Friday, August 7, 2009

PS 80-46: Bird species richness and abundance associated with water availability and climate in south-central Nebraska

Enrique H. Weir, Platte River Whooping Crane Maintenance Trust


The Central Platte River and Rain Water basins at south-central Nebraska, USA, are remarkable habitats for both aquatic and terrestrial bird throughout the year. Birds use these habitats as stopovers during spring and fall migrations, breeding grounds, and wintering grounds. In this study I compared bird richness and relative abundance between two periods of time: 1979 - 1987 and 1998 - 2006, with the purpose of evaluating changes in bird species richness and abundance in relation to hydrology, climate (local and global), and habitat changes. I used historical data from North American Breeding Bird surveys, Christmas Bird counts, and spring and fall surveys (Nebraska Ornithologists Union) from Buffalo, Phelps, Kearney, Hall, and Adams counties. 

Results/Conclusions Bird species richness was reduced by 4 percent in the 2000’s and the relative abundance of bird species was reduced as well in this period. Many of the remaining aquatic and terrestrial birds that were abundant, common or fairly common in the 80’s were uncommon, rare, casuals or accidentals in the 2000’s (7, 70, and 41 species respectively decreased in abundance). The long drought period during the 2000’ could be one of the main drivers of changes in bird species richness and abundance. Directly due reduction of water availability in Central Platte River and Rain Water Basins (that reduced resources associated with these water bodies), and indirectly via changes of habitat physiognomy of the landscape where width and flow reductions are stimulating tree and shrub invasions along the coast of and inside of the river and rain water basin areas where the water availability is intermittent.