32 MIGRATION OF BIRDS 



ical Survey, pp. 1-79, one map. 1904. RUSSELL, I. C., North America, 

 Chap. Ill, Climate, pp. 184-203 (Appleton). 



NOTE. Discussion of the faunal affinities of the region in question 

 will frequently be found as introductory matter in 'local' or state bird 

 lists; see especially (in the Bibliographical Appendix) under Georgia, 1909, 

 Howell; Illinois, 1890, Ridgway; Iowa, 1907, Anderson; Kentucky, 1910, 

 Howell; Maine, 1908, Knight; Maryland, 1900, Merriam and Preble; 

 Massachusetts, 1901, Howe and Allen; Nebraska, 1909, Wolcott; New 

 Hampshire, 1904, Allen; New Jersey, 1894, 1909, Stone; New York, 1910, 

 Eaton; North Carolina, 1886, Brewster; Ohio, 1903, Jones; Pennsylvania, 

 Stone, 1891, 1894; Dwight, 1892; Todd, 1893, 1904. South Carolina, 

 1890, 1891, Loomis; Tennessee, 1910, Howell; Virginia, 1890, Rives; West 

 Virginia, 1890, 1898, Rives. 



THE MIGRATION OF BIRDS 



Times of Migration 

 Extent of Migration 

 Routes of Migration 

 How Birds Migrate 

 Why Do Birds Migrate? 



Migration is the most distinctive phase of bird-life. Certain mam- 

 mals, fishes, and even insects migrate, but no animals approach birds 

 in the extent of their migrations. Wholly aside from the interest which 

 is attached to a study of bird migration in the broader aspects, as we 

 attempt to determine its origin and extent and the various factors 

 which govern the times and manner of a bird's journeys, there is a 

 fascination and excitement for the student in observing the arrival and 

 passage of the great army of feathered travelers which ever renews 

 itself when birds 



"Part loosely wing the region; part more wise, 

 In common, ranged in figure, wedge their way 

 Intelligent of seasons, and set forth 

 Their aery caravan, high over seas." 



To the nature lover birds are a living calendar. "What was that 

 sound that came on the softened air? It was the warble of the Blue- 

 bird from the scraggy orchard yonder. When this is heard, then has 

 spring arrived." 



Times of Migration. According to the nature of their occurrence 

 the birds of temperate regions may be grouped seasonally as follows: 



1. Permanent Residents. Includes species that are represented 

 in the same locality throughout the year. In temperate and boreal 

 Eastern North America few species are permanently resident as indi- 

 viduals. Possibly Ruffed Grouse and Bob-whites pass their lives in a 

 comparatively restricted area. But the winter Crows, Jays, and Nut- 

 hatches of a certain locality are probably not the ones that nested there. 



2. Summer Residents. Includes species that come to us from 

 farther south in the spring, rear their young, and return to the south 

 in the fall. As a rule, the first species to come in the spring are the last 



