Avian response to old world bluestem (Bothriochloa ischaemum) monocultures in mixed-grass prairie

Abstract

Despite persistent and widespread declines of grassland birds in North America, few studies have assessed differences between native and exotic grasslands 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. My objectives were to investigate the influence of OWB monocultures on grassland bird abundance and community composition by identifying patterns in vegetation structure and food availability. In the breeding and winter seasons of 2007-2009, I used distance sampling to survey breeding and wintering songbirds, and conducted vegetation and arthropod surveys in 6 native 6 OWB fields in Garfield, Grant, and Alfalfa counties, Oklahoma.While OWB fields supported a higher abundance of some bird species, native fields supported more complex bird communities during the breeding and winter seasons, including several species of conservation priority. Additionally, native fields supported higher arthropod biomass, an important food source for breeding birds. Some bird species were correlated with vegetation characteristics, regardless of field type, suggesting that management may be more important than plant species composition for some bird species. Native vegetation is superior to OWB monocultures for grassland bird habitat and should be promoted in conservation programs.