Evening star., 1923-10-02
BIRD MIGRATION
INTERESTS 10000
Licenses to Aid in Banding
for Observation Applied
For to u. S.

Interest in bird migration is In
creasing. according to reports reach
ing the United States biological sur
yey.
In 1915 the survey received migra-
tion notes from more than 1000 diff
ferent observers. According to re-
cent reports, more than 10000 per-
sons have applied to the survey for
licences to aid in banding birds. show
ing how widespread is the recent de-
velopment of this important phase
of nature study.
Migration Mystery.
For more than 1000 years the
phenomena of bird migration have
been noted; but while the extent and
course of the routes traversed have
of late become better known, no con-
elusive answer has been found to the
question. Why do North American
birds migrate?
According to one migration theory,
the birds real home Is the south
land. All bird life tends to over
production and at the end Of the
glacial era, the birds, seeking in all
grounds with less keen competition
than in their tropical winter home,
gradually worked northward as the
retreat of ice made habitable vast
reaches of virgin country. But the
winter abiding place was still the
home. and to this they returned as
soon as the breeding season was over.
The beginning of migrtion ages
ago undoubtedly was intimately con-
nected with periodic changes in the
food supply. While North America
possesses enormous summer supplies
of bird food, the birds must return
south for the winter or perish, ex-
perts point out.
Day and Night Travellers.
Some birds migrate by day, but most
OF them seek the cover of darkness.
Day migrants include ducks and geese,
which also migrate by night haWKs'
swallows, the night hawk and the CHM
ney swift. The last two, combining
business and pleasure, catch their morn
ing or evening meal during q zigzag
flight that tends in the desired direction.
The daily advance of such migrants
cover only few miles and when a large
body of water is encountered they pass
around rather than cross it. The night
migrants include all the great family
Of warblers, the thrushes, the ny
catcners, vireoS, orioles. tanagers,
shore birds and most of the sparroWs
after dark and end it before dawn and
go farther before than after midnight
Migrating birds, scientists say, do not
lily at their fastest speed. Their migra-
ton speed, it is said, is usually from
thirty to forty miles an hour and rarely
exceeds fifty. Flights OF a few hours
at night, alternating with rests of one
or more days make their spring and
fall advances very slow, averaging Tor
all species not more than twenty or
twenty-five miles a day, but with great
variations of daialy rate among the
different species.
Hard to Fix Mileage.
The exact number of miles which
n particular bird makes during one
,ays journey has not yet been de-
tcrrnined and cannot be aScertaine d
until tagging or banding of birds by
means of metal rings is carried out
on moro extensive scale. How
ever, liz this connection, II may be
said that the United States biologl-
cal survey is perfecting wonder
ful and interesting system of bird
landing as an aid to the study of
migration. The solution of the
presented by this mystery of the bird
world is of practical value in such
matters as the protection and in
crease of migratory birds: These
problems have long attracted the at
tention of many ornithologists. both
in the United States and Europe. I.
The length of the migration
journey of birds varies enormously.
\ few birds like the grouse, quail,
Cardinal and Carolina wren are more
migratory. Many a bobwhite rounds
out It's full existence without ever
going ten miles from the nest where
it Is hatched. Some other species,
for instance, the meadow larks, the
pine warbler and the black headed
grosbeak, do not venture in winter
south of the breeding range.
Natures mt Variance.
With them fall migration Is only a
withdrawal from the northern and a