Action: Use prescribed burning
- Nine studies evaluated the effects of prescribed burning on bat populations. Eight studies were in the USA and one study was in Australia.
COMMUNITY RESPONSE (1 STUDY)
- Community composition (1 study): One replicated, controlled, before-and-after, paired sites study in Australia found that the composition of bat species differed between burned and unburned woodland sites.
POPULATION RESPONSE (4 STUDIES)
- Abundance (4 studies): Two replicated, site comparison studies (including one controlled study) in the USA found that the activity (relative abundance) of open habitat bat species and evening bats increased with the number of prescribed fires, but there was no effect on other bat species, including cluttered habitat bat species7. One replicated, controlled, before-and-after, paired sites study in Australia found that prescribed burning resulted in higher overall bat activity. One site comparison study in the USA found that two of seven sites that had been burned alongside other restoration practices had higher bat activity than unrestored sites.
USAGE (4 STUDIES)
- Use (4 studies): One replicated, controlled before-and-after study in the USA found that more female northern myotis bats roosted in burned than unburned forest. Two replicated, controlled, before-and-after studies in the USA found that fewer female northern myotis bats and male Indiana bats roosted in burned than unburned forest. One replicated study in the USA found that evening bats roosted in burned but not unburned forest.
- Behaviour change (2 studies): Two replicated, controlled, site comparison studies in the USA found no difference in roost switching frequency or the distance between roost trees for female northern myotis bats and male Indiana bats in burned and unburned forests. One replicated, controlled, before-and-after study in the USA found that female northern myotis home ranges and core areas did not differ in size between burned and unburned forests, but home ranges were closer to burned forest than unburned forest.
Prescribed burning is a practice used in forest management where controlled burns are conducted to reduce the risk of more damaging uncontrolled natural fires and to stimulate tree germination. Controlled burning alters forest structure, opens up the tree canopy and creates potential roosts in snags.
Although prescribed or controlled burning may benefit bats, there may also be negative effects such as heat injury, smoke and carbon monoxide poisoning, and arousal from torpor. Consideration must be given to fire intensity, ignition procedures and seasonal timing of burns (Dickinson et al 2010).
Dickinson M.B., Norris J.C., Bova A.S., Kremens R.L., Young V. & Lacki M.J. (2010) Effects of wildland fire smoke on a tree-roosting bat: integrating a plume model, field measurements, and mammalian dose-response relationships. Canadian Journal of Forest Research, 40, 2187–2203.
Supporting evidence from individual studies
A replicated, controlled, site comparison study in 2001–2002 in nine pine forest sites in South Carolina, USA (Loeb & Waldrop 2008) found that burned tree stands had similar activity of three bat species to unburned control tree stands, and two bat species had higher activity in thinned stands than burned stands. Activity of big brown bats Eptesicus fuscus, eastern red bats Lasiurus borealis and eastern pipistrelles Perimyotis subflavus did not differ significantly between burned tree stands (big brown bats: average 0.3 bat passes/night; red bats: 0.3 bat passes/night; eastern pipistrelles: 0.1 bat passes/night) and unburned control stands (big brown bats: 0.1 bat passes/night; red bats: 0.5 bat passes/night; eastern pipistrelles: 0.1 bat passes/night). Activity was significantly higher in thinned tree stands than burned stands for big brown bats (1.2 bat passes/night) and eastern red bats (0.7 bat passes/night), but similar for eastern pipistrelles (0.4 bat passes/night). Nine 14 ha stands (loblolly pine Pinus taeda and shortleaf pine Pinus echinata) were surveyed with three replicates of three treatment types: thinning to 18 m2/ha (in winter 2000–2001), prescribed burning (burned in April 2001 with strip head fire and flanking fires), and a control with no treatment. Bat activity was sampled with two bat detectors at random points in each of 12 stands for two full nights/month from May–August 2001 and 2002.
A replicated study in 2003–2004 in a 1,200 ha deciduous forest in Missouri, USA (Boyles & Aubrey 2006) found that evening bats Nycticeius humeralis roosted only in areas of the forest where prescribed burning had occurred. Twenty-three bats were tracked to 63 tree roosts in burned areas, and no roosts were found in unburned areas. The burned area of the forest had a more open canopy and significantly more dead trees than the unburned area. Prescribed burning began in 1999 after 50 years of fire suppression and was done every two years in March or April in 55% of the study area. Bats were caught from March 2003 to March 2004 using mist nets across forest roads between the burned and unburned areas of the forest and in 2–3 ponds or roads in both areas. Twenty-three bats (11 females and 12 males) were fitted with radio-transmitters and tracked to roost trees each day until the transmitter was shed or expired.
A site comparison study in 2004–2005 in nine forest fragments within the Chicago metropolitan area, USA (Smith & Gehrt 2010) found that two of seven forest fragments that had undergone restortation, including prescribed burning, had higher bat activity than two unrestored forest fragments. Bat activity was higher in two forest fragments that had been restored with multiple prescribed burns, invasive plant species removal and snag recruitment (average 7–19 bat passes/survey) than in two control sites with no restoration (average 1–4 bat passes/survey). Bat activity was similar between control sites and five other forest fragments that had been restored with multiple prescribed burns and various combinations of invasive species removal, snag recruitment and deer population control (1–6 bat passes/survey). Six bat species were recorded in total (see original reference for data for individual species). The study does not distinguish between the effects of prescribed burning and the other interventions carried out. Fire suppression over the last 100 years had altered the structure of the nine forest fragments (10–260 ha in size). Seven of the nine forest fragments were being restored to open up the canopy, reduce tree density and remove invasive plant species. At each of nine sites, four bat detectors recorded bat activity for four hours from sunset for five nights/year in June–September 2004 and May–August 2005.
A replicated, controlled, before-and-after study in 2006–2007 of three mixed forest sites in Kentucky, USA (Lacki et al 2009) found that burned forest had more female northern myotis Myotis septentrionalis roosts than unburned forest, and home ranges were closer to burned than unburned forest. Following prescribed fires, more female northern myotis bat roosts were in burned forest (26 roosts, 74%) than unburned forest (nine roosts, 26%), although no statistical tests were carried out. The average size of home ranges and core areas did not vary significantly between bats radiotracked before (home range: 60 ha; core area: 11 ha) and after fires (home range: 72 ha; core area 14 ha), but home ranges were closer to burned habitats than unburned habitats following fires. Two sites (435 ha, 185 ha) that were previously unburned were subject to prescribed burning in April 2007, with 54% of the area burned. A third site (2,400 ha) was left unburned. Bats were captured in June–July 2006 and April–September 2007 using mist nets over ponds in burned and unburned sites. Eighteen female bats were radiotracked nightly for an average of six days.
A replicated, controlled, site comparison study in 2007–2008 of four mixed forest sites in West Virginia, USA (Johnson et al 2009) found female northern myotis bats Myotis septentrionalis roosting in tree stands treated with prescribed fire and in unburned forest, and roost switching frequency and the distance between roost trees did not differ between burned and unburned forest. Twenty-five roosts were in burned tree stands and 44 in unburned forest, but the difference was not tested for statistical significance. Roost switching frequency and the distance between roost trees did not differ significantly between burned (1–6 days, average 152 m) and unburned forest (1–5 days, 230 m). In April–May 2007 and 2008, three stands (45, 13 and 21 ha) were burned for one day using a strip head fire technique. The remainder of the 1,900 ha forest was left unburned. Bats were captured over streams, pools, trails and service roads at burned and unburned sites using mist nets in May–August 2007 and 2008. In 2007, three female bats were radiotracked to eight roosts. In 2008, 33 female bats were radiotracked to 65 roosts, four of which were used previously in 2007.
A replicated, controlled, site comparison study in 2007–2008 in two mixed forests in West Virginia, USA (Johnson et al 2010) found male Indiana bats Myotis sodalis roosting in tree stands treated with prescribed fire and in unburned forest, and roost switching frequency and the distance between roost trees did not differ between burned and unburned forest. Sixteen roosts were in burned tree stands and 34 roosts were in unburned forest, but the difference was not tested for statistical significance. Roost switching frequency and the distance between roost trees did not differ significantly between burned (1–4 days, average 220 m) and unburned forest (1–2 days, 477 m). In April–May 2007–2009 three stands (12, 13 and 121 ha) within one of two of the forests (Fernow Experimental Forest, 1900 ha) were subjected to prescribed burning using a strip head fire technique. In the other forest (Petit Farm, 400 ha) in March 2003 an escaped campfire had burned part of the forest stand. Control stands were unburned areas in each of the two forests. Bats were captured over streams, pools, ponds and trails using mist nets in burned and unburned forest in June–July 2004–2006 at Petit Farm and June–July 2008–2009 at Fernow Experimental Forest, and also at a cave swarming site at Fernow Experimental Forest in September–October 2007–2008. A total of fifteen male bats were radiotracked.
A replicated, site comparison study in 2008–2009 of 48 sites in two mixed forests in Florida, USA (Armitage & Ober 2012) found that the frequency of prescribed burns had no effect on the activity of cluttered habitat bat species, but open habitat bat species were recorded less in forest sites with longer periods between burns. The activity of bat species adapted to cluttered habitats did not differ significantly in forest sites with different burn frequencies (1–2 year burn: average 6 bat passes/site/night; 3–5 year burn: 4 bat passes/site/night; >8 year burn: 6 bat passes/site/night). Bat species adapted to open habitats had significantly lower activity in forest sites with a longer period between burns (>8 years: 0.03 bat passes/site/night) than forest sites with more frequent burns (1–2 year burn: 0.1 bat passes/site/night; 3–5 year burn: 0.05 bat passes/site/night). Twenty-four 40 ha study plots were randomly selected in each of two forests with eight plots for each of three burn frequencies (burns every 1–2 years, 3–5 years or >8 years). Bat detectors recorded nightly bat activity at two randomly chosen sites/burn frequency/night for four evenings/week with sites rotated weekly in May–August 2008 and 2009.
A replicated, controlled, before-and-after, paired sites study in 2008 in six tropical eucalypt woodland sites in northern Queensland, Australia (Inkster-Draper et al 2013) found that prescribed burning resulted in higher bat activity and a change in species composition. Significantly more bat calls were recorded at treatment sites after prescribed burning (average 2,423) than before (1,174). There was no significant difference in bat calls at unburned control sites over the same period (‘before’: 1,008; ‘after’: 1,568 bat calls). Species composition also differed at the treatment sites before and after burning, but did not differ at unburned control sites over the same period (data reported as statistical model results). At least ten bat species were recorded (see original reference for data for individual species). One site from each of six pairs was burned with a low intensity fire for two days (treatment) with the other remaining unburned (control). Bat activity was recorded using bat detectors at six paired sites for 336 bat detector nights in June and July 2008 before burning, and for 234 bat detector nights during August, September and October 2008 after burning.
A replicated, controlled, site comparison study in 2010–2012 in 26 savanna and woodland sites in Missouri, USA (Starbuck et al 2015) found that prescribed burning increased occupancy rates of burned sites for one of five bat species. Occupancy rates of the evening bat Nycticeius humeralis significantly increased at burned sites with a greater number of prescribed fires in the past 10 years (data reported as statistical model results). The number of fires did not have a significant effect on the occupancy rates of burned sites for four other bat species (northern long-eared bat Myotis septentrionalis, big brown bat Eptesicus fuscus, eastern red bat Lasiurus borealis, tri-coloured bat Perimyotis subflavus). At each of 26 sites, surveys were carried out at 4–28 sampling points in managed forest and unmanaged mature forest. Managed forests had been burned (with 1–8 fires over 10 years) and thinned to restore savanna or woodland. Bat detectors recorded bat activity at each sampling point for two full consecutive nights during 1–2 years in 2010–2012.
- Loeb S.C. & Waldrop T.A. (2008) Bat activity in relation to fire and fire surrogate treatments in southern pine stands. Forest Ecology and Management, 255, 3185-3192
- Boyles J.G. & Aubrey D.P. (2006) Managing forests with prescribed fire: Implications for a cavity-dwelling bat species. Forest Ecology and Management, 222, 108-115
- Smith D.A. & Gehrt S.D. (2010) Bat response to woodland restoration within urban forest fragments. Restoration Ecology, 18, 914-923
- Lacki M.J., Cox D.R., Dodd L.E. & Dickinson M.B. (2009) Response of northern bats (Myotis septentrionalis) to prescribed fires in eastern Kentucky forests. Journal of Mammalogy, 90, 1165-1175
- Johnson J.B., Edwards J.W., Ford W.M. & Gates J.E. (2009) Roost tree selection by northern myotis (Myotis septentrionalis) maternity colonies following prescribed fire in a Central Appalachian Mountains hardwood forest. Forest Ecology and Management, 258, 233-242
- Johnson J.B., Ford W.M., Rodrigue J.L., Edwards J.W. & Johnson C.M. (2010) Roost selection by male Indiana myotis following forest fires in Central Appalachian Hardwoods Forests. Journal of Fish and Wildlife Management, 1, 111-121
- Armitage D.W. & Ober H.K. (2012) The effects of prescribed fire on bat communities in the longleaf pine sandhills ecosystem. Journal of Mammalogy, 93, 102-114
- Inkster-Draper T.E., Sheaves M., Johnson C.N. & Robson S.K.A. (2013) Prescribed fire in eucalypt woodlands: immediate effects on a microbat community of northern Australia. Wildlife Research, 40, 70-76
- Starbuck C.A., Amelon S.K. & Thompson F.R. III (2015) Relationships between bat occupancy and habitat and landscape structure along a savanna, woodland, forest gradient in the Missouri Ozarks. Wildlife Society Bulletin, 39, 20-30