Date of this Version
Nebraska Ornithologists’ Union Occasional Paper Number 8, 2004.
The Rainwater Basin (RWB) has received limited attention as an important stopover area for migrant shorebirds because of an absence of basic survey data. Here I present the first comprehensive inventory of shorebird migration for the eastern Rainwater Basin (eRWB). These data document the importance of this region as a stopover site for migrants and will serve as a baseline for future monitoring efforts. During five years of spring and three years of fall surveys that covered a majority of wetlands in the eRWB, an average of 23,700 and 5,581 shorebirds were recorded in spring and fall, respectively. Of 38 species recorded, most numerous in decreasing order were Whiterumped Sandpiper, Wilson’s Phalarope, Semipalmated Sandpiper, Long-billed Dowitcher, Stilt Sandpiper, and Baird’s Sandpiper during spring and Pectoral Sandpiper, Long-billed Dowitcher, Lesser Yellowlegs, Least Sandpiper, and Stilt Sandpiper during fall. The RWB is an important stopover area for these species and it has been estimated that 200,000- 300,000 shorebirds stopover in the region each spring. The surveys were conducted at a time when over 90% of the RWB wetlands have been destroyed and the remaining wetlands are degraded. Prior to settlement there were nearly 4,000 individual wetlands totaling up to 100,000 acres. The dramatic reduction in terms of both quantity and diversity of wetland types and the degradation of existing wetlands has severely reduced the capacity of the RWB to provide adequate shorebird habitat. This reduced capacity has had implications not only locally and regionally, but also on international and hemispheric scales.
The RWB is a distinct ecogeographical region where wetlands are dispersed over 10,000 square kilometers. It has been customary for researchers and conservationists to focus on individual wetlands rather than recognize a group of small wetlands as a single entity even though shorebirds likely recognize and utilize a group of dispersed wetlands in the same manner as they would a single, large wetland. No single RWB wetland provides adequate habitat or hosts large numbers of shorebirds regularly since these wetlands are greatly influenced by climate, vegetation, and disturbance and are thereby highly dynamic. Nevertheless, during any particular migration or year there is a high degree of certainty that favorable habitat and large numbers of shorebirds will be found somewhere in the RWB. Individual wetlands that vary in size and type are merely components of a larger entity, a wetland complex. Focusing on individual wetlands essentially penalizes the RWB and similar complexes when considering the criteria set forth by the Western Hemisphere Shorebird Reserve Network for recognition as a site of international importance. However when considered as a single entity, the RWB surpasses these criteria. Furthermore, the region may be of hemispheric importance to the Buff-breasted Sandpiper.