Avian Response To Herbaceous Riparian Filter Strips In Northeast Missouri
D. Todd Farrand, Dept. of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO 65211; (573) 884-7474; FAX (573) 884-4688; FarrandD@missouri.edu
Mark R. Ryan, Dept. of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO 65211
Robert A Pierce II, Dept. of Fisheries and Wildlife Sciences, University of Missouri, Columbia, MO 65211
Government programs to idle agricultural lands, especially multi-year set-aside programs such as the Continuous Enrollment Conservation Reserve Program (CCRP), provide opportunities to diversify agroecosystems in a way that benefits wildlife populations. Differences in implementation within a program create variability in the potential to beneficially impact a specific wildlife population or community. We investigated the factors affecting wildlife use, including avian response, of the CCRP practice herbaceous riparian filter strips. Three common filter strip planting mixes were examined: cool-season grass monoculture, warm-season grass monoculture, and cool-season grass and forb mixture. All strips were planted between row crop fields and existing woody stream bank vegetation. Avian abundances in filter strips were compared empirically to crop field sites suitable for filter strips in terms of species richness, average abundance per survey, and conservation value based on Partners in Flight (PIF) weightings. Nest success was examined in filter strips only and compared to reported values for alternative habitats (e.g., pasture, CRP). These comparisons were used to test hypotheses related to patch, landscape, and edge effects. Preliminary results indicate that the pre-existing woody vegetation is a dominant factor in determining species composition at each site. Thus, filter strip sites differed little from crop sites, in terms of species richness and average abundance. However, PIF scores showed important differences in community structure. Mayfield estimates of nest success were very low, less than 10% for all species with more than 5 nests. The narrow, curvilinear nature of herbaceous riparian filter strips and their proximity to woody vegetation creates low quality habitat for birds.