Wildlife on roadways exacts a terrible cost. If the animal is large enough, it can kill the occupants of the car that hit it, and even smaller creatures can do plenty of financial damage. In addition, it is estimated that a million animals are killed on U.S. roads every day.
Sometimes there are ways to persuade animals to spend their lives on one side of a highway, but often there are good reasons for them to cross. If isolated to small pockets, species will lose genetic diversity, and can even die out when climatic conditions leave the grass insufficiently green on their side.
This is where wildlife bridges and tunnels come in. However, as this video from MinuteEarth makes clear, getting the bridge just right is not easy. What suits one species is not applicable to another, and with millions of kilometers of highways, a lot of crossings are required. Still, progress is being made.
No matter what bridge is provided, some animals will still venture onto the roadway. Let's face it, how many times have you hit a bird while driving? It's not like they don't have other options. However, well-designed bridges can cut the toll enough to keep species alive, and save the bodywork on some cars while they are at it.