The ducks and geese are day migrants, flying seldom more than an hour at a time, passing from one well-known feeding stop to another 
The Migrations of the Birds 
ONE OF THE MOST FASCINATING BRANCHES OF NATURE STUDY-WHICH 
BIRDS MIGRATE AND WHY—HOW FAR THEY TRAVEL AND HOW FAST 
by Wells W. Cooke 
BIOLOGICAL SURVEY j UNITED STATES DEPARTMENT OF AGRICULTURE 
Photographs by A. R. Dugmore, Scott & Van Altena and Julian A. Dimock 
T HE mystery of bird migration has proved a fascinating sub- two thousand different persons, showing how widespread has be- 
ject from the earliest times. The birds were noticed to come the late development of nature study. 
The ever recurring question of 
why do birds migrate arises at 
once in the mind of every student 
of bird movements. No definite 
and complete answer has been or 
can be given to this question. It 
can be stated, however, that some 
advantage must accrue to the in¬ 
dividual or the species as a result 
of the long journeys or else they 
would long ago have been aban¬ 
doned or curtailed. Birds are not 
instruments of fate; they can and 
do change their breeding areas 
and modify their migration routes 
correspondingly. Yet two classes 
of migratory movements can be 
distinguished. In the one the bird 
seems eager to migrate. Exam¬ 
ples of this are to be found among 
the geese and ducks, the robin, 
flicker and some of the black birds. 
All these birds press forward in 
the spring as soon as the tempera- 
(3ii) 
disappear in the fall and reappear 
in the spring, and not knowing 
where the intervening season had 
been spent many fanciful theories 
were advanced of hibernation in 
trees or in the mud, and stories 
were current of whole flocks seen 
to disappear beneath the waves of 
the Mediterranean to winter in its 
depths. With the later years has 
come a fuller knowledge of the 
particular region in which each 
species passes the cold season and 
more definite information in re¬ 
gard to the routes employed in the 
spring and fall journeys. But the 
increase of knowledge has not 
lessened the interest in the gen¬ 
eral subject. More persons today 
are watching the birds and noting 
their times of arrival and depart¬ 
ure than ever before. Indeed, the 
Biological Survey has received 
migration notes from more than 
One of the great migration mysteries is the destination of the 
chimney swift, traced until he reaches the northern coast of 
the Gulf of Mexico, to which he returns five months later 
from no one knows where 
