TRADITION AND RACIAL ISOLATION 



or 4 different species." Mayr (1951:97) notes further that in the Canada 

 Geese "it occasionally happens that neighboring nesting colonies differ in 

 body size, voice (honking vs. cackling), nesting site (sea-coast vs. island), 

 nest (mound vs. scrape), migration season and other features." Delacour 

 (1951 ) recognizes only one species, Branta canadensis, which, however, he 

 divides into twelve subspecies. All of these have the white cheek patch, 

 black head and neck "stocking," and similar body patterns ; but they vary 

 widely in size, voice, darkness of plumage, and behavior. The brant of 

 North America show three distinct subspecies (Delacour 1954), while the 

 Snow Goose and the White-fronted Goose each have two. 



It is quite another story for North American game ducks.* Taxonomists 

 recognize subspecific variation in only one species, the Florida Duck.f 

 All the other game ducks show no racial divisions on this continent. More- 

 over, some North American species are quite the same as those of northern 

 Europe, and Mayr (1942:241) says that "many of the Holarctic ducks, such 

 as the Gadwall (Anas strepera), Shoveller (Spatula clypeata) and so forth, 

 have no subspecies, or only one or two very slight ones, in spite of their 

 wide circumpolar distribution." This monotypic pattern apparently stems 

 from the absence of traditional ties in the male. In the gregarious societies 

 of winter there is opportunity for the meeting of males and females from 

 widely separated breeding places. In such matings, the male, faithful to 

 his bride, follows her wherever she may go, spreading hereditary material 

 widely, allowing no true isolation. Thus taxonomists cannot distinguish a 

 Minnesota-bred Pintail from one hatched in Alaska. 



This monotypic characteristic in ducks is evidence that the waterfowl 

 flyways of North America, described by Lincoln (1935a), are not strictly 

 isolated entities. There must be free genetic mixing of populations from dif- 

 ferent flyways, and evidence of this overlap is shown in the patterns of 

 dispersal reported by Aldrich et at. (1949), such as the "round-robin" mi- 

 gration of the Pintail, and in the winter vagrancies of the Ring-necked Duck. 

 In the light of the wide winter movements of most ducks, the narrow 

 range of the Florida Duck seems significant. This is not a migratory species, 

 and, though there is a seasonal shift from one place to another, the breeding 

 grounds and wintering range are approximately the same (Bent, 1923:72, 

 75). The eastern race of the Florida Duck, Anas fulvigula fulvigula, has 



° All North American ducks except the eiders and tree ducks. 



t The "Red-legged Black Duck" (Anas rubripes rubripes), once regarded as a distinct race, 

 is now known to be the adult male of the Common Black Duck ( Shortt, 1943 ) . 



239 



