Bat bridge

A bat bridge is a structure of varying construction crossing a new or altered road to aid the navigation of bats following the destruction of a hedgerow, and to cause the bats to cross the roadway at a sufficient height to avoid traffic. Bats are thought to follow the lines of hedgerows and woods, and removing these may confuse the bats.

The theory is that these "bridges" will be seen by the bats' sonar as linear features sufficiently similar to the old hedgerows as to provide an adequate substitute. The Highways Agency is performing a study of those on the Dobwalls bypass to determine if this assumption is justified.

The first bridge to be installed in France is on the A65 motorway between junctions for Roquefort and Caloy in the Landes department.

Two additional bat bridges were completed in November 2012 near Balbigny, on the A89 motorway.

Two metal bridges were built in 2013 to protect the Mouse-eared Bat at Biberach an der Riss, Baden-Wuerttemberg. The structures cost £375,000.

The overall cost of bat bridges has been criticised in the House of Lords by Lord Marlesford.

A team from the University of Leeds examined the effectiveness of bat bridges, gantries and underpasses. They found that one underpass, placed on a commuting route, was used by 96% of bats, but few bats used the other underpasses and gantries, preferring routes which put them in the path of traffic.

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