September 1, 2013 - A popular trivia game asks, “What is the most abundant mammal in Algonquin Provincial Park?” Most people who ponder the question will respond with answers such as deer, moose, bear, rabbits, beaver or raccoons. Some may delve into the realm of smaller mammals and respond with chipmunks, squirrels, mice, shrews, moles or voles. Very seldom is the correct answer given – bats. Yes, bats!
About 1,000 species of bats exist in the world. Some of these species use their eyes and keen sense of smell to locate and eat ripe fruit, others to find flowers in order to drink nectar. Some bats eat fish, lizards and small birds but most eat insects. The Vampire Bat can be found only in Central and South America and it feeds solely on blood.
Bats vary in size from the gigantic Flying Fox Bat in Southeast Asian countries such as Malaysia, Philippines and Borneo that weighs over one kilogram and has a wingspan of about two metres, to the tiny Bumblebee Bat, which can be found in western Thailand, and southeast Burma, which weighs only two grams and is about 30mm long.
What is a mammal?
A mammal is a creature that drinks its mother’s milk in the early stages of its life. Only mammal mothers can supply milk. Normally we think of mammals as four-legged land animals, but mammals include humans (who walk on two legs), whales (that swim in the oceans), and bats (that fly in the air). Bats are the only true flying mammal and they share the air with birds and flying insects. The mammal known as the flying squirrel doesn’t actually fly; it leaps off trees and glides on stretched out folds of skin connected to its legs.
Where is Algonquin Park?
Algonquin Park measures 7,653 square kilometres and is located in the province of Ontario between the deciduous forests in the south and coniferous forests in the north. The park contains over 2,400 lakes with 200 kilometres of flowing water and has approximately 50 species of mammals. There are four predominant bat species in Algonquin Park:
- Little Brown Bat is Myotis lucifugus
- Keen's Bat (Myotis keenii)
- Silver-haired Bat (Lasionycteris noctivagans)
- Hoary Bat (Lasiurus cinereus)
The Little Brown Bat is the most common bat in Algonquin Park and it often roosts in the nooks and crannies of park buildings. The other three species have been recorded only once but this does not mean they are rare because most bats roost where they are not often discovered.
The silver-haired bat and hoary bat migrate south from Canada each fall. The other two probably leave Algonquin Park as well but hibernate in mines and caves in Ontario where the humidity is high and the temperature stays above freezing.
The Little Brown Bat has an average weight of 9.5 grams and a wingspan of about 250 mm (10 inches). My daughter found a Little Brown Bat that washed up on the shore of our lake (pictured below).
Where do bats roost?
During the day, most bats roost under loose bark, in tree cavities, or under rocks and woodpiles, and they are very difficult to detect. They also roost in nooks and crannies of buildings, under eaves and in attics. They can squeeze through very tiny openings as narrow as six millimetres. Such roosts have very little or no light, and provide good shelter.
Bat roosts often have southwestern exposures so when the sun is setting the heat helps to wake the bats from their daily sleep, which averages about 20 hours per day. Bats rest in night roosts after feeding for a few hours in the evening. The night roosts are in the same location as their day roosts, but in different spots (which keeps their feces away from the day sites and therefore their presence is less known to predators). The bats cluster together to keep warm during the night, especially when temperatures fall below 15°C. They awake at dawn, fly out to catch insects for breakfast and then return to their day roosts.
Hinterland Who’s Who provides a good description of a third kind of roost – the hibernation roost. “Some Canadian bats migrate long distances south in the fall and north in the spring, just like birds. However, this is not the case for the Little Brown Bat, which does not migrate…" "Individuals can move up to 1,000 km from summer roosts to winter roosts where they hibernate. These winter roosts are called hibernacula. Between August and early October, individuals from many different summering locations swarm together in large groups during the night in mines and caves in order to mate…" "Hibernacula are chosen for their high humidity and stable, above-freezing temperatures.”
The Little Brown Bat slows down its metabolism, heart rate, and breathing, but still wakes periodically to drink or eliminate waste. Because food is not available during the winter, it relies on its fat reserves to survive. However, during warming periods in winter (which occur more often now because of the changes in our weather) they may awaken to feed on insects that hatch under those conditions.
What is Echolocation?
My home is located in a forest beside a lake near Algonquin Park where I occasionally go bass fishing at dusk. Three things happen as the sun sets: the bass start biting, mosquitoes (looking for a meal of blood) and moths appear, and bats start to fly. Often, when I twitch the end of my fishing rod, a bat will come swooping in towards it – and veer away at the last moment. The bats are hunting for flying insects and there are lots of mosquitoes in the air for dinner. Bats hunt at night, and most locate flying insects by echolocation. They emit high-pitched shrieks at regular intervals and listen for the echoes that bounce off an insect’s body. Sometimes the narrow tip of my fishing rod temporarily confuses them since it is up in the air and will bounce the sound back to the bat’s sensitive ears.
The Reader’s Digest book “Exploring the Secrets of Nature” (1994) explains the process of echolocation very well. “A bat’s echolocation shrieks are too high for a human ear to hear, but they need to be. Sound travels in waves; the length of a wave is determined by the pitch of the sound. The higher the sound, the shorter its wavelength, and therefore the smaller the objects it bounces off. The highest bat sounds can reach a frequency of 200,000 hertz (waves per second) and can pick up something the size of a midge (pictured left) from 18 metres (20 yards) away. The echoes not only reveal the presence of an object, they also tell the bat its position. Because sound always travels at the same speed in the air, the bat can judge distance by the length of time an echo takes to return, and the relative intensity of the sound in each ear tells it the direction.”
Contrary to popular belief, bats are not blind – and they don't get tangled in people's hair.
A wonderful description of how an insect is caught is captured in The Ontario Ministry of Natural Resources booklet “Mammals of Algonquin Provincial Park” (1983) where it states, “These are not captured with the mouth, but are scooped up in the pouch formed by a continuation of the wing membrane, from the hind feet to the tail. After capture, the prey is transferred to the mouth and eaten while the bat is still airborne.”
"If an insect is too large to swallow, they will land on their feet to eat it. Typically, they consume 30-50% of their body weight in insects each day. The Couples Resort Area Guide states, “Little Brown Bats are very beneficial to man since in a single minute they can eat seven or eight insects, including water insects that they skim off the water of ponds. If they happen to crash into the water, they can swim. This bat can fill its stomach in 15 minutes and empty its digestive system several times in a night between feedings.” Scientists estimate that the bat eats a gram of insects per hour – and even more in the spring and fall when there are more hours of darkness.
Contrary to popular belief, bats are not blind – and they don’t get tangled in people’s hair. These myths likely originated from the fact that bats often fly very close to humans, swerving and darting about. This seemingly erratic behaviour is not because of blindness, and won’t result in hair snarls. Insects are attracted to humans and bats are attracted to insects. If a bat can tell the difference between the tip of a fishing rod and an insect, it has no problem avoiding a big head of hair!
Predators of the Little Brown Bat include owls (which hunt them at night), hawks (which capture them before total darkness falls), snakes and raccoons (which may prey upon them while they roost), mink, martens, and fishers (which take advantage of weak young that fall, or hibernating individuals that are dislodged while grooming). Because bats often roost near human habitations, house cats are also a deadly predator. Humans, of course, have to be included in the list of their enemies. Many people have a fear of bats because they have a bad reputation. They are often described as looking like a mouse with wings, but with a fiercer face because of their large ears and mouth full of sharp teeth. Bats that establish a roost in the attic of a house or accidentally fly into a house through an open window may come into conflict with humans and they often suffer.
The Ministry of Natural Resources references a section called “Living with Bats" wherein they state, “People and wild animals live side by side in Ontario. We all share responsibility for preventing and handling human-wildlife conflicts. If you must take action against wildlife, please consider all your options and follow all relevant laws and regulations.” Here are some helpful directives.
How Can I Prevent a Conflict?
Bat-proof your home by:
- Assessing sites where bats may get into your home, including chimneys, joints, at building corners, where pipes penetrate ceilings or walls in attics, between porches/additions and the main structure, between shingles or where walls meet eaves. From October to March, when bats are hibernating elsewhere, or after you are sure no bats are roosting in the attic, seal all potential entry holes.
If a bat is roosting in your home:
- If you find a bat in your home and there was no human or animal contact, try to confine the bat to one room, turn out the lights and open a window. The bat should fly out early in the evening.
- Encourage bats to leave by shining bright lights, pointing a fan or playing loud music in their roost site.
- Begin the harassment process shortly before dark and keep it in place day and night.
- Use ultrasonic devices, which emit sounds that bats don't like but are inaudible to humans. These devices, which are available online, are placed in an area with the roosting bats.
- Call a local wildlife control agent for assistance with bat problems.
How Can I Handle a Conflict?
If you have direct contact with a bat:
ü Always wear gloves and other protective clothing when bats are present.
ü Warn children to stay away from bats and to report any contact with them.
ü Although the percentage of rabid bats is very low in Ontario, any bat encountered should be considered rabid unless captured and proven otherwise.
ü If anyone has had direct contact with a bat, the bat should be safely captured and not released.
ü Contact your local public health unit or your doctor for assistance in evaluating potential rabies risk and submitting the bat for testing.
ü Report any unusual bat deaths to the Canadian Cooperative Wildlife Health Centre at or the Natural Resources Information Centre at .
Lethal action is ONLY a Last Resort
- Trapping a bat inside a structure is needlessly cruel and can create a serious odour problem.
- A landowner may humanely kill or trap bats that are damaging or about to damage his/her property. Firearm regulations and bylaws must be followed.
- You can hire an agent to act on your behalf.
Many years ago, a bat flew into my sister’s kitchen. After many failed attempts to shoo it out of an open window, the bat tucked itself into one of the corners near the ceiling. With the intention of catching it and releasing it, my brother climbed on a chair and slowly reached his hands up to surround the bat and then closed his hands around it. The bat bit him but he held on to it and then tossed it out of the open window. Ouch!
Being very concerned about rabies my sister brought him to the hospital. Like all mammals, bats are susceptible to rabies (a viral disease that causes progressive paralysis and death). Found in saliva the virus is transmitted by the bite of an infected animal and although the incidence of rabies in bats in Canada is low, it may still occur.
The doctor stated that the administration of one dose of human rabiesimmunoglobulin(HRIG) and four doses of rabies vaccine over a 14-day period are required to treat rabies. Knowing that the bat was not available for testing because it was released and taking all the facts into consideration the doctor concluded that the bat was probably just acting in self-defence because it was scared after being caught, and that its actions were not the result of abnormal behaviour brought on by the disease. My siblings decided not to have my brother undergo the treatment, and fortunately it was the right call. However good his intentions were, he should have heeded some of the advice given above: wear gloves before making contact – and if bitten, do not release the bat (keep it for testing by the Public Health Unit).
You Can Build a Bat House
We can assist bats by providing them with appropriate roosts and building bat houses for them. There are many plans for such projects on the internet. Here are a few:
National Parks – Free Bat House Plans
WikiHow – Build a Bat Box
Canadian Woodworking & Home Improvement – Build a Bat House
Canadian Wildlife Federation – Putting Up a Bat House
Be aware of criteria for locating a bat house
People without provocation kill bats, and other human endeavours have hurt bat populations. Scientists estimate that by 2020 wind turbines will kill 33,000 - 111,000 migratory tree-dwelling bat species annually in the Mid-Atlantic Highlands alone. But no human threat to bats has been as destructive as the new disease called White Nose Syndrome, the result of a fungus called Geomyces destructans, which has already killed 5.7 to 6.7 million bats in North America.
Izaak Walton League of America, one of the oldest and most respected conservation organizations published an article called “Battling for Survival” that describes how the first bats with the disease were discovered in a cave near Albany, New York in February 2006. It goes on to explain: “For most mammals, a fungal infection isn’t life threatening. That’s because our warm body temperatures keep fungal growth in check. The cold, humid caves or mineshafts where bats hibernate turn out to be the ideal conditions for the G. destructans fungus to grow, however. Scientists also believe that a side effect of bat hibernation might be suppression of a bat’s immune system responses, which could also help the fungus grow aggressively on hibernating bats.”
The following excerpt was taken from a story called, "Little Brown Bats Facing Extinction," published in 'The Record' a newspaper in Waterloo, Ontario last July 2011.
“This syndrome came out of nowhere,” said Ian Barker, director of the Guelph-based Canadian Cooperative Wildlife Health Centre, who is working with the Ministry of Natural Resources to monitor the situation. “What we’re seeing is an epidemic disease that is extremely, extremely high mortality. It is very rare that you see a disease with 90 to 95% mortality, and that’s exactly what we’re seeing here.” Since it was first found in Canada near Bancroft in March 2010, it has spread as far as Nova Scotia and parts of Quebec and as far south as Oklahoma. “It’s going to spread across the continent, as far as these bats are found,” said Barker. “One thing can be sure, and it’s that we can’t control it. We are fundamentally looking at nature playing itself out now.” To date, millions of bats have died from the syndrome. One site in New York that had the largest Little Brown Bat population in the world saw the population fall from 200,000 to 3,000 in just two years.”
"One site in New York that had the largest Little Brown Bat population in the world saw the population fall from 200,000 to 3,000 in just two years.”
Ian Barker, Director of the
Cooperative Wildlife Health
Even if there are groups of bats that avoid the deadly fungus, it will be difficult for the population to regenerate itself. Bats have a long lifespan and they reproduce slowly. Females only give birth to one youngster (although twins are possible) each year. The young bat is fed its mother’s rich milk, and in the first few days of its life it clings to its mother’s chest while mama flies in her hunt for insects. Later, babies are left in the roost while hunting occurs, and mothers are able to return to them to let them suckle for milk. By the age of 18 days, the youngsters have grown sufficiently to fly and they will begin to eat insects, as well as their mother’s milk.
Both Canada and the United States are taking steps to try to save the bat population. The U.S. Fisheries and Wildlife Service is considering taking healthy bats into captivity while the fungus rages through the wild populations, with the idea of releasing them in the future when the situation improves. Some ecologists, suspecting that the fungus interrupts the sleep of hibernating bats, are looking at another approach.
Justin Boyle, a graduate student in biology at Indiana State University, and Craig Willis of the University of Winnipeg tested the idea, suspected by many in the bat research community, that the fungus causes bats to spend more time out of hibernation during the winter. Mammals must rouse from hibernation periodically, but doing so too often or for long periods of time is energetically costly. When they rouse, the bats must use body energy to keep warm; spending too much time out of hibernation may deplete their fat reserves and cause them to starve to death.
Science Daily (March 2009)
The researchers reasoned that one way to help affected bats save their energy reserves and survive the winter is to provide them with a heat source, so they don't have to create as much body heat when they rouse. Bats often fly to the warmest parts of their cave during bouts of arousal. "They already do this in the wild," Boyles says. "What we're suggesting is accentuating that behaviour." When their simulation was altered to include localized heat sources the bats could gather around during arousals, the model showed that mortality levels dropped to as little as 8% but this may only be a stop gap measure. Saving afflicted animals may not be sustainable in the long term. “If WNS is transmitted in spring and summer by surviving bats, saving its carriers will also save the disease.” At present, the search for a remedy for this mysterious fungus continues to stymie scientists.
The Value of Bats to the Agricultural Industry
Hallowe’en uses images of ghosts, goblins, witches, and bats to present a scary scenario, but bats aren’t in the same classification as those other ghouls. Horror movies give us images of vampires and vampire bats sucking our blood. But our bats are different. People in the conservation community know that bats play a critical role in ecosystems across the continent. Bats eat bugs – from mosquitoes that bite us to moths and beetles that damage crops. Bat predation on crop-eating insects saves crops, saves money and prevents excessive use of pesticides. Other kinds of bats are important pollinators. In the American southwest, bats pollinate the Saguaro cactus. In tropical forests, they pollinate fruit-bearing trees like banana and mango.
Researchers estimate the value of bats to the agricultural industry is roughly $22.9 billion a year, with the extremes ranging as low as $3.7 to a high of $53 billion a year. "These estimates include the reduced costs of pesticide applications that are not needed to suppress the insects consumed by bats. However, they do not include the downstream impacts of pesticides on humans, domestic and wild animals and our environment," said Gary McCracken, head of the Department of Ecology and Evolutionary Biology at the University of Tennessee, Knoxville. "Without bats, crop yields are affected. Pesticide applications go up. Even if our estimates were quartered, they clearly show how bats have enormous potential to influence the economics of agriculture and forestry." According to the researchers, a single colony of 150 big brown bats in Indiana eats nearly 1.3 million insects a year -- insects that could potentially be damaging to crops. (Excerpt from Science Daily - April 2011)
After rodents, bats are the second largest group of mammals in Canada, or the world. The fact that few people ever see them should make you realize how little harm they do to us. Some scientists believe that the number of bats in Ontario equals the number of birds in the province! If there were no bats, how many insects would there be? That’s a frightening thought!
References and Resources
Ontario Ministry of Natural Resources - Mammals of Algonquin Park (1983) by Dan Strickland & Russell J. Rutter
Reader's Digest - Exploring the Secrets of Nature - Using Echolocation to Capture Prey (Pages 214-215)
The Couples Resort Area Guide- Little Brown Bat - Ontario, Canada
Biokids: Kids’ Inquiry of Diverse Species - Little Brown Bat
Hinterland's Who's Who - Little Brown Bat
Wikipedia - Little Brown Bat
Ontario Ministry of Natural Resources - Living With Bats
The Izaak Walton League of America - Battling for Survival
The Waterloo Record Newspaper - Little Brown Bats Facing Extinction
Science Daily - Economic Importance of Bats in the Billions a Year Range
Science Daily - White-Nose Syndrome Death in Bats: First Prevention Proposed by Ecologists
Canadian Wildlife Federation - Bats and Echolocation
Wild Birds Unlimited - Fun Facts about Bats
Canadian Wildlife Federation - Hinterland Who’s Who Launches Little Brown Bat!
National Geographic - Vampire Bats