Uh-oh, a brown-headed cowbird! These birds lay eggs in other birds' nests and leave the young to be cared for by the surrogate parent! Oftentimes, the offspring will hatch first and push the other eggs out of the nest, and if laid in a smaller bird's nest, may actually overpower the smaller chicks to the point of starving them.

The theory is that these birds followed the herds of bison that once roamed freely throughout the American plains and did not stay in one place long enough to care for chicks.