In 1938, the first year a population survey was conducted, only 29 whooping cranes remained in the wild. Three years later only 16 were left. Hunting and reduction of their wetland habitat had decimated the population, and concerted efforts to salvage remnant birds did not begin until the late 1960s. In 2022 it was estimated that there were more than 500 birds, thanks in large part to innovative breeding programs. Though a plan that involved transferring whooping crane eggs to the nests of related sandhill cranes for fostering ultimately failed, captive rearing and reintroduction have established two wild populations in Florida, one of which has been taught to migrate to Wisconsin. Neither is self-sustaining. The only self-sustaining population migrates between Alberta, Canada, and Texas, U.S.
