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<br />," r' I ~ '~l <br />~.J,~ <br /> <br />IMPACT OF NARROWS UNIT ON PLATTE RIVER CRANE HABITAT <br /> <br />The "big bend" area of the Platte River is an aD-mile reach from <br />Overton, Nebraska, to Chapman, Nebraska. This reach is heavily used <br />by waterfowl, wading birds, and raptors. Severe flow depletions and <br />associated habitat degradation have eliminated sandhill crane use <br />of other reaches of the Platte River in Nebraska. Additional loss of <br />habitat in the "big bend" area could impact sandhill crane populations. <br />Concern has been expressed that the Narrows Unit could cause flow <br />depletions which would effect the existing sandhill crane habitat in <br />the "big bend" area. The purpose of this analysis is to assess the <br />effect of the Narrows Unit on the "big bend" area based on estimated <br />flow depletions and their effect on the river mechanics of this reach <br />of the Platte River. <br /> <br />Sandhi 11 Cranes <br /> <br />Each spring, multitudes of waterfowl and wading birds descend on the <br />Platte River in Nebraska. Annually, aO-l00 percent of the midcontinent <br />population of lesser sandhill cranes, variously estimated to number <br />between 200,OOO~300,OOO birds. :stage in portions of the'P1atte and North <br />Platte River Valleys, on their way to nesting grounds in the tundra <br />and boreal forests of S i beri a, Alaska, and Canada (Fi sh and Wi 1 dl i fe <br />Service, 1976; Sanderson, 1977). The cranes begin their northward <br />migration from wintering grounds in west Texas, southern New Mexico, <br />and northern and central Mexico. The fact that both the wintering and <br />nesting grounds of the sandhi11s are extremely widespread gives rise <br />to the term "hourglass" migratory pattern. The "stem" of the "hourglass" <br />consists of 11. primary roosting sites within the "big bend" portion of <br />the Platte River in Nebraska, an aO-mi1e stretch from just east of <br />Lexington downstream to Chapman (see exhibit 1). Crane habitat is also <br />found in a small area between North Platte and Sutherland, Nebraska <br />(see exhibit 1). <br /> <br />Historically, sandhill cranes made extensive use of the Platte River <br />from Chapman all the way to the city of North Platte. Now, the riverine <br />habitat from just west of Overton upstream to North Platte receives <br />no crane use (see exhibit 1). <br /> <br />25 <br />