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Volvime VI September-October, Number 5 
Some New Facts About the Migration of Birds „ 
HY Wlil.l.s \V. COOKK 
BIOLOGICAL SURVEY, U. S. DEPARTMENT OP AGRICULTURE 
W HAT becomes of our summer birds? Where do they spend tlie winter? 
By what routes do they travel to their destinations? How do they find 
their way? For many centuries these and similar (piestions liave puz- 
zled the brain of man. In default of exact knowledge, fanciful theories have been 
advanced, such as that swalUnvs hibernate in the mud, and that small birds cioss 
the Mediterranean as passengers on the backs of cranes. Such notions have held 
their own well into modern times. Scarcely a hundred years have elap.sed since 
systematic knowledge on the subiect began to accumulate, and only in the last half 
century has there resulted any noteworthy progress toward a .solution of the ques- 
tions of migration. 
For nearly twenty' years the Biological Survey has been accumulating data 
on the migration of birds. Its own field naturalists, whose visits have extended 
over the North American Continent from Guatemal.i to the Arctic Circle, have 
furnished voluminous notes, besides which the assistance of ornithologists 
throughout the country has been enlisted, so that reports are received in the 
spring and fall of each year from hundreds of observers. These reports give, for 
each species, the date when the bird was first seen, when it became eommon, and 
when it disappeared. Light-house keepers also have supplied valuable informa- 
tion concerning the destruction of birds at their lights. The facts thus gathered 
a From Yearbook of Department of Agriculture for 1903. This article is of such general interest and con- 
tains .so much new information, that it is here reprinted, with little alteration, for the benefit of readers of The 
Condor, and with the consent of Prof. Cooke and the Biological Survey. — F d. 
