Whooping cranes are endangered and slowly recovering from a low point of just 15 birds and one migratory population in the wild. New efforts have established an eastern second migratory population from captive-bred birds, although not without some difficulty, since migration routes are learned from other adults. In the eastern population two methods were used to teach a new migration pathway: imprinting cranes on ultralight aircraft on the ground, which would lead the cranes to an overwintering destination; or imprinting them to follow older whooping cranes or wild sandhill cranes when they migrate. After the first season, whooping cranes are no longer guided, and gradually change their migration pathways, shortening the migration distance each year. A comparison of the two methods of imprinting (ultralights vs. other cranes) finds big differences in the first few years of age in migration distance, but by age 6, the migration paths of the two groups had converged and shortened to similar distances and locations. The new research by Claire Teitelbaum and Thomas Mueller of Goethe University, Germany, and SAFS professor Sarah Converse, appears in Conservation Letters.