What Works in Conservation 2020
| , , ,2. Bat conservation
2.4 Threat: Transportation and service corridors
Texte intégral
2.4.1 Roads
Likely to be beneficial
Install overpasses as road crossing structures for bats
1Three studies evaluated the effects of installing overpasses as road crossing structures for bats. Two studies were in Europe and one in Australia.
2COMMUNITY RESPONSE (1 STUDY)
3Richness/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.
4POPULATION RESPONSE (0 STUDIES)
5BEHAVIOUR (2 STUDIES)
6Use (2 studies): One replicated, site comparison study in Ireland found that three bat species used overpasses but up to three-quarters of bats crossed the road below at traffic height. 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.
7Assessment: likely to be beneficial (effectiveness 45 %; certainty 42 %; harms 0 %).
8https://www.conservationevidence.com/actions/977
Install underpasses or culverts as road crossing structures for bats
9Six studies evaluated the effects of installing underpasses or culverts as road crossing structures for bats. Five studies were in Europe and one in Australia.
10COMMUNITY RESPONSE (0 STUDIES)
11POPULATION RESPONSE (0 STUDIES)
12BEHAVIOUR (6 STUDIES)
13Use (6 studies): Six studies (including four replicated studies) in Germany, Ireland, the UK and Australia found that bats used underpasses 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.
14Assessment: likely to be beneficial (effectiveness 52 %; certainty 50 %; harms 0 %).
15https://www.conservationevidence.com/actions/976
Unknown effectiveness
Divert bats to safe crossing points with plantings or fencing
16One study evaluated the effects of diverting bats using an artificial hedgerow on bat populations. The study was in Switzerland.
17COMMUNITY RESPONSE (0 STUDIES)
18POPULATION RESPONSE (0 STUDIES)
19BEHAVIOUR (1 STUDY)
20Use (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.
21Assessment: unknown effectiveness (effectiveness 10 %; certainty 10 %; harms 5 %).
22https://www.conservationevidence.com/actions/981
Install green bridges as road crossing structures for bats
23One study evaluated the effects of installing green bridges as road crossing structures for bats. The study was in the UK.
24COMMUNITY RESPONSE (0 STUDIES)
25POPULATION RESPONSE (0 STUDIES)
26BEHAVIOUR (1 STUDY)
27Use (1 study): One study in the UK found that a green bridge was used by 97 % of bats crossing a road.
28Assessment: unknown effectiveness (effectiveness 70 %; certainty 27 %; harms 0 %).
29https://www.conservationevidence.com/actions/979
Maintain bat roosts in road bridges and culverts
30One study evaluated the effects of maintaining bat roosts within a bridge on bat populations. The study was in Ireland.
31COMMUNITY RESPONSE (0 STUDIES)
32POPULATION RESPONSE (0 STUDIES)
33BEHAVIOUR (1 STUDY)
34Use (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.
35Assessment: unknown effectiveness (effectiveness 55 %; certainty 20 %; harms 0 %).
36https://www.conservationevidence.com/actions/1966
Unlikely to be beneficial
Install bat gantries or bat bridges as road crossing structures for bats
37Two studies evaluated the effects of installing bat gantries as road crossing structures for bats. Both studies were in the UK.
38COMMUNITY RESPONSE (0 STUDIES)
39POPULATION RESPONSE (0 STUDIES)
40BEHAVIOUR (2 STUDIES)
41Use (2 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.
42Assessment: unlikely to be beneficial (effectiveness 2 %; certainty 40 %; harms 0 %).
43https://www.conservationevidence.com/actions/978
No evidence found (no assessment)
44We have captured no evidence for the following interventions:
- Avoid planting fruit trees alongside roads in areas with fruit bats
- Create spaces for roosting bats in road bridges and culverts
- Deter bats from roads using lighting
- Deter bats from roads using ultrasound
- Install hop-overs as road crossing structures for bats
- Minimize road lighting to reduce insect attraction
- Replace or improve habitat for bats around roads.
Table des illustrations
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