Date of this Version
The waters of many western rivers have been diverted by man for irrigation and other consumptive uses (Ohmart et al. 1977, Johnson 1978). As flows in certain rivers diminished precipitously during this century, numerous conflicts have arisen brought on by changes affecting various interests. The Platte River is such an example. With approximately 69 percent of the annual flows destined for the Platte now removed upstream (Kroonemeyer 1979) and additional projects proposed that would utilize remaining flows, intense competition and widespread concern have developed among the factions relying on the river's flows to meet their needs.
One effect of the growing water shortage in the Platte River Basin has been alteration of riparian habitats in the Big Bend reach of the Platte River, an area of major importance to populations of several species of migratory birds (Figure 1). Foremost among the biological concerns has been the impact of habitat alteration on the midcontinent population of sandhill cranes (Grus canademis) (Frith 1974, Lewis 1977, Krapu 1979). The cranes gather along the Platte and North Platte Rivers from late February to mid-April each year, reaching a peak population of approximately a half-million birds during late March (U.S. Fish and Wildlife Service 1981). Upon departure, the birds stop briefly on the Canadian prairies and then disperse to breeding grounds in central and arctic Canada, Alaska, and Siberia.
The U.S. Fish and Wildlife Service (FWS), recognizing the need to protect riparian habitats suitable for the cranes, attempted in the early 1970s to establish a 14,993-acre (6070-ha) national wildlife refuge along the Platte River near Grand Island. This plan met with strong opposition from landowners who feared condemnation of their properties (Wallenstrom 1976); local resistance culminated in political opposition to the plan within the State. In the debate that followed announcement of FWS plans, numerous questions were raised concerning the need for a refuge in the Big Bend reach of the Platte River to satisfy the requirements of cranes and other migratory birds. To acquire the necessary information to answer these questions, FWS began a 3-year investigation in 1978. The study was part of an Interior-directed project also involving research by the U.S. Geological Survey and U.S. Bureau of Reclamation. The purpose of this paper is threefold: (1) to describe changes in riparian habitats along the Platte during modem times and identify underlying causes of habitat alteration, (2) to describe effects of habitat alteration on the staging sandhill crane population, and (3) to consider alternatives for maintaining the habitat base needed to support the crane population during the stopover period.