Bats
Bats are highly beneficial to people, and the advantages of having
them around far outweigh any problems you might have with them. As
predators of night-flying insects (including mosqui toes!), bats play a role
in preserving the natural bal ance of your property or neighborhood.
Although swallows and other bird species consume large numbers of
flying insects, they generally feed only in daylight. When night falls,
bats take over: a nursing female little brown bat (Myotis lucifugus) may
consume her body weight in insects each night during the summer.
Contrary to some widely held views, bats are not blind and do not
become entangled in peoples’ hair. If a flying bat comes close to your
head, it’s probably because it is hunting insects that have been attracted
by your body heat. Less than one bat in 20,000 has rabies, and no
Washington bats feed on blood.
More than 15 species of bats live in Washington, from the common little brown bat (Myotis lucifugus) to the rare
Townsend’s big-eared bat (Corynorhinus townsendii). Head to tail, bats range in length from the 2.5-inch-long
canyon bat (Parastrellus hesperus), to the 6-inch long hoary bat (Lasiurus cinereus). The hoary bat has a body
approximately the size of a house sparrow and a wingspan of 17 inches.
The species most often seen flying around human habitat include the little brown bat (Myotis lucifugus), Yuma
myotis (Myotis yumanen sis), big brown bat (Eptesicus fuscus, Fig. 1), pallid bat (Antrozous pallidus), and
California myotis (Myotis californicus).
Facts about Washington’s Bats
Food and Feeding Behavior
• Washington bat species eat vast quantities of night-flying
insects, including moths, beetles, mosquitoes, termites,
and flies.
• Most bats hunt in flight or hang from a perch and wait
for a passing insect to fly or walk within range.
• The pallid bat captures crickets, grasshoppers, spiders,
scorpions, and other prey on trees or on the ground.
• Bats locate flying insects primarily by using a radar system
known as “echolocation.” The bat emits high-pitched
sound waves that bounce back to the bat when they strike
a flying insect. A bat locates prey by interpreting the
reflected sounds.
• Bats often capture insects when flying by scooping them into their tail or wing membranes, and then putting
the insects into their mouth (Fig. 3). This results in the erratic flight most people are familiar with when they
observe bats feeding in the evening.
Figure 1. Big brown bat
(Photo by Ty Smedes)
Figure 2. Bats are the only
true flying mammals and they
belong to the mammalian
order Chiroptera, which means
“hand-wing.” The bones in a
bat’s wing work like those of
the human arm and hand, but
bat finger bones are greatly
elongated and connected by a
double membrane of skin to
form the wing.
(Oregon Department of Fish and
Wildlife.)
• Bats will fly 1/2 to 6 miles
from their roost to a
feeding site, using
temporary roost sites there
until returning to their
main roost.
Hibernation Sites
•
To cope with winter
conditions, most bats use a
hibernation site, called a
“hibernaculum.” (See
“Bats in the Winter.”)
• Hibernation sites include cavities in large trees, caves, mine shafts, tunnels, old wells, and attics.
• The hibernaculum protects the bats from predators, light, noise, and other disturbances. Temperatures in the
hiber naculum must be cool enough to allow bats to maintain a low body temperature but not freeze; humidity
must be high and constant enough to prev ent bats from dehydrating.
• Bats hibernate alone or in groups, and enter hibernation sites in late September or October.
Nursery Sites
• Most Washington bats breed during late fall or winter at their hibernation site. Females store sperm until the
following spring, when fertilization takes place after the females rouse from hibernation.
• The young, called “pups,” are born and raised in nursery colonies occupied only by breed ing females and their
young.
• Males roost alone or in small groups during this time, leaving the warm roosts and optimal feeding grounds to
females.
• Attics are often used as nursery sites because they maintain the warm temperatures, from 85 to 104 degrees F
needed for raising young; the heat actually speeds the development of bat pups, both during fetal develop ment
and after birth.
• Most bat species produce one pup in May, June, or July; the specific dates depend on the species, locality, and
weather.
• In the nursery, the young remain with their mothers and suckle frequently.
• Pups are unable to fly for about a month, and are left in the nursery when the mother hunts.
• Female bats may return to the exact location where they were born year after year.
Mortality and Longevity
• Bats have few predators. Hawks, owls, house cats, and raccoons occasionally prey upon them.
• Heavy storms kill bats during migrations, and long winters can kill even more of them.
• Through habitat alteration, commercial pesticide use, and control practices, humans are a main source of
mortality among bats. Exposure to pesticides kills bats either directly through exposure, or indirectly through
ingestion of sprayed insects.
• For their size, bats are the world’s longest-lived mammals. The big brown bat has been recorded to live 19
years in the wild. The record for a little brown bat is 33 years.
Figure 3. Bats often capture insects when flying by scooping them into their tail or
wing membranes, and then putting the insects into their mouth.
(Oregon Department of Fish and Wildlife.)
Viewing Washington’s Bats
The safest way to view and enjoy bats is to watch them in action. Bats are fascinating flyers, zigging and zagging
about as they chase and eat insects. Little brown bats and Yuma bats prefer to hunt over water. Big brown bats are
often seen hunting along the margins of wooded areas, or silhouetted against the lighter sky as they twist and turn
high above the tree canopy.
It’s also fun to watch bats drink, which they usually do first thing after leaving their day roost. They scoop up
mouthfuls of water with their lower jaws as they fly over lakes, streams, ponds, or water troughs. Most bats do
not come out to eat or drink in heavy rain or when the air temperature remains below 50 degrees F.
To view bats, follow these tips:
Choose a warm summer evening and a place where you can sit and view the place where bats will emerge from a
roost site or have been spotted in the air.
When waiting for bats to emerge from a roost site, such as an attic or bat house, remain still and quiet, and listen
for the squeaks or clicks that many species make before emerging.
Some species of bats begin their night flights 20 to 30 minutes before dark—the common big brown bat may be
out foraging earlier. The rare canyon bat from the arid regions of Washington emerges before the sun goes down,
and has been seen foraging with vio let-green swallows. Other species don’t emerge until after dark.
The best places to see bats in flight are where night-flying insects abound, such as next to a stream, lake, or pond,
over a meadow or large lawn, along a forest edge, or around bright streetlights or porch lights.
With the aid of an inexpensive, commercial bat detector, listen for the echolocation calls bats make when
navigating and locating prey.
Bats in the Winter
With few flying insects available to them during winter in Washington, bats survive by hibernating, migrating to
regions where insects are available, or a combination of these strategies.
During hibernation, metabolic activities are greatly reduced—a bat’s normal body temperature of around 100
degrees F is reduced to just one or two degrees higher than that of the hibernaculum, and their heart rate slows
to only one beat every four or five seconds. A hibernating bat can thus survive on only a few grams of stored fat
during the five- to six-month hibernation period.
Banding studies indicate that little brown bats will migrate 120 miles between hibernacula and summer roosts,
and, if undisturbed, they occupy the same site year after year. They select areas in the hibernaculum where there
is high humidity (70–95 percent), and the temperature is 34 to 41 degrees F. Still, there are some species, such
as the big brown bat, that can hibernate in relatively exposed situations in buildings where there is considerable
fluctuation in temperature. Hibernation lasts until April or early May, but in coastal regions bats may arouse in
late winter—little brown bats have been found feeding in the Puget Sound region in mid-March.
It is important not to disturb hibernating bats. If a bat rouses early from hibernation, it must use its fat reserves
to increase its body tempera ture. A single disturbance probably costs a bat as much energy as it would normally
expend in two to three weeks hibernating. Thus, if disturbed multi ple times, hibernating bats may starve to death
before spring.
It is important not to disturb roosting bats at any time of the year. In the spring, disturbing a maternity colony
when flightless young are pres ent may cause young bats to be dropped to their deaths, or abandoned, by panicked
females. Because some bats hibernate in buildings during the win ter months, batproof a building only when you
are sure no bats are hibernat ing in it. If bats are found hibernating inside after October 15, they should be left
alone until early spring (prior to the birthing period in May) after the weather has warmed enough for insects to
be out regularly. Meanwhile, seal all potential entry points into human living spaces, and develop a plan so the
exclusion process can be accomplished effectively in spring (see “Bats Roosting in Buildings”).
Bat Houses
Some bat species prefer man-made structures to their natural roosts, whereas others are forced to roost in
buildings when natural roosts, such as caves and hollow trees, are destroyed.
Two bat species that frequently use bat houses are the little brown bat and the big brown bat.
A well-designed, well-con structed, and properly located bat house may attract these and other bats if they live in
or pass through your general area.
For bats living in Washington, especially west of the Cascades, bat houses should be painted with multiple coats
of flat black exterior latex paint and placed where they will receive full sun. A house baking in the sun is what
our bats need and seek—a nice warm place to raise their young, and that lets them decrease their metabolic needs
during roosting.
Build or buy a bat house that is at least 2 feet tall and 14 or more inches wide (see WDFW weblink). Bigger is
better. A roughened or screen-covered landing platform measuring 3 to 6 inches should extend below the house.
The house can be single -chambered or multi-chambered, but chambers should be ¾ to 1 inch wide—a varie ty of
sizes is good to provide for the needs of different species.
The houses should be caulked during construction and prefer ably be screwed together. The idea is to create a
tight microcli mate inside the house capable of trapping both the heat captured during the day and the warmth
generated by the bats.
Place the house in full sun, preferably on its own pole; the next-best location is on the south ern side of a building
in full sun. The optimal temperature range is between 85 and 104 degrees F. Don’t put it on a tree, as it will be in
too much shade and too close to perch sites used by hawks and owls. Keep the area around the entrance clear of
obstructions for 20 feet.
Don’t worry that adding a bat house to your property will encourage bats to move into your attic or wall space. If
bats liked your attic or wall spaces, they would probably already be liv ing there.
(See “Additional Information and Resources” for more on bat house design, placement, and maintenance.)
Preventing Conflicts
For some people bats don’t pres ent a problem. For others, bats can be a worry, especially when they become
unwanted guests in an attic, inside a wall of a home, or inside the home itself.
Unlike rodents, bats only have small teeth for eating insects, so they do not gnaw holes in walls, shred material for
nests, chew electrical wiring, or cause struc tural damage to buildings. Damage caused by bats is usually minimal,
but they can be noisy and alarm ing, and the smell of bats and their droppings can be offensive. It is possible to
learn to coexist with bats, and to benefit from their presence.
If a conflict arises, first make sure bats are the cause by observing the following:
Bat droppings: Bats defecate before entering buildings and places where they roost. In buildings where there is an
attic roost or a roost in a wall, an accumulation of droppings may fall through cracks and stain ceil ings and walls.
Insects associated with bat droppings rarely bother humans.
Droppings are usually the size of a grain of rice, crumble easily between the fingers, and contain shiny, undigested
bits of insects. The droppings of mice are much harder and more fibrous.
Bat sounds: Bats often squeak before leaving their roost at night, and may chatter on hot days when they move
around seeking refuge from the heat. Baby bats separated from their mothers will squeak continuously. All these
sounds are loud enough to be heard from a distance of up to 30 feet. Thus, an increase in such noises near dusk
probably indicates bats.
Scrambling, scratching, and thumping sounds coming from attics
and walls at night may be caused by rats, mice, flying squir rels,
opossums, or raccoons. In rare cases, chirping and rustling sounds
in a chimney at night may be caused by swifts (birds similar to
swallows).
Bat odors: Bats produce a musky solution from their scent glands
and their roosts may take on a strong musky odor. Areas occu pied
by rats and mice also often have a musky smell.
Bats Roosting in Buildings
Like other wild animals, bats will seek shelter in an attic, wall,
chim ney, or other area of a structure. Bats are able to squeeze
through surprisingly narrow slits and cracks; the smaller species
need only a ½-inch opening.
When bats occupy a house, homeowners often feel they have a
crisis they must deal with imme diately. But in fact they may have
been living with the bats for years. The following are suggestions
for reducing conflicts:
Excluding Bats
The best way to get rid of bats is also the safest—both for the
bats and the humans involved. This is to humanly exclude them.
However, because old buildings offer many points of entry it may be impossible to completely exclude bats from
them, or from those with shake or cedar shingle roofs that have no underlayment.
A wildlife damage control company experienced in exclud ing bats can be hired, or you can do the exclusion work
your self (see WDFW link, this is a short one and I can send it to ASAP if needed). In attics and areas where large
numbers of bats have been roosting for years, it is safer for you to hire a professional to do the work, including
the cleanup of accumulated droppings.
Note: Never trap flightless young or adult bats inside a struc ture; this is needlessly cruel to the bats inside and can
create a serious odor problem (see “Bats in the Winter” for important informa tion about when not to exclude
bats).
Trapping and relocating bats is not recommended. Traps can be fatal to bats if left unattended and can quickly
become over crowded. In addition, bats have excellent homing instincts and, when released, they may simply
return to the capture area. Yuma myotis bats released 240 miles from their roost have found their way back.
Prior to excluding bats, con sider partitioning bats off from the area where they are in conflict with humans, and
allowing them to roost elsewhere in the struc ture. An effective partition can be made from construction grade
plastic sheeting and wooden bat tens. Another consideration is to provide an alternate roost site, such as a properly
designed and installed bat house mounted close to one of their exits. Install the bat house before excluding the
bats as described below.
The following will work to exclude bats from most structures:
Option A – Build bats out: From mid-October to mid-March, when bats should still be hiber nating, or after you
have made sure no bats are roosting in the attic or other area, seal all poten tial entry holes (see Fig. 5). Enter ing
the attic during the day may reveal light shining through other wise unnoticed cracks and holes. Insert pieces of
fiberglass insula tion or bits of stick in these holes to mark them for repair from the outside.
Large openings can be sealed off with aluminum flashing, wood, or ¼-inch mesh hardware cloth. Small holes
around pipes, cracks, and gaps in shakes and tiles can be stuffed with balled-up galvanized win dow screening,
pieces of fiber glass insulation, copper Stuff-it
®
, or copper or stainless-steel mesh scouring pads (steel wool will
quickly corrode after becoming wet). Use weather-stripping, caulk, or expandable foam to seal spaces around
doors, windows, and vents, and replace loose boards and roofing materials. Close the damper in the fireplace.
Figure 4. The lateral view of a big brown
bat skull. Unlike rodents, bats do not gnaw
holes in walls, shred material for nests, chew
electrical wiring, or cause structural damage
to buildings.
(From Verts and Carraway, Land Mammals of
Oregon.)
If caulk or expandable foam is used, apply it early in the day so that it is set up and no longer sticky if bats inspect
the area in the evening. If there are large areas to be foamed, it may be worth purchasing a foam gun of the type
used in building construction. Foam is very messy to use, so wear gloves when applying it, and don’t get it on your
clothes or skin.
The advantage of caulk over foam is that it comes in a variety of colors and it is easier to apply. Before
purchasing, check the label to make sure the caulk can be painted.
Insulation blown into wall spaces may be an effective barrier, but it must be done when bats are absent to avoid
trapping them in the fill.
If bats are present, holes can also be blocked over a period of days early in the evening after the bats have left
the structure to feed. Do this only from mid-August to mid-October (after the young bats have learned to fly
and before cold weather arrives). Another window of opportunity occurs in early spring, before the birthing
period in May.
For several days, bat counts should be made as holes are closed, leaving the main exit open. On the night of
the final count after the bats have left, the main hole should be plugged to prevent their reentry. The following
evening, the plugging should be removed to allow any remaining bats to leave before the exit is sealed.
Option B – Harassment: If bats are present and have to be excluded, persuade them to move to one of
their alternate roost sites by creat ing an undesirable atmosphere. The time to do this is from mid -August to
mid-October, after the young bats have learned to fly and before cold weather arrives. Another window of
opportunity occurs in early spring, before the birthing period in May.
Bats don’t like to roost under bright, windy, or noisy conditions. Therefore, locate the area where bats are
roosting and light the area with a bright light, such as a mechanic’s drop-light or trouble light, located away
from burnable objects. (Use a fluorescent light to save on electricity and keep the heat level down.) In addition,
aim a fan and a loud radio at the bats. Begin the harassment process shortly before dark and keep it in place day
and night.
Because bats may move to a dark, protected area, you may need to move the lights and other equipment, or
install them in vari ous areas. Putting up sheets of plastic to separate the bats from the rest of the area can be
effec tive, but make sure you don’t block the bats’ exit or exits.
Figure 5. Common entry points used by bats.
Down chimneys and where chimneys and other masonry meet the side of a house
Joints between window frames and house siding
Joints around large exterior beams
At building corners
Where pipes or wires penetrate the ceiling or walls in attics
Between porches or other additions and the main house
At roof edges, ridge caps, soffits, and fascia boards
Where walls meet eaves at the gable ends of an attic
In gaps under shingles.
(Bat Conservation International.)
Commercially available ultrasonic
devices may be effec tive if they are
placed in a small, confined area with
the roosting bats. Since bats can hear
high frequency sounds, these devices,
inaudible to humans, supposedly
bombard the bat’s range with
jackhammer-like noise.
Naphthalene flakes or moth balls should
not be used to exclude bats. These
contain chemicals that can be toxic to
humans and other life forms; poisoned
bats may fall to the ground where they
die slowly and are more likely to come
into contact with children or pets.
If the exclusion process was successful, immediately seal up the exits to prevent bats from reenter ing. If necessary,
install a chimney cover, available from home improvement centers.
Option C – Install exclusion devices: Again, from mid-August to mid -October (after the young bats have learned
to fly and before cold weather arrives), or in early spring (before the birthing period in May), identify the exit(s)
bats are using. Have friends or family members stationed at the corners of the structure after sunset on a warm
calm night. They need to be far enough away to see as much of the structure as possible with out having to turn
their heads; it takes only a second for a bat to exit and take flight. Note which side of the structure bats are seen
from. On subsequent nights, focus your attention there to locate the exit hole. Remember this hole can be as small
as ½-inch.
Bats often defecate when exit ing and reentering a building, so look closely for rice-sized black droppings clinging
to the side of the structure. If droppings are observed, the exit hole will be directly above it. (To make sure
droppings are new, remove the existing droppings or lay down newspaper over them to see if more droppings
appear.) Bat body oils may also discolor a well-used opening.
Seal all entry holes but one using the methods described in Option A.
Exclude bats by covering the one existing entry hole with a device that allows bats to exit the structure, but
prevents them from reentering (see Figs. 6–10). Install the exclusion devices during the day and leave them in
place for five to seven
days (longer during
particularly cool or rainy
weather).
When bats are using
multiple openings to
exit and enter, exclu sion
devices should be placed
on each opening, unless
you can be sure that all
roosting areas used by
the bats are connected. If
all the roosting areas are
connected, all but one
or two exit holes can be
sealed as described below.
Place exclusion devices
over the one or two
remaining exit holes.
Figure 7.
One-way tubes
work where one-way doors
won’t, such as on horizontal
sur faces. A flexible pipe or
cardboard tube is easy to fit
into a crevice or cut to create
flaps that can be fit over
an opening and be stapled,
nailed, or taped to a building
(Fig. 8). Do not let the tube
project more than ¼-inch
into the opening to make
sure that bats can easily enter
the tube.
(Bat Conservation
International.)
Figure 6. A one-way door allows bats to
exit a structure, but prevents them from
reentering. Hang a sheet of construction grade
plastic, screen-door material, or light weight
polypropylene netting (1/2 inch mesh) over
the exit. Use staples or duct tape to attach
the material to the building. The one-way
door should extend 18 to 24 inches below the
bottom edge of the opening. Leave the material
loose enough to flop back after each bat exits.
(Bat Conservation International.)
However, if the colony con tains
a hundred bats or more, which is
common, leaving only one exit point
can create a “bat log jam.” In these
cases, some bats might start looking
for alternative ways out of the roost
area, lead ing to bats finding their way
into human-occupied areas. So, always
watch to make sure bats are able to
exit freely. If they do not appear to be
exiting, or appear to be hav ing trouble
doing so, open addi tional exits.
After all bats have been excluded,
remove the exclusion devices and
immediately seal up the exits to
prevent bats from reentering. If
necessary, install a chimney cover,
available from home improvement
centers.
Bats Roosting above Porches
and Other Areas
Bats temporarily roost above porch-
es or under overhangs at night to eat
large prey, digest, rest, and socialize.
In such cases, they may frighten
humans, or their drop pings may
accumulate. Nontoxic aerosol sprays,
designed to repel dogs and cats, can
prevent bats from night-roosting in
these areas.
The spray is applied
by day when bats are
not present, and is
reported to be effective
for several months.
However, aerosol
repellents are not an
adequate substitute for
excluding bats that are
using the area as a day
roost, and should never
be applied when bats
are in a roost.
Mylar balloons or
strips of alu minum foil
hung from the porch
ceiling and allowed to
move in the breeze may
also discourage bats
from roosting in that
area.
Figure 9. Some areas have
lengthy crevices used by bats.
Multiple exclusion tubes will
need to be placed every few
feet along the length of each
crevice; spaces between the
tubes should be closed with
heavyweight netting or other
material. The same proce dure
can be used in lengthy crevices
created where flashing has
pulled away from a wall.
(Bat Conservation International.)
Figure 8. One-way tubes should be at least 2-inches in
diameter, 10 inches in length, and have a smooth interior
so bats are unable to cling to the inside. One -way tubes
can be made from PVC pipe, flexible plastic tubing,
empty caulking tubes, or dryer vent hose. To
reduce the likelihood of bats reentering, a
piece of plastic sheeting can be taped
around the exit end of the tube.
(Bat Conservation
International)
Figure 10. One-way tubes for chimneys.
If bats are roosting inside a chimney,
construct a wire cage from ¼-inch mesh
hardware cloth. Insert a modified section
of 2 inch PVC pipe through holes cut
in the sides of the wire cage. To further
reduce the likelihood of bats reentering,
a piece of plastic sheeting can be taped
around the exit ends of the tube.
(Bat Conservation International.)
Public Health Concerns
Large accumulations of bat drop pings may harbor histoplasmosis fungi spores, which when inhaled can result in a
lung infection referred to as “histo.” No histo cases have been reported in Washington, but precautions should be
followed when cleaning or removing large accumulations of bat droppings. Call your local health department for
recommendations.
Rabies
People are more often concerned about bats because of rabies, a virus that affects the nervous sys tem of all
mammals, including humans.
Rabies is spread when the saliva of an infected animal enters another body through a bite or scratch, or makes
contact with their eyes, nose, mouth, or a break in the skin. There is little risk of contracting rabies from a bat as
long as you exercise caution. People cannot get rabies from touching bat droppings, blood or urine, or fur.
Five to 10 percent of sick, injured, or dead bats tested by the Washington State Depart ment of Health (WDH) have
rabies; however, WDH estimates that probably less than 1 percent of the native wild bat population has rabies.
If a bat does contract rabies, it is unlikely to be a threat to humans as long as simple pre cautions are followed. Most
bats infected with rabies become paralyzed and fall to the ground. (Note: Young bats also fall to the ground when
learning to fly. They may also have hit a win dow and been stunned, or simply be cold and unable to fly.) This means
a person may contract rabies from a bat only if they pick up a sick bat, which then bites the person in self-defense.
Thus, if you do not handle bats, your odds of contracting rabies are extremely small.
If you think you have been bitten, scratched, or exposed to rabies via a bat:
1. Wash any wound or other area that came into contact with the bat thoroughly with soap and water.
2. Capture or isolate the bat, if you can, without risking further contact (see “Bat Encounters Inside or Outside
Your Home” for safe capture techniques). The captured bat will be sent to a laboratory for rabies testing.
3. Call your doctor or local health department. An evaluation of the potential of rabies expo sure and the need
for follow-up treatment will be done. Arrange ments to have the bat tested for rabies, if necessary, will also be
made.
People usually know when a bat has bitten them. However, because bats have small teeth and claws, the marks may
be difficult to see. Contact your local health department or your doctor in the following situations, even in the
absence of an obvious bite or scratch. In such cases, the bat should be captured for testing:
1. A bat is found in a room with a sleeping person.
2. A bat is found in a room with an unattended child.
3. A bat is found near a child outside.
4. A bat is found in a room with a person under the influence of alcohol or drugs, or who has another sensory or
mental impairment.
What About Rabies and Your Pet?
Once dogs presented the major domestic risk of rabies, but now cats do. Routine rabies vaccination is not as widely
practiced with our domestic cats as with dogs. Yet cats often play or hunt in natural areas.
All cats should be vaccinated for rabies, even indoor cats. The National Association of State Public Health
Veterinarians publishes the Compendium of Animal Rabies Control yearly. These guidelines are clear: An
unvaccinated animal that comes in contact with a potentially rabid animal (bats in Washington) that cannot be
tested should (1) be euthanized; or (2) be held in strict quarantine for six months. Few people are willing to do
either.
The message for everyone is: vaccinate your pets! Dogs require vaccination
against several dis eases. Puppies begin their series of vaccinations at six to eight
weeks of age, and annual boosters are necessary to maintain immunity.
Bat Encounters Inside or Outside Your Home
In spring and fall, migrating bats may temporarily roost outside on window
screens, fence posts, piles of lumber, and other unlikely places. If a bat is seen
roosting outside during daylight hours, leave it alone. It will probably be gone
the following morning.
If a bat flies into your home it’s probably a juvenile learning to fly, a soli tary
male following prey, or an adult that has been excluded from its roost. Bats
often enter through an open door or window, or by coming down a chimney
into an unused fireplace.
If a bat is found inside during the day, confine it to one room. Place a towel
under doors to prevent the bat from moving into other parts of the house.
Leave the area alone until nightfall.
At nightfall (if you are sure the bat has not been in contact with humans or
pets), turn off any lights in the room where the bat is confined, open all doors
and windows that lead outside, and stand in the corner. This allows you to
watch the bat while staying out of its way. (If you must move around the room,
stay as near to the wall as possible.) Be prepared to watch the bat for up to 20
minutes. Normally, the bat will fly around the room to orient itself, and then
leave.
If the bat seems to have disappeared but you didn’t see it leave, it may be
perched somewhere, such as behind a curtain, in hanging clothes, or in a
houseplant. The bat will generally choose a high place to roost. Moving these
things around with a broomstick may arouse the bat.
If the bat doesn’t leave, it can be caught and released outdoors away from
people and pets. Approach the bat slowly and place a container (small box,
large glass, Tupperware container, coffee can) over it. Next, gently slide a piece
of cereal box paper or cardboard underneath the bat (be gentle—bats are fragile
ani mals). Using the paper as a cover, take the bat outside. The ideal release pro-
cedure is to place the container against a tree, slowly slide the paper away, and
then remove the container. Releasing the bat against a tree allows the bat to rest
safe from potential predators—like the neighbor’s cat.
You may also catch the bat using a pair of leather gloves and a pillow case. (Never handle a bat with your bare
hands.) Put your gloved hand inside the pillowcase and gently place it over the bat.Then fold the pillow case
over the bat so it is inside. Take the bat outdoors and safely release it on a rough tree trunk or lightly shake the
pillowcase until the bat flies off. In the absence of a container or pillowcase and gloves, a thick towel can be used.
Roll the bat up gently and release it outside.
Note: State wildlife offices do not provide bat removal serv ices, but they can provide names of individuals or
companies that do. To find such help yourself, look up “Animal Control,” ”Wildlife Control,” or “Pest Con trol” in
you phone directory.
Figure 11.
Bats can be caught
and released outdoors away
from people and pets.
(Bat Conservation International.)
Legal Status
Many Washington bats are currently being studied and may be recommended for protection under the
Endangered Species Act. For current legal status and other information, contact your local wildlife office.
All species of bats are classified as protected wildlife and cannot be hunted, trapped, or killed (WAC 232-12 011).
The Department of Fish and Wildlife makes exceptions for bats found in or immediately adjacent to a dwelling
or other occupied building. In such cases, these ani mals may legally be removed and no permit is necessary (WAC
232 12-011).
Additional Information
Books
Ingles, L. G. Mammals of the Pacific States. Stanford, CA: Stanford University Press, 1965.
Link, Russell. Landscaping for Wildlife in the Pacific Northwest. Seattle: University of Washington Press and the
Washington Department of Fish and Wildlife, 1999.
Link, Russell. Living with Wildlife in the Pacific Northwest. Seattle: University of Washington Press and the
Washington Department of Fish and Wildlife, 2004.
Maser, Chris. Mammals of the Pacific Northwest: From the Coast to the High Cascades. Corvalis: Oregon State
University Press, 1998.
Nagorsen, David W., and Mark R. Brigham. Bats of British Columbia. Vancouver, BC: University of British
Columbia Press, 1993.
Tuttle, Merlin D., and Donna L. Hensley. The Bat House Builder’s Book. Austin, TX: Bat Conservation
International, 1995; University of Texas Press, 2001.
Organizations and Internet Resources
Burke Museum’s Mammals of Washington:
www.washington.edu/burkemuseum/mammalogy/mamwash2.html
Bat Conservation International
www.batcon.org
Bats Northwest
www.batsnorthwest.org
Adapted from “Living with Wildlife in the Pacific Northwest” (see http://wdfw.wa.gov/wlm/living.htm)
Written by: Russell Link, WDFW Urban Wildlife Biologist, Linkrel@dfw.wa.gov
Design and layout: Peggy Ushakoff, ITT2
Illustrations: As credited
Copyright 2004 by the Washington Department of Fish and Wildlife.
This program receives Federal financial assistance from the U.S. Fish and Wildlife Service. It is the policy
of the Washington State Department of Fish and Wildlife (WDFW) to adhere to the following: Title VI of
the Civil Rights Act of 1964, Section 504 of the Rehabilitation Act of 1973, Title II of the Americans with
Disabilities Act of 1990, the Age Discrimination Act of 1975, and Title IX of the Education Amendments
of 1972. The U.S. Department of the Interior and its bureaus prohibit discrimination on the bases of race,
color, national origin, age, disability and sex (in educational programs). If you believe that you have been
discriminated against in any program, activity or facility, please contact the WDFW ADA Coordinator at 600
Capitol Way North, Olympia, Washington 98501-
