Reducing light pollution improves connectivity for bats in urban landscapes

Laforge, Alexis; Pauwels, Julie; Faure, Baptiste; Bas, Yves; Kerbiriou, Christian; Fonderflick, Jocelyn; Besnard, Aurélien

doi:10.1007/s10980-019-00803-0

Cited by 49 publications

(41 citation statements)

References 51 publications

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“…The studies carried out at the landscape-scale revealed negative effects of ALAN on the activity and probability of occurrence of four common species of bats: P. pipistrellus, P. kuhlii, E. serotinus, and N. leisleri, which are considered as « light attracted » species at the more local scale [22][23][24]. These hidden negative effects of ALAN at a landscape scale could also be explained by the fact that artificial lighting does not only influence species foraging behavior, but also reproduction and commuting behaviors [57], and landscape connectivity [7].…”

Section: Discussionmentioning

confidence: 99%

“…This pressure can affect individual fitness, sexual selection, and reproductive success [3][4][5]. In addition, species responses to ALAN are driven by repulsion/attraction behaviors, thereby artificial lighting can alter the movement and distribution of species at multiple spatial scales [6][7][8][9]. Taken together, ALAN effects can dramatically affect biological communities [10,11] and ecosystem functions [12].…”

Section: Introductionmentioning

confidence: 99%

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Switching LPS to LED Streetlight May Dramatically Reduce Activity and Foraging of Bats

et al. 2020

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Artificial light at night is considered a major threat to biodiversity, especially for nocturnal species, as it reduces habitat availability, quality, and functionality. Since the recent evolution in light technologies in improving luminous efficacy, developed countries are experiencing a renewal of their lighting equipment that reaches its end-of-life, from conventional lighting technologies to light emitting diodes (LEDs). Despite potential cascading impacts of such a shift on nocturnal fauna, few studies have so far dealt with the impact of the renewal of street lighting by new technologies. Specifically, only one study, by Rowse et al.2016, examined the effects of switching from widely used low pressure sodium (LPS) lamps to LEDs, using bats as biological models. This study was based on a before-after-control-impact paired design (BACIP) at 12 pairs in the UK, each including one control and one experimental streetlight. If Rowse et al. 2016 showed no effect of switching to LEDs streetlights on bat activity, the effects of respective changes in light intensity and spectrum were not disentangled when testing switch effects. Here, we conduct a retrospective analysis of their data to include these covariates in statistical models with the aim of disentangling the relative effects of these light characteristics. Our re-analysis clearly indicates that the switches in spectrum and in intensity with replacement of LPS with LED lamps have significant additive and interactive effects, on bat activity. We also show that bat activity and buzz ratio decrease with increasing LED intensity while an opposite effect is observed with LPS lamps. Hence, the loss or the gain in bat activity when lamp types, i.e., spectrum, are switched strongly depends on the initial and new lamp intensities. Our results stress the need to consider simultaneously the effects of changes in the different lights characteristics when street lighting changes. Because switches from LPS to LED lamps can lead to an increase in light intensity, such technological changes may involve a reduction of bat activity in numerous cases, especially at high LED intensities. Since we are currently at an important crossroad in lighting management, we recommend to limit LED intensity and improve its spectral composition toward warmer colors to limit potential deleterious impacts on bat activity.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Switching LPS to LED Streetlight May Dramatically Reduce Activity and Foraging of Bats

et al. 2020

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“…By reducing habitat availability and quality, ALAN was also suggested to decrease the functional connectivity of landscapes for bats (Laforge et al, 2019) and can have dramatic impacts on their relative abundance at a larger scale (Azam et al, 2016;Pauwels et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Artificial light may change flight patterns of bats near bridges along urban waterways

Barré

Spoelstra

Bas

et al. 2020

Animal Conservation

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Artificial light at night (ALAN) is considered as a major threat to biodiversity, especially to nocturnal species, as it reduces availability, quality and functionality of habitats. However, its effects on the way species use landscape elements such as rivers are still largely understudied, especially the effect of crossing infrastructure lighting on bridges. These elements are nevertheless key commuting and foraging habitats in heavily urbanised landscapes for several taxa such as bats that are particularly affected by ALAN. We studied the effects of the illumination of facades and undersides of bridges on the relative abundance of pipistrelle bats, on their 3D distribution and their behavioural response (i.e. flight speed) close to bridges. We setup an innovative approach based on a microphone-array to reconstruct positions and flight trajectories in 3D. We studied the effect of lighting on bats in the close proximity of six similar bridges, mostly differentiated by the presence or absence of lighting (3 lit and 3 unlit). All bridges cross the same waterway, within a uniformly and highly urbanized agglomeration (Toulouse, France). We found that bat activity was 1.7 times lower in lit sites. Bats tended to keep a larger distance, and to fly faster close to illuminated bridges. These results suggest that bridge lighting strongly reduces habitat availability and likely connectivity for bats. In that case, results call for switching off the illumination of such bridges crossing riverine ecosystems to preserve their functionality as habitats and corridors for bats.

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“…Such a physiological consequence of ALAN may have a longterm negative effect on individuals' fitness across populations (Touzot et al 2020). ALAN also fragments habitats, altering the functional connectivity of landscape for many species (Laforge et al 2019). Indeed their avoidance-attractiveness mechanisms at more local scales (Barré et al 2020) greatly depend on the species sensitivity according to their traits, e.g., fast-flying vs. slow-flying species, and light parameters, e.g., intensity and spectrum (Spoelstra et al 2017.…”

Section: The Ecological Implications Of Alanmentioning

confidence: 99%

“…For example, this major anthropic pressure is not taken into account in the network of Natura 2000 sites, the European policy flagship tool for the preservation of biodiversity. As a consequence, conservation planning tools urgently need to account for ALAN effects on habitat loss and fragmentation, namely examples from highly mobile taxa such as bats (Laforge et al 2019. Hence, it is essential to retain and develop "dark ecological networks."…”

Section: Introductionmentioning

confidence: 99%

Grasping darkness: the dark ecological network as a social-ecological framework to limit the impacts of light pollution on biodiversity

Challéat¹,

Barré²,

Laforge³

et al. 2021

E&S

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Artificial light at night (ALAN) is nowadays recognized as a major anthropogenic pressure on the environment on a global scale and as such is called light pollution. Through its attractive or deterrent effects, and its disruption of the biological clock for many animal and plant taxa, ALAN is increasingly recognized as a major threat to global biodiversity, which ultimately alters the amount, the quality, and the connectivity of available habitats for taxa. Biodiversity conservation tools should, therefore, include ALAN spatial and temporal effects. The ecological network, i.e., the physical and functional combination of natural elements that promote habitat connectivity, provides a valuable framework for that purpose. Understood as a social-ecological framework, it offers the opportunity to take into account the multiple uses of nocturnal spaces and times, by humans and nonhumans alike. Here we present the concept of "dark ecological network." We show this concept is able to grasp the effects of ALAN in terms of habitat disturbances and integrates temporal dimensions of ecological processes into biodiversity conservation planning. Moreover, it is also intended to trivialize the practices of darkness protection by turning them into the ordinary practices of land use planning. From an operational point of view, the challenge is to translate the levers for reducing ALAN-induced effects into a political method for its "territorialization." To achieve this objective, we propose a course of action that consists of building an interdisciplinary repertoire of contextualized knowledge (e.g., impacts on wildlife, human/lightscape relationship, existing legal tools, etc.), in order to deduce from it a number of practical supports for the governance of the dark ecological network in response to societal and ecological issues.

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Reducing light pollution improves connectivity for bats in urban landscapes

Cited by 49 publications

References 51 publications

Switching LPS to LED Streetlight May Dramatically Reduce Activity and Foraging of Bats

Switching LPS to LED Streetlight May Dramatically Reduce Activity and Foraging of Bats

Artificial light may change flight patterns of bats near bridges along urban waterways

Grasping darkness: the dark ecological network as a social-ecological framework to limit the impacts of light pollution on biodiversity

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