Disturbance and Landscape Effects on Avian Nests in Agricultural Conservation Buffers

We studied the effects of periodic disturbance (prescribed burning and light disking) and landscape composition on nest density and success for grassland birds in agricultural conservation buffers in southeastern United States agroecosystems. During the 2007-2009 breeding seasons, we located 387 nests in buffers of a northeast Mississippi agroecosystem. Dickcissel (Spiza americana) and red-winged blackbird (Agelaius phoeniceus) were the most common nesting species. Time since disturbance influenced nest densities of dickcissels and red-winged blackbirds; densities were lesser during the first growing season post-disturbance but increased during the second growing season post-burn. Nest densities for both species were least in buffers adjacent to woodland. Inclusion of disturbance did not improve models of dickcissel and red-winged blackbird nest survival, suggesting that disturbance influenced nesting density, but not nesting outcomes. Amount of grassland surrounding dickcissel nests was positively associated with nest survival, but confidence intervals included zero indicating effects were not strong. Although distance to nearest crop or developed edge were included in competing models of red-winged blackbird nest survival, their effects were negligible. Agricultural conservation buffers will best serve breeding grassland bird populations if they are established in areas with minimal woodland cover, maximize total grassland in the landscape, and are maintained with prescribed burning. These results will help characterize the contribution of agricultural conservation buffers in agroecosystems of the southeastern United States. (c) 2013 The Wildlife Society.