Ontario Bats

Going 'Batty'?

Bat on tree

Bats have made their contribution to our vocabulary. You dingbat, the old bat, he's gone a little batty, going like a bat out of hell and bats in the belfry.

Mention the word bat and people immediately think of Vampires, Dracula and Ghosts. It always amazes me how such small animals, (little brown bats weigh about 8 grams), can evoke such horror in people. I was once called to a home where a man in his 40s had run right through the back screen door (without opening it) trying to get away from a bat in the house.

Bats are the only true flying mammals (flying squirrels only glide). There are 8 species in Ontario of which only 2, the little brown bat and the big brown bat commonly occur in homes. Both hibernate in Ontario in places such as caves and old mines. Big brown bats will also hibernate in their summer roosting areas such as homes or other buildings. Little browns will migrate considerable distances to their hibernation sites. Bats are nocturnal leaving their roosting sites at dusk and returning at dawn. They feed on live insects catching them while flying and can consume large numbers in a night. Bats have poor vision and rely on echolocation (similar to sonar) to catch their prey and avoid flying into objects. They can make a high pitched chirping or squeaking sound when annoyed. In homes they prefer attics for their roosting and nursery sites. In hot summer weather, they are often found out in the soffit area, behind shutters, under porch overhangs etc. Droppings can often be found under roof peaks or outside lights where the bats sit during the night. Bat droppings can be distinguished from mouse droppings by using a hand lens and sharp probe. Bat droppings break apart easily and are composed entirely of undigested insect fragments.

There are several health concerns with bats. A very small percentage are found to be infected with rabies, most of these being big brown bats. Their guano can cause a persistent and strong odour and old droppings have the potential to harbor histoplasmosis.

Elimination of bats may cause some of their ectoparasites such as mites and bat bugs to migrate down into the house. All of the above incidents are rare but care should be taken if bats are handled or their guano removed. Always wear leather gloves or use a net or tongs if you must handle a bat and wear an appropriate mask (should have a hepafilter) if removing their droppings.

Bat proofing is the best and most permanent way of eliminating a bat colony from a structure. This involves sealing all openings that will allow them to enter. This should be done in early spring before the young are born or later in the summer after the young are able to fly. Sealing should not be done between May and August. Permanent sealing can be done either after the bats have left at dusk or after a temporary method of exclusion has been installed. To locate all entry points, sit outside at dusk and watch for the bats to emerge. All sides of the house should be checked. In the daytime check the house for any other openings, little brown bats need only 1cm (½ inch) to gain entrance. For individual bats that get into the house, opening windows and doors and turning lights off or catching them with a net or towel usually will work.

Ontario bats do not attack people or try to get into your hair. Because they hang upside down to roost, they will drop in order to spread their wings and take flight. If you are standing underneath or nearby when this happens, it appears as if the bat is flying at you. In fact, they probably want to get away from you as much as you do from them. If you have bats and are not bothered by them then leaving them is a great method of natural control as they can consume up to 50% of their body weight in insects in a night.