Barn Owl Magic
(Page 2 of 4)
December/January 2003
By Terry Krautwurst
But barn owls share many of the traits that make all owls amazing creatures. Like humans, they have forward-facing eyes that give them three-dimensional, stereoscopic vision. But unlike humans, they can't move their eyes in their sockets. That's why owls always seem to be staring straight at you, and why they tend to nod and bob their heads — the slightly varying points of view give them better depth perception. And to look around, owls literally look around: Thanks to a ball-and-cup neck bone structure, an owl can turn its head 270 degrees — three-fourths of a full circle or about four times farther than we can.
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Owls are also of a feather when it comes to ... well, their feathers. Most birds' flight feathers are stiff-edged, but an owl's are soft and fringed, allowing noiseless, deadly flight. A vole hears nothing before talons sink into it. Among the slowest-flying of all birds, the barn owl is particularly stealthy. Cruising silently just a few feet above a field at night, it flaps its wings once stiffly, then glides ... then flaps ... then glides.
Sensing the Night
Of course, it's one thing to fly through the night, and another to find a meal. Owls have notoriously good night vision, thanks to large eyes packed with dim-light-gathering cells. Owls unquestionably use their extraordinary vision to locate prey. But scientists have found that for most owls, hearing is an even keener, more crucial sense for finding food at night. Certainly that's the case with the barn owl. Its eyes are comparatively small for a night-hunting bird, but its hearing is unsurpassed. No other owl species — in fact, no other bird of any kind tested so far — has better hearing than T. alba.
In the 1950s, researchers at Cornell University showed that a barn owl can find and snatch running mice in total darkness, using only its hearing. Not only was the bird able to track the direction in which a mouse was moving, but its hearing was so precise that in the split-second before it struck, it would align its talons with the long axis of the victim's body, increasing the odds of a kill.
In the half-century since the Cornell study, scientists have worked to gain a better understanding of the barn owl's astonishing aural acuity. One element is the bird's facial disc, also found in other owls but best developed in the super-eared barn owl. The disc lies beneath the bird's soft outer facial feathers and consists of layers of short. stiff feathers packed together in a circular pattern, forming a concave, parabolic dish. The raised outer edge of the dish is heart-shaped, giving the bird its distinctive "monkey face." The right and left halves of the disc work like hands cupped behind ears. Sound waves caught in the dish are directed into two long curving grooves, one on each side of the disc, that lead to the owl's ear openings. The grooves collect and concentrate faint sounds — the pitter-patter of eensy mouse feet, for instance.
