North American Crane Working Group
Date of this Version
PROCEEDINGS OF THE NORTH AMERICAN CRANE WORKSHOP 15:34-52
Since the 10-year status update in 2011, the first parent-reared whooping cranes (Grus americana) were released in the Eastern Migratory Population, the ultralight program (UL) ended, and cranes were released at new sites in eastern Wisconsin. During 2011-2020, 117 captive-reared whooping cranes were released; 75 costume-reared (35 in UL and 40 in the Direct Autumn Release program) and 42 parent-reared. There were no significant differences in 1- or 3-year survival rates based on rearing technique or release site. The population size remained at about 100 cranes during 2010-2018 but then decreased during 2018-2020 due to a reduced number of releases of captive-reared cranes and low recruitment. Predation remained the leading cause of death (54.1% of confirmed cases) for cases in which the cause of death could be determined, followed by impact trauma (18.8%), gunshot (10.5%), and disease (9.0%). The winter distribution shifted northward into more agricultural landscapes, with the majority of the population wintering in southern Indiana or northern Alabama. The summer distribution remained concentrated in Wisconsin, and breeding areas expanded into eastern Wisconsin. As a management response to nest abandonments caused by avian-feeding black flies (Simulium spp.), the first clutch of eggs was removed from nests at Necedah National Wildlife Refuge (i.e., forced renesting), which increased renesting rates from 42% to 79%. In total, 152 cranes were confirmed to have hatched in the wild, 27 of which survived to fledging. Two male whooping cranes nested with female sandhill cranes (Grus canadensis) and produced hybrid chicks. Three cranes were removed from the population due to using an active air strip on an Air National Guard base. As of April 2021, the estimated population size was 76 individuals (38 females, 36 males, and 2 of unknown sex), 16 of which were wild-hatched.
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