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UUU6J3 Ziewitz, Sidle & Dinan: Nesting Least Terns and Piping Plovers 13 sent the Central Platte by its downstream-most gage near Grand Island. Figure 6 shows mean daily flows of the Platte River during water years 1958-88 as meas- ured at Grand Island, North Bend, and Louisville. Table 5 shows calculations that relate our nest elevation measurements to the 30 years of daily discharge records of the nearest river gage: Grand Island, North Bend. or Louisville. We calculated the percentage of years and the per- centage of days that the discharges corresponding with the minimum, median, and maximum nest elevations were exceeded. The two nests that occurred on an artificially cleared island in the Central Platte (rm 184) were excluded from this analysis. We repeated these calculations for four periods of the year: the first half of the nesting season (1 April to 15 June), the second half of the nesting season (16 June to 31 August), the non-nesting season (l September to 31 March), and the entire year. The discharges corresponding to the minimum, median, and maximum ele- vations of nests on the Central Platte were exceeded consistently more often in all three seasons of the year than those of the Lower Platte. Although nests on both the Lower and Central Platte were generally located on the highest sparse- ly vegetated sites available on a sandbar, these calculations suggest that such habitat is under water more often on the Central Platte. Table 5. Frequencies that discharges associated with least tern and piping plover nest elevation measurements were exceeded in a 3D-year period (October 1, 1958- September 30, 1988) at Grand Island, North Bend, and Louisville river gages along the Platte River, Nebraska. Minimum Nest elevations Median Maximum Reach of Platte Rivera: GI NB lV GI NB lV GI NB lV Discharge (ems) associated with nest elevation: 9.7 89.9 149 82.0 392 524 164 677 1,550 Aprill-)une 15 % days exceeded: 9404 8004 75.3 25.0 7.1 12.6 11.9 1.8 004 % years exceeded: 100.0 100.0 100.0 66.7 46.7 66.7 33.3 20.0 10.0 June 16-August 31 % days exceeded: 54.5 33.9 32.6 11.8 3.3 4.6 5.7 1.5 0.5 % years exceeded: 100.0 100.0 100.0 60.0 50.0 56.7 33.3 20.0 16.7 September I-March 31 % days exceeded: 94.9 61.5 42.3 14.8 1,9 2.9 2.8 004 0,2 % years exceeded: 100.0 100.0 100.0 76.7 63.3 63.3 40.0 23.3 10.0 January 1-December 31 % days exceeded: 86.3 59.6 47.1 16.3 3.3,5.3 5.3 0.9 0.3 % years exceeded: 100.0 100.0 100.0 76.7 63.3 66.7 40.0 23.3 16.7 aGI=Grand Island gage representing the Central Platte; 11 nest elevations measured in this reach. NB-North Bend gage representing the lower Platte above the confluence of the Elkhorn River; 135 nest elevations measured in this reach. l V=louisville gage representing the lower Platte below the confluence of the Elkhorn River; 89 nest elevations measured in this reach.