North American Crane Working Group

 

Date of this Version

1997

Document Type

Article

Citation

Nesbitt, Stephen A., Martin J. Folk, Marilyn G. Spalding, James A. Schmidt, Stephen T. Schwikert, Jane M. Nicolich, Marianne Wellington, James C. Lewis, and Tom H. Logan. An experimental release of whooping cranes in Florida -- the first three years. In: Urbanek RP, Stahlecker DW, eds. 1997. Proceedings of the Seventh North American Crane Workshop, 1996 Jan 10-13, Biloxi, Mississippi. Grand Island, NE: North American Crane Working Group. pp. 79-85.

Comments

Used by permission of the North American Crane Working Group.

Abstract

Fifty-two juvenile whooping cranes (Grus americana) were soft-released in Florida from February 1993 to April 1995. The birds were released in groups ranging in size from 5 to 14 individuals. The first-year survival rate was 0.42 for all years combined. First-year rates for each year were 0.36 for 1993, 0.32 for 1994, and 0.47 for 1995. Most mortality (62%) occurred during the first 3 months following release. The survival rate of 0.81 the second year after release was similar to that of Florida sandhill cranes (G. canadensis pratensis) (0.87). Predation by bobcats (Lynx rufus) was the only known source of mortality. We attempted to modify the roosting behavior and habitat use of released birds. Before and immediately after release, efforts were made to condition birds to roost in water and avoid rank, overgrown habitat. Most dispersal distances were similar to those of local populations of sandhill cranes, but there were 2 episodes that exceeded the normal range of local cranes. Four pairs have formed among birds that survived for greater than 1 year. Two pairs defended territories in spring 1995, and 1 completed a nest platform within the defended territory.