What Works in Conservation 2021
| , , ,2. Bat conservation
2.4 Threat: Transportation and service corridors
Texte intégral
2.4.1 Roads
Likely to be beneficial
Create spaces for roosting bats in road/railway bridges and culverts
1One study evaluated the effects of creating spaces for roosting bats in road bridges. The study was in the USA.
2COMMUNITY RESPONSE (0 STUDIES)
3POPULATION RESPONSE (0 STUDIES)
4BEHAVIOUR (1 STUDY)
5Use (1 study): One review in the USA found that spaces created in road bridges for roosting bats to replace those lost during bridge works were recolonized by bats in similar or greater numbers to the original roosts at four of eight sites.
6Assessment: likely to be beneficial (effectiveness 60 %; certainty 40 %; harms 0 %).
https://www.conservationevidence.com/actions/1967
Install overpasses as road/railway crossing structures for bats
7Four studies evaluated the effects of installing overpasses as road crossing structures for bats. Three studies were in Europe and one in Australia.
8COMMUNITY RESPONSE (1 STUDY)
9Richness/diversity (1 study): One site comparison study in Australia found that the same number of bat species were recorded at an overpass and in nearby forest and bushland.
10POPULATION RESPONSE (0 STUDIES)
11BEHAVIOUR (3 STUDIES)
12Use (3 studies): Two replicated studies (including one site comparison) in Ireland and France found that two or three bat species/species groups used overpasses but up to three-quarters of bats crossed the road below at traffic height or crossed at other nearby locations. One study in the UK found that an overpass with planters was used by two-thirds of crossing bats, and an unvegetated overpass with a paved road over it was not used by crossing bats. Assessment: likely to be beneficial (effectiveness 50 %; certainty 46 %; harms 0 %).
https://www.conservationevidence.com/actions/977
Install underpasses or culverts as road/railway crossing structures for bats
13Eight studies evaluated the effects of installing underpasses or culverts as road crossing structures for bats. Seven studies were in Europe and one in Australia.
14COMMUNITY RESPONSE (0 STUDIES)
15POPULATION RESPONSE (0 STUDIES)
16BEHAVIOUR (8 STUDIES)
17Use (8 studies): Eight studies (including six replicated studies) in Germany, Ireland, the UK, Australia and France found that bats used underpasses and culverts below roads, and crossed over the roads above them, in varying proportions. One replicated, site comparison study in Australia found that bat species adapted to cluttered habitats used small culverts and underpasses more than bat species adapted to open or edge habitats. One replicated, site comparison study in France found that the use of underpasses by five bat species was influenced by underpass type and height, road width, and the amount of forest and hedgerows in the surrounding landscape.
18Assessment: likely to be beneficial (effectiveness 60 %; certainty 60 %; harms 0 %).
https://www.conservationevidence.com/actions/976
Maintain bat roosts in road/railway bridges and culverts
19Two studies evaluated the effects of maintaining bat roosts within road bridges on bat populations. One study was in Ireland and one in the USA. COMMUNITY RESPONSE (0 STUDIES)
20POPULATION RESPONSE (0 STUDIES)
21BEHAVIOUR (2 STUDIES)
22Use (2 studies): 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. One review in the USA found that when bat roosts were maintained during bridge replacement works, Yuma myotis and Mexican free-tailed bats recolonised most roosts in similar numbers to before the works, but pallid bats did not return.
23Assessment: likely to be beneficial (effectiveness 70 %; certainty 45 %; harms 0 %).
https://www.conservationevidence.com/actions/1966
Unknown effectiveness
Divert bats to safe crossing points over or under roads/ railways with plantings or fencing
24One study evaluated the effects of diverting bats using an artificial hedgerow on bat populations. The study was in Switzerland.
25COMMUNITY RESPONSE (0 STUDIES)
26POPULATION RESPONSE (0 STUDIES)
27BEHAVIOUR (1 STUDY)
28Use (1 study): One controlled, before-and-after study in Switzerland found that up to one fifth of lesser horseshoe bats within a colony flew along an artificial hedgerow to commute.
29Assessment: unknown effectiveness (effectiveness 10 %; certainty 10 %; harms 5 %).
https://www.conservationevidence.com/actions/981
Install green bridges as road/railway crossing structures for bats
30One study evaluated the effects of installing green bridges as road crossing structures for bats. The study was in the UK.
31COMMUNITY RESPONSE (0 STUDIES)
32POPULATION RESPONSE (0 STUDIES)
33BEHAVIOUR (1 STUDY)
34Use (1 study): One study in the UK found that a green bridge was used by 97 % of bats crossing a road.
35Assessment: unknown effectiveness (effectiveness 70 %; certainty 27 %; harms 0 %).
https://www.conservationevidence.com/actions/979
Provide alternative bat roosts during maintenance work at road/railway bridges and culverts
36One study evaluated the effects of providing alternative bat roosts during maintenance work at road bridges. The study was in the USA.
37COMMUNITY RESPONSE (0 STUDIES)
38POPULATION RESPONSE (0 STUDIES)
39BEHAVIOUR (1 STUDY)
40Use (1 study): One review in the USA found that bat houses provided as alternative roosts during bridge replacement works were used by fewer Mexican free-tailed bats than the original roost at one site and were not used by bats at all at three sites.
41Assessment: unknown effectiveness (effectiveness 20 %; certainty 22 %; harms 0 %).
https://www.conservationevidence.com/actions/2942
Unlikely to be beneficial
Install bat gantries or bat bridges as road/railway crossing structures for bats
42Three studies evaluated the effects of installing bat gantries as road crossing structures for bats. Two studies were in the UK and one in France.
43COMMUNITY RESPONSE (0 STUDIES)
44POPULATION RESPONSE (0 STUDIES)
45BEHAVIOUR (3 STUDIES)
46Use (3 studies): Two replicated studies (including one site comparison) in the UK found that fewer bats used bat gantries than crossed the road below at traffic height, and one bat gantry was not used at all. One replicated study in France found that a temporary bat gantry was used by three bat species/ species groups, but almost half of crossing bats flew over the road at other locations.
47Assessment: unlikely to be beneficial (effectiveness 20 %; certainty 42 %; harms 0 %).
https://www.conservationevidence.com/actions/978
No evidence found (no assessment)
48We have captured no evidence for the following interventions:
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Avoid planting fruit trees alongside roads/railways in areas with fruit bats
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Change timing of maintenance work at road/railway bridges and culverts
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Deter bats from roads/railways using lighting
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Deter bats from roads/railways using ultrasound
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Exclude bats from roosts during maintenance work at road/railway bridges and culverts
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Install hop-overs as road/railway crossing structures for bats
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Manage vegetation along utility and service line corridors to increase foraging habitat for bats
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Minimize road lighting to reduce insect attraction
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Replace or improve habitat for bats around roads/railways
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Replace or improve roosting habitat for bats along utility and service line corridors.
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