Protection from Predators
Nesting birds are extremely vulnerable to cats,
as are fledglings and birds roosting for the night. Bell collars on
cats offer birds little protection. Nailing a sheet metal guard or
cone to a tree trunk is unsightly, but may deter less agile felines.
Houses mounted on metal poles are the most difficult for predators to
reach, especially if you smear the poles with a petroleum jelly and
hot pepper mixture. The best deterrent is for owners to keep their
cats inside whenever possible.
Pet dogs are a hazard to nestlings in the spring
and summer. Don't let your dog run loose during nesting time.
Red squirrels, and sometimes gray squirrels, can
become a serious menace to bird houses and the birds themselves. If
you find your riest hole enlarged, chances are a red squirrel is the
culprit. Once inside the box, squirrels make a meal of the eggs and
young. Adding a predator guard made of sheet metal to the entrance
hole is usually enough to keep squirrels out.
Raccoons and Opossums
Raccoons and opossums will stick their arms
inside nest boxes and try to pull out the adult, young, and eggs.
Adding a '/.,-inch thick predator guard to the bird house or an
inverted cone to its pole support is a simple solution.
Snakes play an important part in the balance of
nature. If you find one in your bird house, don't kill it. Snake-proof
your house by putting it on a metal pole lathered with petroleum jelly
or red cayenne pepper.
House Sparrows and Starlings
If you don't discourage them, these two
nuisance species introduced from Europe will harass or kill
cavity-nesting birds. Since house sparrows and starlings are not
protected by law, you may destroy their nests. But remember, other
birds are protected by law.
House wrens sometimes interfere with the nesting
success of other birds by puncturing their eggs. But, unlike the house
sparrow and starling, these birds are native to North America and are
protected by law. Don't be tempted to intervene when wrens appear at
your backyard birdhouse.
Many insects lay their eggs and pupate in bird
houses. Inspect your bird houses for signs of gypsy moths, blow flies,
wasps, ants, gnats and bees. Keep bees and wasps from attaching their
nests by coating the inside of the roof with bar soap. In areas where
gypsy moths abound, avoid placing boxes in oak trees, which the gypsy
Pyrethrin and rotenone
insecticides are recommended for killing fly larvae, bird lice and mites
after birds have finished nesting for the season.