A Prolonged Bird Song: Light Pollution Artificially Lengthening Birds' Days

As a species, humans are really good at making light. Street lamps, traffic signals, billboards, car headlights, storefronts — we can make a city glow. Even on the darkest nights. We’re so good at it, in fact, that some of the species we share our world with, like birds, have been tricked into thinking that days are longer than they really are. 

Neil Gilbert and Brent Pease are scientists who study birds. The pair listened to thousands of samples of bird songs. The samples were from over 500 species around the world. The songs were captured on BirdWeather devices. They help people learn what kinds of birds frequent their backyards. Gilbert and Pease were able to use the data to identify the birds. They tracked when the birds started singing each day. They published their research in the journal Science.  

"For these birds, (their day is about) an hour longer. They start (singing) about 20 minutes earlier in the morning and they stop (singing) about 30 minutes later in the evening," Gilbert told NPR. He and Pease found that many bird species, such as those roosting in nests exposed to the open air, were active for up to an hour longer each day than other birds. They also found that the birds’ active times grew in places where there was more light pollution. 

"American robins will sometimes be singing, you know, two hours before sunrise in some of these polluted areas," Gilbert said. 

Other scientists have taken note of how Gilbert and Pease used the information provided by BirdWeather. 

“That's what's really cool about this study," wildlife ecologist Jeff Buler told NPR. "They've (used) this growing global dataset of automated recordings of birds that have been collected essentially by the public." 

Reflect: How do you think things people build or use every day can change the way animals live?

Gif of bird from GIPHY.