Qggs of J^aiive Pennsylvania "^irds. 



The favorable situation of the state of Pennsylvania for native 

 and transient bird life becomes apparent when we study the topo- 

 graphy and climatic conditions of the territor3^The Appalachian 

 Mountain System, here attains its greatest altitude, forming as it 

 does, 'a great central back bone through which the numerous 

 tributaries of the Delaware and Susquehanna Rivers cut their 

 winding courses. On the southeastern side of the mountains the 

 land falls rapidly to a general slope toward the sea, while on the 

 west and northwest the sloping land draws gradually to the 

 Mississippi Valley and the Great Lakes' Basin. The tributaries 

 of the Ohio river penetrate and have their sources in the west- 

 ern slope. 



Being close to the seaboard, a great thoroughfare of bird mi- 

 gration, the eastern section of the state is visited by many wan- 

 dering seabirds. The mountainous section opens a highway for 

 the more hardy northern species, while the western portion lies 

 in the Mississippf Valley, that unparalleled passage for the mi- 

 grating forces. Being in proximity to the Great Lakes the north- 

 western part is visited by inland seabirds, straggling from their 

 breeding grounds in various sections of the region drained by 

 the lakes. 



When winter loosens his hold and the warm balmy days fore- 

 tell the approach of spring, the hills and valleys ring with music 

 as birds arrive from their southern haunts to mingle during the 

 summer with their more hardy relatives who have withstood the 

 severity of the cold. This is a season of great activity in bird 

 life. Many of our winter residents leaving for their nesting 

 grounds in the far north, accompanied by great waves of transi- 

 ents who tarry with us a few days to feed and rest. 



As the season advances the great bird stir becomes quiet, and 

 we find ourselves surrounded by numberless birds that are set- 

 tling down in favorite haunts for their summer homes. These 

 are our native birds, and includes not only migratory species but 

 many varieties which remain with us the year round. 



Of the various Life Zones which govern the distribution of 

 the native birds of eastern North America, three extend through 



