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Providing evidence to improve practice

Action: Retain remnant forest or woodland on agricultural land Bat Conservation

Key messages

  • Six studies evaluated the effects of retaining forest or woodland on agricultural land on bat populations. Four studies were in Australia, one in the UK, and one in Brazil.

COMMUNITY RESPONSE (4 STUDIES)

  • Community composition (2 studies): One of two replicated, site comparison studies in Australia and Brazil found that remnant woodland had a different composition of bat species to plantations and treeless paddocks. The other study found that bat species composition was similar between remnant forest and plantations.
  • Richness/diversity (4 studies): Three of four replicated, site comparison studies in Australia and Brazil found more bat species in remnant forest and woodland than in plantations or treeless paddocks or pasture. The other study found a similar number of bat species in remnant forest, plantations and paddocks.

POPULATION RESPONSE (6 STUDIES)

  • Abundance (6 studies): Five replicated, site comparison studies in Australia, the UK and Brazil found higher bat activity (relative abundance) or more bats in remnant forest or woodland than in plantations, treeless paddocks or pasture, or on arable land. One replicated study in Australia found higher activity for three of 10 bat species in remnant woodland than in treeless paddocks.

USAGE (1 STUDY)

  • Use (1 study): One replicated, site comparison study in Australia4 found bats roosting in trees within remnant woodland but not in trees within plantations.

Supporting evidence from individual studies

1 

A replicated, site comparison study in 1999 of four agricultural sites with remnant forest and plantations in Western Australia (Hobbs et al 2003) found that remnants of native forest had higher overall bat activity and more bat species than plantations or agricultural grazing land. More bat passes were recorded in remnant forest (75 bat passes) than in plantations next to remnant vegetation (52 bat passes), isolated plantations (4 bat passes) or over agricultural grazing land (14 bat passes), although no statistical tests were carried out. More bat species were recorded in remnant forest (8 species) than in plantations and grazing land (2–4). Eight bat species were recorded in total (see original reference for data for individual species). All four sites had remnants of original native forest, farm forestry plantations (4–6 year old native bluegum Eucalyptus globulus), and open grazing land. At each of four sites, one location within each of four habitats (remnant forest, plantations next to remnants, isolated plantations and grazing land) was sampled with a bat detector for one full night in October 1999.

2 

A replicated, site comparison study in 2002 of 120 sites in an agricultural area in New South Wales and Victoria, Australia (Law & Chidel 2006) found that remnants of original forest had higher bat activity than plantations or treeless grazed paddocks, but the number of bat species did not differ. More bat passes were recorded in remnants of original forest (average 302 bat passes/night) than in plantations (87 bat passes/night) or treeless grazed paddocks (50 bat passes/night). However, a similar number of bat species were recorded in remnants of forest (7 species), plantations (5–7 species) and paddocks (5 species). Eleven bat species were recorded in total (see original reference for data for individual species). Grazing land with small remnants of forest had been planted with native tree species from the mid-1970s to 1991. There were twelve treatments including different shapes or sizes (narrow, small, medium, large, very large) and ages (<10 or >10 years old) of remnants of original forest, plantations, and grazed paddocks with and without trees. For each of twelve treatments, 10 points were sampled with bat detectors for one full night in November–December 2002.

3 

A replicated study in 2002 of 12 agricultural sites in southeastern Australia (Lumsden & Bennett 2005) found that remnants of native woodland had higher activity for three bat species than paddocks without trees, but no difference was found for seven other bat species or species groups. Average bat activity was significantly higher in remnants of woodland than treeless paddocks for the chocolate wattled bat Chalinolobus morio (remnants: 2.3 bat passes; treeless paddocks: 0.3 bat passes), western broad-nosed bat Scotorepens balstoni (remnants: 0.9 bat passes; treeless paddocks: 0.1 bat passes) and little forest bat Vespadelus vulturnus (remnants: 36 bat passes; treeless paddocks: 2 bat passes). There was no significant difference between remnant woodland and treeless paddocks for the white-striped free-tailed bat Tadarida australis, southern free-tailed bat Mormopterus spp., eastern free-tailed bat Mormopterus spp., Gould’s wattled bat Chalinolobus gouldii, the large forest bat Vespadelus darlingtonia, the southern forest bat Vespadelus regulus or long-eared bats Nyctophilus spp. (see the original reference for detailed results for each species). Two remnant woodlands (<10 ha) and two treeless paddocks were surveyed in each of three study areas. Each of 12 sites was sampled with a bat detector for four nights in January–April 2002.

4 

A replicated, site comparison study in 2006–2007 at 14 farms in Tasmania (Law et al 2011) found that remnant native woodlands had higher bat activity, more bat species and more bat roosts than plantations and treeless paddocks, and species composition also differed. Bat activity and the number of bat species recorded was higher in remnant woodland (650 bat passes/night, 10 species) than in plantations (87 bat passes/night, 6–8 species) and paddocks (40 passes/night, 7 species), although no statistical tests were carried out. Twenty-eight bat roosts were identified in remnant trees, but none in plantations. Species composition differed in remnant woodland compared to plantations and paddocks (data reported as results of statistical models). Twelve bat species were recorded in total (see original reference for data for individual species). Forty-four sites were surveyed across 14 farms (11 in remnant woodland, 27 in plantations, six in treeless paddocks). Plantations (2–40 ha) consisted of 1–4 Eucalyptus spp. and were 4–5 or 10 years old. Each of 44 sites was surveyed for two consecutive nights/site in September 2006 and February 2007. Ten bats were caught in harp traps and radiotracked in late summer and spring 2008 at three farms.

5 

A replicated, site comparison study in 2009–2010 of 34 woodland patches in an agricultural landscape in central Scotland, UK (Fuentes-Montemayor et al 2013) found that remnant woodland patches had higher activity for three bat species or species groups than surrounding pasture or arable land. The average number of bat passes recorded was significantly higher in the interior of remnant woodland patches than over pasture or arable land for common pipistrelle Pipistrellus pipistrellus (woodland: 0.9; pasture/arable: 0.1), soprano pipistrelle Pipistrellus pygmaeus (woodland: 22; pasture/arable: 2) and Myotis spp. (woodland: 0.1; pasture/arable: 0.02). All of 34 broadleaved or mixed woodland patches (0.1–30 ha) were >60 years old and surrounded by pasture and/or arable land. At each of 34 woodland patches, bat activity was recorded with bat detectors for 10 minutes at 2–4 sampling points in the woodland interior and two sampling points over pasture/arable land >20 m from the woodland edge. Each of 34 sites was surveyed once in June–August 2009 or May–July 2010.

6 

A replicated, site comparison study in 2010–2011 in eight sites of remnant forest and plantations in an agricultural area of central Brazil (Pina et al 2013) found that remnant forest fragments had more bats and bat species captured within them than plantations, but species composition did not differ. Significantly more bats and more bat species were captured in remnant forest fragments (134 bats of 13 species) than in plantations (75 bats of 8 species). However, species composition did not differ significantly (data reported as statistical model results). Four fragments (150–378 ha) of each of two habitat types were surveyed: Eucalyptus spp. plantations and semi-deciduous native remnant forest. Fragments were surrounded by soybean or sugar cane plantations and cattle pastures. Each of eight fragments was sampled for one night/month between December 2010 and April 2011 with 10 mist nets deployed along linear transects for four hours from sunset.

Referenced papers

Please cite as:

Berthinussen, A., Richardson, O.C., Smith, R.K., Altringham, J.D. & Sutherland, W.J. (2018) Bat Conservation. Pages 67-93 in: W.J. Sutherland, L.V. Dicks, N. Ockendon, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2018. Open Book Publishers, Cambridge, UK.