Date of this Version
Clegg, Kent R. and Lewis, James C. Continuing studies of ultralight aircraft applications for introducing migratory populations of endangered cranes. In: Ellis, David H., ed., Proceedings of the Eighth North American Crane Workshop, 11–14 January 2000, Albuquerque, New Mexico (Seattle, Wash: North American Crane Working Group, 2001), pp. 96-108.
This research tested whether captive-reared cranes led by an ultralight aircraft (UL) along a migration route, would, after release on a wintering area, integrate with wild cranes and migrate in spring to their natal area without human assistance. This was the historical first motorized migration involving an endangered species. In 1997, whooping cranes (Grus americana) and greater sandhill cranes (Grus canadensis tabida) were group-reared in species-specific pens and 80% fledged. Beginning 13 October, 4 whooping cranes and 8 sandhill cranes were led along a 1, 133-km migration route from Grace, Idaho, to Bosque del Apache National Wildlife Refuge (BdANWR), New Mexico. The migration took 8.5 days with daily flight distances ranging from 27 to 185 km at averages of 52.5 kmIhr and 300 m elevation. During migration, 1 whooping crane was injured in an attack by a golden eagle (Aquila chrysaetos) and 1 sandhill crane died in an accident with the ultralight (UL). The 11 surviving cranes were released at BdANWR on 21 October. During winter 3 cranes died, 1 killed by a coyote (Canis latrans), 1 by a bobcat (Lynx rufus), and 1 killed by a hunter. The 8 surviving cranes migrated north on their own initiative in spring, returning to sununering areas appropriate for their natal area. Sixty four percent of the released birds survived more than 18 months. We believe the percentage surviving can be increased in future experiments. Whooping cranes can be group-reared, trained to follow experimental aircraft, and will revert to wild behavior on a wintering site in the same manner as captive-reared sandhill cranes released in previous experiments. Basic techniques of training, migration, and introduction to the wild were suitable and show promise for improved use in future reintroductions. Techniques are described for captive rearing, migration, integrating cranes to the wild, and activities post-release.