild I was unsuccessful. 



DISTKIHUTION 



Breeding range. — In the West Indies (Cuba, Jamaica, Haiti, Porto 

 Rico, St. Croix, Barbados, and Trinidad). INfainly in eastern South 

 America, in Ar<>:entina, eastern and central Brazil, Guiana, Vene- 

 zuela, etc. 



