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Date: 2022
Authors:
HILLARY L. THOMPSON, International Crane Foundation
M. SUSANNA GLASS, International Crane Foundation
MARIANNE M. WELLINGTON, International Crane Foundation
KIM H. BOARDMAN, International Crane Foundation
GLENN H. OLSEN, USGS Eastern Ecological Science Center
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Citation:
Thompson, H. L., M. S. Glass, M. M. Wellington, K. H. Boardman, and G. H. Olsen. 2022. Effects of release techniques on parent-reared whooping cranes in the Eastern Migratory Population. Proceedings of the North American Crane Workshop 15:53-71.
Abstract:
Reintroduction of an Eastern Migratory Population (EMP) of whooping cranes (Grus americana) in the United States
by release of captive-reared individuals began in 2001. As of 2020, the EMP has approximately 21 breeding pairs and has had
limited recruitment of wild-hatched individuals, thus captive-reared juveniles continue to be released into breeding areas in
Wisconsin to maintain the population. We investigated the effects of release techniques on survival, behavior, site fidelity, and
conspecific associations of 42 captive-parent-reared whooping cranes released during 2013-2019 into the EMP. Individuals
were monitored intensively post-release, then as a part of a long-term monitoring program, locational, behavioral, and habitat
use data were collected and analyzed. Most cranes roosted in water post-release; however, we documented 4 parent-reared
cranes roosting on dry land. Most cranes eventually associated with other whooping cranes; however, juveniles released near
single adult cranes were less likely to associate with other whooping cranes during their first migration or winter than juveniles
released near other types of whooping crane pairs or groups. Parent-reared and costume-reared whooping cranes had similar
rates of survival 1 year post-release (69.0% and 64.4%, respectively). The highest risk of mortality was within the first 100 days
post-release, and the leading known causes of death were predation and impact trauma due to powerline or vehicle collisions.
Both costume- and parent-reared cranes had strong fidelity to release sites. We advise releasing parent-reared cranes near pairs
or groups of whooping cranes and taking measures to reduce the risk of mortality during the immediate period after release
(e.g., predator aversion training, marking powerlines).
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© 2022 North American Crane Working Group
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