An Exceptional Fall Migration of Shorebirds along the Big Bend Reach of the Platte River

The Big Bend reach of the Platte River extends about 80 miles from Overton to Chapman, Nebraska. This area is characterized by braided channels with numerous riverine islands bordered by cottonwoods (Populus deltoides) and willows (Salix spp.) along the high banks. Habitat between the high banks consists of open water, barren sandbars and mudflats, herbaceous islands, shrub islands, and floodplain forest. Prolonged summer flows during 1983 were among the highest recorded this century; in excess of 20,000 cfs (cubic feet per second). Spring 1984 also consisted of high flows resulting in much scouring and shifting of alluvial sediments. By early July 1984, flows had dropped from about 3,000 cfs to less than 400 cfs by the end of the month. These low flows continued until 6 September; then they increased to over 3,000 cfs. During the drawdown phase of these flows, large mudflats were exposed in low-lying and backwater areas. These nutrient-rich sediments hosted multitudes of aquatic insect larvae, especially larvae of Chironomidae (midges). The abundance of both suitable habitat and an available food source coincided with the “fall” or southward migration of several species of shorebirds. These conditions resulted in an exceptional shorebird flight along the Platte River. The following species account summarizes our observations