Evening star., 1938-08-11
OF STARS,
MEN AND ATOMS
Notebook of Science Progress
in Field, Laboratory
and Study.
By THOMAS r. HENRY.

A strange four-year cycle in the
abundance of animals and birds In the
Eastern Arctic is taking the wits OF
Canadian biologists.
This is, 1t so happens, very decidedly
an economic as well as biological cycle
because the money" Of the region is
the white fox pelt and there are enor-
nous fluctuations In the numbers of
this particular animal.
So far as mammals are concerned the
cycle seems to be built up on the fluctu-
ations OF the Jennings, little creatures
very closely related to meadow mice
that have much the same habits and
that burrow under the snow In the
winter. Every four years they reach
enormous numbers. Almost Immediately
these are cut down by great epidemics.
Otherwise the little creatures commit
mass suicide by the millions by UNDER
taking great migrations into the sea-
fate similar to that which some
biologists have predicted for the human
race as result Of its great population
squirt in the last three centuries.
The white foxes feed on the Jennings.
Hence, when the micelike animals be-
come scarce the foxes starve. Simul-
taneously, however, they are affiicted by
curious brain disease which kills them
in vast numbers. They 60 crazy, run
about in straight lines, foam at the
mouth. finally get paralysis of the legs
and die Of great weakness. Although
similar in symptoms, the disease is very
different from rabies in dogs.
The curious thing is that in countries
inhabited by white foxes, where there
hA .&~
cyclic phenomenon takes place There
are apparently two independent cycles
working together.
Is the snowy owl. Only in very cold
winters does one occasionally come 50
far south as the Northern United States.
But there Is a four-year cycle In their
appearance In great numbers many
miles south Of their summer breeding
range. This also has been found to
coincide with the fluctuations Of the
Jennings.
But what causes the lemming cycle?
"The evidence now suggests strongly"
says DR.. Charles Elton Of the University
Of Oxford. England. who reports on the
problem for the Canadian Department
OF the Interior. that there is some
regular climatic pulsation. probably in
the form Of a variation Of storminess,
wind direction or winter snowfall, which
affects the life OF the lemming. prob
ably In winter. The circumstantial evi-
dence for this theory is overwhelming,
but 1t must be admitted that We know
as yet little about the exact nature OF
the climatic cycle"
Other Arctic animals also are affected
by similar fluctuations. although not so
violent he reports. Thus the caribou
are said to be in much better condition
in some years than others and they have
periodic changes In their migration
routes, the cause Of which never has
been established. Arctic hares also
fluctuate. There is not yet enough evil
dence to state whether this is the result
Of four-year cycle. or whether 1t occurs
once every 10 years. The later is the
case with the snowshoe rabbits farther
to the south. Polar bears are known to
fluctuate locally, but this is mainly due
to erratic movements Of the polar ice.
Sea fish also vary greatly in numbers.
This has long been known and efforts
have been made to associate it with the
l1-year sunspot cycle with Indifferent
success. Recently there has been OBJ
served q remarkable mass movement Of
cod northward towards the Greenland
coast which has forced the relocation
Of fishing grounds.
So far as the land life is concerned.
1t seems as If the Arctic is an erratic
mother. She is extravagently lavish Of
food one season, thus bringing about
mammal and bird population which
cannot possibly be supported. They
must be decimated in order for any to
live-and they are with great regularity.
To the human observer there seems little
difference in the actual amount of
sustenance from one season to another.
A very little may make all the difference
to the teeming millions Of jennings
The fox epidemics, however, hardly
can be attributed to lack of food. There
Is possibility that they are associated
with some necessary change in the diet.
It is a serious matter because it can be
communicated to dogs and in 1881 led
to a great canine pandemic which al
most wiped out the Eskimo teams.
That the cycle is Of long standing is
shown by records Of the Hudson's Bay
Co. since 1882 Of the annual numbers
Of white fox pelts brought in by the
Indians and the Eskimo.
Why these life cycles do not occur
markedly elsewhere is an open problem.
There Is a good deal Of evidence that
they do, perhaps even among human
beings. They are not marked enough
to attract much attention. however, and
usually pass unnoticed. Under the harsh
Arctic conditions an organism must be
very delicately adjusted to the environ
ment to live at all. A very slight altera-
ton In this environment can easily be
fatal.
In the more luxuriant south life has
q wider range. 1t has an opportunity
to pick and choose. Survival does not
depend on any one minute element In
the complex Of nature.