One barn owl eats about
155 pocket gophers each year,
with owlets eating five times
this amount!
Over 2,000 each year total per family of owls?
How GREAT is this!
A barn owl brings a
gopher to a nearly grown owlet...
Rodent-eating machines.
Barn
owls, described by some as "nothing but a beak and
stomach," are among the most skilled rodent hunters
in North America. Installing barn owl nesting boxes in
orchards and vineyards has become a popular integrated
pest management practice, but an effective program
involves more than just putting up a box. Design of the
box, placement, number, and maintenance all influence
roosting and rodent control success.
Boxes provide both a place for barn owls to roost in the
fall and a safe nesting spot to raise their family of
owlets in the spring, The barn owls will provide you
with 365 nights a year of 'thumping' your rodents in
your fields.
Numerous studies of barn owl diets show that the silent,
night flyer is an amazing rodent-eating machine. About
the size of a house cat but weighing only a pound
compared to the cat's nine, barn owls consume one to two
pocket gophers a day. One study cited that was conducted
in California, found that during an eight-week period of
feeding their young from hatchling to fledgling, the
barn owl diet included pocket gophers (42 percent),
voles (30 percent), deer mice (17 percent), house mice
(6 percent) and other prey (5 percent).
One barn owl will eat, on average, 155 pocket gophers or
53 pounds of pocket gophers per year, The owlets eat
five times that amount! However, you won't find ground
squirrels in their diet, because ground squirrels are
diurnal, sleeping at night. Growers with ground squirrel
problems should put up raptor perches to encourage
squirrel patrol by hawks.
Male owls do most of the hunting, aggressively killing
prey with their talons. They only eat what they can
swallow whole, although the hen will tear off chunks and
break up the food for the young.
Barn owls have a highly developed hearing system, using
their satellite-dish–shaped face and asymmetrical ears
to hear their rustling prey on the ground. They can even
hear gophers tunneling below ground.
Barn owls are not territorial, but they are about 'as
smart as a box of rocks', noting that growers must make
it easy for owls to find nesting boxes.
Design and
location
The phrase 'build it and they will come' is true for
boxes and perches for barn owls, raptors, and bluebirds.
Barn owls prefer holes that are elliptical in shape,
about 4.5 inches wide by 3.5 inches deep.
Elliptical-shaped holes look more natural and give owls
a more secure feeling.
A perch should never be included on the barn owl box, as
it invites other predators like great horned owls. To
safeguard the owlets from unwanted predators, it is
recommended building a half-wall inside the box to keep
raccoons from easily reaching the nest inside.
Boxes should always face east to increase the odds of
successful roosting. By facing east, the hole is
illuminated either by the moon or early morning sun,
providing better contrast for the bird to find it. Also,
because jet streams typically blow from west to east,
boxes are more protected from prevailing winds.
In hot climates, barn owl boxes will need a sun shield
with a four-inch gap on the back and top to help
insulate it from excessive heat.
Don't hang barn owl boxes in trees because the location
is easy pickings for predators like raccoons, opossums,
and great horned owls. Additionally, the barn owls may
not notice the boxes that are in the trees.
It is recommended to place the boxes on 15-foot steel
poles or four-inch by four-inch wooden posts, which will
result in boxes being about 12 to 13 feet from the
ground. Height is not that important, but placement is.
Owls need to see the box above orchard trees and have a
flight corridor to make it easy for coming and going.
Owls usually "hook" or fly to the right after
leaving the roost, so growers should try to have a tree
or tree line 15 to 20 feet to the right of the box. If
trees are not available, a raptor perch can be
substituted.
The birds DO need water. Unobstructed water troughs
work, but birds need to be able to get out of the water
easily and safely.
Kill zone
Boxes should be placed in a triangle pattern to create
an overlapping kill zone. To avoid detection from
predators, barn owls will not hunt for food under their
nesting sites and generally glide out 50 to 100 yards
before transitioning into the hunting mode.
It is wise to place boxes between 100 to 200 yards apart
in an overlapping triangle pattern.
The old thinking about barn owls was to have one box for
every 25 acres. We now know that barn owls are not
territorial, so we can take advantage of having lots of
nests for lots of barn owls.
The number of boxes depends on the grower's preference.
It could be as few as 3 per acre or as many as 12 for
each 25 acres, depending on the rodent populations and
terrain.
Boxes should be cleaned out once a year after owlets
have left the nest.
It is recommended to replace the bedding with oak or
pine wood chips in July after fledglings have left, and
checking the box again in the fall for wasp nests. If
wasp nests are present, spray the box with pyrethrin-based
products and remove the nests.
Be sure to wear a dust mask and wear disposable gloves
when cleaning owl boxes; always wash hands thoroughly
afterwards.
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