, 1915-05-20

lUklSH6NHUi methods of this remarkable phe-
uol==lll nomenon. Theories are plen-
- tiful, but a demonstrable expla-
nation of all the facts involved is still wanting.
Some of the inherent characteristics of migra-
ton, such as the apparent sense of direction
possessed by birds, seem to defy observation
and analysis. and to be absolutely beyond our
ken SO far as any understanding goes. The
cause itself of this curious habit so far is only
conjectural, but the most logical explanation
seems to be a search for food. This apparently
holds good for the fall flight from North to
South, when insects have persisted from the cold,
and vegetation died, SO that both insectivorous
and grain-eating birds are alike affected Yet
some members of both species, crows. jays, quail,
cartridges, wood ducks, cardinal grosbeaks 1.-THE
, ordinary red Bird and often some red-headed
woodpeckers, remain North throughout the win
ter and manage somehow to make a living and
perpetuate their species.
Even If these be exceptions to the general rule,
there still remains the unanswered question. Why
do not those birds who winter in the South re-
main there throughout the year instead Of going
North when the spring opens? Food is abundant
and apparently southern latitudes are as fitting
for the rearing of young as the far North. AS a
matter of fact. we really do not know. though
we have some interesting and plausible theories
about it that do not bear the test of questioning.
so as usual when we run across some mystery in
animal life that we cannot unravel, we call it
instinct" and let 1t go at that. OF this one
thing we may, however, be quite sure. that in.
stinct in animals always serves some useful pur-
pose, and is usually an expression of natures
care for the preservation of the species.
Years of observation have developed the inter.
esting fact that there are certain well-de6ned
routes in all countries which the migratious
follow. certain water courses, certain chains of
mountains, certain valleys, and this seems to
obtain from one generation of birds to another.
Whether the younger birds learn this from the
older birds who have been before, or whether
they simply mechanically follow the older birds
In their flights is largely conjecture. but two
facts seem well established. First, that animals
evidently have some method of communicating
with each other. Everyone who has heard Bob
White call together the scattered covey, or the
hen give the alarm for a hawk to her chickens, is
convinced on this point. The second fact seems.
however, to controvert the theory of the older
teaching the younger ones the way they should
go, for 1t has been shown in many instances
that focks composed entirely of the years broods
of young birds make their first migratory fight
alone and unattended by the older birds, and find
their way unerringly along the usual routes of
migration. Once more we have to fall back upon
instinct.
Just how birds find their way from one distant
latitude to another is the most inexplicable OF
all the many mysterious facts of migration. The
length of the flight from northern habitat to
southern winter resort varies according to the
different species OF birds all the way from 1000
to 5000 miles, and in a few cases to 5000 miles.
Yet these distances are apparently traversed in
generally direct straight lines. and with the most
orderly and businesslike methods of procedure.
To say that the older birds show the younger
birds the way (since this has been shown to be
untrue in many cases) only removes the difficulty
back into the remote past. for at some time
there had to be some birds to find the way the
first time, and we only dodge this difficulty when
VI talk of inherited instinct.
II is clearly not a case of birds seeing their
way and being guided by landmarks. 1t is known
that migrations as a rule take place at night. and
that in general birds fly very high, in fact, at
tremendous heights. when migrating. Under
such conditions finding their way by sight is i'm.
possible. Moreover, the sight theory breaks down
in the case of those birds who cross great
stretches of water where there are no landmarks
whatever. There is a species of cuckoo which
summers in New Zealand and winters in eastern
Australia, which means a straight flight OF some
1,2OO miles without rest or stop across the track
less waters. Certain species OF humming birds
that winter in Central and South America spend
their summer vacation in the United States, and
to do so must fly across some 1000 miles of the
Gulf of Mexico.
A recent experiment demonstrated that neither
the theory or seeing the way nor previous knowl-
edge of the route can account for the finding OF
the way in migration. Fifteen terms were taken
from their nesting places on Bird Key, Tortugas
tone of the islands of the Florida reef and were
released at distances varying from 20 to $50
miles from their home. and 10 of the 10 found
their way back safely. Observations have also
shown that the same birds return to the same
spot year after year. Robins that winter in
Florida will build their nests in the same tree
in a northern state as long as they live. An ex-
plantation which is in much favor is the probable
possession of a sixth sense-the sense OF direc-