Staunton spectator. [volume] (Staunton, Va.) 1849-1896, 1855-11-21
NO.. |.
7..,,n,1 and sense of sight in Birds.

Audubon has written an amusing book called
Ornithoogica Biography. BY numaer OF cruel
experiments he has proved to his own eniire SAILS
faction, and that Of many others, that vultufes are
led TO their food by the sense OF sight alone; Ias
sense of smell, which they were supposed 10 pos
sess in an exquisite degree, afordlng them not
the slightest assistance. Though the senses IN
animals are means of obtaining them food, ihey
are not the sole means as We very well know
II is most curious question, and well worth more
attention than it has ever yet received. For want
of a better explanation ne usually say there IS an
instinct that enables animals TO find their food.-
MANY 90 from great distances directly to it. Pl-
geons find out newly sown fields Immediately ,and
will frequently go several miles to held the very
first morning after il is sown. Wild ducks That
feed at night, are equally quick in finding their
food and in this case we would be glad to know
what sense they employ. The red deer inyarIa-
bly, knows when the shepherds patch OF gram IS
fit for his food, and will frequently come down ~
such numbers as to eat up the entire crop IN
single night. In fact, all birds, whatever their
food may be, have an instructive power ot dlscov-
ering it Immediately and that from such distances
as no acuteness of either sight or smell Will account
for. Without allowing this, you cannot explain
facts too numerous, aud too well authenticated to
be doubted. II is precisely the same faculty,
whatever il may be, that enables the carrier-p pi-
peon to find lis way home. take it what distance,
and any way covered up you WILL Toss 1t up in
the air. and afier circling for few moments, II
adops its line flight without hesitation and with
ont mistake. Audubon himself furnishes an In
stance of the exercise of this faculty in his descrp
lion of the razorbill. He says: "The instinct
or saoacty which enables the razorbills, after be-
ino scattered in all directions, in quest OF iood
during the long night often at great distances iTom
each other, to congregate towards morning, pre-
viously to their alighting on spot to rest, has
appeared to me truly wonderful; and have been
tempted to believe that their place OF rendezvous
had been agreed upon the evening before" In
disnutng about the comparative value of the SEN
ees of siSbt and smell in birds, authors notice
much more curious fact-the great power birds
nossess Of altering the focal length of their eyes.
To see equally well an object at distance OF
rnanv miles. and minute seed or insect an inch
from the bill. may we'll amaze u.s. Observe the
first person of your acquaintance you meet, who
bannens to wear spectacss II he looks at an object
near him. he looks through his glasses-lf at a
more distant one, over them. Go TO a practical
ontician and desire him TO construct an instru-
ment that will enable you to do what birds are
constantly doing in this, and he VIII most liKeiy
tell you the thing is impossible.
Man probably surpasses birds in extent of vision
as much as birds surpass man in sharpness. Ross,
in his voyage to Baffin's Bay, proved that man,
nnder favorable circumstances, could see over the
surface of the sea so miles. II Is not probable
that any animal can equal this for extent. ln
SHARPNESS of sight, on the other hand, birds great
ly excel US. The eagle, soaring at such hight
that he seems mere speck sees the grouse walk
inu in the heather, which it closely resembles In
color as readily to escape the sportsman's eye
Schmidt threw to considerable distance from
thrush number of beetles, of pale gray color.
which the unassisted human eye failed to detect,
vet the bird observed them Immediately. Many
birds readily perceive insects on branches wheie
the sharpest sighted person can detect nolhing'
The ewes of birds are remarkable for their great
comparative size, the great convexity of the cor
uea. and for having the sclerotic coat formed De-
fore to circle of bony plates The optic nerves
are very large, and unite SO intimately as to aP-
near perfectly incorporated. The iris is exceed
inoly contraciile-as all may have observed who
have watched bird dying. Birds do not expire
with ewes open. as is the case with man and the
lower animals, and when they are expiring, you
NAV readily observe the great power they possess
Of dilatng and contracting the pupil. Ihe mus
cles. as in man, are six in number-iour stfaigh'
and two oblique. In many birds the eye ball pos
sesses very little mobility and in some OF the Owls
il is so closely fitted into the orbit as 70 Oe lm'
movable.