In autumn every walnut tree that is bearing nuts becomes a focal point of activity for squirrels. Over a period of weeks the squirrels concentrate their attention on the walnut crop, continuing until virtually every nut has been harvested. Walnut seems to be the one most important food source, for both the fox squirrel and the gray squirrel. Most of the nuts are stored for future use. Many buried separately and never retrieved by the squirrels, grow into new trees. White-footed mice often store the nuts in their nests, in burrows, beneath rocks or in crevices. In summer, groves and isolated trees of walnuts are favorite haunts of the yellow-billed cuckoo, which finds concealment in the thick foliage, and probably feeds upon the tent caterpillars that commonly infest these trees. #Carya ovata.#--Shagbark hickory is one of the more important hardwoods of the area. The trees are relatively small compared with the larger oaks, elms, ashes and hackberry. However, on several parts of the area this hickory is dominant. It grows mainly on north slopes and hilltops. The trees most frequently associated with it are black oak, American elm and chestnut oak. Scattered through the woodlands are occasional mature hickories of DBH 18 inches or more. However, many of the trees are six inches or less DBH and a large proportion of these have originated as stump sprouts from trees cut in the early thirties or before. Shagbark is especially tolerant of shading. Numerous young trees and seedlings noted all were growing in dense woods of larger hickories, oaks, or mature elms. None has been found in open fields or even in edge situations. This hickory is resistant to drought; relatively few died during the drought of 1952-1954, and these were mostly small trees in crowded stands. In parts of the woodland dominated by shagbark hickory the trees are mostly 5 to 6 inches or even smaller in trunk diameter and 20 to 30 feet high, sometimes growing in nearly pure stands, and with a leaf canopy so dense that shrubs and herbaceous vegetation are sparse. The mast crop produced by shagbark is an important food source for both fox squirrels and gray squirrels. Both kinds of squirrels often use these hickories as sites for their stick nests. White-footed mice also store the nuts as a winter food source. Birds which are most often seen in groves of shagbark include the yellow-billed cuckoo, tufted titmouse (_Parus bicolor_), black-capped chickadee (_P. atricapillus_), blue jay, summer tanager (_Piranga rubra_), and red-eyed vireo. The Cooper hawk (_Accipiter cooperii_) has been recorded nesting in this hickory. In dead trees of this species that are still standing, the interiors may decay more rapidly than the armorlike bark plates. On several occasions tufted titmice and chickadees have been recorded as nesting in such cavities.