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The Palaearctic Element in the New World Avifauna 



Kenneth C. Parkes 



Carnegie Museum, Pittsburgh, Pennsylvania 



In the March 1946 issue of The Wilson Bulletin, 

 Ernst Mayr pubHshed an important paper entitled "History of the 

 North American bird fauna," a review that represents a much- 

 quoted landmark in the study of the zoogeography of North America. 

 Mayr summarized the recent advances in zoogeography in general, 

 with particular reference, of course, to birds, and pointed out 

 especially the contributions of the palaeontologist and the tax- 

 onomist. After a brief review of the geological history of North 

 America, he proceeded to classify the avifaunal elements of the 

 Americas on the basis of probable geographic origin. He pointed 

 out that it is impossible to place many of the bird families as to 

 probable major land mass of origin. In the first place, many families, 

 mostly oceanic or freshwater, are now so widely distributed as to 

 make speculation as to their genesis fruitless. Mayr calls these the 

 "unanalyzed element." This group includes such sea birds as the 

 petrels and gulls, such freshwater birds as ducks, herons, rails, 

 the shore birds, and a few families of land birds, including the 

 diurnal birds of prey, the woodpeckers, and the swifts. 



Another group of uncertain origin is also widespread but only, 

 at present, in the tropics. Mayr calls this the "pantropical element" 

 (this adjective strikes me as less awkward than "tropicopolitan," 

 used by Darlington (1957) and others). This group includes aquatic 

 birds like the anhingas and skimmers, and a few land birds, the 

 trogons, barbets, and parrots. In the arctic and north temperate 

 zones the loons, auks, and some other birds constitute still another 

 group of families that is now so widely dispersed that no continent 

 can be named as their original source. 



The strictly New World families, or rather the families of New 

 World origin, since some of these have found their way to the 

 Old World, were divided by Mayr into (1) those of probable North 



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