156 PROBLEMS OF BIRD LIFE. 



near alike as to be very remarkable. For instance, one kind 

 of bird would be found in northern Maine and New Hampshire, 

 in the Adirondack Mountains, in the Catskills and down along 

 the Alleghany chain even as far south as the Carolinas, but 

 nowhere else in the United States except perhaps in northern 

 Michigan and Minnesota. Then another bird, entirely unlike 

 the first, would be found in the same places and in no others. 

 Then a third and a fourth and many more, until it dawned 

 upon you that you had discovered a bird state. Then you would 

 find other birds visiting southern Florida, but never getting 

 north of a line drawn from Tampa Bay to Cape Malabar ; and 

 others still that were found only in a little point of land at the 

 very southern part of Texas ; some that lived on the Great 

 Plains only, and some that were found in the Great Basin, 

 and others that followed mountain ranges, and though they 

 travelled south the whole width of the United States, never 

 strayed more than a few miles east or west. These limits 

 would mark the bounds of other bird states, which we could 

 increase until the whole continent was divided among them. 



The curious point would be the fantastic shape of these 

 bird states. Why should Arctic birds be found along a nar- 

 row strip leading far down into Mexico ? Why should birds 

 of the warm Mississippi Valley push up into the cold North 

 as far as the Saskatchewan and Athabaska rivers ? Why 

 should the different kinds all agree to make the same skips 

 and jumps ? 



The men who study the geography of animals and draw 

 maps of their states undertake to explain these puzzles. 

 They say that there is a reason for the shape of these bird 

 and animal states, and they call the whole study zoogeography, 

 or the geography of animals ; or, when speaking of a single 

 species or of a few species, they, talk of their distribution. 



