Evening star., 1938-10-29
OF STARS,
MEN AND ATOMS
Notebook of Science Pro9ress
in Field, Laboratory
6 and Study.
By THOMAS r. HENRY.

The swiftest bird night ever recorded
accurately is in the neighborhood Of ITS
miles an hour.
Ordinary, unhurried flight averages
from 20 to 40 miles an hour, according
to the species
The United States Department Of Agri-
culture has just compiled = complete
record Of the measured flight speeds Of
North American and European birds.
The swiftest denizen Of the skies, accord
ing to this compendium. is the California
duck hawk whose speed, measured with
stop watch from an airplane, was found
to be between ITS and 18O miles an hour.
The eagle is relatively slow. May
Thatcher Cooke, the Department Of Agri-
culture compiler, found one rather Ques-
tionable recorded speed OF 100 miles for
. golden eagle. Only two entirely trust
worthy records OF eagle speeds were
found-one of 80 and the other OF 60
miles.
Bird speed records more than 20 years
old are worthless the report explains,
because any possible means OF measure
ment was quite inaccurate and some fan
tastic estimates were made, ranging up
to or 6 miles a minute. Most such
guesses, and by far the most trustworthy,
were made by hunters. A hunter, aim
ing at bird in flight, had to make three
subconscious estimates-the distance OF
his target, the speed at which it was
moving in order that he would know how
far ahead to aim and the speed of his
bullet The skilled marksman learned
to make allowance for these three factors
instinctively, but never could explain sat-
isfactorily how he did it. Only one OF
these elements Of craftsmanship, the
velocity of the bullet, could be measured
accurately.
But, says the report, "it has been found
recently by experiment that there Is an
appreciable loss of time in pulling the
trigger. Against the sky it is practically
impossible to gauge the exact distance OF
the bird, and the distance it travels may
be exaggerated because momentum will
carry shot bird some distance before 1t
falls. An overeStimate OF q very few feet
in these figures will result in the compu-
tation OF very high speeds for game birds.
GunnerS have been prone to attribute
speeds of 100 or even $50 miles an hour
to ducks"
Three reasonably accurate methods OF
measurement now are pOSsible-stop
watch observations from an airplane,
racing birds in an automobile and watch
ing the Speedometer and measuring the
time OF passing between two fixed points
by means of the surveyors instrument,
the theodolite. All these methods are
subject to error, but great body of data
IS being built up from observations all
over the world in which the errors even
tually will cancel themselves.
Among the more reliable bird fight
measurements are those of Dr. Alexander
Wetmore, assistant secretary of the
Smithsonian Institution, who observed
from an automobile the speeds Of herons.
hawks, horned larks, ravens and shrikes.
He found rates varying from % to %
miles an hour. Flight in all these cases
was normal and unhurried. BY far the
most comprehensive data on the subject
10 date has been compiled by Col Rich
ard Menertzhagen of the British Army,
who followed bird flights with theodolites
designed to estimate the speed of air
planes at anti-aircraft stations, and by
using stop watches along measured
courses. Common speeds were as follows,
as reported by the Smithsonian Insti-
tuition:
Members of the crow family, 81 to As
miles per hour; smaller perching birds.
such as larks and buntings, 20 to 81
miles; starlings, SO to 40 miles; geese. ~
to 55 miles; ducks, A to SO miles; falcons.
40 to AZ miles, and sand grouse 43 to At
miles.
The greatest speed recorded by the
British aviation officer was for swifts in
MeSopotamia. These passed the obServ-
ing airplane and circled around it when
1t was moving at 68 miles an hour. He
estimated that this required a normal
speed OF at least 10 miles an hour, and
that when trying to escape from danger
such q bird can easily attain a speed of
about 100 miles an hour.
When frightened, says Dr. Wetmore
who has made some Of the most accurate
American measurements, most birds are
capable OF increasing their speeds even to
double their normal rates, but they can
not keep it up very long. When cruising
about in search for foods they fly so as
not to waste their strength. This is
particularly true on migrations, which,
while instructive with certain species for
countless generations, tax heavily the
Myers reserve strength. DR.. Wetmore
recently returned from Venezuela, where
he observed North American birds at the
end OF their long nonstop aight over
the Caribbean to escape the Northern
winter He found that 1t was all most
of them could do to make it. Some would
fall exhausted on the beach.
Considering 10 hours as a fair DAYS
flying time over land, DR.. Wetmore saws
the measured speeds would carry crows
from 80 to $50 miles over land between
sunrise and sunset, smaller birds from
200 to 370 miles, ducks from 44O to $50
miles and geese from 420 to $50 miles.
Considering that they fly in straight lines.
this means that they make very good
time from point to point. 1t is highly
probable, he points out, that most mi
grating birds proceed in leisurely man.
ner and that after flight of few hours
they pause to feed and rest for a few
hours, or even q few days If they find
the surroundings congenial.
Few reliable measurements have been
made of the speed of insect flight. Two
years ago there was report to Science
the official journal of the American
Association for the Advancement of Sci
ence, of bug known as the cephenomyia.
reputed to fly "8l0 miles an hour" The
publication aroused storm of dissent
from entomologists all over the country
most of whom frankly didn't believe it
and didn't see how it could be verified.
H1o.o %l,o Cl