We usually think of bats as being most active at night, in the warm summer months. Why do we sometimes see bats at other times?
Bats flying in winter
In winter, bats go into a hibernation-like state called torpor. Their body temperature lowers and their metabolic rate slows, meaning they use less energy and can survive on the fat they have stored up while their insect food source is unavailable. During hibernation, bats need roosts that are cool and remain at a constant temperature. They sometimes move into underground sites, such as caves.
Being aroused from hibernation can cost bats a lot of energy, and the loss of body fat can lead to starvation. Bats wake naturally at times during hibernation usually to feed opportunistically, when temperatures are warm enough for insects to be flying, or to move to another roosting site.
If you have seen a bat flying in winter, it may have been awake naturally due to milder weather, disturbed by human activity, or not have been in very good condition at the start of hibernation: if a bat runs out of hibernation fat reserves it will wake up to feed regardless of temperature.
Bats flying in daylight
It is unusual to see bats in the middle of the day, as they are more at risk of predation during daylight hours. However, if a bat is hungry (for example, a female bat with a baby to feed), thirsty (in a hot summer) or has been disturbed by human activity, it may take greater risks to feed.
If you find a bat hanging from a wall in an exposed place, the ground, it could be injured or exhausted through lack of food and should not be returned directly to the wild. Instead, please follow the advice in our ‘Help I’ve found a bat’ section.