A bird that ends up splattered across your car windshield is a sure sign of bad luck – for both you and the bird. Some believe accidental bird-window impacts just zap your luck, while others describe them as an omen of death. No matter what your beliefs, it's interesting to note that an estimated 80 million birds in the United States meet their end each year by flying into car windows, which means plenty of bad luck to go around.
While it makes sense that faster speeds mean more birds making contact with car windows, researchers have found that birds do pretty well at avoiding cars – up to the point where cars start significantly exceeding the speed of predators. At this threshold, the bird's internal system that tells it when to get out of the way breaks down, making it nearly impossible for it to avoid your car. This may not be much comfort when you're cleaning feathers off your windshield, but at least it can help you to not take the incident too personally [source: Ball].