Biology Reference
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I first observed this trait many years ago while watching Spooky, the resident great horned owl (Bubo
virginianus) at the Museum of Science in Boston. Fascinated by its huge, yellow eyes, I somehow con-
ceived the idea of a staring contest to see who would blink first. It was a difficult struggle at first, for
I had to exercise a great deal of determination to avoid blinking. After a substantial time, however, I
“won” the contest—not because Spooky blinked, but because I suddenly found myself staring at the
back of its head!
After a few seconds the owl snapped its head forward again, and a somewhat briefer staring contest
ensued. Then I once more found myself viewing the back of Spooky's head. This sequence was re-
peated several times more, with each staring episode becoming shorter and shorter. Finally it reached
the point where the owl was taking only a split second to see that I was still staring—then snapping its
head backward, then forward, then backward, and so on. At that point, fearful that the owl would twist
its head off, I took pity on the distraught creature and left poor Spooky in peace. Clearly, a great horned
owl doesn't appreciate having its stare returned—at least for any length of time!
Owls' hearing is even more astonishing than their eyesight. Indeed, despite superb nocturnal vision,
owls hunt at night more by sound than sight. So incredibly sensitive is their hearing that, according to
researcher Allen Eckert, some species of owls can hear a mouse squeak as much as a half-mile away!
An owl's hearing ability consists of far more than mere sensitivity, however; it also has a special ad-
aptation enabling it to locate its prey's position in three dimensions with uncanny precision. Indeed,
experiments in the laboratory have demonstrated that sightless owls can catch mice by sound alone.
The ear cavities in an owl's skull are asymmetrical, so that one ear receives more sound from above,
the other more from below. This ear placement permits the owl to locate its prey accurately in the ver-
tical plane. Simultaneously, an acute ability to process the infinitesimal difference in the time it takes
a sound to reach each ear accomplishes the same thing in the horizontal plane. Also, the facial disk—a
feature that helps give owls a vaguely human appearance—further aids this phenomenal hearing appar-
atus by capturing sound and reflecting it toward the ears.
If the prey makes the slightest sound while an owl homes in on it, the owl immediately “views” the
location of the prey in three dimensions. Incidentally, what are widely regarded as “ears” on some owls
are merely feather tufts that have nothing to do with hearing. The actual ears are only openings in the
skull and are invisible.
Silent flight completes the package of adaptations that make the owl such a ruthlessly efficient pred-
ator. Exceptionally soft leading edges on flight feathers, combined with a very large wing area in rela-
tion to body weight, plus soft head and body feathers, make an owl's flight almost noiseless. The mouse
rustling in the grass or the rabbit hopping across a forest glade has no warning that death is descending
upon it as the owl ghosts down for the kill. Not until talons seize the prey in a deadly grip does the
victim have the slightest inkling of its fate. These days we make much of the technological wizardry
of our stealth fighters and stealth bombers, but owls on ghostlike wings were nature's original stealth
aircraft long ages earlier.
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