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Whistler’s Bat World

By Cathy Conroy and Stéphane Perron

Whistler Naturalists

Few animals invoke as many negative reactions from people as bats.

Creepy little rodents flying through the dark of night just waiting to scare the living daylights out of you? Oh, please.

Let’s dispel a few myths about bats: They don’t get caught in your hair, they won’t suck your blood (at least not B.C.’s bats), they aren't rodents with wings, and they don't all carry rabies. In North America, one in 1,000 bats captured in the wild IS infected with rabies, about the same level as found in pigs.

But let’s discuss the bats that we have living here in Whistler. The Whistler area is probably home to Hoary Bats and Silver-Haired Bats, secretive loners of the bat world. More common, and more communal in nature, two of Whistler’s most common bat species are Little Brown Bats ( Myotis lucifigus ) and Big Brown Bats ( Eptesicus fuscus ). The Little Brown Bats can be seen all the way in to the sub-alpine in the summer.

There has been practically no work done studying bats in the Whistler area. Even generally speaking, bats are not well studied. They are notoriously difficult to study in the wild, and research interest has simply lagged behind the study of other mammals.

Whistler’s bats only eat insects – tons of them (literally) in a year. One little brown bat weighs as much as an Oreo cookie (6 grams) and can eat about 600 mosquitoes during an hour of nighttime feeding. Considering that your typical little brown bat spends four-five hours feeding each night, that’s a lot of mosquitoes, certainly better than your average patio bug zapper or mosquito coil can do. In fact, a small colony (100) of little brown bats will eat about 19 kg of insects over the summer months. Now that’s insect control!

Since bats are effective at reducing mosquito populations, bats will play a role in reducing the risk of being bitten by a West Nile virus-carrying mosquito. Bats can safely eat West Nile mosquitoes without becoming infected. There is a concern that in the fight against the West Nile Virus, more pesticides will be used to kill mosquitoes. Because accumulated pesticide residues get released when bats use their fat reserves during migration or hibernation, bats are susceptible to poisoning by pesticides.

All of B.C.'s bats have quite low metabolisms. In order to save their energy for night time feeding, they seek out warm, secure spots to roost during the day – places like attics or barns, under shingles, under tree bark or in specially made bat houses. During the day bats lower their heart and breathing rates, and depending upon the weather they will sometimes slip into a day-time torpor or hibernation-like state. When dusk arrives, they leave the security of their roosts and seek out areas close to water to forage the night away.