Bats are among the most
gentle, beneficial and necessary animals on earth.
Bats are exceptionally vulnerable to extinction because they
have such a slow reproductive rate having only one baby a year. More than 50%
of American species are in serious decline or already listed as endangered.
There are more than 40 different species of bats found
throughout Canada and the United States but only a few of these species ever come into
conflict with humans. Typically house- or building-dwelling bats such as the little
brown bat, the big brown bat, the evening bat and the free-tailed bats are the ones that
cause problems for people.
Some bats live in colonies; others are solitary.
All of the bats found in North America are nocturnal, although
they begin foraging at dusk.
Almost all bats migrate, and both the summer colonial and
solitary species will collect in groups, often at caves used as hibernation sites.
All Common North American bats feed on insects which they
usually catch in flight. They detect their prey by echolocation
which is the remarkable ability to emit high-frequency sounds (outside of human hearing)
to discern objects by the sound reflected back to the bate. Some species can detect
objects no wider than a human hair.
Most species give birth to their single baby in early to late
May, with the young unable to fly until sometime in July. The newborn of some
species cling to the mother while she hunts, but all offspring are left behind as they
grow too large to be carried. Attics are often used as nurseries because they
maintain desired temperatures for raising young. Nursery colonies only contain
breeding females and their babies as the adult males roost elsewhere at these times.
Although bats are more commonly
associated with the transmission of rabies to people than any other type of animal, the
incidence of this disease in bat populations is estimated to be less than one-half of l
percent. Rabid bats generally do not become aggressive and do not bite without
provocation, but any bat may bite in self-defense if handled with bare hands.
The sight of bats flying at dusk above the yard is no cause
for alarm this is perfectly natural the bats are foraging for flying
insects. It has been documented that bats can eat up to 600 mosquitoes in one hour.
Bats flying in the skies above our homes are performing a welcomed
Bats in the house, while still no cause for alarm, may require
Bats rely on existing openings to enter buildings and
therefore do not cause structural damage by making or enlarging entry holes. Small,
l/2 inch or greater, openings high on houses, around chimneys, at the union of dormers
with roofs or at loose siding can all provide access. Bats roosting in houses often
go unnoticed for years. Then, they may first be noticed after an accumulation of
feces and urine leach through the attic spaces to stain the wall or ceiling on the living
area below. At this point the homeowners go into a panic believing they have a
crisis requiring immediate action when, in fact, they have been living with the bats for
A second type of problem occurs when an individual bat is
found inside the house. In this case, getting the bat out of the house becomes a
The rule in any encounter with a bat is to remain calm and
keep companion animals and children away. The myth of bats becoming entangled in
ones hair is exactly that a myth. Keep as near to a
wall as possible when moving around the room. Because of the confined space, the bat
will have to follow a U-shaped path, gaining altitude near the walls and losing altitude
in the center of the room. A person standing in the middle of the room may feel that
he is being attacked when actually all that is happening is that the bat is trying to stay
Close interior doors and give the bat an exit by opening an
outside door or window. If the bat disappears before an exit has been provided, it
probably has landed somewhere it can hang behind curtains or upholstered furniture,
on hanging clothes or in house plants. Search for it, and try to capture it using a
net if one is available. If a net is not available and the bat is hanging on a
curtain or other vertical surface, carefully place a jar or plastic tub over it (metal cans will quickly cool bats down to temperatures that are unsafe
for them) and gently work a piece of hardboard or stiff paper between the opening
and the surface of the wall, trapping the bat inside.
A thick towel is a good way to capture a bat on the floor or
within reach. Roll the bat up gently, take the towel outside to a location
safe from bystanders and domestic animals and unroll it. Be prepared for the bat to
loudly protest when picked up.
NEVER HANDLE A BAT WITH BARE HANDS.
After the bat has been freed, it is important to find how it
entered the house. Possible entry routes are through an open door or window, but if
these can be ruled out, then it is more likely the bat has been roosting somewhere within
the outer walls of the house and accidentally found a route to the living space.
Common entry points include gaps around window air conditioners, chimneys and openings in
interior walls that lead to attics or cellars that may harbor even more bats.
Inspect and seal these interior entrances immediately if it appears they could allow
entry. The inspection must be thorough because bats can fit through openings as
small as l/2 inch.
The most likely place for a bat colony to become established
in a house is the attic. The key to excluding a bat colony from a building is to
find any and all openings that the bats are using. A well-used opening will
sometimes be discolored on the outside from the body oils that come from the bats rubbing
against it when coming and going. A "bat watch" just at dusk can reveal
other entrances. Watch closely from before sunset until at least thirty minutes
The best strategy for excluding a bat colony from a building
is to allow the bats to leave on their own and then to deny them reentry. Bats should be evicted from a building only when it is known that no
young animals are present. From May through August, then, is not a
good time to try to solve bat colony problems. Waiting until they have left for the
winter hibernation cave allows the exclusion to be done in a more careful and deliberate
If the colony must be excluded at once, all outside entrances
should be located and noted. All except the largest or most obviously used should be
sealed with appropriate building materials (hardware cloth, netting or sheet metal).
The last entrance can be fitted with a one-way bat check-valve which allows bats to
exit from a building but not return. This consists of netting draped overbut
left open at the bottoman entrance being used by house-dwelling bats. Bats
will exit, crawl down the side of the house and leave, but they will not be able to
return. Left in place for several nights, these devices should give all bats a
chance to exit but frustrate their returning. If possible, check the attic to be
sure that there are no bats left, and watch the outside of the house in the evening again
to make sure the bats have not found another way in. If they have, move the excluder
to the new entrance. After the bats are gone, remove the excluder and seal the last
opening. Netting is available by calling Internet Plastic at
800-328-8456. Request l/6 inch mesh size, order # OV-7100. You can learn more
about this product by visiting Internetplastic
but orders for the netting cannot be made on-line you will have to call.
Bat Conservation International
(BCI) is the best source of advice and information on bats, although some states have
local bat conservation societies that can be helpful also.
BCI can be reached at
P.O. Box 162603
Austin, TX 78716
Telephone: (512) 327-9721
Fax: (512) 327-9724.
Bats have suffered terribly at
the hands of humans based solely on superstition, myth and false information. These
gentle creatures have an important role to play and should be protected, respected and