The whooping crane is in the family Gruidae, Order Gruiformes, and is the tallest bird in North America. Mating is characterized by monogamous life-long pair bonds.
Individuals remate following death of a mate.
Experienced pairs may not breed every year, especially when habitat conditions are poor. Whooping cranes ordinarily lay two eggs. Although two eggs are laid, whooping cranes infrequently fledge two chicks. In the 19th century, the principal breeding range extended from central Illinois northwest through northern Iowa, western Minnesota, northeastern North Dakota, southern Manitoba, and Saskatchewan to the vicinity of Edmonton, Alberta. By 1941, the migratory population contained only 16 individuals.