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Bats are among the most adaptable animals on the planet. They not only thrive in a variety of climates, but they can also live in a variety of habitats, including rainforests and deserts.
So, what happens to bats when winter arrives? Do they all go into hibernation? Do some people migrate south? Let’s take a look at where bats go during the winter and what they do to stay warm.
Bats in Winter
How do bats know when it’s time to start packing their bags for winter?
When bats prepare for winter, they consider a variety of factors. The first is the temperature. Bats are very sensitive to temperature changes and use them to predict when winter will arrive.
Another factor is the availability of food. Bats typically eat insects, and as the insect population declines in the fall, bats realize they must find a new source of food.
Finally, bats pick up on cues from other bats. If bats in their roost start acting strangely or leave for migration, it’s a sign that winter is approaching and they should follow suit.
Bats go to great lengths to get ready for the winter. They spend the fall building up their fat reserves, which they use to get through the cold months when they can’t find food. They also spend time looking for a suitable winter roosting location.
However, different bat species have different habits when it comes to how they spend the winter.
Bats Migration
Bats migrate to warmer climates in search of food every winter. Given that bats are the only mammals capable of true flight, this is an incredible achievement. Bats can travel up to 100 miles per day during their migration.
They usually take the same routes year after year, which helps them avoid predators and dangerous weather. While flying south for the winter, bats will occasionally stop to rest in caves or trees.
These resting places are known as roosts, and they provide a safe place for bats to sleep and eat while traveling. Migration is an important part of a bat’s life cycle because it allows them to survive the harsh winter months.
The little brown bat, which breeds in Canada and winters in the southern United States, has one of the most impressive migrations. Every autumn, these bats embark on a 2,000-mile journey, reaching speeds of up to 60 miles per hour. Long-distance migrants face a variety of challenges, including inclement weather and a lack of food.
Nonetheless, bats have been making this journey for millennia and will most likely continue to do so for many more.
Bats Hibernation
While most animals curl up for a long winter nap, bats take a different approach to surviving the cold months. Many bat species, such as the brown bat, do not like to travel and migrate during the cold winter, so they prefer to stay in caves and wait for the insects to return as temperatures begin to rise again.
During the winter, bats go into hibernation (usually in mid-October), a deep sleep state characterized by the slowing of the heart rate, metabolic rate, and other bodily functions so they could conserve energy in order to survive the winter.
During this time, the energy costs of bats are reduced by 98 percent, and the heart rate drops from an average of 200-300 beats per minute to around 20 beats per minute.
Hibernating bats actually enter a state of torpor, which is generally determined by a number of factors such as body mass, ambient temperature, latitude, reproductive cycle, sociality, and fat deposits. These factors cause a wide range of responses, ranging from short-term torpor to hibernation.
To avoid confusion, hibernation refers to a longer, seasonal state of inactivity (mostly during the winter), whereas torpor alludes to the animal’s body’s short-term unconscious changes in response to cold temperatures, and lasts from a couple of minutes to a couple of hours.
When hibernating, bats can go for minutes without breathing and their body temperature can drop to near zero. Torpor allows bats to balance the need to conserve energy with the risk of freezing, because if their body temperature drops too low, they may not wake up.
However, hibernation is not as simple as it appears. As bats spend the winter months in dark caves where it is cool with little or no food available, they should accurately judge when it is time to awaken from their slumber. Failure to notice when the weather warms and food becomes abundant may result in starvation after many months of relying on stored body fat.
Hibernacula, or places where bats hibernate, have just the right temperature and humidity levels to keep the bats from freezing to death during the winter months.
Caves, various rock formations, and man-made structures provide ideal conditions for winter hibernation but keep in mind that bats can also hibernate in your home (attic) as well. It is important to check your property before winter in case of a bat infestation.
Winter Dangers
Bats may store enough fat to survive the winter and choose the ideal location with optimal conditions for their seasonal stay, but the wise tactic of hibernation does come with a risk.
White-nose syndrome, caused by the fungus Pseudogymnoascus destructans, is a fungal disease that actually can kill bats. This fungus, which is common in cold and wet environments, infects bats and grows on their noses and wings.
Throughout the winter, when they are unable to forage for food, bats slowly metabolize their stored fats until the winter ends. However, fungus irritates the bats, causing them to awaken from their hibernation more frequently. As their body functions return to normal, they require food to compensate for the fats they lost while hibernating.
Because of the double risk of not being able to find food in the middle of winter or not being able to return to hibernation, many bats die as a result. Moreover, infected bats will most likely end fatally because the infection causes them to use twice as much energy during hibernation as healthy bats, even before they wake up.
Conclusion
The next time you’re bundling up to go outside in the middle of winter, take a moment to think about the bats. Even though they might be hibernating right now, they’re still working hard to make sure our world keeps spinning.
Thanks, bats!
