The distraction of a meal there on the roadside can be fatal to diners like raptors; eagles and vultures eat carrion. And some birds, ruffed grouse for example, seem to never have evolved a conclusive understanding of motor vehicles. You find them standing on the road, as though overthinking the situation.
Bird remains soon disappear. It might have been me. I’ve carried roadkill home for dinner (only game birds, always in season). That puts me in league with hawks, owls, crows, ravens, gulls, fox, coyote, domestic dogs and cats, raccoon, mink, skunk, badger, weasel and ground squirrels.
So, reasons for death along roads and the lawn beneath your windows are easy. Those clues can be obvious. Off the road, the “how” mystery is not so easily determined.
To learn causes of mortality related to wind turbines in southwestern Minnesota, a dead-bird study was conducted several years ago. The point was accurate numbers of possible turbine kills, the problem the speed at which bird carcasses disappear.
The study team planted dead birds of various sizes in various habitats, and then tracked what happened to them.
Small birds usually were gone in fewer than five days. This seems a long time, but a bird in field vegetation can be hard to see. Odor helps scavengers find that meal.