FACTORS INFLUENCING THE FUTURE OFWHOOPING CRANE HABITAT ON THE PLATTERIVER IN NEBRASKA

Lands along 86 km of the Platte River in Nebraska were designated by the U.s. Department of Interior as critical habitat for the endangered whooping crane (Crus americana) in 1978. The designation established the legal basis for the continued protection of lands critical to the survival and recovery of whooping cranes. Currently there are 14 federal, state, and local water projects planned for the Platte River system. If completed, total withdrawal would be about 80% of the remaining 30% of the original flow. In this paper I summarize those projects and discuss their potential impact on whooping crane habitat. Management activities by several conservation groups are summarized. The Platte River system provides important habitat for fish and wildlife resources of national and international significance. Over 80% of the world's sandhill cranes (Crus canadensis) stage annually during migration on the Platte and North Platte rivers to prepare for the continuation of their migration (U.s. Fish & Wildlife Service 1981). The Platte River supports nearly 100% of the mid-continent population of greater white-fronted geese (Anser albifrons) (Currier et al. 1985) and provides important wintering habitat for mallards (Anas platyrhynchos) (Jorde 1981). The Platte River also provides wintering habitat for the bald eagle (Haliaeetus leucocephalus) (Lingle and Krapu 1986). Significant populations of the endangered interior least tern (Sterna antillarum) and the threatened piping plover (Charadrius melodus) nest annually on some of the remaining unvegetated sandbars in the river (Faanes 1983). Among endangered species, however, the Platte River is probably best known as a migration stopover area for whooping cranes (Allen 1952). Recognizing the importance of the river system in that regard in 1978, the U.s. Department of the Interior designated about 86 km of the river as critical habitat (43 Fed. Register 20938-20942). About 70% of the historic annual flow in the Platte River system has been diverted upstream for consumptive uses in Colorado, western Nebraska, and Wyoming (Williams 1978; U.S. Fish & Wildlife Service 1981). As a result, channel widths have been reduced by 80 90% in some portions of the 101 Proc. 1988 N. Am. Crane Workshop Big Bend reach (Currier et al. 1985). Reductions in peak flows and reduced annual flows, and subsequent agricultural development caused by water impoundments and diversions, have resulted in significant losses of floodplain wet meadow crane feeding habitat. Reduced flows have allowed encroachment of woody vegetation that have rendered some reaches of the Platte unsuitable for crane roosting (Fri th & Faanes 1982; Currier et al. 1985). Historically, flows in the Platte River were estimated at about 2.6 million acre-feet annually. But, mean annual flows in the Platte River at Overton, Nebraska, are currently about 900,000 acre-feet (U.s. Bureau of Reclamation unpubl. data). In this paper, I report on the status of planned water diversion projects in the Platte River system that threaten to further reduce the annual flows. Additionally, activities regulated by the U.s. Corps of Engineers that are contributing to a reduction in the integrity of the riverine system are discussed. I also report on the activities of several private conservation organizations in preserving and managing whooping crane habitat on the Platte River. I appreciate the helpful comments provided by J.B. Brabander, D.B. Bowman, J.C. Sidle, K.J. Strom, J.W. Ziewitz, and K.L. Ziewitz. The manuscript benefited from numerous earlier philosophical discussions with C.R. Lingle about whooping cranes and their habitats. J. Hanson typed several drafts of the manuscript.