Cross-fostering whooping cranes to sandhill crane foster parents.

Authors(s): R. C. Drewien and E. G. Bizeau

Publication: Endangered birds: management techniques for preserving threatened species.

Publisher: University of Wisconsin Press

Publication Date: 0000-00-00

Type:

Location: Madison Wisconsin

Abstract: The Canadian Wildlife Service and U.S. Fish and Wildlife Service began a cooperative experiment in 1975 to reintroduce whooping cranes into the Rocky Mountain region of the United States. Eggs from wild whooping cranes were collected in Wood Buffalo National Park, Northwest Territories, and placed in nests of greater sandhill cranes at Grays Lake National Wildlife Refuge. This experiment at Grays Lake was designed to evaluate the technique of cross-fostering whooping cranes to sandhill cranes. This paper describes the progress of the experiment from May 1975 through August 1977; for final results of this experiment see Garton et al. 1989. Sandhill crane pairs that had histories of high hatching success and fledging rates, nested in areas that were relatively free from human disturbance, and wintered at Bosque del Apache National Wildlife Refuge, New Mexico, were selected as foster parents. Eggs from whooping cranes at Wood Buffalo National Park (n=45) and from captive cranes at Patuxent Wildlife Research Center, Maryland (n=16) were transported by air to Grays Lake during 1976 and 1977. In each foster nest, 1 whooping crane egg was substituted for crane eggs. Young whooping cranes were captured, banded, and color-marked in August each year, and their movements, migration, and survival monitored. Of the 45 eggs received from Wood Buffalo, 35 hatched, 6 were lost to predators, and 4 were addled or infertile. Of the 16 eggs from Patuxent, 5 hatched, 6 were addled or infertile, 3 were deserted due to snowstorms, and 2 were lost to predators. Foster pairs readily accepted hatched young regardless of duration of incubation, which varied widely. Activities and interactions between foster young and parents appeared normal. None of the young from 16 eggs originating from Patuxent fledged, and 13 of the eggs from Wood Buffalo fledged. Percentage of young that fledged paralleled declines in water levels, general habitat conditions, and sandhill crane production during the 3-year period. Sources of mortality of prefledged and fledged young are described. Foster-parent families successfully migrated to wintering areas in the middle Rio Grande Valley, New Mexico and returned to Grays Lake via San Luis Valley, Colorado each spring. Excessive mortality of young prior to fledging was a major problem was related to drought conditions during 2 of the 3 years. An intensive predator control program was planned for later years of this experiment.

Keywords: Gray's Lake, Idaho, animal, bird, Aves, ornithology, population, mortality, nest, nesting, habitat, human activity, banding, color mark, management, migration, predation, crane, sandhill crane, Grus canadensis, whooping crane, Grus americana