No, birds can't decipher the numbers on speed-limit signs. But researchers suggest that they've learned to observe our posted limits in their own way, reports the Canadian Press. Essentially, the higher the speed limit is on a road, the faster the birds take off to avoid oncoming traffic. That may seem like a no-brainer, but here's the part that especially intrigued the researchers: The birds don't react based on the speed of a particular vehicle, but on the average speed of the road. They'll take their sweet old time on slow roads and rush on fast ones, no matter the speed of an individual car.
"In other words, the birds appear to have adapted street savvy to survive alongside these strange metal-clad beasts, our cars, by judging their typical behavior," writes Stephen Messenger at Treehugger. That, of course, makes drivers exceeding the speed limit especially dangerous to them. National Geographic quotes the study's co-author explaining how the findings could be applied to wildlife safety: "If you have different speed limits for similar roads in similar landscapes, it could be dangerous for birds because they hardly have any cues of those changes." Also of note: More birds tend to get hit in the spring, possibly because young ones haven't yet learned the rules of the road, notes New Scientist.