The dead birds were discovered Dec. 30 near Albany in Calhoun County, The Atlanta Journal-Constitution reported Wednesday. Tom MacKenzie, a spokesman for the U.S. Fish and Wildlife Service, said the three, all equipped with radio transmitters, had been tracked Dec. 10 in Hamilton, Tenn., where they were roosting.
Whooping cranes are among the rarest birds on Earth, with a global population of 570,400 in the wild. About 100 birds are in the population reintroduced into the eastern United States by the Whooping Crane Eastern Partnership.
The three dead cranes were among a group of seven first-year birds released in Wisconsin in October.
The wildlife service has offered a reward of $12,500 for information leading to the killers. The carcasses were sent to a lab in Oregon for examination.