The Farmington times. (Farmington, St. Francois County, Mo.) 1905-1926, 1919-07-04
HOW HIGH DO BIRDS FLY?

The night of September 3, 1887,
while an American scientist, F. M.
Champman, was observing the moon
through an astronomical telescope, he
suddenly became aware of number
of birds passing in front of the lens,
silhouted against the glaring light of
the moons face. For more than two
and half hours-from p. m. to
1850 p. M, to be precise--an inter-
mittent stream of migrants flowed
southwark across his field of view,
and among these Mr.. Chapman was
able to recognize the outlined forms
of Carolina rails, grackle, snipc and
ducks. These, roughly estimated,
travelling at elevations from six thou
sand to fourteen thousand feet.
Until the advent Of airplanes, near
~ a quarter of a century later, this
observation formed practically the
sum total of our knowledge of the
height at which birds travelled to and
from their summer quarters. 1t was
realized, of course, that certain pass
crime species, e. g., swallows, wag-
tails, pipits, larks, rocks, etc, usually
migrated at comparatively low
height; but of many birds and espe-
cially Of the larger species, We knew
next to nothing. True, we occasional
ly obtained distant view of skein of
geese moving in orderly formation
across the gray background OF an au-
tumn sky, but it was always difficult
to compute their height.
1t is hoped that in course of time
aviators will be able to throw flood
of light upon this obscure but intense
ly interesting branch of orinthology.
Already a number of observations
have been recorded, but these are gen.
orally lacking in detail, and no very
definite conclusions can as yet be
formed. Up to the present | believe
the greatest height at which a bird
has been seen from an airplane is
fifteen thousand feet, when Lieut.. j..
S. Risen of the 57th Squadron OBJ
served "two large birds" over st.
Omer in August, 1917.
Probably the majority of species
seldom travel under normal conditions
above ten or twelve thousand feet;
but of course the height at which
they fly or any given day depends
very largely upon the weather. When
the air is thick or heavily charged
with moisture, if birds are migrating
at all under such conditions, they are
inclined to keep low, and think it is
only in clear atmosphere that they
rise to higher strata. Wind is an
other and az very important factor.
What appears to be contrary wind
on the ground will almost certainly
veer to a shoulder wind at two thou
sand or three thousand feet; while it
happens to be bowling from the east,
complete reversal, of direction may
occur before fifteen thousand feet is
reached.
There is every reason to believe
that the power of birds fight is re-
duced as it ascends to more rarefied
atmosphere, for an appreciable de-
crease in density must mean, among
other things, loss of buoyancy, an
insufficient supply of oxygen, and a
too thin, unresisting medium for
wing propulsion.
From the few records available, |
think it may be assumed that the ma
jority of high-fiying day migrants
such as plovers, ducks, geese, cranes,
etc.--prefer to travel between four
thousand and eight thousand feet, but,
as already stated, more data and pre-
else information are required before
any definite conclusion can be ar
rived at.-Toronto Globe.