Thu. Dec 7th, 2023
Going crazy in Ontario parks

Today’s post comes from Natural Heritage Education Supervisor, Alistair MacKenzie, and Bat Management Technician, Heather Sanders.

Bats are the only mammal capable of true sustained flight and, with more than 1,300 species and counting, they constitute the second largest order of mammals.

Photo: Sherri & Brock Fenton

this is the order Chiropteranswhich means “hand wing” in Greek, and its wings consist of elongated hand bones joined by a membrane of skin.

Most of us are familiar with the phrase “blind as a bat.” In fact, bats are not blind and have vision comparable to that of humans, but most species are nocturnal and use echolocation, a form of biological sonar, to supplement their night vision.

Bat species are found throughout the world except in the most remote Arctic and Antarctic regions and therefore a lot of variation is seen between different species.

Most bats eat fruits or insects, but some species have also been observed eating rodents, fish, frogs, birds, smaller bats, and the blood of livestock and birds.

Ontario bats

Little brown bat (Myotis lucifugus)

*Endangered in Canada*

Size: 4-11g, average forearm size 38mm
Hangers: Small, enclosed spaces including rock crevices, hollow trees, and man-made structures such as houses, barns, and bat boxes.
Diet: Wide variety of insects, often found above water.
Winter behavior: hibernates in caves or abandoned mines
Fun Fact: It is often found in homes, so humans frequently see it.

Large brown bat (Epthetic Brown)

Size: 10-21g, average forearm size 45mm
Hangers: small cavities in hollow trees, rock crevices and buildings
Diet: wide variety of insects, especially beetles
Winter behavior: hibernates in caves, abandoned mines or buildings
Fun Fact: the second largest bat species in Ontario; It is often found in homes and is therefore frequently seen by humans.

Eastern red bat (Lasiurus borealis)

Size: 8-18g, average forearm size 40mm
Hangers: lonely in the foliage
Diet: wide variety of insects, especially moths
Winter behavior: migrates, but migratory routes are unknown
Fun Fact: high and fast flyers; It is often seen foraging for food around streetlights.

Hoary bat (Lasiurus cinereus)

Size: 18-39g, average forearm size 54mm
Hangers: lonely in the foliage
Diet: insects (especially moths), occasionally grass, small snakes and small bats
Winter behavior: migrates, probably to Mexico
Fun Fact: largest bat species in Ontario; It is often seen foraging for food around streetlights.

Tricolor bat (Perimiotis subflavus)

*Endangered in Canada*

Size: 5-7g, average forearm size 35mm
Hangers: small spaces or in foliage
Diet: wide variety of insects
Winter behavior: hibernates in caves or abandoned mines
Fun Fact: the only foliage roosting species in Ontario that roosts in groups

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Silver-haired bat (Lasionycteris noctivagans)

Size: 9-13g, average forearm size 41mm
Hangers: Cavities like hollow trees.
Diet: wide variety of insects, often on water
Winter behavior: migrates, but migratory routes are unknown
Fun Fact: sometimes perches on the exterior of buildings during fall migration

Eastern small-footed myotis (Myotis leibii)

*Endangered in Canada*

Size: 3-5g, average forearm size 32mm
Hangers: Few records exist in Ontario, but probably in small spaces, such as the area behind shutters.
Winter behavior: hibernates in caves or abandoned mines
Fun Fact: the least studied Ontario bat species; It looks very similar to the Little Brown Myotis but is smaller and has a dark facial mask.

Northern long-eared myotis (northern myotis)

*Endangered in Canada*

Size: 4-7g, average forearm size 36mm
Hangers: in small cracks, under the bark or in man-made structures
Diet: wide variety of insects, including flightless insects and spiders
Winter behavior: hibernates in caves or abandoned mines
Fun Fact: the only bat in Ontario that has been observed gleaning (catching flightless prey from tree leaves, grass or the ground)

Why are bats important?

Since bats are found almost everywhere in the world, they play an important role in many different types of ecosystems and provide many ecosystem services to humans.

pest control

Most bat species are insectivorous and consume up to their body weight in insects each night.

Many of these insects are harmful agricultural pests that wreak havoc on crops such as corn and rice. Research has shown that bats are worth billions of dollars a year in reducing crop damage and unnecessary pesticide use, meaning bats are helping our economy in addition to reducing the amount of pesticides entering to our ecosystems.

And more good news: bats eat mosquitoes too! A bat can consume up to 1,000 mosquitoes in an hour.


Many fruit- and nectar-feeding bats pollinate plants of ecological and economic importance around the world.

In fact, more than 500 species of flowers depend on bats as primary or exclusive pollinators, including bananas, peaches, cacti, and blue agave, the plant from which tequila is made!

Seed dispersal

batAs forests continue to disappear around the world, bats play a critical role in restoring natural areas by dispersing plant seeds in clearings.

Unlike birds, which avoid flying over clearings for fear of exposing themselves to predators, bats must cover long distances at night to find food. This allows them to access areas that other seed dispersers cannot reach. In fact, the seeds dropped by bats can account for up to 95% of the first new growth!

Bats also disperse seeds of many economically important plants, such as cashews, figs, avocado, and papaya.

Threats to bats

Bats reproduce very slowly: females typically only give birth to one offspring per year, and as a result, they find it extremely difficult to recover from a substantial population decline.

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Several major threats are causing significant losses to bat populations around the world.

Loss of habitat

Forests everywhere are disappearing at an alarming rate, usually as a result of logging, urbanization, or clear-cutting for agriculture.

View of the forest looking up from the forest floor.

Many species of bats use forests to rest or search for food. As these forests disappear, so do the resting places and food supplies of these species. Other species roost in caves and are chased away by cavers, miners or even tourists looking to take a photo.

It is vital that bats are not disturbed when they sleep; Be sure to stay away from caves and plan building maintenance work during times when bats are absent in the fall, winter and spring, whenever possible.

white nose syndrome

White nose syndrome (WNS), caused by a fungus called Pseudogymnoascus destructansIt was first discovered in North America in late 2006. In infected hibernaculas (caves where bats hibernate), the mortality rate can be as high as 80%-100%.

In total, the WNS is estimated to have killed approximately 10 million bats since 2006.

The fungus was found in caves in Ontario in 2009 and continues to spread westward. All four of Ontario’s endangered bat species hibernate in caves and have been affected by the disease. Learn more about white nose syndrome.

Pesticide use

Pesticides have been shown to have negative effects on many insectivorous animals and bats are no exception. Pesticides are sprayed on plants or insects and then consumed by bats and stored in their fat deposits until winter.

During hibernation or migration, bats must use stored fat reserves. However, at that time, large quantities of pesticides may have accumulated in their warehouses, causing pesticide poisoning.

In winter, this can mean excessive burning of fat reserves and immunosuppression, making poisoned bats more susceptible to infection caused by the fungus responsible for white-nose syndrome.

Even if a bat is able to survive the symptoms of winter poisoning, it often suffers reproductive problems, such as stillbirths in the spring.

Learn more about threats to bats:

You can help the bats!

To ensure that Ontario’s bat species exist for future generations to enjoy, there are a few simple things you can do:

  • Build a bat box: Bat boxes are easily built (or purchased) and provide bats with critical resting places. Not only is this beneficial for the local bats, but you will also be able to sit back and watch these incredible acrobats as they hunt for insects high in your backyard.
  • Give hibernating bats some peace and quiet: Entering caves or abandoned mines can disturb bats and reduce their ability to survive the winter.
  • Report any strange behavior: If you see bats flying during the day during winter or see dead bats, call the Canadian Cooperative Wildlife Health Centre, Natural Heritage Information Center or your local MNRF office.