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How are birds able to obey the speed limit?

21 August 2013 Last updated at 14:08 BST

Birds can judge the speed limit of a road, researchers at Cardiff University have discovered.

They found that birds are able to work out the average speed of a road and adjust their flight responses, in order to reduce the chance of crashing.

However this does make birds vulnerable to speeding cars, as they may not realise the vehicles are travelling faster than normal.

Dr Sarah Perkins, who was behind the study, told BBC Radio 5 live's Breakfast: "If you speed, the birds are in that area are adapted to the speed limit not your speed, so you may be more likely to cause wildlife roadkill."