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Citation:
Schmidt, S. M., and H. L. Thompson. 2025. Releases of after hatch year and adult whooping cranes in the reintroduced Eastern Migratory Population. Proceedings of the North American Crane Workshop 16:146-156.
Abstract:
The reintroduced Eastern Migratory Population of whooping cranes (Grus americana) experiences low recruitment
and high mortality. To support and supplement this population’s growth, ex-situ breeding and release programs prioritizing the
release of juvenile whooping cranes (121.1 ± 2 days after hatch) are used. However, extenuating circumstances have resulted
in the release of 4 after-hatch-year and 1 adult whooping crane between 2018 and 2022. Although the sample size is small,
these unique cases are informative for future management and release, revealing lower survival 1 year after release (20%) than
traditional release methods (parent-reared: 69.0%; costume-reared: 64.4%), and average post-release survival of 314.5 days and
39.0 days for spring and fall releases, respectively. Causes of mortality for the 5 released cranes in this study include emaciation,
lead exposure, powerline collision, predation, and entrapment in a forest canopy. Additionally, monitoring of after-hatch-year
and adult whooping cranes immediately post-release revealed a greater selection for forested and upland habitats than expected.
Using the results of this study, we recommend limiting future releases of older birds, allowing only for spring releases under
unique circumstances, and providing standing water, live food items, and predator aversion training for whooping cranes in
captivity to encourage and support natural behaviors and higher survival.
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© 2025 North American Crane Working Group
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