8 HOW TO NAME THE BIRDS 



small ranges interspersed with valleys. The highest 

 mountains seldom exceed 2,000 feet, while many por- 

 tions of the belt are only high and rugged hills. But 

 elevation being equivalent to northern latitude, this re- 

 gion is largely Canadian in climate, and retains in sum- 

 mer many species not found elsewhere, except on the 

 ^' northern edge ; " on the other hand, the southern lati- 

 tude of the lowlands induces many species to remain in 

 winter that move southward from New England and 

 New York in the fall. Moreover, though not a seaboard 

 State, its large rivers and fifty-mile shore-line of Lake 

 Erie attract many marine species in winter, and water- 

 fowl are more largely represented throughout Pennsyl- 

 vania than in any other State. 



In such a work the water-fowl must not be ignored ; 

 yet it would not be feasible to present chis branch of our 

 avifauna with the same thoroughness as the land division, 

 since the majority of water-birds are simply migrants along 

 the coast, and practically inaccessible to almost all stu- 

 dents. It has, therefore, seemed sufficient for the pur- 

 pose of this book to mention only those few that sum- 

 mer within the territory, those that migrate inland, and 

 the commonest that are found on the coast and inland 

 during the winter. 



The Analytical Key is indispensable for quickly trac 

 ing a species to its proper number. It is analogous to 

 any botanical key, and is prefaced by full directions 

 But, to make its use perfectly understood, let us illus- 

 trate the method of learning the name of an unknown 



