What Works in Conservation 2020
| , , ,2. Bat conservation
2.3 Threat: Energy production
Texte intégral
2.3.1 Wind turbines
Beneficial
Increase the wind speed at which turbines become operational (‘cut-in speed’) to reduce bat fatalities
1Four studies evaluated the effects of increasing the wind speed at which turbines become operational (‘cut-in speed’) on bat populations. One study was in Canada and three studies were in the USA.
2COMMUNITY RESPONSE (0 STUDIES)
3POPULATION RESPONSE (4 STUDIES)
4Survival (4 studies): Three randomized, replicated, controlled studies (including one before-and-after study) in Canada and the USA, and one review in the USA found that bat fatalities were significantly reduced when the wind speed at which turbines became operational (‘cut-in speed’) was increased.
5BEHAVIOUR (0 STUDIES)
6Assessment: beneficial (effectiveness 80 %; certainty 70 %; harms 0 %).
7https://www.conservationevidence.com/actions/1960
Likely to be beneficial
Automatically reduce turbine blade rotation when bat activity is high
8Two studies evaluated the effects of automatically reducing turbine blade rotation when bat activity is high on bat populations. One study was in Germany, and one in the USA.
9COMMUNITY RESPONSE (0 STUDIES)
10POPULATION RESPONSE (2 STUDIES)
11Survival (2 studies): Two replicated studies (one randomized, controlled and one paired sites study) in Germany and the USA found that automatically reducing the rotation speed of wind turbine blades when bat activity is predicted to be high resulted in significantly fewer bat fatalities for all bat species combined and for little brown bats.
12BEHAVIOUR (0 STUDIES)
13Assessment: likely to be beneficial (effectiveness 80 %; certainty 55 %; harms 0 %).
14https://www.conservationevidence.com/actions/971
Deter bats from turbines using ultrasound
15Two studies evaluated the effects of deterring bats from wind turbines using ultrasound on bat populations. The two studies were in the USA.
16COMMUNITY RESPONSE (0 STUDIES)
17POPULATION RESPONSE (1 STUDY)
18Survival (1 study): One randomized, replicated, controlled study with a before-and-after trial in the second year in the USA found mixed results. In the first year of the study, 21-51 % fewer bats were killed at turbines with an ultrasonic deterrent fitted than at control turbines, but in the second year, from 2 % more to 64 % fewer bats were killed at turbines with ultrasonic deterrents fitted.
19BEHAVIOUR (1 STUDY)
20Behaviour change (1 study): One paired sites study in the USA found significantly fewer bats flying near one of two wind turbines with an ultrasonic deterrent compared to turbines without.
21Assessment: likely to be beneficial (effectiveness 40 %; certainty 45 %; harms 7 %).
22https://www.conservationevidence.com/actions/968
Prevent turbine blades from turning at low wind speeds to reduce bat fatalities
23Three studies evaluated the effects of preventing turbine blades from turning at low wind speeds on bat populations. Two studies were in Canada and one review was in the USA.
24COMMUNITY RESPONSE (0 STUDIES)
25POPULATION RESPONSE (3 STUDIES)
26Survival (3 studies): Two replicated, controlled before-and-after studies (including one randomized study) in Canada and one review in the USA found that bat fatalities were significantly reduced when turbine blades were prevented from turning at low wind speeds.
27BEHAVIOUR (0 STUDIES)
28Assessment: likely to be beneficial (effectiveness 80 %; certainty 50 %; harms 0 %).
29https://www.conservationevidence.com/actions/970
No evidence found (no assessment)
30We have captured no evidence for the following interventions:
- Apply textured coating to turbines
- Close off potential access points on turbines to prevent roosting bats
- Deter bats from turbines using low-level ultraviolet light
- Deter bats from turbines using radar
- Modify turbine placement to reduce bat fatalities
- Paint turbines to reduce insect attraction
- Reduce rotor diameter
- Reduce turbine height
- Remove turbine lighting to reduce bat and insect attraction
- Retain a buffer between turbines and habitat features used by bats.
2.3.2 Mining
Trade-off between benefit and harms
Install and maintain gates at mine entrances to restrict public access
31Nine studies evaluated the effects of installing gates at mine entrances on bat populations. Eight studies were in the USA and one in Australia.
32COMMUNITY RESPONSE (1 STUDY)
33Richness/diversity (1 study): One replicated, before-and-after study in the USA found that fewer bat species entered mines after gates were installed. POPULATION RESPONSE (3 STUDIES)
34Abundance (3 studies): Two replicated, site comparison or before-and-after studies in the USA and Australia found fewer bats in mines or at mine entrances after gates were installed. One replicated, controlled, before-and-after study in the USA found that bat activity (relative abundance) remained stable or increased at five of seven gated mines, and decreased at two gated mines. BEHAVIOUR (6 STUDIES)
35Use (2 studies): One before-and-after study in the USA found that 43 of 47 mines continued to be used 12 years after gates were installed, however bats abandoned four mines with ‘ladder’ design gates. One replicated study in the USA found that gate design and time since gate installation had varied effects on the presence of four bat species.
36Behaviour change (4 studies): Four replicated, before-and-after or site comparison studies in the USA and Australia found that bats at mine entrances circled more and entered mines less after gates were installed.
37OTHER (2 STUDIES)
38Collisions with gates (1 study): One replicated, controlled, before-and-after study in the USA found that up to 7 % of bats at mine entrances collided with mine gates.
39Assessment: trade-off between benefit and harms (effectiveness 50 %; certainty 50 %; harms 46 %).
40https://www.conservationevidence.com/actions/1963
Unknown effectiveness
Maintain microclimate in closed/abandoned mines
41One study evaluated the effects of maintaining the microclimate in an abandoned mine on bat populations. The study was in the USA.
42COMMUNITY RESPONSE (0 STUDIES)
43POPULATION RESPONSE (1 STUDY)
44Abundance (1 study): One before-and-after study in the USA found that modifying the microclimate of an abandoned mine by closing a man-made entrance resulted in a greater number of bats hibernating within the mine. BEHAVIOUR (0 STUDIES)
45Assessment: unknown effectiveness (effectiveness 45 %; certainty 20 %; harms 0 %).
46https://www.conservationevidence.com/actions/1964
Restore bat foraging habitat at ex-quarry sites
47One study evaluated the effects of restoring bat foraging habitat at ex-quarry sites on bat populations. The study was in France.
48COMMUNITY RESPONSE (0 STUDIES)
49POPULATION RESPONSE (1 STUDY)
50Abundance (1 study): One replicated, site comparison study in France found that gravel-sand pits had higher overall bat activity (relative abundance) 10 years after restoration than gravel-sand pit sites before or during quarrying. BEHAVIOUR (0 STUDIES)
51Assessment: unknown effectiveness (effectiveness 50 %; certainty 35 %; harms 0 %).
52https://www.conservationevidence.com/actions/2286
No evidence found (no assessment)
53We have captured no evidence for the following interventions:
- Exclude bats from roosts prior to mine reclamation
- Provide artificial subterranean bat roosts to replace roosts in reclaimed mines
- Relocate bats from reclaimed mines to alternative subterranean roost sites
- Reopen entrances to closed mines and make suitable for roosting bats
- Retain access points for bats following mine closures.
Table des illustrations
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