What are they?
Bats are flying creatures of the night, not much bigger than a house mouse. Bats can live up to 10 years. The wingspan of the two most common Canadian species (the little brown bat and the big brown bat) ranges from 20 to 35 cm (8 to 14 inches), though some can be larger.
Should I be concerned?
A single brown bat is very beneficial: it can easily capture 600 mosquitoes each hour. A colony of 500 bats can eat a million insects nightly.
When bats invade buildings and homes though, they become a nuisance. Their presence, the parasites they carry, and the smell from their droppings and urine can all be a problem.
Bats may bare their teeth and squeak loudly, leading many people to believe they are vicious. In reality, the bat is only trying to ward off a possible attack from one of their predators (which include hawks, falcons, owls, cats, snakes, and humans).
Rabies is a potentially fatal viral disease in humans and other mammals that is spread by bites or scratches and through contact with saliva or bodily tissues. Although attacks by rabid bats are rare, anyone bitten or scratched by a bat or any other wild animal should get medical help right away.
Bats emit a high-frequency sound that humans cannot hear. These sounds bounce off objects in their paths, helping them avoid obstacles and find flying insects.
- Cats and dogs stand the greatest chance of becoming infected by picking up a diseased animal, because they use their mouths to do so. The best way to protect a pet from rabies is to vaccinate them regularly.
- Anyone who spends a lot of time in attics, caves, or other possible bat roost sites may want to consider getting immunized against rabies.
- Children should be taught not to handle any wild animal floundering on the ground or a pet behaving strangely.
- Bat exposure is considered to be very high risk, as bat bites are very small and not easily seen. People exposed to a bat can get rabies even though no bat bite is noticed. If a bat is found in a room where someone was sleeping or where a young child may have been alone even for a few moments, get medical attention just to be safe. The bat should also be captured for testing.
- Dead bats found on the ground should be shovelled into a container and brought to public health authorities for autopsy.
If you have been bitten by an animal and think you may have been exposed to rabies, you should wash and flush the wound with soap and water right away. See a health care professional as soon as possible.
Histoplasmosis is a fungal disease in humans that may be caught by inhaling dusty bat manure. Most infections have no symptoms or appear as a mild respiratory illness. Bats are not the only source of this pathogen: it can be found in soil and bird droppings, and is carried by the wind. A respirator and other protective clothing should be worn when working in bat roost sites.
How do I know if I have a problem?
Bats are usually noticed by their droppings or noise-making. Their musty smelling droppings can be mistaken for those of mice or birds. Bat droppings can look like crushed, fine, shiny undigested insect parts, while mouse droppings are firm and do not break apart easily. No white colour appears in bat droppings, like it does in bird feces.
- To save energy, bats have the ability to enter a dormant state that makes them look like they are sick, asleep, or dead.
- Sometimes bats can be seen around outdoor lights that have attracted insects.
- Sometimes in favourable conditions (like high humidity and temperatures above freezing), bats will roost in buildings throughout the winter.
To tell if bats are roosting in a building, inspect the outside of the building before dark when bats leave their roosts, or when they return at dawn. Watching for an hour should be enough to find entry and exit points.
Because bats are nocturnal (night) creatures, they will not leave their roosting sites if they are faced with bright light. So, when inspecting the outside of a building, keep a dim light on it by putting several layers of red cellophane over the head of a flashlight, secured with a rubber band.
How can I get rid of bats?
If a bat accidentally enters your house through a window, door, or unused chimney:
- Open only the doors and windows that allow access to the outside and wait for the bat to follow the fresh air. Since bats usually rest during the day, you may want to wait until nightfall when the bats will leave on their own. Just make sure the room is dark enough for the bat to realize that it is night.
- If the above method does not work, try capturing the bat and releasing it outdoors. The bat can be netted or captured in a small box, can, or paper towel tube. Wear leather work gloves, place a container with breathing holes over the bat, and carefully slide a piece of cardboard under the container, leaving no space for the bat to fly away. Remember: these are fragile creatures that should be handled with care.
It is easier to dislodge newly installed bat colonies than more established ones. When a bat infestation takes place in your home, consider a combination of methods. The best time to control bats is in the spring before they return to the roost, or in the fall when they leave for the season (to make sure no young bats remain trapped inside the structure).
- Staple or duct-tape bird netting over entry points, with the bottom part hanging loosely at one to several inches from the building. This will allow the bats to crawl under and leave the roost site, while returning bats will not be able to re-enter.
- Watch your house for several evenings at dusk to make sure bats have not found another way to get in. Once bats are no longer seen leaving the building, the netting can be taken down and the holes sealed.
- Since bats tend to avoid daylight, lighting an infested area may cause them to leave. This method is believed to be most effective if done shortly after bats return from their hibernating sites.
- If you have successfully removed bats from your home, the best way to keep them out is to seal all points of entry (like spaces under eaves, electrical conduits, and holes around the chimney and windows). Vents that must be kept open can be protected with a fine screen. Larger openings can be sealed with a high quality caulk, sheet of metal, or window screen. Unlike rodents, bats will not gnaw their way through, but they will push aside loose barriers.
Bats help control mosquitoes, so they should be encouraged to roost in our neighbourhoods (just not in our homes or buildings).
- Install bat houses in trees where bats will not be a nuisance. Bat houses can be bought in hardware stores and garden centres, or easily built with rough leftover wood. Install them facing east or southeast, and be careful that tree branches do not block the door.
No pesticides are registered in Canada for the control of bats.
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