Flooding, forest management, and scale related to habitat characteristics of Swainson's warblers

Swainson's warbler (Limnothlypis swainsonii; SWWA) is an inhabitant of dense understories and a species of high conservation priority in the Southeast. A flood in 2008 inundated my study areas, the White River National Wildlife Refuge (WRNWR) and Saint Francis National Forest (SFNF). I selected 27 stands at SFNF and 8 at WRNW and compared my data and previous data (2005--2007) to assess flood effects on SWWAs occupancy and vegetation characteristics. After the flood, SWWA occupancy was 59% at WRNWR compared to 87% at SFNF Also, the mean leaf litter volume decreased at both study sites in historically occupied SWWA territories. I evaluated how the year in which a stand was last harvested, was related to SWWAs abundance and to the total understory stem density. The year last harvested predicted SWWA abundance (R2 = 1.24, P = 0.04) but not stem density. The hypothesis that forests of 10--20 years old should contain highest SWWA abundance was not supported. I propose forests in eastern Arkansas should be managed in 30--60 year intervals. Finally, I analyzed how variables at the territory (6.15 ha) and landscape (314 ha) scales affected SWWAs occupancy compared to available random plots. The habitat heterogeneity was not different between used and random sites, but differed significantly between study sites (P = 0.001). At the landscape scale, used territories had less edge density than random sites (42.96 +/- 2.83 m/ha and 53.62 +/- 4.3 m/ha, respectively).