Birds 91 



The Bohemian Waxwing (Bombycilla garrula), which occasionally 

 appears in large flocks, was described from Europe. Recent 

 critical studies have however led to the separation of our bird as 

 a subspecies, B. g. pallidiceps. The Cedar Waxwing (JB. cedrorum) 

 is confined to North America. It is smaller than the other bird, 

 with under tail-coverts white instead of chestnut, and the wing 

 feathers without white or yellow tips. 



LAN 1 1 DAE 



The shrikes, which might be called the hawks of the passerine 

 series, have a strongly hooked bill, which distinguishes them at 

 once from their allies. They are common on both sides of the 

 world. Of our two species, one, the Northern Shrike (Lanius 

 borealis invidus of Grinnell)* appears in winter; the other, the 

 White-rumped Shrike (L. ludovicianus excubitorides) is a summer 

 visitor. The former is larger, and has no black frontal band. 



VIREONIDAE 



The Vireos, like the humming-birds, are essentially a neo- 

 tropical group, extending northward into the United States and 

 Canada. The bill is distinctly hooked at the end, thus recalling 

 the shrikes; but this appears to be an independent development, 

 though formerly the two groups were associated. As long ago as 

 1866, Baird pointed out the distinctness of the Vireonidae. Ex- 

 cluding the two species which appear to occur only as stragglers, 

 our Colorado vireos are as follows. The genus Vireosylva, 

 without wing-bars, includes the Red-eyed Vireo (V. olivacea) and 

 the Western Warbling Vireo (V. gilva swainsoni), the latter the 

 commoner bird. They are very similar, olive green to grayish, 

 with a white stripe on each side of the head; but the back is 

 distinctly olive green in V. olivacea, more gray in the other. In 

 the first, also the tenth primary is practically lacking, whereas 

 in V. g. swainsoni it is distinct though small. The remaining 

 species have two pale wingbars. The Plumbeous Vireo (Lani- 

 vireo solitarius plumbeus of Coues) is gray above, with the edges 

 of the wing whitish; Bell's Vireo (Vireo belli of Audubon) is olive 

 green above. 



The validity of the subspecies is disputed. 



