Night Lights May Affect Urban Birds

Birds exposed to artificial light in cities get an early start to mating season.

The big city’s bright lights may be waking up wildlife, with complex consequences. Ecologists at Germany’s Max Planck Institute for Ornithology have found that light pollution can cause urban birds to gear up for mating season by singing and molting earlier than their country counterparts. The researchers captured wild European blackbirds and exposed one group of them to natural lighting cycles and another group to extra light intensity at night. The birds that slept with the additional night light were ready to go more than three weeks earlier than those kept under more natural conditions. “The light intensity we used was about one-thirtieth of light intensity under a street lamp, so it’s very surprising to see this effect already,” says lead researcher Davide Dominoni. It’s too soon to say whether these early birds will get the worms. Dominoni explains that the city birds might even experience a disadvantage, laying eggs before there is enough food available for their young. Luckily, cities from Paris, France, to Santa Rosa, California, are starting to see the light and put in place rules to go dark at night, a move intended to save energy that also helps birds.

This story originally ran in the May-June 2013 issue as "Dark Side of Light."