Occupying the eastern half of Allegany County and the part of Washington County west of Hancock, Green Ridge IBA comprises one of the largest forest areas in Maryland. This ridge and valley landscape on the eastern flank of the Appalachians was mostly deforested by the end of the 19th Century but has now reverted to oak-hickory forest. The site includes three extensive protected areas, Green Ridge State Forest, Warrior Mountain WMA, and part of the C & O Canal National Historic Park, and a number of smaller state-owned parcels. The Green Ridge State Forest is actively managed for timber but also has several areas designated as Wildlands where no timber is harvested.
This IBA hosts a diverse avian assemblage of Forest-Interior Dwelling Species (FIDS), birds defined by Maryland DNR as requiring large, intact areas of forest. 24 species of FIDS breed regularly. Green Ridge likely contains the largest population of Cerulean Warblers in Maryland. This WatchList species is rapidly declining across its range. Another Watchlist species, Golden-winged Warbler, occurs here in small numbers in early successional habitats near forest edges. Regenerating forest in clearcuts provides habitat for Praire Warblers, also on the WatchList. Other bird species considered at-risk and having significant populations at this site include Black-billed Cuckoo, Whip-poor-will, Wood Thrush, Worm-eating Warbler and Louisiana Waterthrush.