Q: Do birds have voluntary control of...

Q: Do birds have voluntary control of their defecation? Do they deliberately target cars?

A: No, according to biologist Tom Scott of UC Riverside. Birds move their bowels whenever they are triggered by fullness. They most often do so when they are perched because they spend most of their time perched. Flying “is a very costly activity” in terms of energy consumption, Scott said. It appears that birds target cars only because cars are so plentiful and feces are most visible there. But birds “don’t even have a clue that we exist,” Scott says.

Incidentally, birds, like insects and reptiles, do not urinate. Water is removed from urine and the leftover uric acid is mixed with solid wastes, which are then eliminated together.