Baffling Bats

Photo: Don Conway

The Canadian Wildlife Foundation recently donated $5,000 to Ph.D. candidate Lynne Burns, of Dalhousie University and Chair of Biology Hugh Broders of St. Mary’s University. The team is researching the fall migration patterns and health of Atlantic Canada bat populations.

Blowin’ in the Wind

En route to breeding and hibernating sites during fall migration, bats are increasingly vulnerable to wind turbine related fatalities. A 2006 research project conducted by Robert Barclay, a biology professor at the University of Calgary, studied bat carcasses found below turbines near Pincher Creek. Barclay found that 90 per cent of the bats had died from internal hemorrhaging while only 50 per cent had shown evidence of actually colliding with the wind turbine blades. This suggests that most bats had experienced barotrauma — from a sudden drop in air pressure — when they flew close to the turbine blades.

Photo: Tom Lusk

Powder Your Nose

White-nose syndrome has spread across bat hibernacula in the northeastern U.S. killing tens of thousands of bats. Bats affected by the syndrome are found with their noses, wings, ears and tails covered in this white fungus, leading to a dramatic loss of their fat reserves, which they use to survive the winter. They can also be found flying outside during the day and hibernating at the entrance of their hibernaculums — a rare sight for bats that usually hibernate deep within their hibernaculums. To date, the eastern pipistrelle, little brown, northern long-eared, small-footed and Indiana bats have been affected by the syndrome in New York, Vermont, Massachusetts and Connecticut. Canadian researchers are concerned the disease will hit home territory because the disease spreads so quickly. In two years, it’s spread in a 250 kilometre radius to various hibernaculums, wiping out between 70 to 95 per cent of the bats that reside there.

Photo: Michael Durham

On the Move

When it comes to finding a companion, bats really go the distance. In early August, male bats peruse caves and mines searching out spots to spend the winter and mate with females. On their search, bats span tens and potentially hundreds of kilometres between overwintering spots. But what happens after the love fest is a bit of a mystery to researchers. We’ve assumed they settle in for hibernation, however, bat banding recoveries show that bats still migrate well into the fall — up to 60 kilometres a night — suggesting bats may hob nob at multiple hibernation sites when the temperature dips before choosing their final resting spot for winter.

Where Broders’ and Burns’ Research Fits

With researchers stumbling upon bat carcasses strewn about the entrance of overwintering sites and under wind turbines, red flags are being raised about the health of these winged wonders. Burns’ and Broders’ team will cover 32,000 kilometres of caves and abandoned mines in N.B. and N.S. where they’ll report on the bats’ general health including their body condition, reproductive condition and will collect small hair and wing membrane tissue for genetic testing. They’ll also study the movements and activities of bats that might relate to the spread of the disease. By installing passively integrated transponder (PIT) antennae at the entrances of key hibernacula sites and capturing and tagging bats with PIT tags, the team will be able to track individual bats and record which individuals visit each site. These records will allow the team to determine the hibernacula bats actually overwinter in. They’ll also help to determine if bats really do move around from hibernaculum to hibernaculum before settling down to overwinter and how their mating activities work to shape bat populations. The results will help conservationists track down key mating and hibernation sites that need protection.