14 A GUIDE TO THE BIRDS 



And as all life is intimately associated, the student of birds 

 would have felt sure from the presence of the sweet gum 

 trees in Fairfield County, Conn., that certain birds, the 

 Southern Water-thrush for example, would be found breed- 

 ing there, and from the spruces on Greylock or in northern 

 Vermont, that Black and Yellow Warblers nested among 

 them. 



To predict what birds will be likely or certain to be found 

 in any one place, we must, therefore, know first its lati- 

 tude, — southern Connecticut and northern Maine will have 

 few birds in common ; next, we must know the altitude of 

 its hills and the character of their vegetation, — if they 

 are high enough to be clothed with spruce, they will be 

 frequented by birds unknown as summer residents in the 

 lowland. 



So regularly do certain groups of plants and animals, in- 

 cluding birds, confine themselves to certain well-marked re- 

 gions, that it has been found convenient to employ certain 

 fixed terms to designate the areas where these groups are 

 found. The sweet gum and the Southern Water-thrush are 

 characteristic of the Atlantic Plain from southwestern Con- 

 necticut to Florida ; they are representatives, therefore, of 

 what is known as the Carolinian or Upper Austral Life Zone. 

 The spruce and the Black and Yellow Warbler occur through- 

 out the forested region of Canada ; they are representatives, 

 therefore, in northern New England of the Canadian Life 

 Zone. So closely is the presence or absence of a certain well- 

 marked group of birds correlated with the presence or absence 

 of the spruce and fir, that the nature of the forests becomes 

 the first point one must settle with regard to any locality in 

 southern New Hampshire or Vermont, or northern Massa- 

 chusetts or New York. The accompanying map shows the 

 extent in New England of the Upper Austral and Canadian 

 Life Zones. 



The country between these zones possesses many birds 



