18 A NATURAL HISTORY OF THE DUCKS 



It is fitting here to say something about color-patterns in the group as a whole. 

 Dr. G. M. Allen has shown that in Teal Ducks we find six of what he calls primary 

 color patches. These are a median crown patch, two ear patches, two neck patches, 

 two shoulder patches, two side patches, and two rump patches. A reduction in the 

 color strength of one of these patches, either by partial albinism, or during the evo- 

 lution of a new species, has in many cases demonstrated the breaks between these 

 color areas. The interesting thing about this arrangement of epidermal colors is the 

 fact that very likely it is of a fundamental nature, and applies not only to birds but 

 to mammals. 



Moults. In all the typical arctic and Northern-Hemisphere ducks, of both the 

 New and the Old World, the adults of both sexes have two annual moults. Pairs 

 arrive at the breeding area in full plumage. Soon after the females commence to 

 incubate, the males retire and begin to change to the "eclipse" plumage. During the 

 eclipse, which is a much plainer and less-differentiated dress that remains in its full 

 development for only about three or four weeks, the primary wing-feathers as well 

 as the tail-feathers are moulted, and the bird becomes flightless. These feathers are 

 shed only once during the year, and always earlier in the male than in the female. 

 The female does not moult until the young are more or less able to care for them- 

 selves, and thus she is some four or five weeks behind the male in this respect, an 

 adaptation obviously of great value. 



In assuming the winter dress again, the old males are the first to change, and in 

 some species, as, for instance, the Mallard, the specimens in full dress may be found 

 by early October. In most of the northern ducks, however, the winter plumage is 

 hardly perfect before November, and, in birds of the year, not before December or 

 later. In the Shoveller and the Blue-winged Teal perfect plumage does not come 

 before early spring. 



The typical diving ducks, Pochards and Scaups, have their moults a good deal 

 like those of the surface-feeders, but the eclipse is not so perfect, and young birds do 

 not reach maturity until their second winter. Some of them do not breed the first 

 year. 



The Ruddy Duck is an exception to the above, as his true red breeding-plumage 

 is not assumed until March or April, and lasts only a short time, through the sum- 

 mer instead of the winter. Thus he retains his eclipse plumage from August (for 

 males stay with the females and young and moult late) all through the later summer, 

 autumn, and winter. 



The species in which the sexes have similar and dull coloring do not, of course, 

 have an eclipse, but they do have a double moult. None of the males of South Amer- 

 ican or Australian ducks have an eclipse, the significance of which is not clear at 

 present. 



