The Bird Department 



Bv A. A. Ai^LEN, Ph.D. 

 Assistant Professor of Ornithology, Cornell University 



The Departure of the Birds 



E\'ER since the last of July the birds have been 

 leaving, but the dimunition in their numbers has 

 been so gradual and the entrance of others from 

 the north has been so inconspicuous that probably few 

 people have realized that a migration has been in prog- 

 ress. It is not until October that most of us recognize 

 that the birds are departing. For the fall migration is 

 very different from that of the spring. 



In the spring the coming of the birds is so conspicu- 

 ous a part of the change from winter to summer that 

 it has been heralded since biblical times and even earlier. 

 But in the fall there are no bright colors, no joyous songs 

 to announce the passing. In silence the birds slip past 

 us and few are the chronicles that record the travels of 

 [he modestly attired wayfarers which, after the nestling 

 season, begin the long flight to the south, some of them 

 travel over 8,000 miles from Alaska to Patagonia, many 

 of them but a few weeks out of the nest and making the 

 journey for the first time, and all with no compass to 

 guide them. 



THE DEPARTURE OF THE BIRDS 



It is not surprising that birds in migration have fas- 

 cinated mankind, not surprising that governments em- 

 ploy scientists to study and investigate them and little 

 wonder that thousands of people, scientists and laymen, 

 spend much time following the birds in an effort to learn 

 their secret. The facts which have been discovered 

 have relieved us of much of our ignorance but the great 

 mystery of how migration originated still remains and 

 we can, at best, offer but theories to account for it. 



Let us first consider some of the more interesting 

 phases of migration that modern investigation has thrown 

 light upon. It is now a matter of common knowledge 

 that all birds do not migrate. Many species in the north 

 are able to accommodate themselves to the rigors of 

 winter and never pass out of the neighborhood in which 

 they are raised. The chickadees, nuthatches and wood- 

 peckers that come to one's feeding station in winter, in 

 northern United States, remain in the spring to nest in 

 the vicinity, while in the south, the familiar mockingbirds 

 and cardinals are ever present. The farther south one 

 goes, the larger is the percentage of non-migrant birds 

 until one reaches the tropics where no real migration 

 occurs. Even here, however, the coming and going of 

 our iiDrthern species are conspicuous features of the bird 

 life, and there is probably no place in the world where 

 migrating birds are never seen. In places of the same 

 latitude, however, migration is more pronounced in some 



than in others, reaching its maximum in eastern United 

 States and western Europe, and being much less pro- 

 nounced in the southern than in the northern hemisphere. 

 Between the birds that do not migrate at all and the 

 Arctic tern which migrates 10,000 miles twice a year 

 between its Antarctic wintering ground and the Arctic 

 shores where it nests, there are all gradations of migrants. 



A PAIR OF BOBOLINKS 



These birds nest in the northern part of the United States and 

 winter in Brazil. Each year after traveling ten thousand miles 

 they return to the same meadow. 



Some birds like the meadow lark, robin, bluebird and 

 chipping sparrow which nest throughout most of United 

 States and Canada, merely withdraw into the southern 

 part of their breeding range during the winter while their 

 places are taken by such birds as the tree sparrow, snow 

 bunting, pine grosbeak and siskin that nest in northern 

 Canada and migrate in winter as far south as northern 

 United States. Other species that nest in northern 

 United States and Canada, such as most of the flycatch- 

 ers, warblers and vireos, pass out of the United States 



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