A cowbird is a type of bird famous for tricking other birds into raising its babies. Instead of building her own nest and caring for her eggs, a female cowbird sneaks into another bird's nest when the owner isn't looking, lays an egg there, and flies away. The unsuspecting host bird, often a warbler or sparrow, hatches the cowbird egg alongside her own and feeds the baby cowbird as if it were her own chick.

This behavior, called brood parasitism, seems clever but creates problems. Cowbird chicks often hatch earlier and grow faster than their nest-mates, taking most of the food the parent brings. Sometimes the host bird's own babies don't survive because the cowbird chick crowds them out or gets all the attention.

Cowbirds originally followed herds of bison across the Great Plains, eating insects stirred up by the moving animals. Since the herds kept moving, cowbirds couldn't stay in one place long enough to raise families themselves, which may be how they developed their unusual parenting strategy. Today they follow cattle instead. Scientists study cowbirds to understand animal behavior and how different species affect each other in nature.