9 



Lands End in England, illustrates the enormous effect of the cold Arctic 

 current, coming down from Davis strait, in contrast with the influence of 

 the warm Gulf stream that dies against the English shores. 



We can also observe minor groupings that are based upon conditions 

 other than temperature, these determining factors being mostly variations 

 of humidity. Thus the life of the eastern woodlands is plainly different 

 from that of the more arid plains of the prairie provinces and both are 

 strikingly different from that of the moist Pacific slope. 



Taking the eastern forms as typical in the ordinary acceptance of the 

 word, comparable birds of the prairie are slightly smaller and considerably 

 paler in coloration, whereas on the humid Pacific coast they are larger 

 and much darker in colour. Through these influences, therefore, we find 

 in the west many subspecies of eastern forms. Comparatively few species 

 range unmodified across the continent, many are represented east and west 

 by two or more subspecies showing greater or less differentiation, and in 

 other cases they are replaced by closely allied species or are absent 

 altogether. 



In noting these faunal divisions, however, it must be remembered 

 that as far as birds are concerned, these associations have to be based 

 entirely upon breeding individuals. Birds travel so widely and along so 

 many devious routes in their migration, that they may pass through several 

 faunal areas in spring and autumn though breeding in only one. Therefore, 

 in determining the faunal zone to which any given area should be referred, 

 such transients must be disregarded. 



Though the distributions given under the following specific headings 

 are rather vague, many tend to follow similar general lines. Thus some 

 are given as "the lower Great Lakes region"; these are probably Upper 

 Austral forms. "Southern Ontario and Quebec" refers to Transition 

 species, whereas "beyond dense settlement or to the limit of cultivation" 

 refers, naturally, to species of the Canadian zone. 



The following species are given as representative of what birds are to 

 be expected in each zone: 



Upper Austral 

 Cardinal 

 Orchard Oriole 

 Carolina Wren 

 Grasshopper Sparrow 

 Blue-grey Gnatcatcher 

 Dickcissel 



Transition 1 

 Bobolink 

 Wood Thrush 

 Yellow-throated Vireo 

 Baltimore Oriole 

 Towhee 

 Cuckoo 

 Field Sparrow 

 Bluebird 

 Catbird 



Canadian 



Hudsonian Chickadee 

 Red-breasted Nuthatch 

 Olive-backed Thrush 

 Three-toed Woodpecker 

 Hermit Thrush . 

 White-throated Sparrow 

 Canada Jay 

 Grey-cheeked Thrush 

 Slate-coloured Junco 



Hudsonian 



Bough-legged Hawk 

 Fox Sparrow 

 Northern Shrike 

 White-crowned Sparrow 

 Pine Grosbeak 

 American Pipit 



Arctic 



Ptarmigan 

 Snowy Owl 

 Snow Bunting 

 Gyrfalcon 

 Longspur 



1 Most of the species of this zone also occur in the Upper Austral , but reach their northern limit here. The occur- 

 rence of these with the absence of the species of bordering zones are the most marked characteristics of the Transi- 

 tion zone. 



