Pre-1870: Scientists estimate there were 15,000-20,000 whooping cranes. Whooping cranes were widespread in North America. The birds nested across the north-central United States, and in Manitoba, Saskatchewan and Alberta, Canada. The migratory range of these birds extended from the Arctic into central Mexico and from Utah to New Jersey and south to Florida.

1870: Settlers moved west, damaging whooper habitat to make farmland. They also shot birds for feathers to make popular adornments on women's hats. Biologists estimate that no more than 1,400 whoopers were left by 1870, and perhaps as few as 500.

1918: The Migratory Bird Treaty Act of 1918 brought market hunting of the cranes and other migratory birds to an end.

1937: Reduced by hunting and habitat destruction to about 15 birds. Federal government establishes the Aransas National Wildlife Refuge on the Texas coast to protect the crane's last wintering ground.

1940: A hurricane wiped out a non-migratory group of cranes in Louisiana.

1967: The whooping crane was listed under an early form of endangered species legislation. The U.S. Fish and Wildlife Service began a whooping crane recovery program, relying initially on captive breeding to build up the population. While captive breeding was successful, reintroduced whoopers failed to migrate.

1973: The Endangered Species Act of 1973 is passed, and true recovery begins for the whooping crane.

1975: The U.S. Fish and Wildlife Service launched a new recovery effort, by placing whooping crane eggs in the nests of sandhill cranes. The goal was to have sandhill cranes teach baby whoopers how to migrate. The chicks did grow and learn how to migrate, but they had imprinted on the sandhill crane parent, and so tried to mate with sandhill cranes. Only one foster whooper has ever reproduced, and it hatched a hybrid.

1993: The U.S. Fish and Wildlife Services reintroduced a non-migratory flock in the Kissimmee Prairie region of central Florida.

1999: The wild Texas-based flock of whooping cranes grows to 180 birds.

2000: Wild whooping crane chicks hatched in Florida for the first time in 60 years, but are lost to predation.

2001-present: Whooping cranes are taught how to migrate from Florida to Wisconsin (Necedah National Wildlife Refuge) using ultralight planes.

NWF's work to help the whooping crane