Status of wintering grassland birds in a post-hurricane, salvage-logged forest

Abstract

North American grassland birds have been declining at an alarming rate. Winter habitat for grassland species in the southeastern U.S. generally occurs within forests subject to management. I studied wintering grassland bird communities in De Soto National Forest in southern Mississippi. My objectives were to: 1) Assess bird communities and vegetation structure in upland forest stands that were salvage-logged following Hurricane Katrina, in stands managed for Red-cockaded Woodpeckers (Picoides borealis, RCW), and in stands containing bogs; and 2) Determine the extent of the association between vegetation and occurrence of the common wintering grassland birds. I conducted bird and vegetation surveys in 27 stands over two winters. The wintering grassland bird community included Bachman’s Sparrow (Aimophila aestivalis), Henslow’s Sparrow (Ammodramus henslowii), and Sedge Wren (Cistothorus platensis). Forest-stand associations varied among species. Bachman’s Sparrows occurred only in upland and RCW-managed stands, Henslow’s Sparrows occurred only in bogs and RCW-managed stands, and Sedge Wren occurred in all stand types. None of these species’ densities was statistically different between salvaged and unsalvaged stands. There were no statistically significant differences in total grassland bird density or species richness among stand types. Henslow’s Sparrow use of RCW stands was mostly ephemeral, but our data were consistent with previous studies suggesting that RCW management benefits grassland birds. Spatially uniform, dense herbaceous cover, and cover of Scleria muhlenbergii, a preferred food item, best predicted Henslow’s Sparrow stand occupancy. Increased woody understorey vegetation and decreased tree density best predicted Sedge Wren occupancy. I recommend management practices focusing on small-scale herbaceous ground-layer restoration in bogs, an increase in the number of RCW clusters, and the thinning of trees in dense stands.