The bat is the best flying animal

A unique mammal: the bat

Every year in late summer, nature conservation initiatives offer night walks and excursions in many places. Because at this time of the year bats can be observed particularly well. They only become active at night. One of the actions is the "Batnight", the international night of the bats. It takes place every year on the last weekend in August, in 2021 for the 25th time.

Environmental organizations in more than 30 countries then offer excursions or provide information about the way of life of these fascinating animals with exhibitions and presentations. An overview of the nationwide events related to the "Batnight" can be found on the Internet on the Naturschutzbund (NABU) website. Europe-wide events can be viewed and registered on the EUROBATS website. EUROBATS is an agreement for the conservation of the European bat populations.

Education about the life of the bat is important because many people are afraid of the animal night owls. Not only since "Dracula" have they been decried as bloodsuckers and vampire assistants. They were already associated with the devil in the Middle Ages. The corona pandemic has further deteriorated their image. Because science assumes that the new coronavirus originally came from bats in China, even if initial transmissions of the virus to humans do not go directly back to these animals.

The Federal Agency for Nature Conservation therefore points out that the bat species living in Germany and Europe have nothing to do with the transmission of the virus. Because native bat species are not infected with SARS-CoV 2 - the virus that triggered the corona pandemic. Other viruses (including coronaviruses) could be detected in native bat species, but these do not belong to the human SARS coronaviruses and are harmless to humans.

In addition, the risk of such viruses being transmitted to humans increases as a result of the destruction of ecosystems and the associated decline in biodiversity. The further a person penetrates into untouched natural areas, the more frequently there is a risk of coming into contact with an infected wild animal. More information on this in the topic of the week Zoonoses: When environmental crises lead to health crises.

Human interference with nature is also the reason why bats are endangered and many species are threatened with extinction. As a result of intensive agriculture, the food supply for insects has decreased and the possibility of finding shelter is becoming more and more difficult for bats.

The only mammals that can fly

Bats, along with the fruit bats, belong to the chiroptera, the ancient mammal group, the palm wing. With more than 1400 species worldwide, they are the second largest mammal order in the world after rodents. Science assumes that bats descended from small, nocturnal insectivores that jumped for their prey. In the course of time this jumping developed into gliding and from this in turn the ability to fly. So evolution has made them the only mammals that can fly.

Bats live everywhere except for the northern polar region and the Antarctic. Most species, however, prefer a warm climate. Like migratory birds, some of them fly back and forth between their summer and winter roosts every year and, like the noctule bat (Nyctalus noctula), cover up to around 1,600 kilometers. The rough-skin bat (Pipistrellus nathusii) even makes it 1900 kilometers.

The European species feed mainly on beetles, flies and butterflies. But spiders and centipedes are also part of their favorite food. At dusk and at night they leave their tree hollows, attic or basement and go hunting. The species divide the nocturnal airspace among themselves: water bats only hunt close to the surface of water, noctule bat hunt high above the treetops, and other species collect insects from the leaves of trees and bushes.

On the hunt with an echo sounder

Researchers assume that bats have adapted their life to the night in order to avoid food competition from diurnal birds. When hunting at night, they use the echo sounder as an aid: the animals emit sounds via their mouths or specially trained noses and analyze the echoes that are thrown back from their surroundings. This allows bats to "see" with their ears in the dark. To do this, they use ultrasound, i.e. sound with very high frequencies that are imperceptible to humans. Fortunately, because their screams would be louder than a circular saw. Bats calculate the distance to an object based on the time span from the sending of the call to the arrival of the echo. Fluctuations in the frequency (the pitch), the duration and the volume of the echo tell the animals whether the object is large or small, smooth or rough, stands still or flaps its wings. In this way they recognize obstacles, find prey and communicate with their fellow species.

Upside down into hibernation

In autumn, the bat hunting season is over. By then they will have put on a small layer of fat. Then it is called "hang out" in the truest sense of the word. Mouse-eared and gray long-eared bats prefer to go to a rock cave, noctule bat and rough-skin bat hide in a tree cave. They stay there for five or six months, upside down in hibernation. They hold onto the ceiling of their hiding place with the sharp claws of their hind feet. A mechanism on the ankles makes this possible. Due to its weight alone, a tendon locks into place, which fixes the claws in a crooked position and prevents the animals from falling down while they sleep. Even if they die, they'll stay hanging from the ceiling for a while.

The bat cycle is also adjusted to the position. It pumps the blood back from the head to the heart without any problems. In this position they not only sleep, but also clean themselves and give birth to their children.

Bats are important to us and our ecosystems

Bats play an important role in various ecosystems around the world. In Europe, they help to reduce pests in agriculture and forestry. The small animals devour lots of insects. Some bats catch up to 4,000 mosquitoes a night. On average, this corresponds to a third to half of their own body weight. In subtropical and tropical ecosystems, bats are particularly important because they spread plant seeds and pollinate crops. Because there are some species there that feed on pollen or fruits.

They are also potentially valuable for human and veterinary medicine, for example to gain knowledge about their properties in containing pathogens. Bats carry a variety of viruses without actually getting sick from them. More research is needed in this area.

Bats - an endangered species

There are 25 different bat species in Germany alone. They are all strictly protected, as four of them are already threatened with extinction. This is not due to their natural predators like owls or martens or their low reproduction rate. Because bats are only children: the parent animals usually only have one offspring each year.

The threat comes from humans. The industrialization and intensification of agriculture has led to a decrease in the supply of prey such as moths, flying insects and beetles. Species of bats that specialize in this food have difficulty finding sufficient food. They have therefore disappeared from many of their original habitats.

In addition, the nocturnal animals no longer find shelter so easily. The cave-rich old wood in particular was deliberately removed from the forest for a while. Old mine tunnels and cellars are being filled in and caves are being expanded for adventure tourism. Even in the attics, the animals are nowadays difficult to get, because cavity walls are filled with foam and joints are sealed.

Numerous bat species need safe resting and feeding places on their hundreds of kilometers of migrations between summer and winter quarters. The destruction of biotopes and the lack of food have contributed to their disappearance from many of their original habitats.

Bats are more recently threatened by wind energy. The animals can be killed by the rotor blades or suffer a so-called barotrauma. The internal organs of the bats are damaged due to the turbulence and the pressure differences on the rotor blades, so that the animals perish. The number of animals killed is not sufficiently known, so far only estimates are available. The NABU assumes that 200,000 animals die each year as a result of the facilities. The victims include not only bat species from the region, but also migrating species such as the great and small noctule bat.

International cooperation for the protection of animals

International cooperation is necessary to protect bats because many species travel long distances between their summer and winter roosts. With this in mind, EUROBATS was created: a Europe-wide agreement for the conservation of domestic bat populations (Agreement on the Conservation of Populations of European Bats), which will celebrate its 30th anniversary in December 2021. Since its inception, EUROBATS has steadily advanced bat protection. In the meantime, 37 countries have committed themselves to protecting the 51 species native to Europe. Since some of these species also temporarily migrate to North Africa or the Middle East, states in these regions can also join the agreement. EUROBATS operates under the United Nations Environment Agreement and is based in Bonn.

According to the agreement, the member states of EUROBATS should improve the food supply and nesting opportunities for bats and raise awareness among the population for the protection of the endangered species. One contribution to this is the European Bat Night, which is organized by local nature and species protection associations such as NABU and which will take place for the 25th time in 2021.

EUROBATS calls for research to be promoted in addition to public relations work. For example, the aim is to find out which flight corridors the bats follow on their migrations. This is an important basis for reducing future damage from wind turbines. In Germany, the Federal Agency for Nature Conservation has taken up this and published a study on "Bat migration routes".

The Naturschutzbund Deutschland (NBS) and the NABU are calling for future wind turbines not to be built in these corridors if possible. For the existing facilities, the conservationists particularly recommend shutdown times during migration periods or on nights when the bats are particularly active.

In addition to EUROBATS, there are other international agreements that serve to protect bats, such as the Bonn Convention for the Protection of Migratory Wildlife Species or the Bern Convention for the Conservation of European Wildlife and Their Natural Habitats.

Within the European Union, the decisive protection instrument for bats is the Fauna-Flora-Habitat Directive (FFH), which in its Appendix IV lists all species of bats as "strictly protected animal species of Community interest".

In Germany, the Federal Nature Conservation Act generally forbids killing or disturbing animals or even destroying their roosts.

What can each and every individual do to protect bats?

One possibility for active bat protection is to create or maintain bat roosts and hunting areas. Old trees with caves should be preserved as far as possible and small entry slits to attics or cellars should be kept open. Bat boxes in the garden can also be an alternative.

In order to enrich the food supply for the night owls, beds with flowers that open their blossoms at night are suitable. The scent of evening primrose, light carnation, mint and co. Attracts butterflies and other insects that bats eat. A pond is also an advantage, as bats will find a rich insect buffet and a water source here.

In addition, the garden should be worked without poison in order to protect bats and other living things. Because they ingest pesticides and other toxins through the insects that they eat. The toxins are stored in your fatty tissue. During hibernation, the animals use up these fat reserves, and the poison concentrated in them gets into the organism. That can be fatal.

Watch bats

Even a layperson can easily recognize the more common bat species based on their characteristic features. However, it is not that easy to spot them at all.

While the noctule bat, which is about the size of a blackbird, already flies over the treetops at dusk in search of large insects, other species do not leave their roosts until it is dark. Some species are found near lanterns because their light attracts insects.

Especially with water bats, it is possible to make their flight maneuvers visible with handheld searchlights. These animals usually hunt close to the surface of the water. However, they are sensitive to the light, it should be dampened with red light foil.

In contrast to other mammals, bats are not bothered by the presence of humans. Tips for observation can be found, for example, on the website of NABU e.V.

Related Links

Federal Environment Ministry (BMU): Bats

Federal Agency for Nature Conservation (BfN): EUROBATS: Bat Conservation in Europe

Naturschutzbund Deutschland (NABU): Bats - Help for the beauties of the night Pflanzen/saeugetiere/fledermaeuse/index.html

Download material