Advocate staff photo by SCOTT THRELKELD -- Frances Kepley of the Audubon Species Survival Center releases a crane Tuesday. Six Mississippi Sandhill cranes were tagged and released Tuesday, Nov. 3, 2015, at the Mississippi Sandhill Crane National Wildlife Refuge in Gautier, Miss. The cranes, a critically endangered species, hatched six months ago at the Audubon Nature Institutes Freeport-McMoRan Audubon Species Survival, Center on the Westbank. The cranes will spend about a month acclimating to their new environment inside a 2-1/2 acre pen, one of five in the 19,300-acre refuge. Members of the Audubon team and refuge agents tagged the birds and attached transmitters to their legs. Right now they are learning to be cranes, said Scott Hereford, senior wildlife biologist at the refuge. Wing restraints will be removed at the end of the month and the birds will be able to join other cranes on the refuge, Hereford said. The Mississippi Sandhill crane population at the refuge hovers between 120 and 130 birds.