Vol. XXVI 



1909 



Dwight, Black Duck of North America. 423 



April, 1902, pp. 183-188) that Mr. Brewster separated the birds 

 of the northern part of the range of the Black Duck under the name 

 Anas obscura rubripes or Red-legged Black Duck, restricting the 

 name obscura to the southern birds. Presently it was discovered 

 that the name obscura was preoccupied some twenty-five years by 

 an Old World species, so, according to the rules of nomenclature, 

 obscura had to be dropped as a synonym and rubripes took its place. 

 This left the ordinary Black Duck without a name until Mr. 

 Brewster provided the name tristis, so that the two races stand, 

 up to date, as Anas rubripes rubripes and Anas rubripes tristis. 



The ornithological side of the question has hitherto been pre- 

 sented only from the describer's standpoint and he has been un- 

 fortunate in lacking some trenchant facts that put the others in 

 quite a new light. His characters for the Red-legged Black Duck 

 {rubripes) are bright red legs and feet, a yellow bill, heavy streak- 

 ing about the head and throat and large size; while the birds 

 (tristis formerly obscura), from which the new form is separated, 

 have brownish legs, dusky olive bills, and less streaking while they 

 are smaller in size. Now, these differences are exactly the ones 

 that distinguish old birds from young whether they occur in the 

 United States or in Canada. My evidence on this point is con- 

 clusive for I have skinned and dissected fully fifty specimens repre- 

 senting many localities, north and south, besides examining dozens 

 of others shot by friends or found hanging in the markets. It is 

 rather singular that Mr. Brewster in his articles has said practically 

 nothing of the differences between old and young because the 

 plumages as well as the colors of the soft parts in old and young are 

 quite different. They correspond to the characters that have been 

 considered subspecific and due to geographical variation. This 

 has been suspected but no one has been able to prove it, nor could 

 it be proved from dried museum specimens in which the original 

 colors and age are only matters of guess work. 



For some years I have taken great pains to obtain the fresh 

 material necessary for study. A series selected from many fresh 

 specimens sent me from Long Island, New York, shows that the 

 Black Duck, like many of the other ducks, slowly passes from the 

 juvenal into the first winter plumage, a change in the color of the 

 feet and bill taking place at the same time. The feet of grown young 



