The people's messenger. (Okolona, Miss.) 18??-1???, 1895-11-20
ANIMAL VISION.
Long Sight Not a Common Prop
STty Among Birda
The Great Gray shirke mas sharp Eyes
NocturNal Animals Have No En-
hahceI Powers when tho
Light n strong.


Birds are commonly credited with
an extraordinary range Of vision
Circumseir lend aid 70 the devel
opmento9 the mental factors in theil
case. The usual distance at which
terrestria species use their eyes Is
limited by the ground horizon. But
in the case Of the soaring birds, such
as vultures and eagles, the horizon,
natural limit Of sight, is enormously
extended. Macgillivray early noted
that though birds Of prey have or
bits Of great size-the eyeball OF the
common Ouzzard being one and one
eighth inches In diameter-they do
not, as a rule, soar when seeking
their prey The eagle, when hunt
ing flies low, just as do the sparrow
hawk and tie hen-harrier
Yet the vultures and condors,
birds which admittedly do soar when
seeking food have been proved to
find carbon by sight. A carcass
was covered with canvas and some
otfal placed upon It, The vultures
saw this, descended and ate il, and
then sat On the covered portion
within a lew inches OF a putrid car
cass. When q hole was made I'm the
covering they saw and attacned the
food below But the rapid congre-
cation OF v1ltures from a distance
to q carcass is probably due to their
watching heir ucighbors each OF
which Is surveying a limited area.
Charles Darwin pointed out that in
a level country the height Of sky
commonly noticed by a mounted
I'D 49, AsERthan fifteen degrees
above the horizon; and a vulture on
the wing al the height Of between
three thousand feet and four thou
SAND feet woAd probably be two
miles distant, and invisible Those
which descend rapidly, and appear
to have come from beyond the range
OF human sight, were perhaps hover
ing vertically over the hunter when
be killed his game.
There remains one undoubted In
stance Ia which bird vision is far
keener than that OF man. The great
gray shrs Lauins eEcubitor, is hab-
i-WI.y st Z BY the men who catch
fa.e0ss CIV 4lhenswaard TO give no
tice o the approach Of hawk. The
bird sees It far sooner than the men,
and q once gives notice Of its APP
preach This is a single instance IL
which the specialized acuteness Of
sight may be due 70 the fact that the
bird In question much resembles 10
color the pigeons, which are the fall
cons t2vorite God.
But long sight, says the New
York Ledger, does not seem a COM
mon property Il bird vision. The
ganA itch fish at sea, de-
scend from . considerable height,
but they kill their prey on the sur
face Of the water or near It. Moo
turnal birds and animals, though
able to see with little light, have no
powers when the light Is
more powerful; and those animals
which, Ike deer, feed by night or
day indifierently, have only devel-
oped a keenness Of vision from con-
slant fear aud vigilance. Horses
end cattle which have the same
power Of sight by night, have never
increased their visual range. Dogs
rely 90 another sense,
that Of scent, In preference 10 their
eyes, and will walk over a dead bird
while their brain is intent 90 discOv-
ering its place by scent alone. Wea-
sells, when hunting, will run up to
human being who initiates the
squeak Of O rabbit and peer up at
him TO discover where the sound
comes frOG The smalluess Of the
eye limits Its powers; just as the
best telescope has usually The largest
object glass, 80 the largest eye will
probably be the best organ Of sight, |
aud, 10 the absence Of any extraor-
binary developments in the size Of
the organ itself in animals, their /
power Of vision must, In the absence !
IF evidence 70 the contrary, be sup
posed 70 be proportionately limited. |