Crows, house sparrows and other species judge when to flee the asphalt by average traffic rates rather than an oncoming car's speed
Highway-savvy birds don’t read road signs but they may pay more attention to speed limits than some human drivers do.
As a car roars toward birds standing on the asphalt, they don’t check the driver’s exact speed when judging how soon to flap out of the way, says behavioral ecologist Pierre Legagneux of the University of Quebec in Rimouski.
Instead, the speed limit on the road, rather than the speed of the approaching vehicle, is a better predictor of how close a car gets before a bird startles into the air, Legagneux and Simon Ducatez of McGill University in Montreal report August 21 in Biology Letters.
Substantial numbers of birds get hit by cars, Legagneux says, so the new paper gives drivers another reason not to speed. Birds may not expect over-the-limit traffic and may fail to dodge away soon enough.