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I I I I I I I I I I' I I I I I I "'!"1~'" ~~ 'J - ..' .) . SEenO.THREE WhOOping Grane available from the BOR GIS database. The only available information on water width and depth profiles is 85 transects at 16 sites, completed in the 19805. This existing stream profile data may no longer accurately represent the individual bridge' segments in the late 19905. 3.4.2 Wet Meadow Habitat During migration, whooping cranes forage in sma1l-grain croplands, upland grasslands, and wetland habitat areas where they have been observed feeding on frogs, fish, crayfish, insects, plant tubers, and waste grains (FWS 1981). A major part of the whooping crane's energy requirements during migration across the Great Plains probably comes from waste agricultural crops. Although the proportions of plant and animal food in the diet are not known, whooping cranes, like sandhill cranes, require animal t1llItter to satisfy their nutritional needs. In general, the foraging strategies of whooping cranes are more closely associated with wetland feeding habitats than are those of sandhill cranes (Johnsgard 1996). Foods used by migrating whooping cranes and that are available in wetlands and bottomland grasslands along the Platte River include small fish, snakes, frogs, frog egg m,,<'leS, crayfish, grasshoppers, crickets, and other insects (FWS 1981, 1994; Currier et al. 1985; Ballinger 1980; Cocbnarand Jenson 1981; Ratcliffe 1981; Davis and Vohs 1993). Many of these organisms depend on aquatic moistUre regimes, or seasonally moist or saturated soils for all or part of their life cycle. 3.4.3 Platte River Habitat Decline The area of open channel and of adjacent wet meadow habitats in the study area have greatly decreased since construction of the Kingsley Dam. Existing habitats and habitat decline are described in Section 2. The mid-continent population of sandhill cranes principally rely on three habitat types during their annual stopover along the Platte River. These are relatively broad channels for roosting and cropland and meadows for feeding. The Platte River near Overton was at one time one of the major spring staging areas for sandhill cranes, but deterioration of habitats has affected sandhill crane distribution (Krapu et al. 1982). Degraded habitat conditions between North Platte and the J-2 Return does not suppon crane use. Sandhill cranes that use the Platte for physiological conditioning and pair bonding prior to their northward migration have also abandoned most of the degraded reach of the river from the J-2 Return to Kearney (Faanes and LeValley 1993). Sidle et aL (1993) and Currier et al. (1985) describe trends of sandhill crane distribution and habitat degradation observed along the Platte River. Sidle et al. (1993) attribute sandhill crane roost distribution to juxtaposition of two primary limiting habitats of wet meadows and open channeL Similar observations were reponed by KIapu et al. (1982). Habitat changes that have affected sandhill crane use of these reaches have affected whooping crane use to an even greater degree. Whooping cranes are more sensitive to. disturbance, and select wider channels for nightly roosting on the Platte River than do sandhill cranes. Whooping cranes rarely use channels less than 500 feet wide and prefer channels 900 feet wide or greater. Though wider channels are highly suitable for sandhill cranes, they often use channels of widths ., a'lIIal!r ~ltClJde ,..,....... 08F_._6I2/1~S2~'" 3-9