3. [•四川]
Their cheery song brightens
many a winter's day. But robins are in danger of wearing themselves out by
singing too much. Robins are singing all night一as well as during the day, British-based researchers say.
David Dominoni, of Glasgow University, said that light from street lamps, takeaway signs and homes is affecting
the birds' biological clocks, leading to them being wide awake when they should
be asleep.
Dr Dominoni, who is
putting cameras inside nesting boxes to track sleeping patterns, said lack of
sleep could put the birds’ health at risk. His study shows that when robins are
exposed to light at night in the lab, it leads to some genes being active at
the wrong time of day. And the more birds are exposed to light, the more active
they are at night.
He told people at a conference,
"There have been a couple of studies suggesting they are increasing their
song output at night and during the day they are still singing. Singing is a
costly behaviour and it takes energy. So by increasing their song output, there
might be some costs of energy."
And it is not just robins that
are being kept awake by artificial light. Blackbirds and seagulls are also
being more nocturnal. Dr Dominoni said, "In Glasgow where I live, gulls
are a serious problem. I have people coming to me saying `You are the bird
expert. Can you help us kill these gulls?'.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 research concluded that robins living in noisy
cities have started to sing at night to make themselves heard over loud noise.
However, some birds thrive(兴旺)in noisy environments. A study from California Polytechnic University found more hummingbirds in areas with heavy industrial
machinery. It is thought that they are capitalising on their predators(天敌)fleeing to quieter areas.