Date of this Version
Wellington, M.M., and R.P. Urbanek. The direct autumn release of whooping cranes into the eastern migratory population: a summary of the first three years. In: Hartup, Barry K., ed., Proceedings of the Eleventh North American Crane Workshop, Sep 23-27, 2008, Wisconsin Dells, Wisconsin (Baraboo, WI: North American Crane Working Group, 2010), p. 215.
This paper describes methods used in an experimental direct autumn release of captive produced whooping cranes (Grus americana) into a reintroduced migratory population in eastern North America. Eighteen chicks (4 in 2005, 4 in 2006, and 10 in 2007) were eventually released in the vicinity of adult whooping cranes or wild sandhill cranes (G. canadensis). Chicks were reared by costumed aviculturists using strict isolation-rearing techniques at the International Crane Foundation (ICF) and then transferred to Necedah National Wildlife Refuge in central Wisconsin. Initially, 23 chicks were transferred from ICF to Necedah at ages of 17-46 days. Isolation-rearing techniques continued in the field while raising the birds to fledging and until release in October. Although the same rearing and release methods were used each year, the number of cohorts and number of birds in each cohort released varied by year. Cranes were color-banded and tracked with VHS and PTT transmitters throughout their lives. Intervention was required to assist several chicks during their first year's migration. Of released cranes, 83% survived their first fall migration, and 67% survived their first year after release. Results are preliminary, and the effects of unequal sex ratios in annual cohorts are unclear; however, release of juveniles in groups of 2 has so far been most successful in facilitating successful first fall migration.