ReviewImpacts of artificial lighting on bats: a review of challenges and solutions
Section snippets
Shedding light on the challenges – how important is light pollution?
Global increases in urbanisation (Grimm et al., 2008) and human development have led to a dramatic rise in both the extent and intensity of artificial lighting throughout the 20th and 21st centuries (Cinzano, 2000, Cinzano, 2003, Cinzano et al., 2001, Hölker et al., 2010a). Light pollution affects every inhabited continent; electric lighting has increased nocturnal sky brightness by 20% (Hendry, 1984). Worldwide, artificial lighting is increasing by around 6% per annum (Hölker et al., 2010b),
Ecological impacts of lighting
Global levels of light pollution are set to increase as human populations rise and become more urbanised. There has been increasing awareness of the ecological impacts of light pollution associated with urbanisation (Davies et al., 2013b, Gaston et al., 2012, Gaston et al., 2013, Harder, 2002, Hölker et al., 2010a, Hölker et al., 2010b, Longcore and Rich, 2004, Navara and Nelson, 2007, Smith, 2009). Light pollution affects ecological interactions across a range of taxa and negatively affects
Impacts of artificial lighting on bats
As the second most species-rich mammalian order in the world (Wilson and Reeder 2005) bats represent a significant contribution to global biodiversity (Altringham, 1996, Racey and Entwistle, 2003). Bats make effective bio-indicators, capturing the responses of a range of taxa and reflecting components of biological diversity such as species richness and biodiversity (Jones et al., 2009). Due to their high niche diversity bats are also effective ecological indicators reflecting responses over a
Species-specific effects
Responses to light pollution are species-specific (Rydell, 1991), and so care must be taken in making generalizations about potential impacts across bat species. Species-specific responses to light may be a function of flight morphology and echolocation: relatively fast-flying bats which typically forage in the open using long range echolocation pulses such as Eptesicus, Nyctalus and Pipistrellus species are attracted to street lights (Blake et al., 1994, Rydell, 1991, Rydell, 1992), whereas
How big are the impacts: community and ecosystem effects?
To date there is no specific evidence of community or ecosystem level effects of artificial lighting on bats. However, evidence suggests that the effects of lighting on bats are likely to cascade to the community level. Lighting may alter the balance of communities through competitive exclusion of less tolerant species, as more light-tolerant species may out-compete them for aerial insect prey. A possible cause of the population decline in Rhinolophus hipposideros in Switzerland was competitive
Avoidance
The simplest and most effective way to minimise the effects of lighting on bats is to avoid illuminating the areas being used by bats. Where the area used by bats, such as foraging or commuting habitat, is already illuminated, lights can be switched off or removed, or light can be excluded using physical barriers such as hedgerows and walls. In many cases existing lamps are outdated, poorly installed and/or maintained, resulting in light trespass into unwanted areas. For example, 31% of UK
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