2.5 Threat: Transportation and service corridors

Based on the collated evidence, what is the current assessment of the effectiveness of interventions for roads?

Likely to be beneficial

● Install underpasses as road crossing structures for bats

Unknown effectiveness (limited evidence)

● Divert bats to safe crossing points with plantings or fencing
● Install bat gantries or bat bridges as road crossing structures for bats
● Install overpasses as road crossing structures for bats

No evidence found (no assessment)

● Deter bats with lighting
● Install green bridges as road crossing structures for bats
● Install hop-overs as road crossing structures for bats
● Replace or improve habitat for bats around roads

Likely to be beneficial

Install underpasses as road crossing structures for bats

1Four studies (two replicated) in Germany, Ireland and the UK found varying proportions of bats to be using existing underpasses below roads and crossing over the road above. Assessment: likely to be beneficial (effectiveness 60%; certainty 50%; harms 0%).
http://www.conservationevidence.com/​actions/​976

Unknown effectiveness (limited evidence)

Divert bats to safe crossing points with plantings or fencing

2We found no evidence for the effects of diverting bats to safe road crossing points. One controlled, before-and-after study in Switzerland found that a small proportion of lesser horseshoe bats within a colony flew along an artificial hedgerow to commute. Assessment: unknown effectiveness (effectiveness 10%; certainty 10%; harms 5%).
http://www.conservationevidence.com/​actions/​981

Install bat gantries or bat bridges as road crossing structures for bats

3One replicated, site comparison study in the UK found fewer bats using bat gantries than crossing the road below at traffic height. Assessment: unknown effectiveness (effectiveness 0%; certainty 35%; harms 0%).
http://www.conservationevidence.com/​actions/​978

Install overpasses as road crossing structures for bats

4One replicated, site comparison study in Ireland did not find more bats using over-motorway routes than crossing over the road below. Assessment: unknown effectiveness (effectiveness 0%; certainty 20%; harms 0%).
http://www.conservationevidence.com/​actions/​977

No evidence found (no assessment)

5We have captured no evidence for the following interventions:

  • Deter bats with lighting

  • Install green bridges as road crossing structures for bats

  • Install hop-overs as road crossing structures for bats

  • Replace or improve habitat for bats around roads