Create artificial caves or hibernacula for bats
Overall effectiveness category Unknown effectiveness (limited evidence)
Number of studies: 2
Background information and definitions
Artificial caves or hibernacula could be created for bats where natural sites are limited or where these habitats have been lost. Hibernacula would need to be carefully designed to ensure a stable microclimate.
For similar interventions, see ‘Threat: Human intrusions and disturbance – Caving and tourism – Provide artificial subterranean bat roosts to replace roosts in disturbed caves’ and ‘Threat: Energy production and mining – Provide artificial subterranean bat roosts to replace roosts in reclaimed mines’. Some bat species may also hibernate in bat boxes, which are discussed in ‘Species management – Provide bat boxes for roosting bats’.
Supporting evidence from individual studies
A study in 2004–2006 at a wetland nature reserve in Cambridgeshire, UK (Gulickx et al. 2007) found that an artificial cave was used by 1–2 hibernating brown long-eared bats Plecotus auritus in each of two years after construction. Bats were found hibernating attached to the cave roof or in between the concrete cave roof sections. The cave (2 m wide x 2 m high x 30 m long) consisted of a trench dug into the underlying limestone with a pre-cast concrete roof containing elongated bat bricks with six gaps in each. A door made of steel and oak boards was constructed to restrict access by predators and humans. Two slots in the top of the door allowed bats to pass through and a fine wire mesh on the bottom of the door allowed air flow. The cave was installed in 2004 and inspected for bats in 2005 and 2006.Study and other actions tested
A study in 2004–2013 in a forest in Thetford, UK (Gibbons 2013) found that an artificial hibernaculum was used by hibernating bats of four species with numbers increasing in each of nine years after it was built. The artificial hibernaculum was first used by one brown long-eared bat Plecotus auritus in 2007, the second winter after it was built. In 2008, two brown long-eared bats were counted in the hibernaculum. From 2009 to 2013, three bat species were counted in the hibernaculum (brown long-eared bats, Daubenton’s bats Myotis daubentonii and Natterer’s bats Myotis nattereri) with the total number increasing each year (2009: 13–16 bats; 2010: 18–31 bats; 2011: 31 bats; 2012: 25–50 bats; 2013: 54–62 bats). The hibernaculum (built in 2004) consisted of a 95 m long ‘Y’ shaped concrete block tunnel with an access grille, ventilation pipes and bat bricks built into the ceiling. Hanging planks and logs with slots cut into them were placed inside the tunnel. Bats were counted inside the tunnel during 1–4 months in winter in 2006–2013.Study and other actions tested