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scenarios in relation to Platte River habitat needs for migratory whooping cranes in <br />the AWP. The approximately 2900 -acre habitat complex per each of 10 bridge <br />segments (such as that described in the Platte River Management Joint Study and <br />referenced in the Cooperative Agreement) is preferred over smaller units. However, <br />smaller units may still be beneficial to whooping cranes if they contain suitable <br />whooping crane habitat and are sufficient in number and spacing to be detectable to <br />cranes flying over the Platte River. Therefore, some flexibility in layout and size of <br />the complexes could be accommodated, but these areas should be protected from <br />disturbance and contain certain key habitat parameters (e.g., wide, wet river <br />channels, wet meadows, lowland grasslands). There is a need for more research on <br />what habitat best provides benefits for whooping cranes along the Platte River. <br />These habitat complexes should not be a substitute for maintaining the ecological <br />integrity of the Platte River system. Existing suitable habitat should remain along <br />the central Platte River exclusive of future restored and managed habitat. There are <br />other species, including sandhill cranes, that require substantially more roosting <br />habitat than would exist only in these habitat complexes. Ultimately, whooping <br />cranes may also be adversely impacted if sandhill cranes become overcrowded by <br />lack of habitat and reduced food base. <br />Present information suggests significant migration movement of whooping cranes <br />west of the central Platte River. 62 However, there is little suitable stopover habitat <br />in that western reach (North Platte to Lexington). Benefits to whooping crane <br />distribution would incur by protecting and managing habitat along the Platte River <br />west of Lexington, similar to habitat complexes proposed for the central Platte River. <br />However, the same intensity of management as in the central Platte River may not be <br />feasible or possible west of Lexington, primarily because of the lower flow <br />conditions upstream of the J -2 Return near Lexington. <br />B.S. Detection of Whooping Crane Use and Population Trends on the Platte <br />River <br />The whooping crane group at the September 2000 workshop was unable to develop <br />specific numbers objectives for whooping cranes on the Platte River primarily <br />because (1) survey techniques currently do not detect all use by whooping cranes, <br />and (2) the erratic and low annual crane use may make statistical analysis difficult. <br />B.5.1. Survey Techniques <br />In the mid to late - 1980's, surveys were intensive, with daily flights of the river <br />in April and October. Surveys since that time were mostly limited to <br />responding to reported sightings. Migration for all individual whooping cranes <br />is highly variable, but can occur from mid - February to mid -May in the spring <br />and from mid - September to early January in the fall and winter. Thus, the <br />survey period is extensive and daily surveys would be necessary if a count of <br />62 FWS records, Grand Island, Nebraska. <br />22 <br />