All 18 endangered young whooping cranes that were led south from Wisconsin last fall as part of a project to create a second migratory flock of the birds were killed in storms in Florida, according to the Associated Press.

The cranes were being kept in an enclosure at the Chassahowitzka National Wildlife Refuge near Crystal River, Fla., when violent storms moved in Thursday night, said Joe Duff, co-founder of Operation Migration, the organization coordinating the project.

The various groups and agencies working on the project had seen the size of the flock grow to 81 birds with the latest arrivals, but the loss of the young cranes drops the total back to 63.

The whooping crane, the tallest bird in North America, was near extinction in 1941, with only about 20 left.

The other wild whooping crane flock in North America has about 200 birds and migrates from Canada to the Texas Gulf Coast. A non-migratory flock in Florida has about 60 birds.

For more information, consult these groups on the Web:
Operation Migration
Whooping Crane Eastern Partnership