No effect of artificial light of different colors on commuting Daubenton's bats (Myotis daubentonii) in a choice experiment

Abstract

Progressive illumination at night poses an increasing threat to species worldwide. Light at night is particularly problematic for bats as most species are nocturnal and often cross relatively large distances when commuting between roosts and foraging grounds. Earlier studies have shown that illumination of linear structures in the landscape disturbs commuting bats, and that the response of bats to light may strongly depend on the light spectrum. Here, we studied the impact of white, green, and red light on commuting Daubenton's bats (Myotis daubentonii). We used a unique location where commuting bats cross a road by flying through two identical, parallel culverts underneath. We illuminated the culverts with white, red, and green light, with an intensity of 5 lux at the water surface. Bats had to choose between the two culverts, each with a different lighting condition every night. We presented all paired combinations of white, green, and red light and dark control in a factorial design. Contrary to our expectations, the number of bat passes through a culvert was unaffected by the presence of light. Furthermore, bats did not show any preference for light color. These results show that the response of commuting Daubenton's bats to different colors of light at night with a realistic intensity may be limited when passing through culverts.

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

“…Only one study to our knowledge investigated the effect of ALAN on commuting bats by recording Daubenton's bats (Myotis daubentonii) passing through culverts. In this study the bat activity was found to be unaffected by the presence of light (Spoelstra et al, 2018). However, another study showed that most bat species, including Myotis species, significantly reduced their number of drinking and activity above water in presence of artificial light (Russo et al, 2019(Russo et al, , 2018(Russo et al, , 2017.…”

Experimentally manipulating light spectra reveals the importance of dark corridors for commuting bats

“…The effect is consistent across a range of light types, including red light, demonstrating that red light may be safe for bats only in specific circumstances. (Spoelstra et al, ; Spoelstra, Ramakers, van Dis, & Visser, ). Despite being deterred, R. hipposideros adapted quickly by switching flight paths and exploiting dark corridors on the opposite side of experimental hedges.…”

Artificial light at night as an environmental pollutant: An integrative approach across taxa, biological functions, and scientific disciplines

“…Two different mammal species are also covered by our special issue. Spoelstra, Ramakers, van Dis, and Visser () reveal that the choice of Daubenton’s bats to commute through tunnels was unaffected by whether such tunnels were illuminated or not. Dimovski and Robert report spectral‐dependent suppression of melatonin levels, as well as changes in oxidative status, in Tammar wallabies ( Macropus eugenii ).…”