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Providing evidence to improve practice

Action: Maintain microclimate in closed/abandoned mines Bat Conservation

Key messages

Read our guidance on Key messages before continuing

  • One study evaluated the effects of maintaining the microclimate in an abandoned mine on bat populations. The study was in the USA.



  • Abundance (1 study): One before-and-after study in the USA found that modifying the microclimate of an abandoned mine by closing a man-made entrance resulted in a greater number of bats hibernating within the mine.


Supporting evidence from individual studies


A before-and-after study in 2004–2007 at one mine in Southern Illinois, USA (Carter & Steffen 2010) found that modifying the microclimate within an abandoned mine by closing a man-made entrance resulted in an increase in the number of hibernating bats, including Indiana bats Myotis sodalis. Before the entrance was closed, <500 bats were counted hibernating in the mine and internal temperatures varied widely during the hibernation period (-2-18°C). After the entrance was closed, internal temperatures were more stable (11-13°C) and more bats hibernated within the mine (one year after: 1,500 bats; two years after: 2,500 bats). In summer 2005, a culvert with a door (1.2 m wide) was built into the horizontal man-made entrance shaft and the rest of the entrance was filled in. Three other entrances to the mine were left open. Hibernating bats were counted within the mine in 2004 before the entrance was closed, and in 2006 and 2007 after the entrance was closed.

Referenced papers

Please cite as:

Berthinussen, A., Richardson O.C. and Altringham J.D. (2019) Bat Conservation. Pages 67-140 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2019. Open Book Publishers, Cambridge, UK.