More than 15.000 bats in the mine

 

More than 15.000 bats overwinter in the limestone mine. Most of these are Daubenton’s bats, but there are also many of the otherwise rare pond bats. In the spring and summer months, there are not many bats in the mines, as they go out to most of Jutland, where they eat insects, so they are ready to winter again.

 

In the summer, the females live together in colonies where they feed their cubs, but already in August the bats meet again in Mønsted Limestone mine, where they mate before they overwinter. During the first winter months, most bats hide in loose lime or cracks. As spring draws near, and most bats have been a trip outside the mine, to see if it’s still winter, all the bats eventually hang on walls and ceilings in the mine, awaiting the arrival of spring.

 

When the bats settle into crevices and cracks in the underground passages to hibernate, they adjust their body temperature to the surroundings. Here with us, this means that the bats turn their body temperature down from the usual 38 degrees to only 8 degrees, which is the year-round temperature in the old mining corridors. In this way, the bats can run at ‘low flare’ all winter, using as little energy as possible. Breathing is reduced, the heart rate slows down and the combustion are reduced, so bats can live all winter long from the insects’ fat reserves built up throughout the summer.

If the bats are disturbed during their overwinter, the body temperature can be raised in a matter of minutes. However, this requires a great deal of energy consumption and should preferably not be done during the winter, as the bats then run out of fuel and can risk dying.

 

Our bats
In Mønsted we have five different species of bats that overwinter in the mines; pond bats, Daubenton’s bats, long-eared bats, brandt’s bats and Natterer’s bat.

 

Out of this stock, about 80% consists of pond and Daubenton’s bats.

Pond bats

Pond bats are rare and live primarily on Bornholm and Central Jutland. It often lives close to lakes and streams, as it prefers to hunt near the water or around trees.

 

Characteristics:

The pond bat is greyish brown on the back and greyish white on the abdomen. It has small ears and a reddish-brown muzzle. Its wingspan measures approx. 30 cm, which makes its size very average within the different species of bats in Denmark.

Daubenton’s bat

Daubenton’s bat  is one of the most common bats in Denmark and can be found in most places in the country. It lives on small flying insects that it most often catches near lakes and streams.

Daubenton’s bat can be up to 20 years old.

 

Characteristics:

Daubenton’s bat resembles the pond bat, but it stands out with its large feet. Its wingspan measures approx. 25 cm.

Brandt’s bats

Brandt’s bat lives primarily on Bornholm, but is also found in small populations in Central Jutland and Lolland. It likes to hunt along forest edges or in open forests. Brandt’s bat can be more than 40 years old, which is very old for a bat, and it is also the species that lives the longest. It usually only gets one cub a year.

 

Characteristics:

Brandt’s bats is one of the small species of bats and has a wingspan of about 20 cm.

Natterer’s bat

Like the long-eared bat, Natterer’s bat likes to fly in between trees and branches as well as close along walls. It eats various insects, including flies, beetles and spiders. Natterer’s bat is found all over the country, but most are on Bornholm, Lolland or in the central Jutland limestone mines.

 

Characteristics:

Natterer’s bat has a wreath of small stiff hairs on the tail – hence its name. Its wingspan measures approx. 25 cm.

Bats are an endangered animal species so we are very much in favor of our bats here in Mønsted doing well. Therefore, in order to allow the bats to sleep all winter in peace and quiet, the limestone mine are closed to tourists from November 1 until spring.

Info box:
Bats are a relatively small flying mammal – in fact, the only mammal that can fly. There are about 1100 different species of bats, 15 of which are found in Denmark.

Long-eared bats

The long-eared bat likes to fly in between trees and branches. It eats insects, which it pills directly from leaves and trees. It is especially fond of eating night sweaters.

 

Characteristics:

On the back, the long-eared bat is brown, while greyish-white on the abdomen. It has, as its name suggests, long ears – in fact almost as long as its body length. It has a wing rim of approx. 25 cm.