Action: Maintain bat roosts in road bridges and culverts
Key messagesRead 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.
COMMUNITY RESPONSE (0 STUDIES)
POPULATION RESPONSE (0 STUDIES)
BEHAVIOUR (1 STUDY)
- 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.
Crevice-dwelling bat species can roost in gaps and cracks within road bridges and culverts (e.g. Keeley & Tuttle 1999, Celuch & Sevcik 2008, Barros 2014). Maintenance and repair work, such as re-pointing, may result in the loss of potential roost sites and/or entombment or injury of roosting bats.
For a similar intervention see ‘Create spaces for roosting bats in road bridges and culverts’.
Barros P. (2014) Agricultural underpasses: their importance for bats as roosts and role in facilitating movement across roads. Pasos agrícolas inferiores de carreteras: su importancia para los murciélagos como refugio y lugar para cruzar la vía. Journal of Bat Research & Conservation, 7, 22–31.
Celuch M. & Sevcík M. (2008) Road bridges as roosts for noctules (Nyctalus noctula) and other bat species in Slovakia (Chiroptera: Vespertilionidae). Lynx, 39, 47–54.
Keeley B.W. & Tuttle M. (1999) Bats in American bridges. Bat Conservation International, Austin, Texas, USA.
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.