Threats to Wildlife and the Platte River

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p. 20 WILDLIFE In addition, the Fish and Wildlife Service noted that "The importance of maintaining tra- ditional habitats such as the Platte is amplified by the impact of man's ongoing conversion of pothole and prairie to hay and grain production which has made nearly all of their original range unsuitable for whooping cranes" ( USFWS 1986.) And, Since the Platte River was used more frequently than other habitats in the past when flows were greater and the channel was less encroached, the recent use by whooping cranes indicates that the Platte River would probably be used more frequently if higher flows of recent years continue, if habitat management continues, and if adverse effects of flow depletions from projects such as Deer Creek are reduced or eliminated. ( USFWS 1987b, p 16). Habitat requirements for Whooping Cranes have been subject to much debate and research. Researchers have evaluated the characteristics of those river sites used for roosting by Whooping Cranes, and what flow is required to provide those conditions in the Platte. The most desirable physical characteristics of river roost sites for Whooping Cranes was determined as follows: * Wide channel, greater than 170 yards (155 m). * Slow current at roost site (1 -4 mph; 2 -6 kph), although water in main channel may be flowing faster. * Shallow water (2 -12 inches; 5 -30 cm), though main channel may be deeper. * Unvegetated. * Fine substrate, usually sand. * Unobstructed bank -to -bank visibility and visibility upstream and downstream, usually for several hundred yards. * Good overhead visibility without overhead vegetation or high banks. * Close proximity to feeding sites (usually within 1 mile; 1.6 km). * Greater than 0.25 mile; 0.4 km from houses, railroad tracks, roads. * Presence of mid -river sandbars with very little slope (often less than 2 degrees and little relief (less than 1 foot; 0.3 m) and little or no vegetation. These appear to offer more security from the approach of predators than river -edge areas. (Source: Johnson and Temple 1980 in Currier et al. 1985, p 27; USFWS 1981, pp 44 -45). In fact, numerous investigators have attempted to determine, in some instances with the aid of a computer model, stream flows that would provide adequate roosting habitat in the river (see table 2D for comparison and explanation of flow rates studied). But the problem still remains that there are many unknowns about the habitat requirements of Whooping Cranes. Thus, scientists are