The autumn has began, and with it the period of migration of bats, which move from summer feeding and breeding areas to wintering locations. From September to November they are easier to find, because during this period they hunt insects more actively than in summer. They do so to accumulate fat reserves for the winter in order to survive cold weather when in hibernation. Body fat of bats at the beginning of their hibernation usually amounts to about 20-30% of body weight. Also during this period we can meet more often individual bats or their groups in various “unexpected places” in our houses and in their vicinity, e.g. in staircases, attics, in boxes with energy meters, in ventilator dampers, behind shutters, etc. Bats treat these places as so-called temporary quarters.
What to do when this unusual guest appears?
First of all, do not panic – bats do not attack people, drink blood, or get caught in hair. The only situation where an animal can bite us is when we hold it with bare hands.
In order for a bat to fly freely, close the doors to other rooms so that it does not fly deep into the apartment, turn off or at least reduce the intensity of the light, open the window wide and move the curtains away.
If you notice a sleeping bat, put it very gently in a box (cardboard box, cheese packaging, coffee cans, etc.), be careful not to touch it with your bare hand (preferably put on thick leather gloves), then release it after sunset .
If bats decide to stay in your attic, basement or other part of the building – let them bring up their young or winter.
If a bat is injured or cannot fly, contact a veterinarian as soon as possible.
If you find a dead animal, pack it in a sealed container and take it to a veterinarian or organization that is engaged in animal health examination and protection as soon as possible.
Winter is a very difficult time for bats because they cannot get food at this time. Thus, bats find caves and cave-like objects (fortifications, basements, dugouts, dug wells, adits, remains of underground mines) and enter hibernation to survive from late autumn to late spring without food.
During hibernation, the body temperature of bats is reduced by more than 30 °C, so it is often just 1-2 degrees above the ambient temperature. Due to this, their respiratory rate, heartbeat is also slowed down, and thus the use of energy stored in the autumn in fat tissue is reduced. During hibernation, bats lose about 0.2% of body weight per day, which in a few months makes up 30-40% of body weight.
The bats do not sleep without interruptions. These animals wake up several to a dozen times during the winter to drink, excrete metabolic products, or move to another place in the hideout (e.g. in the event of temperature change). During sleep, the animal is completely defenseless, which is exploited by predators (e.g. foxes), which penetrate wintering places and eat lower hanging mammals before they can wake up.
People also pose a threat to hibernating bats. Free access to winter shelters is a common problem. Entering objects, prolonged stay, noise, lighting hibernating bats, taking photographs, camping, using open fire or lighting fires can lead to accidental or intentional waking from hibernation. Frequent waking up of individuals in the winter can lead to too early depletion of fat deposits accumulated for the winter and death of the animal (each waking of the bat from hibernation results in a loss of energy, which suffices for about 2-4 weeks of hibernation).