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Providing evidence to improve practice

Action: Maintain bat roosts in road bridges and culverts Bat Conservation

Key messages

Read our guidance on Key messages before continuing

  • One study evaluated the effects of maintaining bat roosts within a bridge on bat populations. The study was in Ireland.




  • Use (1 study): One before-and-after study in Ireland found that a maternity colony of Daubenton’s bats continued to roost in a road bridge over a river in similar numbers after crevices were retained during repair work.

Supporting evidence from individual studies


A before-and-after study in 1988–2005 of a road bridge over a river in northwest Ireland (Marnell & Presetnik 2010) found that after crevices were retained during strengthening work and repairs to the bridge, a Daubenton’s bat Myotis daubentonii maternity colony continued to roost in the bridge in similar numbers as before the work. A maternity colony of approximately 25 Daubenton’s bats was first recorded roosting in the bridge in 1988 (no more recent data provided). After the repair work was complete, four bats were recorded in the original roost crevice in 2004, and 25 bats were recorded in 2005. Strengthening works (including laying cement, pointing and grouting) were carried out on the five-arch masonry bridge in September–October 2003. Roosting crevices were marked and temporarily filled with polystyrene to prevent them from being filled. Bats were counted in the bridge in July 2004 and 2005.

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.