The Barn Owl is one of the most celebrated species in
literature, especially in folk tales. Its habit of nesting in the belfries
of churches and hunting at night over graveyards has made the Barn Owl
somewhat of a superstitious legend in Europe. Barn Owls can be found on
every continent except Antarctica.
Their ghostly appearance, with a golden-tan back and
white underside, and their vocal series of shrieks, snarls and
hisses add to the birds' mystique. Local names for the Barn Owl
include the "ghost owl" and the "monkey-faced owl" - named because
of its expressive, heart-shaped face and dark eyes.
Unlike most bird species, Barn Owl females tend to
be a bit showier than the males, sporting more spots on their
chests. Studies have found that females with greater amounts of
spots had less trouble with parasitic flies and possibly were more
resistant to disease. Another study found that if a female's spots
were covered up, then the male was less likely to feed her chicks.
Natural History
Barn Owls are year-round residents that are found
throughout Maryland, especially in rural areas in the Piedmont and
Coastal Plain where there are grasslands, marshes, hayfields or
abandoned fields. Barn Owls can also be found in brackish and
saltwater marshes. Conversely, they are rarely found in areas
covered with row crops.
Barn Owls nest within easy reach of the fields where
they find their favorite food - meadow voles. One pair of Barn Owls
and their offspring may catch and consume as many as 3,000 rats per
year. Nest sites include abandoned buildings, barns, silos, duck
blinds, hollow trees, rock walls, and holes in banks and cliffs.
Barn Owls lay 2-18 eggs directly on the floor of the nest site they
have chosen. The eggs, incubated by the female, hatch in about 30
days. The male takes on his role after the chicks are hatched and
brings food to them. About 10 weeks later, the chicks are ready to
fly. Barn Owls can nest all year long, but usually do so between
March and September.
Barn Owls on the Decline
Despite their widespread distribution across the
State, Barn Owl occurrences have declined dramatically in Maryland.
Population declines have also been observed in the Midwest as well
as in other eastern states. Reasons for the decline may be due to
the reductions in open grasslands preferred by Barn Owls, increased
use of rodenticides and/or loss of nesting habitat. If you live on a
farm and use pesticides for rodent control, then please try to avoid
products that contain alphachloralose, calciferol and
cholecalciferol. All three of these chemicals may cause secondary
poisoning of rodent predators like owls. If you have large, open
grasslands or marshes on your property, then you may want to put up
nest boxes to encourage Barn Owls to visit your property.
The Maryland Bird Conservation Partnership is collaborating with Calvert County Natural Resources Division and Maryland Department of Natural Resources on a Maryland Farmland Raptor Program. To volunteer to help build and/or monitor nest boxes, please contact farmlandraptors@marylandbirds.org.
How to Build a Wall-Mounted or Free-Standing Nest
Box 
Materials:
- 1" x 16" x 16' untreated lumber
- 1 1/2" nails
- Non-corrosive hinged cabinet lock
- 2 strong, non-corrosive door hinges
Construction:
- Mark and cut the pieces out of the lumber.
- On the front piece, make a square entrance hole, 6"
x 6". Make a corresponding hole in the wall of the barn or silo. The
entrance hole should be 7" from the bottom of the box.
- Use nails to assemble the box: front, bottom, back and
sides. Use the hinges to attach the top to the box.
- Use the cabinet lock with a padlock through the loop to
close the top down onto the box. This will allow you to open the box when
cleaning it and to keep it closed from predators while the birds are
nesting.
- Drill several drainage holes in the bottom of the box.
- Drill small holes in the tops of the sides for ventilation.
- Place the box on an interior crossbeam flush with a barn
wall or directly on the wall itself.
- If in a barn, secure near the wall where you have cut a 6" x 6"
hole.
Tips for Attracting Barn Owls
- Barn Owls are not usually urban or suburban birds, mainly
because there are few large open fields in these areas. You have a chance of
attracting Barn Owls if you live in a rural area with grass, hay, or abandoned
fields nearby or with wet meadows or salt marsh.
- If you have a seldom used or abandoned barn or silo, check for the presence of
Barn Owls by looking for two inch black pellets on the ground inside the
building. These are pieces of indigestible fur and bones from the animals eaten
by the owls. If you see these, you very well may have a resident Barn Owl that
might nest in a Barn Owl box. Try to place your box near the area where the
pellets were found.
- Place your Barn Owl box 20 to 25 feet off the ground in a covered barn or silo
that is not often used.
- Clean your owl nest box once a year. Usually, January is the safest month to
do this, but Barn Owls can be nesting at anytime during the year. Pigeons may
try to nest in the box so be sure to remove them and their litter, as well as
any pellets or other prey remains.
- Do not disturb the owls while they are nesting. Adult owls will sometimes
abandon their eggs if disturbed. Be observant of any occupation of your nest box
before disturbing it.
- Face a wall-mounted box away from prevailing winds.
Invite Wildlife into Your Backyard!
For Additional Information, Contact:
Kerry Wixted
Wildlife and Heritage Service
580 Taylor Ave, E-1
Annapolis, MD 21401
kerry.wixted@maryland.gov
Phone: 410-260-8566
Fax: 410-260-8596
Acknowledgements:
- Close-up of Barn Owl, photo by Dr. Thomas Barnes, USFWS
- Barn Owl on ground, photo by C.F. Zeillemaker, USFWS