We come now to the two chief antagonists in the annual mast hunt, bears and wild boars. The arrival of wild boars in the park has meant added competition for bears, as well as many other disruptive ecological effects. By considering the population dynamics and seasonal activities of these two species, we get a clear contrast between their roles. One fits in with the forest “establishment” and one clearly does not. How many bears live in the park? This is difficult to determine because bears are secretive and tend to wander. The National Park Service estimates that numbers usually range from about 400 up to about 600, depending on reproduction, food availability, extent of poaching, and other factors. The estimates are based on intensive research by the University of Tennessee in the northwest quarter of the park. From about December to March black bears sleep, although they occasionally come out for brief periods. During the University of Tennessee studies it was learned, to the surprise of many, that bears in the Great Smokies had a preference for denning in hollow trees, sometimes as much as 15 meters (50 feet) above the ground. Typically, such a tree has been broken off by storms and provides an entrance and some sort of platform within that supports the bear. In such a den, or one in a protected place on the ground, the female in alternate years gives birth to tiny cubs weighing about a half-kilo (18 ounces) apiece. Most bears leave their dens in late March or April and from then until early summer, when berries begin ripening, they find food scarce. Black bears are primarily vegetarians, though they eat almost any animal matter they can find, from ants to large mammals, as well as carrion. In spring they graze grasses heavily. Squawroot, a fleshy, conelike, parasitic plant, is a favored food then, so much so that local people call squawroot bear potato or bear cabbage. Roots and insect grubs also help to see the bears through spring, a time so lean for them that droppings are seldom seen on the trails. At this season bears roam widely at all elevations. Mating occurs in early summer. From late July until early September the bears concentrate on berries, especially the blackberries growing in open places such as ridgetops and balds, and the blueberries most abundant in open oak-pine woods. Since insects and vertebrate animals are most numerous in summer, bears harvest them more frequently then than at other times. They especially seek beetles and nests of yellowjackets. With throngs of campers in the park bears investigate this source of food, too. National Park Service management practices are aimed at ending such scavenging—which makes bears both dependent on and dangerous to people—and ensuring that the animals live out their normal lives in the forest. Being deprived of garbage will work no hardship because, for bears and most other animals, summer is the season of abundance.