Two biologists from Canada working in France have found that birds that land on roads adapt to average highway speeds—the higher the speed limit, the sooner they take flight when a car approaches. In their paper published in the journalBiology Letters, Pierre Legagneux and Simon Ducatez of the University of Quebec and McGill University respectively, describe the field study they conducted timing birds on roads in France.
Most drivers upon encountering birds in the roadway assume that the birds are attempting to gauge their speed and then take flight just before they arrive. This new study by the pair in France suggests that’s not how it works at all—instead, birds note how fast cars travel over many days, weeks, months, etc. and build a memory map based on the average speed of such vehicles. When a car approaches, they then pull that data from their brains and use it to decide when to fly away when a car approaches.
The researchers found this out by using a stopwatch to measure how much time birds took to take off from the roadway ahead of them as they drove, which they called the Flight Initiation Distance (FID) and then by stopping to measure the distance traveled. They then set about changing their speed relative to the speed limit, sometimes driving under, over or at the set limit. They also tested birds on different roads with different posted limits, from 20 to 110 kmph. In so doing, they found that the birds studied did not try to guess how fast an individual car was traveling, but instead relied on average speed estimates they’d learned from observing traffic patterns on different roads. They also found that the birds tended to take flight earlier if they were standing in the middle of the road rather than to the side.
Read more at: Phys.org