As a child, Andrea Townsend loved feeding her backyard sparrows and chickadees, but she wondered if it was good for them.

Townsend is now an ornithologist at Hamilton College in Clinton, New York, and she still cares about what birds are eating. Usually she gives them natural treats like unsalted peanuts, but for research purposes she tried a popular human food: cheeseburgers.

In a study published today in the journal The Condor, Townsend and her team show how urban living affects the health of American crows, including their cholesterol, and what happened to a rural population when burgers became part of their diet.

Like other successful urban wildlife, crows survive in part by eating our food. Often that means eating whatever