Alberta’s Happy Hibernators: Bats

This is part two of a six part series on hibernators. You can read part one here.

What do bats do in the winter? Do they hang out with Dracula and his friends or plot how to best get tangled in your hair come spring? In Alberta, of our nine bat species, six hibernate:

Eastern red bat

Eastern red bat

and three migrate south to warmer locations:

Those bat species that do migrate arrive at hibernation sites sometime during September or October. The exact time they enter and leave hibernacula depends on weather and food availability.

Where can a bat catch some zees when the snow flies?

Long-eared bats in bathouse

Long-eared bats in bathouse

Bats may roost individually or in clusters. Many bats head to the mountains and other locations where there are suitable caves. We know of five caves in Alberta that are used as hibernacula – two of which are located in National Parks. Bats often swarm in the fall around hibernacula, and males and females may mate at this time.

Bats may travel several  hundred kilometres to reach hibernacula, and like bears, bats have to put on as much fat as possible to last through winter…bug buffet anyone? Before it’s lights out for the season they will have gained up to 40 per cent of their summer weight.

Bats are deep hibernators, meaning that their body temperature drops to about ambient and can go below 5oC, but above 0oC.

Additionally,their heart rate slows down drastically. To compare, the heart rate of a little brown bat when flying can be 1,000 beats per minute but only about 100-200 beats per minute when resting. This drops to about five beats per minute during hibernation

What makes these caves a good place to hang?

In Alberta, temperature in hibernacula are usually around 0oC-0-5oC and have high humidity. These caves maintain approximately the same temperature and conditions all year long.

It is important not to disturb hibernating bats because they will arouse and use up some of their fat reserves; if they are woken up too often they will not be able to survive until spring. This is why people are not allowed in hibernacula from fall to spring. Bats are very vulnerable during hibernation and there are only a few caves that have the right conditions to support them.

Please do not disturb

Alberta is participating in a North American bat monitoring program. This program was initiated because of the declines in bat populations in eastern North America due to White-nose Syndrome.

Bats with White-nose Syndrome

Bats with White-nose Syndrome

Most people have heard about White-nose Syndrome, a devastating disease caused by a  fungus that grows in caves where bats hibernate. The fungus is in eastern North America, and may eventually be in the west. Work to stop the spread is vital to the survival of Alberta’s bat species.

We are trying to discover other hibernacula so we can monitor the bat populations and make sure they aren’t disturbed during the winter – if you know of a potential bat colony, please contact Lisa Wilkinson, Provincial Bat Specialist at

When will we see these winged wonders again?

Bats emerge in spring when the weather is warming and insects are available, this could be sometime in April or May.

Big brown bat

Big brown bat

The last week of October is recognized as Bat Week in many parts of the world. This year, on October 31, people across North America will attempt a world record for most bat houses built in a day. To find out how you can participate, visit

If you are interested in random bat facts, visit the Amazing Bat Facts page.

9 thoughts on “Alberta’s Happy Hibernators: Bats

  1. No one seems concerned about the great numbers of bats killed each year by wind turbines. This is a large contributor to the decline in bat numbers.

    • It is true that bats are killed at wind farms, either through direct collision with the blades or barotrauma (pressure changes in the air at the tips of the blade cause hemorrhaging). The majority of fatalities occur when bats are migrating south in the fall, and there is considerable variation in the number of bats killed depending on the location of the wind farm.

      The Alberta government is aware of this problem, and has been working with researchers and industry to find solutions. Several years ago, a protocol was developed to ensure that bat inventories are conducted at potential wind farm locations prior to construction. A site with high bat activity may not be developed, or certain conditions would apply if developed. There is also a protocol to monitor for bat mortalities (and birds) once wind farms are operational. If results from carcass surveys show unacceptable levels of mortality (outlined in the Bat Mitigation Framework), then wind farm operators are required to work with Environment and Parks to instigate mitigation, such as changing the cut-in speed of turbines (i.e., blades begin turning at higher wind speeds, when bats are less likely to fly).

      As the number of wind farms increase in Alberta, so does the concern about possible cumulative impacts on the bat population. We will continue to work with industry to minimize risks to bats and other wildlife.

  2. Pingback: Alberta’s Happy Hibernators: Amphibians | Alberta Environment and Parks

  3. Pingback: Alberta’s Happy Hibernators: Reptiles | Alberta Environment and Parks

  4. Pingback: Alberta’s Happy Hibernators: Mammals | Alberta Environment and Parks

  5. Pingback: Alberta’s Happy Hibernators: When Hibernators Rise and Shine! | Alberta Environment and Parks

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