Because of the declines in grassland bird populations across North America, many state and federal agencies are making efforts to manage for grassland bird populations, particularly in a landscape context. To effectively manage for grassland birds, we need to understand how grassland bird species use different habitat types within landscapes. We determined the densities of grassland birds in remnant prairie patches and Conservation Reserve Program (CRP) fields and compared those to managed agricultural habitat types (pastures, alfalfa hay and strip crop fields). We also investigated whether densities were associated with landscape features. This study took place in the Military Ridge Prairie Heritage Area (MRPHA) in southwestern Wisconsin May–Jul. 2002 and 2003. Land use in the MRPHA is primarily agricultural, with a relatively large portion of the land in pasture, hay, small grains and idle grasslands enrolled in CRP and relatively few acres of corn and soybeans compared to other areas of the state. This area also has numerous remnant prairie patches. We used line transect surveys to measure species density in the different habitat types. The five most common grassland species in the study area were bobolink (Dolichonyx oryzivorus), eastern meadowlark (Sturnella magna), grasshopper sparrow (Ammodramus savannarum), Henslow's sparrow (A. henslowii) and Savannah sparrow (Passerculus sandwichensis). Densities did not differ between years. Habitat type was the most important factor associated with species density. Bobolink densities were greatest in hay fields, followed by CRP fields. Eastern meadowlark densities were greatest in CRP fields, remnant prairie patches and pastures. Grasshopper sparrow densities were greatest in remnant prairie, Henslow's sparrow densities were greatest in CRP fields and remnant prairie and Savannah sparrow densities were greatest in pasture and hay fields. There was no evidence that densities of any of the grassland species increased with site size within habitat type. Only bobolink and eastern meadowlark were associated with a landscape variable; both species' densities in the field were positively associated with proportion of grassland within 200 m of the site. When managing for grassland birds in a landscape with a large amount of grassland, a diversity of habitat types will be needed to conserve grassland birds as a group.
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