Grassland songbird nest-site selection and response to mowing in West Virginia

Grassland bird populations in the eastern United States have become increasingly dependent on human-altered grassland habitats such as former hayfields and pastures for nesting. We compared grassland bird nest success and nest placement on former hayfields (n = 3) and former pastures (n = 3) and on mowed and unmowed areas on the Canaan Valley National Wildlife Refuge (CVNWR), West Virginia, 1999–2000. We located 83 nests of the 4 dominant grassland species: bobolinks (Dolichonyx oryzivorus; 19% nest success), Savannah sparrows (Passerculus sandwichensis; 34%), red-winged blackbirds (Agelaius phoeniceus; 21%), and eastern meadowlarks (Sturnella magna; 70%). Vertical density of vegetation was taller at successful bobolink nests and maximum height was greater at successful Savannah sparrow nests than at unsuccessful nests. Eastern meadowlarks chose nest sites with more standing dead vegetation, deeper litter, and a greater maximum height of vegetation. Although there were no differences in nest success between mowed and unmowed treatments, mowing some fields at the conclusion of the breeding season may provide long-term advantages to grassland bird nesting success by maintaining former fields as grassland habitats.