364 Bird -Lore 



furthering nature-study, and the most effective methods of accomplishing it? Where 

 and how can j^ou get money to carry on this work? 



15. Is there any larger opportunity than this offered by nature-study, both in and 

 out of our schools, that the Audubon Society should meet? — A. H. W. 



FOR TEACHERS AND PUPILS 



Exercise VI: The Birds' Map of America, continued 



Correlated Studies: Spelling, Geography and Elementary Agriculture 



Turning back for a moment to the last exercise, let us note again that in 

 the Arctic realm both the climate and physiographic features are everywhere 

 much the same; although an Arctic-Alpine fauna may be distinguished to the 

 west, and a barren-ground fauna to the east, showing that certain animals, 

 unlike some that are peculiar to this bleak expanse, are restricted in their 

 range. 



At the most southerly limits of the Arctic realm it is never warmer than 

 32° Fahr.; indeed, one may roughly trace the di\iding line between the Arctic 

 and the North Temperate realms by following the course of the annual iso- 

 therm of 32° Fahr., and similarly, between the North Temperate and the 

 American tropical realms, by the annual isotherm of 70° Fahr. 



There is one interesting fact about the Arctic realm which we should not 

 overlook, and that is the cir cum polar distribution of certain birds, animals 

 and plants found there. In no other part of the North American continent 

 are the same species foimd around the world, except by accident. 



Here, near the North Pole, neither cUmate, oceans nor plains of ice form 

 barriers to prevent them from being distributed completely around the Pole. 

 The reason for this is a story by itself, which we shall take up in some future 

 exercise. 



The North Temperate realm comprises the larger part of North America, 

 and is synonymous with the North American region, since it is made up 

 of a single, continuous land -area, unlike the American tropical realm, for 

 instance, which contains two distinct regions, widely separated by water: 

 namely, the Antillean and the Central American regions. 



The North American region, which extends from the annual isotherm 

 of 32° Fahr. to that of 70° Fahr., is divided into the cold and the warm tem- 

 perate subregions. We have already studied the former, and learned some- 

 thing of the vast transcontinental belt of coniferous forests which distin- 

 guishes it. This subregion, we remember, contains two large faunal areas, 

 running parallel with each other from ocean to ocean; the Hudsonian, where 

 the timber-line begins and arctic conditions disappear, and the Canadian, 

 where agriculture is generally possible and profitable. 



In this subregion there are also two small faunal areas lying well up on the 



