Light Pollution at the Urban Forest Edge and Its Impact on Insectivorous Bats
1 Manuscript: Light pollution at the urban forest edge and its impact on insectivorous bats 2 JK Haddock, CG Threlfall, B Law, DF Hochuli 3 This is published as Haddock JK, Threlfall CG, Law B, et al. 2019. Light pollution at the urban forest 4 edge negatively impacts insectivorous bats Biol Conserv 236: 17-28. 5 Abstract 6 Connectivity and quality of vegetation in cities, including urban forests, can promote urban 7 biodiversity. However the impact of anthropogenic pressures at the forest-matrix edge, particularly 8 artificial light at night (ALAN), on connectivity has received little attention. We assessed the 9 influence of artificial light at forest edges on insectivorous bats. We acoustically surveyed 31 forest 10 edges across greater Sydney, Australia, half with mercury vapour streetlights and half in ambient 11 darkness, and compared the bat assemblage and activity levels to urban forest interiors. We also 12 sampled the flying insect community to establish whether changes in insect densities under lights 13 drive changes in insectivorous bat activity. We recorded 9965 bat passes from 16 species or species 14 groups throughout our acoustic survey. The activity of all bats, and bats hypothesised to be 15 sensitive to artificial light, was consistently higher in forest interiors as opposed to edges. We found 16 that slower flying bats adapted to cluttered vegetation or with a relatively high characteristic 17 echolocation call frequency; Chalinolobus morio, Miniopterus australis, Vespadelus vulturnus, and 18 Nyctophilus spp., were negatively affected by artificial light sources at the forest edge. The 19 emergence time of Vespadelus vulturnus was also significantly delayed by the presence of 20 streetlights at the forest edge.
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