There were about 21 to 22 million acres in 1820. The prairies were lost to farming and the growth of cities and towns. In 1990, low Illinois populations of prairie chickens led to inbreeding problems. All kinds of predators eat prairie chickens' eggs, especially opossums, raccoons, and skunks. Fifty percent of the prairie chickens' nests are destroyed by predators.
Pheasants often lay eggs in the prairie chickens' nests.
Pheasants' eggs hatch quicker than prairie chickens'. The prairie chicken hens often abandon their own eggs to raise pheasant chicks instead.