Evening star. [volume] (Washington, D.C.) 1854-1972, 1930-08-04
BIRDS MIGRATION
DATE ATTRIBUTED
TOLENGTH OF DAY
Alberta Scientist Fools
Crows, Which Fly North in
Winter, in Test.
LIGHTS IN PEN HAVE
EFFECT. OF SUNSHINE
Second Group, Without Artificial
Illumination, Turns South on
Being Released.
BY THOMAS r. HENRY.

The biological mystery of the almost
infallible instinct which makes birds
fly North in the Spring and South in
the Autumn is near solution through
trtcking crows into a reverse migration.
The results have just been reported
to the National Academy of Sciences
by DR. William Rowan of the Univer-
sity of Alberta. The supposedly in
variable migratory instinct appears to
be due to some hormone, an extremely
important chemical substance, released
in the blood stream by one of the
glands of internal secretion which is
activated by the length of the day.
Temperature changes, DR.. Rowan be-
lieves, have nothing to do with it. This
is supported by the fact that birds start
South at just about the same date, diff
fering with the species, whether the
Autumn is warm or cold. The same Is
true of the northward flights. So he
did not change the temperature for
his experimental crows.
Seasons Turned About.
Two groups of crows were used, con-
fined in different aViaries. Fourteen
birds were simply confined, with no
lighting effects, so that they were sub
jected to the same day-length effects
as uncaptured birds. The cage and
shed of the other group, with SO men,
bers, were Illuminated by IS 500-watt
bulbs, approximately reproducing day.
light conditions. Starting on Septem-
Der % of last year the lights were
turned on at sunset. From then until
Thanksgiving day the illumination time
was regulated so that it neutraliZed the
effect of shortening days in that lati-
tude. Allowance was made for both
earlier sunsets and later sunrises. Thus.
for the birds, the seasons were turned
around.
Both groups were given the same
diet. All continued in good health. On
the whole, DR.. Rowan reports, the birds
in the lighted aviary stayed awake sat-
isfactorily during the artiflcially
heightened days, although there were
some individual sleepy-heads.
Groups Released Separately.
Crows were used in the experiment
because they are conspicuous, easily
identified birds. Besides their migra-
ton range is short and there is no
law, either in Canada or the United
States, against killing them. Both
groups were kept until two deys be-
fore Thanksgiving. when the lights
were being kept on until IL pm. Then
they were released, each group sep
arately, so that the behavior of an in
dividual would not be influenced by
that of the opposite group with which
it might get mixed.
Thanksgiving is a heyday for hunt
ers about Edmonton. Requests were
made IN the local newspapers AMI over
the crows they saw on that day and
send them to the university. All the
released birds were banded. The
crows food habits were adapted to IA
cilitate its survival in the Winter WOODS
If it escaped the owners. Edmonton
was many miles north of the ordinary
Winter habitat of the birds and, since
it was early Winter all normally would
be expected to start South at once.
According to DR.. Rowans theory, how
ever. those subjected to artificial IL
Elimination either would remain where
they were or range northwarj over
their customary Summer grounds.
78 Per Cent Turn Away.
Some of the birds remained in the
immediate vicinity and either were
killed or recaptured. But 10 per cent
turned North or South. Of these, 81
in all, % since have been reported killed,
either by local hunters or through the
United States Biological Survey at
Washington, whose address was stamped
on the leg bands. OF the control birds
whose cage was not Illuminated, so
per cent have been reported from the
South or Southeast. But of the eX-
perimental birds eight were killed
north and northwest of Edmonton.
Two we're killed more than 100 miles
northwest, one four months after re-
lease. 1t had survived through the
Winter in a desolate bush and muskeg
country.
CirLt rooor+c loyo Loo,. ,>,,nno.o,,.
from the South, but always referred
to one or two crows together. From
the Northwest the reports have been
fewer, but describe f1ocks of crows num-
bering as many as Is, from the Lesser
Slav Lake country. 800 miles from Ed
monitor. They first appeared nine
days after the experimentals were re-
leased at Edmonton, nearly two months
after the last crow of the Summer sea-
son had been observed there. There
seems little doubt but that they were
the birds released at Edmonton, which
survived the hunters. Several efforts
to shoot some of these birds failed be-
cause of the wildness of the country
and the deep snow which impeded the
hunters.
In view of the facts" says Dr.
Rowan, that so per cent of the con-
trolls we're recovered in the well set
tied country south Of Edmonton and
only IS per cent of the experimentals
it is difficult to believe that anything
but a minority of the latter group
could have gone South. One is left
to infer that the Lesser Slav Lake crows
represent at least some of the missing
48 per cent of our experimental birds.
This distinctly suggests that the ex-
perimental birds actually did what was
anticipated"
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