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Providing evidence to improve practice

Individual study: Protection of overground roosts for bats (particularly roosts in buildings of cultural heritage importance)

Published source details

Marnell F & Presetnik P (2010) Protection of overground roosts for bats (particularly roosts in buildings of cultural heritage importance). EUROBATS report.


This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.

Maintain bat roosts in road bridges and culverts Bat Conservation

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.

(Summarised by Anna Berthinussen)

Create alternative bat roosts within developments Bat Conservation

A before-and-after study in 2000–2007 of a residential development in Portugal (Marnell & Presetnik 2010) found that an alternative roost was used by fewer European free-tailed bats Tadarida teniotis than the original roost in a nearby 15-storey building. In 2000, the original roost was used by 100 European free-tailed bats. Following demolition of the original roost, 22 European free-tailed bats were counted in the alternative roost in 2006, and 11 in 2007. Small numbers of serotine bats Eptesicus serotinus (2006: 12 bats; 2007: 11 bats) and soprano pipistrelles Pipistrellus pygmaeus (2006: 4 bats; 2007: 7 bats) were also found in the alternative roost (numbers in original roost not reported). Original roosts were in crevices on a 15-storey building, which was demolished in 2005. In 2003, an alternative roost (12 m high) was built 150 m from the original roost. Concrete plates from the original building were used on the alternative roost to recreate roosting crevices with similar temperatures. Fifty bats were captured and released at the alternative roost to encourage use of the structure. Bats were counted in the original roost in 2000 and in the alternative roost in 2006 and 2007.

(Summarised by Anna Berthinussen)

Create alternative bat roosts within developments Bat Conservation

A before-and-after study in 2003–2007 of a building development in southwest Ireland (Marnell & Presetnik 2010) found that an alternative roost in a loft within an outbuilding was used by a similar number of lesser horseshoe bats Rhinolophus hipposideros as the original roost in a nearby cottage. In 2003, 150 lesser horseshoe bats were counted in the original roost. Following renovation work, 120 lesser horseshoe bats were counted in the alternative roost in 2005, and 150 in 2007. The original roost was converted for residential use in 2004, and the original bat access points were sealed. An alternative roost was created in an outbuilding (10 x 5 m) located 10 m from the original roost. The outbuilding was roofed with felt and slate, and a loft was created with an access point in one of the gables. Bats were counted at the original roost in 2003 and at the alternative roost in 2005 and 2007.

(Summarised by Anna Berthinussen)