Whitetail deer prefer young forests and mixtures of forest and field because in these areas an abundance of shrubs and herbaceous plants provides ample food. The mature forests of the Smokies have relatively little forage near the ground and so they support only small numbers of deer. In the Cades Cove area, however, the lush meadows and second-growth forest feed several hundred deer. In the fall deer join in the mast harvest, but they do not depend on it as do the bears, gray squirrels, wild boars, and chipmunks. Deer have the option of eating twigs, buds, and herbaceous plants. They eat acorns, however, and this nutritious food will help them enter winter in good condition. Deer mating takes place from September to November in the Smokies, as the mature males each run with a female for several days, then hunt for another. In winter the bucks shed their antlers and join the does and yearlings. In May or June the does give birth to their spotted fawns, usually twins. The summer bands you see in Cades Cove are again separated by sex as the bucks once again grow antlers in preparation for the autumn battles. Now that wolves and other large predators are gone from the Smokies, starvation and disease are the principal checks on deer numbers. Late in 1971 a disease that causes massive bleeding struck the herd in Cades Cove, killing many of the deer and a few cattle. But by the following spring an increase in the production of offspring and the influx of deer from nearby areas brought the herd back almost to its former number. Gray squirrel numbers fluctuate even more dramatically, as populations build up and then collapse, but these oscillations occur even when food is adequate. Until recently, some observers thought these oscillations were amplified by mast failures, but apparently they are not. In the Smokies, gray squirrels are found mostly in the oak and beech forest of the lower and middle elevations, while their smaller cousins, the red squirrels, stick more to the upper elevations. In years of extreme low population swings such as 1946 and 1968, many migrating squirrels have been killed on the highways; others have even been seen attempting to swim Fontana Lake. The loss of gray squirrels in 1946 was estimated at 90 percent for some watersheds. Turkeys and ruffed grouse both feed heavily on acorns in the fall, although they, like the deer, have other possibilities. Turkey and grouse also feed on the fruits of dogwood and wild grape; beechnuts in good years; seeds; and buds. A statewide study in Virginia found that acorns supplied about one-quarter of the annual diet of wild turkeys, and this proportion is much higher in fall. Acorns are also a top food item in fall for ruffed grouse.