Date of this Version
Proceedings of the North American Crane Workshop 13: 42
From 2001 to 2010, 132 costume-reared juvenile whooping cranes (Grus americana) were led by ultralight aircraft from Necedah National Wildlife Refuge (NWR) in central Wisconsin to the Gulf Coast of Florida on their first autumn migration (ultralight-led or UL), and 46 juveniles were released directly on Necedah NWR during autumn of the hatch year (direct autumn release or DAR). Return rate in spring was 90.5% for UL and 69.2% for DAR, the lower value of the latter attributable to 1 cohort with migration problems. Overall population survival 1 year and from 1 to 3 years post-release was 81% and 84%, respectively. Survival 1 year post-release was significantly different between UL (85.1%) and DAR (65.7%) cranes. Since summer 2008, DAR migration and wintering have improved, winter distribution of the population has changed, the migration route of the population has shifted westward, and number of yearlings summering in locations used during spring wandering has increased. Human avoidance problems resulted in 2 birds being removed from the population. As in earlier years, homing to the natal area and prolific pair formation continued (29 of 31 adult pairs have formed in the core reintroduction area), predation continued to be the primary cause of mortality, and parental desertion of nests, especially during the initial (primary) nesting period, continued. During 2005-2010, all 43 of these early nests failed; of 15 late nests or renests, chicks hatched from 8 nests, and 3 chicks fledged. As of 31 March 2011, the population contained a maximum 105 individuals (54 males and 51 females) including 20 adult pairs.