From top to bottom, O’Neil Woods is filled with interesting plants and animals. Open areas are maintained for bluebird habitat. Other avians in the park worth special note are Eastern Woodcocks, Barred Owls, Pileated Woodpeckers, Song Sparrows, Kingfishers and Ruffed Grouse. Oak trees cover the ridges while in the lowlands along Yellow Creek, Black Willows, Eastern Cottonwoods, Sycamores and Black Walnuts are abundant. Ferns and wildflowers carpet the ground. The trail leaves the creek and borders an alder swamp, one of the few in the county. Park visitors often see tracks and other signs of the deer which live in O’Neil Woods.