Bat Houses
Putting a bat house in your yard is
becoming more popular all the time, as one reason that people
want to attract bats is their huge appetite for insects.
Many small insectivorous bats can eat more
than 1000 small mosquito sized insects in an hour, so a small
colony of bats can consume over 500,000,000 bugs in a year's
time. But like any solution, it should be thought of as a
part of your insect control program, not the total solution
to getting rid of the mosquitos in your yard. You also need
to note that not all bats eat insects, but most in the US do.
Bats are mammals, not really birds, but they fly and are the
only mammals that can fly! This means they bear live young
(don't hatch eggs), have hair, and are warm blooded.
Generally, bats can see well, but because they fly in the at
night they have the bat "radar" or "sonar" or echolocation to
help them find their way in the dark.
Attracting bats to your Bat House: There are
a variety of things to try to attract bats to your yard. In
general, lures for bats are not usually very effective in
attracting bats to your bat house. And more than one bat will
occupy a bat house, it's not uncommon to have over 50 bats in
a single chamber house.
Locating your bat house - Where you choose
to put your bat house is one of the most important factors
for attracting bats. A bat has to find the house, so make it
available to them by putting it on a building or a pole. Keep
them away from predators, so not too close to nearby trees.
Recall that if you are successful in attracting bats, you
will have an accumulation of guano and urine under the house,
so plan for it ahead of time. Put your house at least 12 feet
above the ground.
Bat houses mounted on the side of buildings or on poles are
usually more successful than those mounted on metal buildings
or on trees.
Temperature - This is one of the primary
reasons that bats won't use a bat house. Different species
will have different preferred temperature ranges, but in
general a stable temperature of 80 to 100 degrees F is
preferred. Males tend to tolerate a wider range of
temperatures, while mothers with young will be more
selective. In order to reduce the swings in temperature over
the course of the year, it may be preferred to use the side
of a building in colder climates to provide some protection
from the elements. Full day sun is often preferred to get
those warm temperatures., but if the outdoor temperature
exceeds 100 during the day, you may want to place it for some
shade to moderate the temperatures.
Multiple locations - An easy thing to do is
to install more than one house to help you experiment to find
the best locations. It may take more than 2 years for a house
to be occupied, so with more than one house you can improve
the odds of success dramatically.
Types of Bats Attracted to Bat Houses:
Almost any bat that you can find roosting under bridges or
roosting in building can live in a bat house. This will
differ throughout the country, but in the southern part of
the US, some of the more common bats are evening bats and the
Mexican free tail. In the northern states and up into the
lower parts of Canada it is more common to find the little
brown myotis and big brown bat.
What about Rabies?: While it is true that
bats can carry rabies, in the last 50 years there have been
only about 14 people have contracted rabies from the bat
species that occupy bat houses. It's not a major risk to
worry about.
You can find a lot more on bat houses and the proper siting
and successful techniques to attract bats at
Bat Conservation International.