Electrical devices may disrupt the migration of some birds, a study suggests.
A German team has found that weak electromagnetic fields produced by equipment plugged into mains electricity and AM radio signals interfere with the animals' "internal compass".
They believe the effect is greatest when birds fly over urban areas.
The study is published in the journal Nature.
Prof Henrik Mouritsen, from the University of Oldenburg in Germany, who carried out the research, said: "At first, I was highly sceptical that this could be the explanation.
"But if you have seemingly unlikely effects then the proof needs to be much stronger - and that is why we have done so many experiments over seven years and it has taken a long time before we were confident to come out with this to the public."
Full story: http://www.bbc.com/news/science-environment-27313355
