Nearly all of the pellets dissected in classrooms are from Barred Owls (Strix varia), Screech-Owls (Otus asio and Otus kennicottii), Short-eared Owls (Asio flammeus), and Great Horned Owls (Bubo virginianus), but the vast majority are the result of Barn Owls. This is because of the Barn Owl’s close association with farms and suburban areas. Barn Owls are not necessarily more abundant than other owls; they are just concentrated in areas more convenient to humans.

Barn Owls commonly hunt among the rodent-supporting crops humans plant. They also have adapted to using man-made structures such as nest boxes, old chimneys, fire towers, steeples, and of course barns, for nesting. This affinity for man-made housing allows us the opportunity to study in depth their prey selection, habitat use, nesting ecology, and life cycles.

We know, for example, that Barn Owls are prolific nesters. In colder climates a pair nests only in the spring, but in more moderate areas, like the southern United States, Barn Owls may nest year-round. A Barn Owl nest is not built from the sticks and leaves usually associated with bird nests. Instead, owls find a cavity or chamber in which to raise their young. On the floor of this cavity the female spits out her pellets and tramples them into a pile of loose hair and bone. After removing some of the larger bones, she lays eggs directly on this bed of fur.

Incubation begins with the first egg. Additional eggs are laid at 2-day intervals. A clutch of 4

Figure 3 An owl's prey is digested and separated in the glandular and muscular stomachs.  Nutrients and dissolved waste pass into the intestine.

Figure 4  Undissolved waste is formed into a pellet and ejected through the esophagus and out of the mouth.

to 7 eggs is typical, but from 1 to 12 is possible. The first egg hatches about 31 days after it was laid, and the remaining eggs hatch in sequence at about 2-day intervals.  The owlets need 6 to 8 weeks to mature and begin flying. If food is scarce, younger owlets may be starved so that older owlets survive, a common practice among birds of prey and one that almost assures that at least 1 or 2 owlets will fledge.

A nest of young requires a lot of food, and Barn Owls are among the best, arguably the very best, at locating and catching their prey. Their low-light vision is remarkable, allowing them to spot a mouse over 50 m away in nearly complete darkness. And when the clutter of leaves and grass hide the movements of a potential meal, the ears of a Barn Owl can pinpoint the footsteps of a shrew to within millimeters.

These amazing abilities are due to the facial disks—those cup-shaped depressions that give the face a heart shape. Each facial disk (there is one on each side of the face) directs light into an eye and  sound into an ear. Football players sometimes use charcoal to absorb light around their eyes and reduce glare. The white feathers around a Barn Owl’s eyes do the

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