 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 heron , hermit thrushes , and wood ducks . Large numbers of ospreys use the gorge during spring and fall migration periods . The woodlands are inhabited by the ruffed grouse , Pennsylvania 's state bird , and wild turkeys . Swainson 's thrush breeds in the IBA and the northern harrier breeds and overwinters in Pine Creek Gorge . 
