Interspecific Variation in Habitat Preferences of Grassland Birds Wintering in Southern Pine Savannas

—We studied wintering grassland bird communities in De Soto National Forest in southern Mississippi, USA to assess differences in bird communities and vegetation structure among different stand types. We also examined which vegetation structure and plant species predicted occurrence of Bachman’s Sparrow (Peucaea aestivalis), Henslow’s Sparrow (Ammodramus henslowii), and Sedge Wren (Cistothorus platensis). Bachman’s Sparrows occurred only in uplands (x 5 0.5 birds/ha) and stands managed for Red-cockaded Woodpeckers (Picoides borealis; x 5 0.9 birds/ha), Henslow’s Sparrows occurred only in bogs (x 5 3.8 birds/ha) and stands managed for Red-cockaded Woodpeckers (x 5 2.1 birds/ha), while Sedge Wrens occurred in all stand types (x 5 0.1–0.3 birds/ha). There were no significant differences among stand types in total bird densities for all three species combined. Dense, spatially uniform herbaceous cover and cover of Scleria muhlenbergii, a preferred food item in bogs, best predicted Henslow’s Sparrow occurrence (39% s explained). Increased woody understory vegetation and decreased tree density best predicted Sedge Wren occurrence (17% s explained). Management for Henslow’s Sparrows should focus on small-scale herbaceous ground-layer restoration in bogs. Bachman’s Sparrows will respond more to thinning dense upland stands. Sedge Wrens and Bachman’s Sparrows benefit from Redcockaded Woodpecker management, whereas Henslow’s Sparrow use of woodpecker stands is ephemeral. Received 6 March 2010. Accepted 9 September 2010. Virtually all remaining longleaf pine (Pinus palustris) savannas are subject to management for habitat improvement and sensitive species. Management, such as that for Red-cockaded Woodpeckers (Picoides borealis; hereafter RCW), may alter portions of forest stands in ways that create distinct patches. Natural variation in local topography in pine savannas, combined with forest management, leads to a variety of localized habitat types that differ in plant species composition and structure (Kirkman et al. 2001, Drewa et al. 2002a). These differences may also be reflected in grassland bird habitat preferences. Understanding these preferences is crucial for developing efficient species-specific conservation plans. The majority of pine savanna habitats in De Soto National Forest (DSNF) can be divided into three distinct types: (1) upland pine stands (‘‘uplands’’), (2) upland pine stands managed for RCWs (‘‘RCW’’), and (3) hillside seepage pitcher plant (Sarracenia spp.) bogs (‘‘bogs’’). RCW clusters are an artificially designated stand type, whereas uplands and bogs are naturally occurring and well documented in the literature (Clewell 1986, Olson and Platt 1995). Concern over the impact of ecosystem management on non-target species has sparked interest in the effects of RCW management on other organisms (Hunter et al. 1994, Brennan et al. 1995, Provencher et al. 2002). Several studies have shown stands managed for RCWs contain different bird communities than unmanaged stands and have higher densities of Bachman’s Sparrows (Peucaea aestivalis) (Conner et al. 2002, Provencher et al. 2002, Wood et al. 2004). No published studies have documented RCW cluster use by Henslow’s Sparrow (Ammodramus henslowii) or Sedge Wren (Cistothorus platensis), common wintering grassland birds in pine savannas. Few studies have examined grassland bird preferences among habitat types in pine savannas. Some studies suggest Henslow’s Sparrows may prefer bogs over uplands (Plentovich et al. 1999, Tucker and Robinson 2003), while others have found birds in upland stands (Carrie et al. 2002, Johnson 2006, Palasz et al. 2010). Henslow’s Sparrows generally use both upland longleaf pine savannas and bogs, but may prefer bogs when both habitat types are in close proximity. Bachman’s Sparrow habitat preferences across different stand types have rarely been studied in winter. Allen et al. (2006) found breeding Bachman’s Sparrows were more common in upland habitats compared to wetter pocosins, a type of bog, in North Carolina longleaf pine savannas. Bachman’s Sparrows, as is also the case for Henslow’s Sparrows (Bechtoldt and Stouffer 2005), prefer to winter in grasslands that were burned in the previous growing season (Cox and Jones 2009). 1 School of Renewable Natural Resources, 227 RNR Building, Louisiana State University and LSU Agriculture Center, Baton Rouge, LA 70803, USA. 2 Corresponding author; e-mail: [email protected] The Wilson Journal of Ornithology 123(1):65–75, 2011