The U.S. Fish and Wildlife Service says this fall’s ultralight-guided migration of young whooping cranes from Wisconsin to Florida will be the last.

The agency says it will discontinue its support of the practice.

For 15 years the endangered animals have migrated from Wisconsin to Florida for the winter with the help of an ultralight aircraft. The idea is to teach them how to migrate.

But the U.S. Fish and Wildlife Service says the whooping cranes haven’t been successful in producing chicks and raising them in the wild.

The nonprofit organization Operation Migration leads the flights.

It says the ultralight escorts have helped the animals survive and opposes ending the program.

The effort has cost more than $20 million.