Latin:
The bat is an incredibly special animal. It is the only mammal that can fly actively. The bat belongs to the Chiroptera order, which consists of flying mammals. There are about 950 different species around the world, while in Denmark there are up to 17 species. The most common bats in Denmark are the dwarf bat, the southern bat, the water bat, and the mold bat, which are only found in North Zealand.
The bat species are quite different. Some look almost like dogs, while others are small sizes at just 4-6 grams. In Denmark, some of the species are even vulnerable and endangered. In fact, all bats in this country are protected.
Appearance
The bat is, as described, the only mammal that can actively fly. The bat’s two wings are formed by a thin fold of skin that is located between the bat’s arm, hand, and fingers as well as the side and hind legs of its body and can be stretched out.
There is also fly skin between the tail and the hind legs that continues all the way down to the feet. However, the feet are completely free of the skin. The feet have a completely different purpose, as the bat uses them when it hangs upside down and rests, or when it has to crawl around on the ground. The same goes for the thumb, which is also free of the skin. Instead, a claw is placed here.
Biology and behavior
A bat’s diet consists mainly of insects. Bats are active at night, so it is also at this time that they hunt their prey. They orient themselves by means of echolocation or sonar. The bat therefore emits small, short ultrasonic screams as it moves around. When the sound of these screams hits a tree, a wall, an animal or an insect, echoes emerge which the bat picks up. In other words, it is a “sound image” of the environment that the bat processes through its sense of hearing.
It is also this ability that enables the bat to move so precisely and safely in the dark and intercept signs of their prey – the insects. We humans are not able to pick up the ultrasound of the bat. Their frequency is in fact above the human hearing limit of 20 kHz.
The breeding season for bats is in late spring or early summer when the females gather in colonies in areas where there is adequate shelter and protection. For instance, under a roof. A colony can consist of between 20 and 200 females.
In some cases, bats seek in and spend the night on ceilings and overhangs on houses. You can read more about bats in houses at the Danish Nature Agency.
A female usually has one offspring, but in some species, it is not unheard of for her to have two offspring at once. The newborn cubs are completely naked and completely helpless. After 4 to 5 weeks, the young bat begins to train their wings and take their first flights. The cubs are a little insecure at first, but quickly begin to master the technique. At this stage, it is not uncommon for the little bat to get a little lost and possibly fly in through an open window.
The mating of bats takes place in late summer and autumn. After mating, the sperm cells remain alive in the female’s uterus while she goes into hibernation. Some species congregate in large flocks during hibernation. During the dormant period, however, the bats can wake up spontaneously, and they like to use the opportunity to mate. But it is not until the following spring that the female ovulates and thus the actual fertilization.
Although bats can sometimes wake up from their hibernation, these abrupt awakenings are not good for them. Bats do not tolerate many disturbances, as it can eat away at their fat layer.
Damage
In Denmark, the bat has many enemies and threats, whereas it does not pose a threat to anyone. And unlike rats or mice, they do not gnaw in insulation or woodwork on the home. In the worst case, they can “snuggle” in the insulation a bit, which does no significant damage.
However, bats can leave some traces in the form of excrement down windows or exterior walls, just as they can cause some noise or odor nuisance. Their excrement can cause odor nuisance and discoloration on floors and walls. But nothing that is dangerous to humans.
Prevention and pest control
In Denmark, the bat is completely protected. Therefore, one must in no way try to fight them. On the other hand, you should be happy that your home and garden can attract protected animal species, so you can experience nature up close. In cases where the bats are an excessively big nuisance, at certain times of the year you can use special exclusion systems that are set up where the bats are located. That way, the bats can fly out of their hiding place, but not fly in again. They are thus forced to find a new place. The period during which this systems can be used is from late August to early September, when the young are able to fly. As well as in early May, before the breeding season, when all individuals are active and on the wings.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)