The study of living birds by the banding method, whereby great
numbers of individuals are marked (fig. 28) with numbered aluminum
leg rings, has come to be recognized as a most accurate means of
ornithological research. Since 1920, banding work in North America
has been under the direction of the Bureau of Biological Survey,
in cooperation with the National Parks Branch of Canada. Every
year volunteer cooperators, working under permit, place bands on
thousands of birds, game and nongame, large and small, migratory and
nonmigratory, each band carrying a serial number and the legend,
NOTIFY BIOLOGICAL SURVEY, WASHINGTON, D. C., or on the smaller sizes,
NOTIFY BIOL. SURV., WASH., D. C. When a banded bird is reported from
a second locality, a delinite fact relative to its movements becomes
known, and a study of many cases of this nature develops more and
more complete knowledge of the details of migration.
The records of banded birds are also yielding other pertinent
information relative to their migrations, such as the exact dates
of arrival and departure of individuals, the length of time that
different birds pause on their migratory journeys to feed and rest,
the relation between weather conditions and the starting times for
migration, the rates of travel of individual birds, the degree of
regularity with which birds return to the exact summer or winter
quarters used in former years, and many other details that could
be learned in no other manner. Banding stations that are operated
systematically throughout the year, therefore, are supplying much
information concerning the movements of migratory birds that
heretofore could only be surmised.