LIFE HISTORIES OF NORTH AMERICAN WILD FOWL 123 



feathers in the male increases during the winter and spring until 

 some of the most advanced birds become nearly all black except on 

 the belly and wings. Doctor Dwight (1914) says: 



Shortly after new feathers appear, the bill of the young male begins to take 

 on the colors of the adult and still more gradually assumes its shape. The 

 colors may closely approximate, by the end of the winter, those of the adult, but 

 the shape is not perfected for at least a year, the swelling of the hump not be- 

 ing marked in the first winter birds, although the yellow color may be brilliant. 

 The bill of the female and the legs and feet of the male remain dusky, adults 

 differing very little from young birds. 



No matter how black the plumage may be nor how bright the colors of bill 

 or feet, young males may infallibly be told from adults by the shape of the 

 first primary, which is not replaced until the first postnuptial molt. The iris 

 in americana is always brown in both sexes at all ages. 



At the first complete postnuptial molt, the following summer, the 

 young bird becomes practically adult ; the plumage is wholly black in 

 the male and wholly dark brown in the female. At this molt the adult 

 wing is acquired, in which the outer primary is deeply emarginated ; 

 the broad tipped outer primary is worn by the young bird for one 

 year only. 



Adults have two molts each year, a partial prenuptial molt in 

 March and April, involving the body feathers and the tail, and a 

 complete postnuptial molt in August and September. There is no 

 evidence of anything like an eclipse plumage in this or in the other 

 scoters. The plumages described as such by European writers are 

 probably produced by wear and fading or by left-over traces of a 

 former plumage. 



Food. — Writing of the feeding habits of the three species of 

 scoters on the Massachusetts coast, George H. Mackay (1891) says: 



These scoters are the most numerous of all the sea fowl which frequent 

 the New England coast, collecting in greater or less numbers wherever their 

 favorite food can be procured — the black mussel (Modiola modiolus), small 

 sea clams (Spisula solidissima) , scallops (Pecten concentricus) , and short 

 razor shells (Siliqua costata), about an inch to an inch and a half long, which 

 they obtain by diving. Mussels measuring 2^2 inches by 1 inch have been 

 taken from them ; but usually they select sea clams and scallops varying in 

 size from a 5-cent nickel piece to a quarter of a dollar. They can feed in 

 about 40 feet of water, but prefer less than half of that depth. As these 

 mussels are frequently difficult to detach, and the sea clam lives embedded 

 endwise in sand at the bottom with only about half an inch above the sand, 

 the birds are not always successful in obtaining them, it requiring considerable 

 effort on their part to pull the mussels off or to drag out the clams. Eight 

 or ten of these constitute a meal, but the number varies according to the size. 

 I have heard of a mussel closing on a scoter's tongue, which was nearly severed 

 at the time the bird was shot (Muskeget Island, about 1854). The fishermen 

 frequently discover beds of shellfish (scallops) by noticing where these birds 

 congregate to feed. In the shoal waters adjacent to Cape Cod, Nantucket. 



