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Bats and Health Risks
Bat Removal Specialists
Far from being pests, all species of
bats found in British Columbia are voracious insect predators. Bats eat
up to half their weight every night in moths, mosquitoes, beetles,
crickets, grasshoppers and flies. A single little brown bat may catch up
to 600 insects an hour.
are 16 species of bats in the province and all are protected under
the provincial Wildlife Act. Most species are dark brown with short
ears and small bodies about the size of mice. Wingspans range from 20 to
42 centimetres (about 9 to 16 inches). The most common species found in
buildings are the little brown bat (Myotis lucifugus) and big brown bat
(Eptesicus fuscus), which thrive throughout the province, and the Yuma myotis (Myotis yumanensis), which is found only in the southern part of
Bats enter a building for a variety of reasons, including simply flying
in by accident. They may use buildings as a temporary, daytime roost, as
a nursery to rear their young or, occasionally, as a hibernation site.
Attics are a favorite bat refuge.
Like other mammals, bats can carry fleas, mites and ticks; in rare
cases, they contract rabies. Unlike other mammals with rabies, however,
they tend to get sick and die before becoming aggressive. According to
Agriculture and Agri-Food Canada, which tests about 100 injured, sick or
dead bats annually, no one has contracted rabies from a bat in B.C.
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Risks relating to Bats
Histoplasmosis is an airborne disease caused by a microscopic fungus
that occurs in soil and in the nitrogen-rich droppings of birds and bats
(Tuttle and Kern 1981, Greenhall 1982, Fenton 1992). A dry cough and
other flu-like symptoms are the usual signs of histoplasmosis, which is
often mistaken for influenza. While histoplasmosis often does not
produce any symptoms, severe symptoms such as high fever, problems with
vision, and life-threatening complications
occasionally do occur.
above information is an excerpt from an excellent booklet "Guide to Northeastern Bats and
White Nose Syndrome: Confirming the Cause of Bat Deaths
It's official: the cold-loving fungus Geomyces destructans is, in fact, the cause of White-nose Syndrome - the fast-spreading wildlife disease that has devastated bat populations through eastern North America. The fungus was confirmed as the WNS culprit in a study by the U.S. Geological Survey's National Wildlife Health Center and its partners. Results were reported this week in the journal Nature. Scientists have strongly suspected the fungus, which was new to science, since it was isolated Learn more »
How to Evict Bats From Your Home
most effective long-term solution for evicting bats from roosting or
hibernating in one's home is to prevent them from getting there. If they are
already present, their place of entry must be sealed while the bats are
are several ways to locate the entry and exit points. Keep in mind that some
bats are small and the ones that use attics and other buildings may enter
through a crack of one-half inch or less. Try watching in the evening around
dusk. See if you can spot the bats emerging, and mark or remember where the
holes are. Another way is to enter the roosting place during daylight hours.
Look for light leaks coming in from the outside daylight. Still another way
is to turn on the lights or place lights in the roost and then look from the
outside for light leaks after dark.
the holes are located they must be sealed in some way, whether it be by
caulking, wood strips, or even steel wool placed in the holes. Do not do
this until late July when the young are able to fly and are leaving to feed.
Another means of exclusion is to hang half-inch polypropylene bird netting
directly above the exit holes. The netting should extend at least one foot
to each side and below the hole. The sides and tops of the netting should be
attached to the building but the bottom should be allowed to dangle free so
that bats leaving the building can find their way out by dropping down to
the open end of the netting. After about two or three nights, all the bats
will have left the building and the entrances can be plugged permanently.
Up After Bats
Once the bats have been excluded from the roost area should be thoroughly
bat droppings can create a strong odor. This odor may also attract bats if
new openings develop in the structure. Use caution cleaning the area to
avoid contracting histoplasmosis. Histoplasmosis is a respiratory infection
caused by inhaling fungal spores which may grow in bat droppings. This
fungus is widespread in soils throughout the world. In this country it is
most prevalent throughout the Mississippi and Ohio River valleys and primary
sources of infection are the droppings of starlings, pigeons and poultry.
Although most people contract histoplasmosis have few if any symptoms or
problems, some people develop serious respiratory conditions.
When cleaning up bat droppings, wear a tight fitting
respirator that will filter particles as small as 2 microns. Dampening the
droppings before cleaning them up will help decrease the spread of any
spores. The droppings should be sealed in plastic bags for disposal. The
area should then be cleaned and disinfected with a solution of 1 part
household bleach to 20 parts water. Clothes worn while cleaning should be
Social bats may roost in caves, buildings, hollow trees, animal
burrows, abandoned mines and other protected areas, while solitary
bats may live among leaves or under the bark of trees, rock crevices
and other suitable spaces. In winter some bat species migrate to
warmer climates up to 1000 miles away to feed; others hibernate in
the regions of their summer roosts.
There are three general types of bat gathering places: day roosts,
night roosts and hibernacula. Maturnity roost comprised of only
females, may be found in; i.e. buildings or mine shafts with
temperatures up to 40 degrees celsius and a high percentage of
humidity to ensure rapid growth in the young. Female bats give birth
to only one or two young annually and roost in small or large
numbers. Males may live singly or in small groups but scientists are
still unsure of the whereabouts of most males in summer.
Many bats use one or more night roosts to rest and digest food. It
is also thought that night roosts may be used as locations to share
information about prey availability.
Winter hibernacula are shared by both males and females of the same
species and may be several hundred kilometers away from summer
roosts. The largest known winter population in B.C. consisted of
about 50 bats while in Eastern Canada 10 - 15,000 bats roost
together. The temperature of the hibernacula is extremely important
to the survival of the bats. If the temperature drops below 0 o C
the bats will freeze to death or die of starvation. In too warm a
place, bats will starve to death due to the rise in the metabolic
rate causing the burn-up of all stored fat reserves.
An intensive inventory of potential hibernation sites in B.C. is
still required. When bats roost in buildings they often get into
conflict with people due to human ignorance or the noise and guano
(droppings) the bats generate. Eviction and exclusion are safe and
permanent solutions to the problem. Bats often choose buildings for
their suitability as nurseries and can be quite persistent in trying
to get in. A gap as small as 5 mm is a potential access point. To
pinpoint entrances observe leaving or returning bats at dusk, and
watch for scratches, stains from body oils and droppings. Screening
of access points is very effective since unlike rats and squirrels
bats cannot chew through wire.
The openings must not be covered during the summer (day or night)
since there might be flightless young in the roost who would starve
to death. The best time to permanently seal off openings and keep
them from returning is late autumn or winter when bats have already
migrated or left to hibernate. There is no evidence that chemicals
(i.e. moth balls) or ultrasonic devices repel bats. Ultrasonic noise
makers may attract bats, while mothballs (naphthalene) are toxic and
dangerous to humans and pets. Other poisons may weaken the bats and
could therefore increase contact between bats and humans or pets.
Weakened bats may also be more susceptible to other diseases i.e.
rabies. Do not use pesticides to "protect" or rid yourself from
bats. Bats are protected under the BC Provincial Wildlife Act and
special permits must be obtained to kill them. The chance of being
"attacked" by a rabid bat is extremely rare in B.C. As a precaution
avoid handling bats altogether, but should it be necessary, thick
leather gloves should be worn to touch live bats and disposable
plastic ones to deal with dead bats.
Eight of the 16 bat species in B.C. are currently listed as
potentially endangered or threatened. Bats eat tonnes of insects per
year and are therefore susceptible to poisoning by pesticides. These poisons accumulate in
the fatty tissues and are released during hibernation, migration or
stress and can also be passed on to nursing young. Bats also pick up
toxins from roofing and insulation materials and treated wood (i.e. Lindane) and PCP (pentachloropherol). Roosts should never be treated
To encourage bat populations in your neighborhood but not in your
attic, bat houses are a "human-friendly" solution.
Habitat loss due to clear cutting and other forestry practices is
one of the major conservation concerns. Tree inhabiting bats like
the Hoary Bat ( Lasiurus cinereus ), Western Red Bat ( Lasiurus
blossevillii ) and the Silver-haired Bat ( Lasionycteris noctivagans
) are adversely affected. The Keen's Long-eared Myotis ( Myotis
keenii ), a rare bat restricted almost entirely to the coastal
forests of B.C. is assumed to be dependent on old growth forests.
All bats need clean drinking water. Pesticide use and some logging
practices contaminate streams, ponds and lakes, continuing to
endanger bat populations and their habitat.