PALAEARCTIC ELEMENT IN NEW WORLD AVIFAUNA 429 



Evidence from other than fossil sources can, of course, be so over- 

 whelming as to be tantamount to proof of origin of some of these 

 passeriform families. The larks (Alaudidae), for instance, comprise 

 a diverse and widespread Old World family, which extends from the 

 arctic to the tropics. It is represented in the New World by a single 

 species, the Horned Lark {Eremophila alpestris), which, although it 

 has penetrated the Americas as far as the vicinity of Bogota, 

 Colombia, remains no more than subspecifically different from the 

 palaearctic forms. 



The distributional history of other passeriform families in the 

 New World is far more obscure. The waxwings (Bombycillidae) 

 are a good example. Mayr, following Lonnberg, listed this family 

 without comment as being of North American origin. The evidence 

 from the three living species is anything but unequivocal. One 

 species {Bombycilla garrulus) is distributed across the northern 

 Palaearctic, from Scandinavia to Siberia, and also in northwestern 

 North America, and breeds about as far southeast into the continent 

 as Glacier Park, Montana. Another species, the Cedar Waxwing 

 {B. cedrorum), is found virtually throughout North America, from 

 southern Alaska and Newfoundland south to the upper southern 

 states. The third species {B. japonica) breeds only in a relatively 

 small area of eastern Siberia in the Amur River basin. There is 

 little here upon which to base conclusions as to origin, but I would 

 say that the balance might be tipped in favor of the Old World. 

 The next step would be to examine the families considered most 

 closely related to the waxwings. Their nearest allies appear to be 

 two other American groups which are, by some "lumpers," even 

 placed as subfamilies of the Bombycillidae. These are the Ptilo- 

 gonatidae of the southwestern United States and Central America, 

 and the Dulidae, a monotypic family known only from Hispaniola. 

 This would seem to argue for an American origin for the \\ax\\ ings. 

 On the other hand, recent investigations indicate that the odd 

 genus Hypocoliiis from the Persian Gulf region is closely related to 

 the waxwings. Such are the difficulties encountered in trying to 

 work out a distributional history for a small family of birds with no 

 significant fossil record and of uncertain near relationships. 



One of the most plausible indications of double invasion of the 

 New W^orld by a palaearctic stock is furnished by the shrikes 

 (Laniidae). It seems clear that the two North American species 



