Nebraska Game and Parks Commission
Date of this Version
5-8-2008
Citation
2008 Authors
Abstract
The purpose of this Conservation Effects Assessment Project (CEAP) assessment was to evaluate the energetic contribution of the Wetlands Reserve Program (WRP) for migratory waterfowl using the Rainwater Basin Wetland Complex (RWB). The RWB is located in south central Nebraska and encompasses 6,150 mi2 that is dominated by row crop agriculture. Historically, > 204,000 acres of playa wetlands were scattered across this region, but currently, just over 40,000 acres of wetlands remain. Annually, an estimated 12.4 million migratory waterfowl use this region during fall and/or spring migrations. Although used with less intensity as a fall stopover, approximately 9.8 million birds use the region during spring migration. This concentration of waterfowl coupled with reduced wetland resources is hypothesized to be causing intense competition between individuals for necessary energetic resources. We developed a bio-energetic model to evaluate the landscape’s capacity to provide energetic resources for migrating waterfowl. Two components are necessary to complete a bio-energetic model, the energetic requirements of the individuals using the region and the energy available in primary forage habitats. Once these values were determined the model allowed us to evaluate both landscape capacity and program specific contribution to regional waterfowl foraging capacity. In total the RWB needs to provide 24.1 billion kcal of energy for migratory waterfowl. Currently waste grain can meet all waterfowl energetic requirements using the RWB region. Although sufficient energetic resources exist, research has documented that food resources other than waste grain are required to meet all waterfowl nutritional requirements (essential amino acids, inorganic elements, and vitamins). We used previous research to estimate that 39% (9.5 billion) of the 24.1 billion kcal should be provided by wetland habitats. Prior to delivery of WRP, the RWB could provide 5.9 billion kcal of energy from wetland habitats. The WRP has supported restoration of approximately 3,050 acres of wetland and 1,050 acres of upland habitats in the RWB. These wetland acres represent an 8% increase in the total wetland base and provide an additional 789 million kcal of energy. The WRP program has increased total wetland forage capacity in the RWB by 13% compared to pre WRP conditions. Despite the additional WRP wetland acres, the RWB is still 3.0 billion kcal short of meeting migrating waterfowl wetland forage requirements. Analysis of average (2004), below average (2006), and above average (2007) precipitation years documented 8,900, 3,200, and 12,650 acres of flooded habitat, respectively. These flooded acres could provide approximately 13%, 4%, and 21% of the total wetland forage that would have been required. These results demonstrate that additional habitat from WRP and other conservation programs will be necessary to ensure sufficient habitat becomes available as a result of variable precipitation events. These results also show the importance of management of existing wetlands, including those tracts restored by WRP, to ensure optimal habitat conditions when wetlands become flooded. A hydrologic model documented that off-site hydrologic modifications can have a tremendous negative effect on RWB wetlands ability to pond water. In the future, additional resources will also be needed to restore hydrology to ensure that under average conditions RWB wetlands function.