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.
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.
There 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 the province.
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.
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.
White-nose Syndrome (WNS), the highly contagious fungal disease that has killed millions of bats in North America, was confirmed in Washington state yesterday by wildlife officials.
The discovery of the infected little brown bat (Myotis lucifugus)— found by hikers on a trail about 30 miles east of Seattle — marks the first time the disease has been documented in the western United States. Finding the disease almost 1,300 miles from the previous westernmost detection of the fungus in Nebraska is devastating news.
White-nose Syndrome has overwhelmed hibernating bats in the east, with the three most affected species, including the little brown bat, experiencing losses exceeding 98 percent in some states. The discovery of the disease in the west is a dire wake up call for all regions in North America, as biologists expect the disease to spread from this new epicenter.
A source cave for affected bats in Washington State, however, has not been found and may not be; bats in the west are dispersed in low numbers across the vast, mountainous landscape, many occupying crevices in rocks, and other hard to reach places. The finding suggests the fungus has been present in the state for at least a couple of years.
Health 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.
The above information is an excerpt from an excellent booklet “Guide to Northeastern Bats and Bat Problems.”
How to Evict Bats From Your Home
The 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 gone.
There 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.
Once 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.
Cleaning Up After Bats
Once the bats have been excluded from the roost area should be thoroughly cleaned as 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 washed immediately.
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 with chemicals.
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.
Bat Removal Professionals
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