Abstracts

Presented by Mike Eichholz - Email: eichholz@siu.edu

A common restoration practice aimed at waterfowl production involves the establishment of low-diversity (3 5 species) Dense Nesting Cover (DNC) areas seeded with a mixture of introduced grasses and forbs. While DNC provides secure duck nesting habitat, low-diversity seeding mixes have demonstrated vulnerability to invasive vegetation and may fail to meet habitat requirements of other grassland species. In attempts to develop more ecologically-stable and heterogeneous habitat, there is interest in shifting seeding practices towards species-rich native vegetation (SRNV) plantings of 16-32 species. In a previous study designed to evaluate the efficacy of DNC and SRNV restorations as duck nesting habitat, we found that ducks select SRNV at a level similar to DNC, but lower Daily Survival Rate (DSR) was observed at SNRV sites in a year of high skunk-abundance. We hypothesized that higher-diversity habitats may be capable of supporting a larger number and diversity of organisms, including increased abundance of co-existing prey and predators which can negatively impact breeding duck populations. In our current study, we compare dabbling duck nest success, meso-predator abundance, small mammal abundance, and arthropod abundance on 26, 20-ha experimental plots across south-eastern North Dakota and north-eastern South Dakota. Plots represented a species richness gradient ranging from low-richness stands of DNC to progressively more species-rich plots (8-34 species). In contrast to our previous study, we found DSR of duck nests increased with vegetation species richness. These results were unexpected, but subsequent analyses of other components of the grassland community including vegetation structure and small mammal abundance suggest the result is a direct relationship with vegetation richness, or a relationship mediated by abundance of predators and/or coexisting prey. We present results obtained during this study, and discuss their implications for grassland management and restoration for wildlife.