Wildlife expert Brian Keating explains Alberta's 9 species of bats
Hibernation and migration key to winter survival
Alberta wildlife lovers were excited to learn about a recent discovery of hibernating bats in Banff.
CBC's wildlife expert Brian Keating, a weekly guest on CBC's The Homestretch and Radio Active afternoon radio shows, explained the new finding last week.
He received so much feedback, Keating decided to delve even further into the topic of bats in Alberta.
"[Bats] are ecosystem maintenance personnel," said Keating. "They get rid of the problem insects that we have around, and many more pollinate various plants."
As Keating explained to Homestretch host Chris dela Torre, there are more than 1,200 species of bats in the world, with 18 in Canada, and just nine making their homes for at least part of the year in Alberta.
Survival strategy #1: Hibernate
Of nine Alberta bat species, six of them hibernate, mostly in caves, but researchers know of very few hibernation sites in the province.
Keating said big and little brown bats hibernate in large numbers in caves, which is why they are the ones Albertans sometimes encounter in the wild.
Many other bat species are solitary hibernators, and some hibernate in rock crevices in the Prairie coulees.
Brown bats' hibernacula (hibernation sites, often abandoned buildings) tend to have low humidity and considerable air movement.
If the temperature drops below –4 C they arouse from their hibernation state and seek a warmer site. This behaviour may explain many of the reports of bats seen during the winter in Alberta.
Survival strategy #2: Migrate
The three Alberta bat species that migrate are the hoary bat (the largest in Canada), the silver-haired and the Eastern red bat.
Eastern Red Bat (Lasiurus borealis)
What's known about the Eastern red bat's migration was just discovered in the past 10 years.
Researchers have found that red bats seem to migrate south and then hibernate by crawling into the leaf litter of forests. Their colouration (actually more orange) may be for camouflage in the leaf litter.
Researchers hypothesize that red bats may come out from their leaf cover to feed on warm nights, so their hibernation periods are shorter than those of species that hibernate in caves and mines.
The Eastern red bat is found as far west as Saskatchewan, as far north as Fort McMurray and south as Drumheller, as well as Calgary.
Until recently, the Eastern red bat was considered an infrequent visitor to Alberta, but it has been heard on bat detectors and captured during bat inventory projects more frequently in recent years.
During the day, Eastern red bats hang by one foot from the base of a leaf, giving the appearance of a dead leaf. This habit may provide some protection from predators like blue jays, hawks and owls.
Eastern red bats are well adapted to environments of fluctuating temperatures — their tail membranes are thickly furred and can be used as a blanket to cover themselves during hibernation.
Hoary bats' winter migration patterns are a mystery.
"Exactly where they go, we're not sure," laughed Brian Keating.
He said researchers only know that the bats migrate thousands of kilometres.
Hoary bats are found widely throughout North, South, and Central America and are one of the most widespread of mammals, said Keating.
Silver haired bats
Silver haired bats are another mystery. They have been found hibernating in the B.C. interior in abandoned mines and caves.
So although they migrate out of Alberta, they may not go as far from the province as other migrating bat species.
Migration: the good and the bad
Alberta's migratory species are not susceptible to white nose syndrome, because they don't hibernate here. But they make up more than 80 per cent of the bats killed at wind turbines in North America.
"It's a very real issue, which is very sad," said Keating.
He explained that bats don't usually get struck by the blades of the turbines, but suffer instead from massive internal hemorrhaging due to the immediate drop in air pressure behind the blades.
Researchers are working on how to deal with this issue. Solutions could include using noise deterrents around the blades.
Shutting down the turbines at night during bat migration dates has also worked to mitigate the deadly effects of wind turbines on bats.