424 Dwight, Black Duck of North America. {ac^t 



birds, at first an olive-brown, become gradually reddened, and 

 finally in. the spring they are of nearly as bright a red as that of the 

 adults, while the dusky bill brightens to greenish and then to yellow- 

 green or yellow. There is nothing unusual in this change of color, 

 which occurs in many species of ducks, as well as among other 

 birds, and we know well how in the case of the Eiders and Scoters 

 there is, in addition to brightening colors, a transformation in the 

 shape and size of the bill. Once the adult colors of the soft parts 

 are attained they are never lost, and so it is with the Black Duck — 

 the bill of the adult is at all seasons of the year a bright greenish 

 yellow and the feet a coral red, these colors dulling only a trifle 

 after the breeding season. In females the colors are regularly 

 duller than those of the males. 



There is considerable variation in the time at which young birds 

 acquire the red legs and yellow bill; some of them resemble adults 

 as early as January while others are still dull in April. A very few 

 laggards in vitality seem to remain immature during their first 

 year, as is often the case with other species, but aside from plumage 

 there are other earmarks of immaturity. The bones, the trachea 

 and larynx and the sexual organs proclaim approximately the age of 

 specimens carefully examined. It is worthy of note that the dusky 

 head-markings of adults merely average darker than those of young 

 birds, which more often have unspotted chins, but the variation in 

 both old and young is considerable. The plumage of adults differs 

 somewhat from that of young birds and it should be remembered, 

 too, that young birds in unlike stages of plumage may be shot on the 

 same day. It may be urged that these variations, due to age and 

 season, belong only to the northern birds and that the southern 

 birds never acquire the red legs and other characters of the sup- 

 posed rubripes, but such is not the case. There are many diffi- 

 culties to be overcome in obtaining breeding specimens which would 

 of course settle the question at once. The males become exceedingly 

 shy and difficult to find in the breeding season and nobody wants to 

 slaughter brooding females even if nests be found. Moreover, the 

 game-laws must be respected, especially by collectors. But before 

 spring shooting was abolished some years ago on Long Island, New 

 York, a number of freshly killed birds were sent me that scarcely 

 needed dissection to prove them to be breeding birds. They were 



