Birds are quicker to fly off to avoid traffic on roads with higher speed limits, Canadian researchers have found.
On roads where the speed limit is lower, birds generally take longer to take to the air, according to the research, which was carried out on a road in western France.
The team of scientists, who admitted breaking the speed limit to carry out the research, drove through the French countryside in a white Peugeot hatchback and recorded the time it took for birds to clear the road when the car approached at 20, 50, 90 and 110 kph.
The car was driven at, under or over the speed limit and the "flight initiation distance" (FID) was measured - this figure is the closest distance the car came before the birds flew out of danger.
In total 134 FIDs were measure for 21 different kind of birds.
Writing in the Royal Society journal Biology Letters, lead researcher Pierre Legagneux, from Laval University in Canada, said: "Birds had significantly higher FID on road sections with higher speed limits.
"By contrast, car speed had no significant effect on FID, both when considering absolute car speed or the difference between car speed and speed limit."
Copyright Press Association 2013