Their cheerful song brightens a winter's day. But robins(知更鸟) are in danger of killing themselves by singing too much. They are singing all night—as well as during the day, British-based researchers say.
David Dominoni, of Glasgow University, said that light from street lights, takeaway signs and homes is influencing the birds' biological(生物的) clocks, making them keep awake when they should be asleep.
Dr. Dominoni put cameras inside the birds' house to record sleeping patterns. He found that being short of sleep could put the birds' health at risk. His study shows that when robins are exposed to(暴露于) light at night in the lab, they become active at the wrong time of day. And the more birds are exposed to light, the more active they are at night.
He said, "A couple of studies showed robins are singing more songs at night. And during the day, they are still singing. And singing takes energy."
And it is not just robins that are being kept awake by man-made light. Some blackbirds and seagulls are also being more nocturnal. Dr. Dominion said, "In Glasgow where I live, seabirds are a serious problem. People often come to me saying, 'You are the bird expert. Can you help us kill these seabirds?'. During the breeding(繁殖) season, between April and June, they are very active at night and very noisy and people can't sleep."
Although Dr. Dominoni has only studied light pollution, other researches show that robins living in noisy cities have started to sing at night to make themselves heard over loud noise.
However, some birds grow actively in noisy environments. A study from California Polytechnic University found more hummingbirds in areas with heavy industry. It is thought that the number of them increases because their natural enemies fly to quieter areas.
