More than 10,000 bats hibernate in the pits because Mønsted Kalkgruber is an optimal winter habitat for the small mammal due to the constant temperature of 8 degrees and high humidity of 98%.

The five species of bats that have Mønsted Kalkgruber as their winter habitat are all small bats the size of a clasped hand or smaller. They do not weigh more than 5 – 25 g and can be difficult to spot. The five species are: Water bat, Dam bat, Fringed bat, Brandt's bat and Long-eared bat. In the area between the administration and the Limeworks, you can learn much more about the five species in our outdoor exhibition.

The bats are protected and must not be disturbed in their winter den. Therefore, as a guest, you cannot visit Mønsted Kalkgruber from 1 November. – March 30. In this way, we ensure the best possible wintering and survival conditions.


Mønsted Kalkgruber received a project grant in 2022 from the Danish Environmental Protection Agency's pool "extra hunting license funds". The project aims to increase our knowledge about the activity of bats by expanding the current counting system with photo identification. With the increased monitoring, we hope to be able to put numbers on the population of each of the individual species that overwinter in the pits. The project is carried out in collaboration with researchers from Aarhus University and volunteers from, among others, Danmarks Naturfredningsforening in Viborg.