As the Sun sets in Chicago, the city begins to bustle with nightlife—and it’s not just from partying humans. Cats, coyotes, possums, raccoons, rats, and skunks all come out of their urban homes to hunt, mate, and roam the city. But a recent study shows that these behaviors can be altered by artificial lighting—street lamps, flood lights, and illumination around homes and businesses.
The study, led by researchers from Northeastern Illinois University, showed that the city’s nocturnal animals roamed less and were less active as nighttime light levels increased. Researchers started seeing significant changes in animal behavior in areas with lighting as dim as 6 lux, a unit of measurement that describes the amount of light falling on the surface. For reference, 6 lux is slightly dimmer than Earth’s surface at twilight; typical kitchen lighting is around 500 lux.
“If larger nocturnal animals are less active around the city at night, their movement patterns can be altered temporally and spatially,” said Aaron Schirmer, lead author of the paper and a biology professor at Northeastern Illinois University. “That would have the potential to affect the food web in ways that we might not fully understand yet.”
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