Action: Protect or create wetlands as foraging habitat for bats
- One replicated, controlled, site comparison study in the USA found higher bat activity over heliponds and drainage ditches within a pine plantation than over natural wetlands.
- One replicated study in Germany found higher bat activity over constructed retention ponds than at sites in nearby vineyards. No comparisons were made between the artificial ponds and natural wetland sites.
Supporting evidence from individual studies
In a replicated, controlled, site comparison study in June–July 2006 and 2007 in intensively managed pine plantations in North Carolina, USA (Vindigni et al 2009) overall bat activity was found to be highest at modified water sources within the plantations than in natural wetlands. The total of averages for all species were 201 call sequences/site/night at heliponds, 61 call sequences/site/night at interior ditches, 60 call sequences/site/night at edge ditches, 21 call sequences/site/night at natural wetlands. Modified water sources were either drainage ditches (1–2.5 m wide and 0.6–1.2 m deep) positioned every 80–100m within stands and along stand borders, or small ponds ‘heliponds’ (12 m x 24 m x 2.5 m deep) used by helicopters for the suppression of forest fires. The natural wetland site was a 350 ha remnant natural forested wetland adjacent to the plantation. Surveys were conducted on 116 nights over the two summers. On each night bat activity was sampled simultaneously from dusk until dawn with bat detectors at two of four water source types rotated in a random order (five heliponds, five interior ditches, five edge ditches and three natural wetlands). Bats were caught in mist nets at heliponds and natural wetland sites to confirm bat species presence. Seven species or species groups were identified. Insect abundance was measured using passive malaise and emergence traps, but did not differ across water source types.
A replicated study in summer 2009 at seven agricultural vineyard sites in Landau, Germany (Stahlschmidt et al 2012) found that total bat activity above artificial retention ponds was significantly higher than above nearby vineyard sites (average 1,543 vs. 25 s of recorded call sequences respectively). Ten species were recorded in total. Activity over retention ponds was 180 times higher than vineyard sites for Pipistrellus species, and 50 times higher for Myotis species. Foraging activity relative to the area of habitat available showed that retention ponds had on average a higher importance as bat foraging habitats than the complete vineyard. Seven retention ponds were sampled from the end of June to the end of August. All ponds had banks lined with trees or bushes, and ranged in size from 0.1 to 1.3 ha. Each site was surveyed on eight or nine nights from sunset to sunrise. Activity was recorded using bat detectors and thermal infra-red imaging cameras simultaneously at the pond and at a vineyard site 80 m away. No comparisons were made to bat activity levels at natural pond sites.
- Vindigni M.A., Morris A.D., Miller D.A. & Kalcounis-Rueppell M.C. (2009) Use of modified water sources by bats in a managed pine landscape. Forest Ecology and Management, 258, 2056-2061
- Stahlschmidt P., Pätzold A., Ressl L., Schulz R. & Brühl C.A. (2012) Constructed wetlands support bats in agricultural landscapes. Basic and Applied Ecology, 13, 196-203