Biology Reference
In-Depth Information
bearer of good fortune—perhaps even as a symbol of wisdom. It's doubtful, however, that any previous
society has placed as much emphasis as ours on the owl's reputed wisdom.
Why have we endowed these birds with such an aura of great wisdom? The answer seems to lie in
the owl's facial structure and large, staring eyes. An owl's eyes are set squarely in the front of its head,
an avian feature shared only by penguins. This eye placement conspires with the feathered facial disk
to give the owl a vaguely human appearance. In addition, those big, staring eyes lend an almost pro-
fessorial appearance to owls, much as horn-rimmed glasses might to a human. Anthropomorphism does
the rest; if owls remind us of ourselves, they must therefore be intelligent.
Appearances notwithstanding, the sad truth is that owls don't rate very high on the intelligence scale,
even among birds. Members of the Corvidae—ravens, crows, jays, magpies, and the like—to use just
one example, are undoubtedly far smarter than owls. Upon careful consideration, it shouldn't come as
any great surprise that owls rate as something of dim bulbs among their bird brethren. After all, so much
of an owl's skull capacity is taken up with the apparatus necessary for vision and hearing that there's
little brainpower left for “wisdom”!
We actually do owls an injustice by regarding them as wise, for in so doing we obscure their true
nature. Owls are, above all else, superb killing machines, with astonishing adaptations for taking their
prey. With their almost unbelievably sensitive hearing and eyesight, as well as virtually silent flight,
owls possess a phenomenal ability to locate and seize a variety of prey by night or day.
Take eyesight, for instance. An owl's eyes are one hundred times more sensitive to light than human
eyes. Even on a dark night, owls can see details of landscape and prey with great clarity. Because most
owls are night hunters, it's popularly supposed that in bright daylight they see poorly at best, and are
perhaps nearly blind. This is a misunderstanding that dates far back in time. Tennyson, among others,
certainly believed this myth when he penned the line “. . . and thrice as blind as any noon-tide owl. . .
.” However, owls can see equally well in darkness or daylight.
Why, then, are most owls mainly abroad at night? There are at least two good reasons. First, this
is the time when the majority of their prey species are most active; mice and other small rodents, for
example, are far more apt to be afoot at night than in daylight. Second, they have no nighttime com-
petition from other raptors—notably hawks and eagles. Equipped by nature with superb tools for night
hunting, owls have thus been able to preempt an important ecological niche.
Because of their size, structure, and placement, an owl's eyes are immobile, but the owl compensates
with a unique adaptation. In both birds and mammals, the first vertebra below the skull is called the
atlas
because, as Atlas supported the globe, it holds up the skull. Mammals have an atlas with two cups
that fit against two projections on the skull; this arrangement severely limits the ability to turn the head.
Birds, on the other hand, have a single cup-and-skull projection, a system that greatly facilitates
movement of the head. Owls have further perfected this useful anatomical feature. In consequence, an
owl can swivel its head not merely 180 degrees to look backward, but 270 degrees—three-quarters of a
full circle.
