Bats in Canada are in big trouble and they need our help. A disease called white nose syndrome (WNS) is wiping out entire colonies of Little Brown Bats and spreading fast.
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White Nose Syndrome
So far white-nose syndrome (WNS) is only found in the eastern half of North America. Bat species that live in the western half have never been exposed to WNS and it is unknown how they would be affected by it. Even in the east, not all bat species are affected by WNS. Some species never enter caves and so are never exposed to the fungus that causes WNS. Some bat species that do enter caves seem to suffer less mortality than others, possibly due to differing physiologies.
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Bats make up nearly a quarter of known mammal species and are second only to rodents in terms of diversity. Bat species unknown to science are still being discovered: 30 new species were identified just last year (2013), bringing the total to 1,293. Most of this diversity in bats is found in the tropics. Bats have a wide distribution and can be found on every continent except Antarctica. Most bats eat insects, but there are also species that eat fruit, nectar, fish, and other vertebrates. Three species of bat drink blood, none of which are found in Canada. The Philippine flying fox (Pteropus vampyrus) is one of the biggest bats and can weigh 1 kg (2 pounds) or more, and has a wingspan of more than 2 meters (6 feet). The smallest bat is the Bumblebee Bat (Craseonycteris thonglongyai) which weighs around 2 grams with a wingspan of ~170mm (6.7 inches). Bats evolved 65-54.8 million years ago and are more closely related to people than rodents.
North America has 48 bat species, with 18 found in Canada. All bats found in Canada are fairly small and eat insects. British Columbia has the greatest diversity of bats (16 species) among the provinces; 8 of those species do not occur anywhere else in Canada. The biggest bat in Canada is the Hoary Bat (Lasiurus cinereus) which weighs 26 grams with a 40 cm wingspan. The smallest bat in Canada is the Tricolored Bat (Perimyotis subflavus) which weighs 4-10 grams with a wingspan of 21-26 cm.
Bats consume a variety of insects, some of which are important agricultural and forestry pests. In other areas of the world bats are also important for seed dispersal and pollination. In the US alone, it is estimated that bats provide insect control services worth $3.7-53 billion per year.
Threats to bats
So far white-nose syndrome (WNS) is only found in the eastern half of North America. Bat species that live in the western half have never been exposed to WNS and it is unknown how they would be affected by it. Even in the east, not all bat species are affected by WNS. Some species never enter caves and so are never exposed to the fungus that causes WNS. Some bat species that do enter caves seem to suffer less mortality than others, possibly due to differing physiologies. Unfortunately it is the most common bat species in Canada that are suffering the most. So far scientists have found 9 bat species with the fungus, but only 6 of these species develop symptoms associated with WNS. The 6 include the Little Brown Bat, Northern Long-eared Bat, Tricolored Bat, Small-footed Bat, Indiana Bat, and Big Brown Bat, with the first 3 species suffering the greatest mortality. For instance, Little Brown Bats often decline by 90-100% in WNS positive hibernacula, while Big Brown Bat declines are more often in the 30-60% range. Bat species in Western Europe that are exposed to the fungus do not appear to decline at all! The reason(s) for the differences are not known but studies are ongoing. Understanding why some bat species are resistant to WNS may offer insight for a future cure.
Wind turbines are estimated to kill 600,000-900,000 bats per year. Bats that are affected by wind turbines are generally migratory species that do not get WNS.
Another threat to bats is habitat loss. During the summer, bats like to roost in large trees, but human activities over the past 100 years have made large trees scarce. Bats adapted to this situation by roosting in barns and people’s attics. However, modern building methods often exclude bats and barns are being torn down, reducing suitable roosts for bats. Bats require roosts that have the right microclimate and are safe from predators and other disturbances.
What you can do?
It is important never to disturb bats, particularly during the winter when they are hibernating. If you find yourself in the presence of a bat, be sure to remain as quiet as possible to minimize disturbance. Avoid bat roosts as much as possible. Do not visit caves or mines during the winter when bats are present. If you do visit a cave, make sure to follow decontamination procedures so as not to spread fungi and other micro-organisms. How to decontaminate »
You can also support forest and wetland conservation as habitat for bats and limit your use of pesticides. You can plant flowers and shrubs in your backyard that encourage moths, an important food source for bats. Download »
You can also encourage the conservation of winter habitat for bats. Caves and mines can be protected from human disturbance by gating. This is particularly true for mines, which are often filled in once they are no longer used by humans.
Lots of people across the world are working hard to help the bats! Here are some other researchers who are studying bats if you would like to find out more:
- Craig Willis, Manitoba
- Hugh Broders, Nova Scotia
- Robert Barclay, Alberta
- Cori Lausen, British Columbia
- Mark Brigham, Saskatchewan
- Brock Fenton, Ontario
- Canadian Co-operative Wildlife Health Center
BlogRead more about bats on CWF’s blog, written by bat researcher Karen Vanderwolf.