Bert Miller Nature Club

October 18, 2009

Our speaker on Oct.18, 2009 at the BMNC was Erin Fraser, PhD. candidate at Western Ontario University. She is a student of Dr. Brock Fenton's lab noted bat scientist. She has worked extensively with Ontario bats. Erin gave a clear presentation and answered many questions after her enlightening talk. Here is some of her presentation. Initially she asked questions of us and our experiences with bats. She said, "Raise your hand if you have bats living in your house?" Only a few did ."raise your hand if you have bats living in a garage, barn or cottage?" Many hands went up. Several of us she discovered had seen bats in flight around built up areas and in rural settings. Erin stated that very few of us really know much about our Ontario bats. "Bats are one of the mystery dwellers of our natural world," she proclaimed. They are extremely common but we seldom get to observe them. For the next half hour Erin showed us close-up shots of the eight bat species found in Ontario.

First shown was the Big Brown bat one of our most common species. She told us about bats and their young and how they winter over. She ended with a graphic display of world-wide threats to the bat population. Bats are mammals. She asked how many mammal species in the world. A few good guesses. Erin said that there are approximately 4,000 mammal species in the world. What proportion are bats? More wide range answers. She said - more than 1100 bat species in the world. Amazing! Incredibly diverse and fascinating they are found on every continent except Antarctica.

There are eight species of Ontario bats and she claimed all eight could be found in the Stevensville area! All of our bats are insectivores, which means that they only eat insects. No fear of blood seeking vampire bats in Ontario! Erin pointed out the diet of bats ranged from moths, beetles to tiny little midges, even some spiders but surprisingly few mosquitoes! Erin pointed out this common misconception about bats. They eat few mosquitoes. Some of our bats specialize. She cited our Big brown bat that eats mainly beetles for its diet.

Bats echo locate. As the bat is flying and pumps its wings it is producing an incredibly high pitched chirping, It is so high-pitched that no human can detect it. These sound waves will travel hitting a tree or an insect in complete darkness. It collects the sound data and determines the object. Most of our bats use "aerial hawking" locating insects and eating hem by echo location. Amazing! Many use the membrane between heir legs and on their wings to scoop up an insect to chew it up and devour it. Erin showed us a photo of a Hoary bat she studied at Pinery Provincial park while doing her Master's degree. "This is the biggest bat in Ontario." She described how this fast moving bat hit a large moth and disembowelled it. She showed a photo of the dead moth on the ground with the moth's wings and thorax still intact. Only its juicy abdomen had been taken. A perfect example of "aerial hawking."

The small Northern long eared bat does it differently. Similar to our Short brown bat it has larger ears. It uses the process of "gleaning" for its food. They listen as they fly. They hear the sounds of crickets and katydids and fly up to where they are perched and snatch them. No echo location or aerial hawking for them. It actually grabs them with its mouth. Go to a bat roost and collect on the floor insect parts. From the/ uneaten parts scientists can determine quite accurately a bat's diet.

Amazingly we were told that a female bat producing milk for its pups can eat one and a half its weight in insects every day. How much do bats eat in a day' Erin's answer was "A lot." She proved this point. The average bat will eat its own weight in insects each night. Bats are not flying mice! Mice have several litters in a year and only live a few years. Bats give birth once a year to usually to one or two pups and they can live to thirty-five to forty years! They can reproduce for many of those years. Again amazing. Erin's favourite bat the Red bat is the exception. This species may give birth to three pups and occasionally as many as five. She showed examples. These pups grow fast and can ingest milk equaling their own body weight each day. They showed a pup's growth progression as in a few weeks - incredibly fast.

Surviving Ontario's winter - Erin said there are two strategies. Some bats stay but don't eat the whole winter. Some bats leave and fly thousands of kilometres to a warmer climate. She described the two means of survival with personal references. Ice caves and rugged northern settings were part of her studies.

Bats are in danger today. This time of year they are at their highest risk. This risk is brand new. Not really habitat loss or global warming but in the last five years there are two very specific threats to bats. Both of them happen in the fall and winter periods.

has caused the death of thousands of bats" Why? Erin believed that these migrating bats that died at these wind turbines not by blunt force but seemingly by extreme trauma to their lungs. As these giant blades are rotating through the air they create a low air pressure. It is so extreme that the bats' lungs rupture. Sad. However, some wind farms experience no bat kills. More research needed. Some say turning the wind turbines off at certain times seems to reduce bat mortality.

Five of our eight bat species hibernate in unused mines and caves in Ontario. Bats stock up body fat for the winter months.

It's a very fragile time. She cautioned not to interrupt bat hibernation. By disturbing them they use up vital bodily stored fat and may die. She showed a slide of hibernating bats. Each bat had a white ring around its nose.

Catastrophic for North American bats known as "White Nose" syndrome. No one knows its cause so far. It is a fungus that eventually kills hibernating bats. Recent surveys are showing more and more bats are afflicted by "White Nose." The fungus is a common one. Erin said that it is also possible that tee afflicted bats have some immune compromise. Bat hibernation sites with "White Nose" after two years 90 % of the bats had died. This an incredibly alarming phenomena! A graphic slide showed the death site of hundreds of bats on a cave floor/ Erin Fraser has travelled with Dr Fenton and cohorts examining carefully hibernating sites in Ontario. Has "White Nose" come to Ontario. So far none.

Erin answered many of the club members questions. It was a great presentation by a very knowledgeable scientist. Thank you Erin Fraser.