We used a long-term citizen science data set of bat roadkill and found the rates of mortality were higher in protected areas than non-protected area at higher elevation in Taiwan. In contrast, roadkill of common bat species was best explained by high levels of light pollution at lower elevations, suggesting that bats might be exposed to higher collision risk when they were attracted by insects around streetlights.

Demand-controlled LED street lights are only fully illuminated when there is traffic and dimmed in the absence of traffic. In our study, dimming reduced the light on average by 35%. Effects of dimmed light on the abundances of nocturnal insects and bats were generally beneficial as fewer insects went into traps and fewer bat signals were recorded when the lights were dimmed.

There are more than 1,400 species of bats worldwide and they play critically important roles in ecosystem health. We conducted an international systematic review and found that many species of bats are significantly impacted by barrier effects due to the presence of roads, by mortality due to collision with vehicles, and by habitat loss and decreased activity due to habitat alteration.

Lighting in wildlife underpasses significantly reduces their use by bats. Bats are more likely to cross the road rather than use the underpasses when they are lit, greatly increasing their risk of mortality.