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Description
What graceful, ghostly bird can locate a mouse by sound
and catch it in the dark of night? The barn owl, one of
Washington’s best natural rodent-traps.
Special
Barn Owl Adaptations
- Flight
feathers are serrated at their tips, muffling the flapping
sound of the wings during flight.
- Short
feathers on side of head form a groove that helps direct
sound waves into the ear opening.
- Sharp
talons for seizing and holding prey.
- Hooked
beak for tearing meat.
- Eyes
in front allow for depth perception and ability to isolate
and efficiently capture prey, as well as to avoid obstacles.
- Eyes
fixed in sockets, so owl¹s flexible neck designed to
turn up to 270 degrees (three quarters of a circle).
Hearing
a barn owl's voice can also be a memorable identifying
experience! Barn owls' high-pitched screeches or hiss-screams
can be very loud, but the birds are not dangerous. They
make these sounds to warn their young of danger, to ward
off enemies, announce their arrival at the nest and to
proclaim their territory.
Barn
owls are sometimes called "monkey-faced owls"
because of their white, heart-shaped faces and dark eyes.
These crow-sized owls are distinguished from other Washington
owls by a pale face, long legs, light underparts and a
rusty back speckled with black. Barn owls and other owls
are classified in the same bird order (Strigiformes),
but barn-owls are in their own family (Tytonidae) because
their skeletal structure and pale, stiff facial feathers
differ from those of typical owls (Strigidae).
Barn
owls don't have ear tufts like great horned owls or screech
owls. But this doesn't mean barn owls don't have ears. Ear
tufts are just feathers; the owl's real ears are behind its
round facial disks, which help direct sound into the ears.
Barn owls' ears also are asymmetrical; they are different
sizes and one is located higher on the head than the other.
This enables the bird to sense direction and distance by differences
in the intensity of the sound that reaches each ear. Barn
owls use their ears to locate food. They are very accurate
hunters, even in the pitch black. Barn owls also have special
feathers on the front edges of their wings that reduce the
amount of noise they make when flying. Their quiet flight
prevents prey from hearing them approach.
Food
Why are barn owls called one of Washington's best natural
rodent traps? Because they eat 1.5 times their weight in food,
mostly mice, meadow voles and pocket gophers each day. That's
like a 100-pound person eating 150 pounds of food every day!
A barn-owl family of two adults and six young may eat as many
as 1,000 rodents during the nesting period. They are active
in Washington year-round. Barn owls are primarily a nocturnal
hunter, with limited crepuscular activity. Their excellent
hearing helps them capture prey, which they usually swallow
whole. They are unable to digest the fur, feathers or bones
of the animals they eat, and cough up the undigested parts
in a dark, fuzzy lump called an owl pellet. We can find out
what an owl has eaten by examining the remains in the pellet.
However owl pellets should be examined cautiously since they
may harbor potentially harmful organisms.
Barn owls
hunt on the wing, from a perch, from hovers, stoops, and in
open fields, wetlands, and grasslands. They also eat shrews,
insects, crustaceans, small birds, reptiles, and amphibians.
Recent studies have shown that decline in vole (and to a lesser
degree, mouse) populations have an effect in reducing barn
owl populations. These studies conclude that providing nest
sites isn’t enough to secure the survival of these fascinating
night-flyers. Their hunting habitat and food supply must also
be present.
Breeding
and Habitat Ecology
When they are one year old, barn-owls are capable of breeding.
The male courts the female by chasing her, bringing her mice
and uttering a series of rapid squeaking noises. A pair may
use the same nesting site each year. Barn owls may nest on
ledges, crevices, or other sheltered areas of cliffs or human-made
structures like attics and barns hence the name. They also
nest in tree cavities or snags, burrows, culverts, or nest
boxes.
Barn owls
are known to breed year-round. In Washington they usually
rear a brood of young in the spring and, if food and other
conditions are favorable, they may rear a second brood in
the late summer or early fall. Eggs are laid on a bare surface
or, if the nest was used the previous year, on a thick mat
of flattened pellets. The female lays an egg every two days
until 4-10 white eggs are in the nest. When the first egg
is laid, she begins incubating. Thus, when the first egg hatches
about 30 days later, that owlet is older than the next one
to hatch. It often is stronger and more able to take food
from the parents.
Both adults
provide food for their snow-white, down covered young. They
bring prey to the nest, where the owlets swallow it whole.
Sometimes competition for food is intense and younger nestlings
don't fare as well as their older nestlings and may die. The
older, stronger owlets may even eat the weaker ones. Great
horned owls and raccoons also eat young barn owls. The young
owls fledge in about 8-10 weeks.
Distribution
and Current Status
Barn owls have a world-wide distribution and can be found
in many parts of Europe, Africa, South America, Southeast
Asia, Australia and North America. They live in temperate
and tropical regions nearly worldwide. Barn owl numbers and
distribution are declining in many parts of the world as farmlands
and nesting structures disappear from the landscape. The use
of nest boxes where prey is still common have assisted barn
owl recovery.
Further
Reading
- Bunn,
D.S., A.B. Warburton and R.D.S. Wilson. 1982. The Barn-owl.
Buteo Books, Vermillion, SD. 264 pp.
- Craighead,
J. J., and F. C. Craighead, Jr. 1956. Hawks, owls and
wildlife. Stackpole Books, Harrisburg, PA. 443pp.
- Ehrlich,
P. R., D. S. Dobkin, and D. Wheye. 1988. The birder's
handbook. Simon and Schuster, New York. 785pp.
- Evans,
F. C., and J. T. Emlen, Jr. 1947. Ecological notes on
the prey selection by a barn owl. Condor 49:3-9.
- Gallup,
F. N. 1949. Brood size in the barn owl. Condor 51:189.
- Guiguet,
C. J. 1960. The Birds of British Columbia (7). The owls. Brit. Col. Prov. Mus., Vancouver. Handb. No. 18. 62pp.
- Henny,
C. J. 1969. Geographical variation in mortality rates
and production requirements of the barn owl (Tyto alba). Bird-Banding 40:277-290.
- Johnston,
T. 2000. The Barn Owls. Charlesbridge Publishing
- Karalus,
K. E., and A. W. Eckert. 1974. The owls of North America. Doubleday Co., Garden City, NY. 278pp.
- Marti,
C. D. 1974. Feeding ecology of four sympatric owls. Condor 76:45-61.
- Payne,
R. S. 1962. How the barn owl locates prey by hearing. Living Bird 1:151-159.
- Pickwell,
G. 1948. Barn owl growth and behaviorisms. Auk 65:359-373.
- Reese,
J. G. 1972. A Chesapeake barn owl population. Auk
89:106-114.
- Tagholm,
T. 1999. Animal Lives: The Barn Owl. Larousse Kingfisher
Chambers
- Thomas,
J. W., ed. 1979. Wildlife habitats in managed forests:
The Blue Mountains of Oregon and Washington. U.S. Dept.
Agric., For. Serv., Portland, OR. Agric. Handb. No. 553.
512pp.
- Udvardy,
M. D. F. 1977. The Audubon Society field guide to North
American birds: western
region. A. Knopf, New York. 855pp.
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