Grassland management for the conservation of songbirds in the Midwestern USA.

摘要

Breeding eastern meadowlarks (Sturnella magna), dickcissels (Spiza americana), Henslow's sparrows (Ammodramus henslowii), grasshopper sparrows (A. savannarum) and field sparrows (Spizella pusilla) were monitored using strip transect surveys in 1995and 1996. The 473-ha study area was an array of 3-ha management units of burned, mowed, hayed, grazed and undisturbed (>1 year) cool- and warm-season grasses and annual weeds, located in Jasper County, Illinois. Management units grouped by habitat type (management regime and grass type) had different (P<0.05) abundances of each species. Eastern meadowlarks and dickcissels were most frequently observed in grazed warm-season grasses. Observation rates of Henslow's sparrows and field sparrows were highestin undisturbed warm-season grasses, whereas eastern meadowlarks and grasshopper sparrows were observed least often in this habitat type. Grasshopper sparrows were observed most frequently in annual weeds; Henslow's sparrows and field sparrows were not observed in this habitat type. Overall avian abundance was lowest in recently burned cool-season grasses. The low-intensity, late-season grazing system was important for creating a heterogeneous habitat mosaic attractive to the five species studied.