 In addition to bald eagles , which live in the IBA year round and have successfully established a breeding population there , the IBA is home to belted kingfishers , scarlet tanagers , black @-@ throated blue warblers , common mergansers , blue and green herons , hermit thrushes , and wood ducks . Large numbers of ospreys use the gorge during spring and fall migration periods . The woodlands are inhabited by wild turkeys and Pennsylvania 's state bird the ruffed grouse . Swainson 's thrush breeds in the IBA and the Northern harrier breeds and overwinters in Pine Creek Gorge . 
