Date of this Version
Urbanek, R.P., L.E. Fondow,and S.E. Zimorski. Survival, reproduction, and movements of migratory whooping cranes during the first seven years of reintroduction. 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), pp. 124-132.
An effort to reintroduce a migratory population of whooping cranes (Grus americana) into eastern North America began in 2001. During 2001-2007, 125 juveniles were costume/isolation-reared and released: 106 were led by ultralight aircraft from Necedah National Wildlife Refuge (NWR), central Wisconsin, to Chassahowitzka NWR, central Gulf Coast of Florida, on their first autumn migration (ultralight-led or UL). The remaining 19 individuals were released directly on Necedah NWR during autumn of the hatch year (direct autumn release or DAR). Of 86 UL and 13 DAR cranes that completed their first spring migration, 72 (84%) and 5 (38%), respectively, returned unassisted as yearlings to central Wisconsin. Yearlings typically returned to Necedah NWR and then wandered to other spring locations, mainly in southern and eastern Wisconsin, but also to locations as far as 1,370 km distant. Most yearlings returned to central Wisconsin by early summer, especially males, and females associated with males. Lake Michigan posed an effective barrier to 16 yearlings that migrated too far eastward during spring migration. Some of these birds and others were retrieved and translocated. For UL cranes, 48% of returning bird-winters occurred in a primary wintering area within 88 km of the original release site and an additional 12% at a smaller area of concentration 82-103 km northward. Other UL and DAR cranes wintered at sites primarily in Florida, South Carolina, Tennessee, Alabama, or Indiana. Excluding 17 UL juveniles that died in a single weather-related event at the winter release site in 2007, 40 individuals (37% of those in the population) died during the first 7 years of the reintroduction. The primary cause was predation (minimally 50%). During 2005-2008, all 22 first nests with eggs failed. Of 2 renests during the same period, 2 chicks hatched from 1 nest and 1 chick fledged in 2006. Consistent nest failures were mainly synchronous and usually occurred on warm days. As of September 2008, the population contained a maximum 68 individuals (39 males and 29 females) including 12 adult pairs.