Bat Conservation: Global evidence for the effects of interventions
120
Bat Conservation: Global evidence for the effects of interventions
120Hardcover(First Edition)
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Overview
This book brings together scientific evidence and experience relevant to the practical conservation of bats. The authors have developed a global list of interventions that could benefit bats. For each intervention, the book summarises studies captured by the Conservation Evidence project.
Product Details
| ISBN-13: | 9781907807909 |
|---|---|
| Publisher: | Pelagic Publishing |
| Publication date: | 05/16/2014 |
| Series: | Synopses of Conservation Evidence , #5 |
| Edition description: | First Edition |
| Pages: | 120 |
| Product dimensions: | 7.00(w) x 10.00(h) x (d) |
About the Author
Olivia Richardson is a conservation ecologist who has recently been working as a Research Assistant and an ecological consultant. She holds degrees in Biodiversity and Conservation (MSc) and Biology (BSc with Honours), both from the University of Leeds. She is a former British Ecological Society Education, Training and Careers committee member and Undergraduate Fellow alumni. Her research interests include bat conservation, urban ecology, citizen science and applied ecology and its translation into policy and practice.
John Altringham is Professor of Animal Ecology & Conservation at the University of Leeds. He works primarily on the ecology and conservation of bats, but has broad interests in conservation. In the past he has studied animals as diverse as tunas and tarantulas. He is the author of numerous scientific papers and reports, and three books on bats, the most recent being Bats, from evolution to conservation, published by OUP in 2011. He is a scientific advisor to the National Trust and other conservation organisations.
Read an Excerpt
CHAPTER 1
Threat: Residential and commercial development
Key messages
Conserve existing roosts within developments
We found no evidence for the effects of interventions to conserve existing roosts within developments.
Retain or relocate access points to bat roosts
We found no evidence for the effects of interventions to retain or relocate access points to bat roosts within developments.
Create alternative roosts within buildings
We found no evidence for the effects of interventions to provide alternative roosts within buildings.
Change timing of building works
We found no evidence for the effects of changing the timing of building works on bats.
Conserve old buildings or structures as roosting sites for bats
We found no evidence for the effects of conserving old buildings or structures as roosting sites for bats.
Maintain bridges and retain crevices for roosting
We found no evidence for the effects of maintaining old bridges and retaining crevices for roosting bats.
Protect brownfield sites
One study in the USA found bat activity within an urban wildlife refuge on an abandoned manufacturing site to be consistent with predictions across North America based on the availability of potential roosts.
Provide foraging habitat in urban areas
One site comparison study in the USA found higher bat activity in restored forest preserves in urban areas than in an unrestored forest preserve. One replicated, controlled, site comparison study in the UK found higher bat activity over green roofs in urban areas than conventional unvegetated roofs.
Retain or replace existing bat commuting routes
We found no evidence for the effects of retaining or replacing the original commuting routes of bats lost to residential or commercial development.
1.1 Conserve existing roosts within developments
• We found no evidence for the effects of interventions to conserve existing roosts within residential or commercial developments.
1.2 Retain or relocate access points to bat roosts
• We found no evidence for the effects of interventions to either retain or relocate access points to bat roosts within developments.
1.3 Create alternative roosts within buildings
• We found no evidence for the effects of interventions to provide alternative roosts within buildings.
1.4 Change timing of building works
• We found no evidence for the effects of changing the timing of building works on bats.
1.5 Conserve old buildings or structures as roosting sites for bats
• We found no evidence for the effects of conserving old buildings or structures as roosting sites for bats.
1.6 Maintain bridges and retain crevices for roosting
• We found no evidence for the effects of interventions to maintain old bridges used as roosts by bats, or to retain crevices within them used as access points.
1.7 Protect brownfield sites
• One study in Denver, USA found that the number and evenness of bat species within an urban wildlife refuge on an abandoned manufacturing site was consistent with predictions across North America based on the availability of potential roosts.
A study in 1997 and 1998 in an urban wildlife refuge on the grounds of a former weapons manufacturing facility near Denver in the USA (1) found that the number and evenness of bat species was consistent with predictions across North America based on the availability of potential roosts. Details of the predictions are not given but the authors state that as expected from the availability of roosts (in a few dead trees and an abundance of buildings), three tree-roosting species and two species known to roost in buildings were captured or recorded, with big brown bats Eptesicus fuscus (common in urban areas) making up 86% of the captures. In total, 176 bats were captured and 955 bat passes were recorded. Activity was more than five times greater in areas of the refuge with tree or water habitat edges than in open prairie. Big brown bats commuted further from roosts in buildings within surrounding urban areas to the refuge (9–19 km) than typically reported for the species elsewhere (1–2 km). Bats were captured over two years from May to August on 53 nights at 18 sites. Mist nets were set up over water or by trees and shrubs within the refuge. Twelve big brown bats were captured and radio-tagged in 1998. Echolocation activity was recorded using bat detectors at eight sites with different habitat types within the refuge. Each site was sampled for a total of 90 minutes on 3–4 nights between June and August 1997. The chemical weapons facility was active up until 1985, and the site was designated and protected as a wildlife refuge with the passing of an Act in 1992. The refuge covers 6,900 ha consisting of grassland with scattered woodland and wetlands. It borders an urban area with a population of two million people, as well as industrial and agricultural land.
1.8 Provide foraging habitat in urban areas
• One site comparison study in the USA found higher bat activity in restored forest preserves in urban areas than in an unrestored forest preserve. Different species responded differently to the changes in forest structure.
• One replicated, controlled, site comparison study in the UK found significantly higher bat activity and more bat feeding events over green roofs in urban areas than conventional unvegetated roofs.
In a site comparison study in 2004–2005 in nine forest preserves within the Chicago metropolitan area, USA (1) the highest bat activity was recorded in two preserves that had undergone restoration with multiple prescribed burns, invasive plant species removal and snag recruitment (average 19 and 16 bat passes/preserve in 2004, average 7 and 18 bat passes/preserve in 2005). The lowest bat activity was recorded in a control site with no restoration (both years average one bat pass in total). Overall bat activity at all sites was positively related to prescribed burning, invasive species removal and small tree density (8–20 cm diameter at breast height) and negatively related to shrub density and clutter at heights of 0–6 m above the ground. Responses to woodland restoration varied among bat species. The eastern red bat Lasiurus borealis was positively associated with small and medium (20–33 cm) tree densities and negatively related to clutter at 0–9 m. Myotis spp. were positively associated with canopy cover, clutter at 6–9 m and small and medium tree densities. The silver-haired bat Lasionycteris noctivagans was positively associated with more open forests. The activity of the big brown bat Eptesicus fuscus was not associated with any vegetation variables in the study. The nine forest preserves varied in size from 10 to 260 ha. Fire suppression over the last 100 years had altered the structural diversity of the forests. Eight of the forest preserves were under management to restore forest to pre-European settlement conditions. Restoration practices were used to open canopy cover, reduce tree density and remove invasive plant species. Bats were monitored for four hours from sunset with bat detectors in June–September 2004 and May–August 2005 for five nights per site per year. Twenty randomly located 30 m line transects were sampled per site with four detectors placed 10 m apart along each transect.
A replicated, controlled, site comparison study from May to September 2010 in urban areas of Greater London, UK (2) found significantly higher bat activity over 'biodiverse' green roofs planted with a variety of wild flowers, herbs, sedums, mosses and grasses than over conventional unvegetated roofs. An average of 8 bat call sequences and 0.56 feeding events/night were recorded over 'biodiverse' green roofs and 5 bat call sequences and 0.38 feeding events/ night over conventional roofs. This was significant when a small amount (< 33%) of suitable bat habitat was located within 100 m of the roof. Bat activity and feeding events over 'sedum' green roofs planted with low-growing succulent plants (average 2 bat call sequences and 0.03 feeding events/night) did not differ from conventional roofs. Common pipistrelle Pipistrellus pipistrellus was most frequently recorded followed by soprano pipistrelle Pipistrellus pygmaeus, Nyctalus/Eptesicus spp. and Nathusius' pipistrelle Pipistrellus nathusii. All species were recorded feeding over biodiverse green roofs, but only common pipistrelles (and one record of a noctule bat Nyctalus noctula ) were recorded over conventional and sedum green roofs. Roof height was found to negatively affect bat activity, with only one feeding event recorded over buildings more than two storeys high. Bat activity was recorded over 13 biodiverse, 9 sedum and 17 conventional roofs for 7 full nights. Conventional roofs were flat or shallow pitched with bitumen felt or paving slabs. All green roofs were low maintenance 'extensive' roofs, with shallow substrate (20–200 mm, but usually 35–75 mm).
1.9 Retain or replace existing bat commuting routes
• We found no evidence for the effects of retaining or replacing the original commuting routes of bats lost to residential or commercial development.
CHAPTER 2
Threat: Agriculture
Key messages – Land use change
Conserve old buildings or structures as roosting sites for bats
We found no evidence for the effects of conserving old buildings or structures on agricultural land as roosting sites for bats.
Retain old or dead trees with hollows and cracks as roosting sites for bats
We found no evidence for the effects of retaining old or dead trees on agricultural land as roosting sites for bats.
Retain or plant trees to replace foraging habitat for bats
We found no evidence for the effects of retaining trees as foraging habitat for bats. Two site comparison studies (one replicated) in Australia found no difference in bat activity and the number of bat species in agricultural areas revegetated with native plantings and over grazing land without trees. In both studies, bat activity was lower in plantings than in original forest and woodland remnants.
Protect or create wetlands as foraging habitat for bats
We found no evidence for the effects of protecting existing wetlands. 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. A replicated study in Germany found high levels of bat activity over constructed retention ponds compared to nearby vineyard sites, but comparisons were not made with natural pond sites.
Retain or replace existing bat commuting routes
We found no evidence for the effects of retaining or replacing the original commuting routes of bats lost due to agricultural land use change.
For all evidence relating to the use of bat boxes/houses, see 'Providing artificial roost structures for bats'.
Key messages – Intensive farming
Convert to organic farming
Four replicated, paired, site comparison studies on farms in the UK had inconsistent results. Two studies found higher bat abundance and activity on organic farms than conventional farms, and two studies showed no difference in bat abundance between organic and non-organic farms.
Introduce agri-environment schemes
One replicated, paired study in Scotland, UK found lower bat activity on farms participating in agri-environment schemes than on non-participating conventional farms.
Encourage agroforestry
Four replicated, site comparison studies (three in Mexico and one in Costa Rica) found no difference in bat diversity, the number of bat species and/or bat abundance between cacao, coffee or banana agroforestry plantations and native rainforest. One replicated, site comparison study in Mexico found higher bat diversity in native forest fragments than in coffee agroforestry plantations. One replicated, randomized, site comparison study in Costa Rica found lower bat diversity in native rainforest than in cacao agroforestry plantations. A replicated, site comparison study in Mexico found that bat diversity in coffee agroforestry plantations and native rainforest was affected by the proportion of each habitat type within the landscape. Three studies found that increasing management intensity on agroforestry plantations had a negative effect on some bat species, and a positive effect on others.
Land use change
2.1 Conserve old buildings or structures as roosting sites for bats
• We found no evidence for the effects of conserving old buildings or structures on agricultural land as roosting sites for bats.
2.2 Retain dead/old trees with hollows and cracks as roosting sites for bats
• We found no evidence for the effects of retaining old or dead trees with hollows and cracks as roosting sites for bats on agricultural land.
2.3 Retain or plant trees to replace foraging habitat for bats
• We found no evidence for the effects of retaining trees as foraging habitat for bats.
• Two site comparison studies (one replicated) in Australia found no difference in bat activity and the number of bat species in agricultural areas revegetated with native plantings and over grazing land without trees. In both studies, bat activity was lower in plantings than in original forest and woodland remnants.
A replicated, site comparison study in late spring and early summer 2002 in an agricultural and forested area of New South Wales and Victoria, Australia (1), found that sites revegetated with native eucalypt plantings did not have significantly higher bat activity or more species than treeless grazed paddocks (average 87 vs. 50 bat passes/night and 5–7 vs. 5 species, respectively). Bat activity in revegetated sites was less than a third of that recorded in small remnants of original forest and woodland (average 302 bat passes/night). There was no significant difference between the number of bat species found in young plantings (average six species) and original remnants (average seven species). Old plantings had fewer bat species than remnant sites of a similar size. There was no significant difference in bat activity between large and small or young and old plantings. Twelve treatment classes including different sizes and ages of plantings, original remnants of forest and woodland, and grazed paddocks with and without trees were sampled with ten replicates per site. Bat activity was recorded at a single location at each site for one full night using bat detectors. The study area was dominated by grazing land with sparse remnants of forest and woodland vegetation. As part of a government initiative, extensive planting of locally indigenous tree species was carried out from the mid 1970s to 1991.
A site comparison study in summer 1999 in four agricultural sites revegetated with native bluegum Eucalyptus globulus plantations in Western Australia (2) found that bat activity was higher in plantations next to remnant vegetation than over agricultural grazing land, although differences were not tested for statistical significance (total 52 vs. 14 bat passes respectively). Bat activity was highest in remnant vegetation (75 bat passes), and lowest in plantations isolated from remnants of original vegetation and surrounded by grazing land (four bat passes). Similar numbers of species (two to four) were recorded in plantations and grazing land. Eight bat species were detected in original remnants, three of which were only found in this habitat type. The four study areas selected consisted of commercially established farm forestry plantations of four to six years in age, remnants of original native vegetation, and open grazing land. Within each study area, four treatment sites were sampled for one full night and bat activity recorded with bat detectors. The treatments sampled were remnant vegetation, plantations adjacent to remnant vegetation, grazing land and plantations adjacent to grazing land. The results from all four study areas were pooled to give totals for each treatment.
2.4 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.
(Continues…)
Excerpted from "Bat Conservation"
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Copyright © 2014 William J. Sutherland.
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