title: The ecological impact of city lighting scenarios: exploring gap crossing thresholds for urban bats.
abstract: As the global population urbanizes, dramatic changes are expected in city lighting and the urban form, which may threaten the functioning of urban ecosystems and the services they deliver. However, little is known about the ecological impact of lighting in different urban contexts. Movement is an important ecological process that can be disrupted by artificial lighting. We explored the impact of lighting on gap crossing for Pipistrellus pipistrellus, a species of bat (Chiroptera) common within UK cities. We aimed to determine whether the probability of crossing gaps in tree cover varied with crossing distance and lighting level, through stratified field surveys. We then used the resulting data on barrier thresholds to model the landscape resistance due to lighting across an entire city and explored the potential impact of scenarios for future changes to street lighting. The level of illumination required to create a barrier effect reduced as crossing distance increased. For those gaps where crossing was recorded, bats selected the darker parts of gaps. Heavily built parts of the case study city were associated with large and brightly lit gaps, and spatial models indicate movement would be highly restricted in these areas. Under a scenario for brighter street lighting, the area of accessible land cover was further reduced in heavily built parts of the city. We believe that this is the first study to demonstrate how lighting may create resistance to species movement throughout an entire city. That connectivity in urban areas is being disrupted for a relatively common species raises questions about the impacts on less tolerant groups and the resilience of bat communities in urban centres. However, this mechanistic approach raises the possibility that some ecological function could be restored in these areas through the strategic dimming of lighting and narrowing of gaps.
authors: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors: James D
authors: JD
authors: Hale
authors: Centre for Urban Sustainability and Resilience, University College London, Chadwick Building, Gower Street, London, WC1E 6BT, UK.
authors: Alison J
authors: AJ
authors: Fairbrass
authors: School of Geography and the Environment, Oxford University Centre for the Environment, University of Oxford, South Parks Road, Oxford, OX1 3QY, UK.|CE3C - Centre for Ecology, Evolution and Environmental Changes/Azorean Biodiversity Group and Universidade dos Açores, Departamento de Ciências Agrárias, Portugal.
authors: Thomas J
authors: TJ
authors: Matthews
authors: Lancaster Environment Centre, Lancaster University, Lancaster, LA1 4QY, UK.
authors: Gemma
authors: G
authors: Davies
authors: School of Geography, Earth and Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK.
authors: Jon P
authors: JP
authors: Sadler
keywords: 
  Pipistrellus pipistrellus
  ; connectivity; gap crossing; lighting; movement; scenarios; urban; urbanization
references: Environ Manage. 2010 Feb;45(2):227-38
references: 20016982
references: Sci Rep. 2014 Jan 21;4:3789
references: 24445659
references: J Appl Ecol. 2012 Dec;49(6):1256-1266
references: 23335816
references: PLoS One. 2012;7(3):e33300
references: 22428015
references: Int J Health Geogr. 2005 Feb 10;4(1):5
references: 15705196
references: J Pineal Res. 2007 Oct;43(3):215-24
references: 17803517
references: Ambio. 2014 May;43(4):413-33
references: 24740614
references: Glob Chang Biol. 2013 Feb;19(2):401-10
references: 23504779
references: Sci Total Environ. 2006 May 1;360(1-3):196-204
references: 16297440
references: J Environ Manage. 2011 Oct;92(10):2714-22
references: 21745709
references: PLoS One. 2013 May 06;8(5):e61460
references: 23671566
references: PLoS One. 2011;6(8):e22355
references: 21829617
references: Curr Biol. 2009 Jul 14;19(13):1123-7
references: 19540116
references: Science. 2011 Jul 29;333(6042):592-4
references: 21798941
references: Proc Natl Acad Sci U S A. 2007 Dec 26;104(52):20672-7
references: 18093930
references: Biol Lett. 2012 Oct 23;8(5):764-7
references: 22628095
references: Curr Biol. 2010 Oct 12;20(19):1735-9
references: 20850324
references: Biol Rev Camb Philos Soc. 2013 Nov;88(4):912-27
references: 23565807
references: Nature. 2009 Jan 1;457(7225):27
references: 19122621
references: Science. 2008 Feb 8;319(5864):756-60
references: 18258902
references: Sleep Med. 2013 Dec;14(12):1422-5
references: 24210607
references: Proc Natl Acad Sci U S A. 2008 Dec 9;105(49):19052-9
references: 19060196
references: PLoS One. 2012;7(6):e38775
references: 22719941
references: PLoS One. 2011;6(8):e23777
references: 21876770
references: Biol Lett. 2011 Oct 23;7(5):763-6
references: 21429910
references: Conserv Biol. 2010 Jun;24(3):660-8
references: 20184653
references: Trends Ecol Evol. 2010 Dec;25(12):681-2
references: 21035893