The bat - the insect hunter of the night
There are 17 species of bats in Denmark and of these, 9 species have been found in the Sønderborg area.
Tired of mosquitoes - then bats are just the thing!
The bat is the only mammal that can fly actively, and the European bat species are nocturnal hunters who orient themselves and find prey via ultrasonic echolocation.
Imagine that the soprano pipistrelle, which itself weighs only 4-7 grams, eats 1-2000 mosquitoes in a single night!
But don't worry, we are not talking about large flying dogs of 40 cm and a wingspan of up to 1.5 metres and which by the way feed on nectar and fruit or vampire bats, which are only found in South and Central America.
You can therefore quite safely observe these little elegant aviators in the evening twilight!
What big ears it has ...
The bat uses bio sonar to orientate and hunt with, the same goes for toothed whales, such as dolphins. During the hunt, the bat emits loud ultrasounds / screams that send an echo back when they hit an object. This echo is picked up by the ears, so the bat listens to its prey. The bat is able to regulate the sound beam so that it can emit a narrow sound beam, which is made shorter and wider when the prey is within a distance of one metre and thus reduces the risk of the dinner escaping, you could say that the bat's ears are its eyes.
The toothed whales emit clicking sounds, a similar method is used by a technical sonar on board submarines that send a ping and by fishing boats with echo sounders.
The bat's ultrasound is at such a high frequency that it requires listening equipment and sound programs for humans to hear. All bat species have their own spectra of ultrasound or audio DNA and often recordings are the best way to identify hunting bats.
There are two different types of the mentioned sound programs, "Heterodyne" and "Time Expansion", and where the first results in "click sounds", the second gives rather "whistle sounds". There are examples of both types in the description of the species below.Photo:Petteri Aimonen - Wikimedia.org
Bat Hot-spots
The good places where you can experience active bats in the Sønderborg area are by the large and small lakes as well as in forests with old trees. But even in urban areas with parks or forest-like stands where there are large trees, you can experience the bat from around sunset to half an hour after - where they leave their roosting site during daytime.
Photo:SDFE & VisitSønderborg
When and how you best can experience bats.
A good bat night is a night after a sunny day with light winds. This is exactly the type of weather where the bat seeks the good eating grounds, when especially the large and smaller lakes and the forests with old trees offer plenty of insects - and the bat knows this.
If you are interested in hearing bat orientation and catching calls, you can get yourself a bat detector. A good Heterodyne detector costs from approx. DKK 1000.
Bat species
A description of the different species found in the Sønderborg area.
Soprano pipistrelle
With a body length of just 4-7 cm and a weight of 3-8 grams, this is the smallest bat species in Denmark. It has a wingspan of 20-21 cm and the flight is relatively straight with few turns and loops. It is strongly associated with deciduous forest as well as park-like stands. Summer quarters are found in buildings, hollow trees and bat boxes. Winter quarters are found in buildings, but also in hollow trees.
🔊lydfil = link to audio file by Keoka posted on Wikimedia commons under the following conditions
The soprano pipistrelle (Pipistrellus pygmæus) likes to fly at low altitudes along forest edges and fences and is probably the most common bat in Denmark. The female gives birth to 1-2 young in the month of July. On the red list, it is listed as LC (least concern), which corresponds to not threatened.Photo:Evgeniy Yakhontov - Wikimedia commons
Common pipistrelle
In appearance, this bat resembles the soprano pipistrelle so much that only DNA can safely distinguish them. It is possible to determine the three species; soprano, nathuisius´ and common pipistrelle based on the ultrasound scream by looking at the constant frequency, which for soprano is approx. 56 kHz, for the common pipistrelle approx. 45 kHz and for the nathusius´ approx. 38 kHz.
The flight of the common pipistrelle is quick with throws to the sides. It is associated with older deciduous forest and is widespread over most of the country. Summer roosting sites are found in houses, hollow trees and bat boxes. Winter quarters are houses and hollow trees.
🔊lydfil = link to audio file by XN posted on Wikimedia commons under the following conditions
The common pipistrelle (Pipistrellus pipistrellus) is confusingly similar to the soprano pipistrelle and it was not until 1999 that they were listed as a separate species. It is red-listed as LC (least concern), which corresponds to not threatened. Its ultrasound scream is at 40-50 kHz, where the soprano pipistrelle's scream is often at 50-60 khz, but overlap makes it difficult to identify individuals.Photo:Barracuda1983 - wikimedia commons
Nathusius' pipistrelle
This is a long-haul flyer. It is similar to the soprano and common pipistrel bats, but with a body length of 4.5-6 cm, a wingspan of 25 cm and a weight of about 10 grams, it is just a little bigger. The nathusius´ pipistrelle, which flies high and with large turns, is associated with older deciduous forest and is widespread in deciduous forest areas from the German border and up along the eastern part of Jutland to the Aarhus area. Summer quarters are found in buildings, hollow trees and bat boxes. Winter quarters are presumably houses and hollow trees.
🔊lydfil = link to audio file by Drahkrub posted on Wikimedia commons under the following conditions
The nathusius´ pipistrelle (Pipistrellus nathusii) uses an ultrasonic sound of 37-44 kHz when hunting insects in the dark night. It is listed on the red list as LC (least concern), which corresponds to not threatened.Photo:Mnolf - Wikimedia Commons
Daubenton's bat
It likes to hunt close to the surface of the water. In summer it roosts in hollow trees. It is one of Denmark's most common bat species and in this country, it has almost never been found in houses. Winter quarters are the Jutland lime mines, bunker facilities and cellars.
🔊lydfil = link to audio file by Keoka posted on Wikimedia commons under the following conditions
The daubenton´s bat (Myotis daubentonii) goes into hibernation from end September early November and it is believed that most mating’s take place in the winterroost. The female gives birth to a single young in the month of June-July. The species is red-listed as LC (least concern), which corresponds to not endangered.Photo:Rauno Kalda - Wikimedia Commons
Serotine bat
With a body length of 12 cm, a wingspan of 35 cm and a weight of 15-35 grams, this is one of the larger species in our area. It likes to hunt in large circles along hedges, forest edges and around street lamps. It uses buildings as a residence all year round, and its summer as well as winter residences have never been found anywhere other than in houses, making it particularly vulnerable to poisoning from wood preservatives.
The serotine bat (Eptesicus serotinus) lives in buildings, but even though it is listed on the red list as LC (least concern), corresponding to not endangered, it is just like all other bat species completely protected. Mating takes place in the autumn, but fertilization does not take place until around May, after which the female gives birth to a single young after 10-11 weeks of pregnancy.Photo:Mnolf - Wikimedia Commons
Brown long-eared bat
This species really has large ears - they are actually as long as the body, which measures 4.5-5 cm. It has a wingspan of 25 cm and can actually stand still and whirl in the air, a technique it uses together with its passive hearing to catch sedentary insects on leaves and branches. It is most often found in large barns and attics, as well as in other types of buildings, but also in hollow trees and bat boxes. Winter quarters are inaccessible places in buildings and hollow trees.
The brown long-eared bat (Plecotus auritus) uses an ultrasound of 27-65 kHz and is especially fond of moths, where the larger catches are brought to a fixed dining area. The female gives birth to 1 young in the month of July. It is red-listed as LC (least concern) and thus not threatened.Photo:San Martin Gilles - Wikimedia Commons
Common noctule
This is the largest species in our area. The common noctule uses only wooden cavities all year round as habitats. It is relatively common in Denmark and is dependent on trees with cavities for daytime roosts in summer, mating quarters in autumn and winter quarters.
🔊lydfil = link to audio file by Alexander Kürthy, posted on Wikimedia commons under the following conditions
The common noctule (Nyctalus noctula) is not only the largest, but also the most common bat species in Denmark. It flies very straight and likes to hunt for insects in the heights at the treetops. On the red list, it is listed as LC (least concern), which corresponds to not threatened.Photo:Andreas Andersen
Natterer's bat
The distribution in Sønderborg Municipality is linked to the forest areas, from Nørreskoven and the forests in midst the island of Als over Sundeved to Gråstenskovene and the forests along Flensburg Fjord.
Natterer´s bats are associated with forest areas and hunt especially inside the forest and along forest edges. It is a rather rare and spotted species in Denmark. It has summer quarters in houses and hollow trees. The winter is spent in basements and casemates, lime pits and the like.
The natterer´s bat (Myotis nattereri) has only been observed in a few places in our area and it is also red-listed as being NT (nearly threatened), which corresponds to almost endangered. It not only catches the prey in the air, but is also able to pick insects directly from leaves, stems and walls.Photo:San Martin Gilles - Wikimedia Commons
Pond bat
In Sønderborg Municipality, pond bats have been found by the lakes at Northern Als, by several of the coastal wetlands and the lakes in the forest Gråstenskovene.
The body length is 11 cm, the wingspan reaches up to 30 cm and the weight is 28 grams. It is found at most major lakes and streams and occasionally at fjords and sounds. The colonies are most often located near the hunting grounds.
The pond bat has so far only been found in a few localities in southern Jutland. It is a relatively rare species in Europe and in Denmark, it is widespread in eastern Central Jutland to the Limfjord area. It seems that the pond bat has day quarters in houses and less often in hollow trees.
The pond bat (Myotis dasycneme) is registered on the red list as VU (vulnerable). As you can probably deduce from the name, the pond bat hunts over water, where it snatches insects from the surface and with a little luck also small fish.Photo:Gilles San Martin - Wikimedia Commons
Parti-coloured bat
It has been located at Nordborg Castle and at Elsmark on Northern Als. It is one of the few species that can be heard with the naked ear when the males in the autumn perform their territory song while flying around tall buildings.
The parti-coloured bat is a building-associated species. Summer roosts are found almost exclusively in smaller detached houses and 1 to 2 storey properties in the countryside and in villages. Winter quarters are always found in buildings, usually very tall buildings with 4-5 floors or more. It typically hunts high and free, especially over open landscapes and lakes, but also over forests and hedges.
The parti-coloured bat (Vespertillion murinus) is red-listed as LC (least concern) and thus not endangered. The female gives birth to twins in June-July and unlike the other European bat species, these females have two pairs of nipples. The male's territory song in the autumn often drops from 30 kHz to 14 kHz, and the ticking sounds can be heard on the low frequencies.Photo:Gor Minasyan - Wikimedia Commons
Did you know...?
that bats go in hibernation in winter and their heart rate drops from 400 beats (below resting heart rate) to just 25 beats per minute
that some bats can be over 25 years old
that bats can forage (hunt) up to 10-20 km from their roosts site
that most bats are sexually mature at 2 years of age and give birth to 1-2 young per year
that the common noctule can withstand a temperature down to -7 ° C and still have a body temperature of + 1-2 ° C
that there are 5400 known mammals globally and of these, one in five is a bat.
The Bat Agreement and the EU Habitats Directive
All bat species are covered by the special bat agreement; Agreement on the Conservation of Populations of European Bats, and thus protected, even if they are red-listed as not endangered.
In addition, all Danish bat species are listed in the EU's Habitats Directive in Annex IV, which means that they and their habitats are under strict protection. So before removing old trees or buildings, it is important to check if bats roost there!
It is therefore not permitted to spooke bats from the attic of one's house, but if large noise and odour nuisances occur, advice and guidance can be sought as well as any permission to move the bats on the Danish Nature Agency's website under the topic of harmful game.
The Danish Bat Association wants to make a difference!
Do you also think that the bat is both useful and interesting?
Then the association Dansk Flagermus Forening might be of interest! In addition to the work of protecting the bats' habitats, work is also being done to set up bat shelter boxes in selected places.
The noctule bat "smiles" at the photographer and shows its pointed teeth. Bats should not be handled and not at all without work gloves. Although the disease Rabies (dog madness) is not widespread in the Sønderborg area, it cannot be ruled out that migratory species are infected, so if you are bitten - seek medical attention immediately!Photo:Kamran Safi - Wikimeadia commons