Influence of Old World bluestem (Bothrichloa ischaemum) monocultures on breeding density of three grassland songbirds in Oklahoma

Despite persistent and widespread declines of grassland birds in North America, few studies have assessed differences between native grasslands and seeded monocultures as songbird habitat. In the Great Plains, many fields enrolled in the Conservation Reserve Program have been seeded to Old World bluestems (OWB), but there is evidence to suggest that OWB may not provide suitable conditions for several grassland bird species. Our objectives were to investigate the influence of OWB monocultures on vegetation structure, composition, and breeding densities of three common grassland bird species. In 2007, we used distance sampling to survey breeding songbirds in 6 native mixed grass prairie and 6 OWB fields in Garfield, Grant, and Alfalfa counties, Oklahoma. Native mixed grass prairie supported taller and denser vegetation, as well as greater forb cover than OWB fields. Breeding density of Grasshopper Sparrow (Ammodramus savannarum) was higher in OWB monocultures, while density of Dickcissel (Spiza americana) and Eastern Meadowlark (Sturnella magna) was similar among field types.