Bears, Boars and Acorns
As frosts touch the earth and the reds and yellows of fall creep down the mountainsides, oaks, hickories, beeches, and other trees shed their fruits. Many animals will join in the harvest of this fruit, but several, especially bear, deer, wild boar, gray squirrel, chipmunk, turkey, and ruffed grouse, are particularly dependent on this mast, as it is called, for their autumn and winter welfare. With the chestnut gone these animals must rely mostly on acorns. Oaks, unlike the chestnut, do not produce consistently, but fruit abundantly some years and fail in others. In the poor years, when competition for mast is keen, the effects are starvation, wandering, and mass migrations. The appearance and multiplication of European wild boars in the park have only added to the pressure on the native animal species. Acorn shortages bring into sharp focus the life styles and survival systems of the mast-dependent animals. From among these the wild boar emerges as an ecological villain, although we should perhaps cast man, who introduced the boar here, in that role.
The loss of the chestnut illustrates how a change in one element can irrevocably alter an entire ecosystem. As the chestnuts of the Smokies died, their place was taken primarily by chestnut oak, northern red oak, red maple, hemlock, and silverbell. The annual mast crop suffered from this change in two ways. First, only about half of the replacement trees were mast-bearing oaks. Second, oaks are not dependable mast-bearers. Mast failures seem to result mainly from spring freezes during the pollinating and fertilization of oak flowers. Chestnuts bloomed in the first two weeks of June when the danger of frost was slight and so they bore well nearly every year. This difference in flowering time has had reverberations throughout the animal world within these mountains. By looking into the life histories and population dynamics of some of the acorn eaters we may get some idea of the nature and extent of those reverberations.
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.
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.
As fall progresses blackberries, blueberries, and beetles diminish in the diet and acorns and beechnuts increase until they become the primary sustenance. Bears are particularly fond of white oak acorns, the sweetest. In their eagerness the huge animals, which sometimes reach 200 kilos (450 pounds) in weight, even climb trees and crawl out on the branches as far as they can to eat the fruits or break off and drop the branch tips for consumption on the ground. They also relish black cherries and serviceberries. A park naturalist told me of watching a very large bear climb a 5-centimeter (2-inch) thick serviceberry on Spence Field, bending the tree double. Throughout the Southern Appalachians you can see small serviceberries broken down like this by bears in their quest for the fruits.
In most years the mast crop is adequate for all the animals dependent on it, but in the years of failure bears are hard pressed to find enough to eat. They wander down out of the mountains in search of food. In such years many are killed by hunters outside the national park. The loss of bears in some of the poorest mast years may be one-third to one-half of the park’s bear population.
Enter now the European wild boar. Its history in the Smokies is another classic example, along with the chestnut blight fungus, balsam woolly aphid, Norway rat, Starling, and a host of other pests, of the damage that can be done by introducing an organism to territory outside its normal range. The wild boars in the Smokies are believed to be descendants of animals, purportedly of stock from Germany, that escaped from a game preserve on Hooper Bald, southwest of Fontana Lake, in the early 1920s. They were first detected in the park about 1950. By the early 1960s wild boars, now with some admixture of domestic pig blood, had spread east to Newfound Gap and, in the lower country, to Cosby and possibly Cataloochee. Their occupation of the entire park seemed imminent.
So now the Smokies have a wild counterpart of the domestic hog, the staple livestock animal that mountaineers once ran year-round in these woods. Horace Kephart’s vivid description of the hog in the 1920s applies almost as well to today’s European wild boar: “In physique and mentality, the razorback differs even more from a domestic hog than a wild goose does from a tame one,” Kephart wrote. “Shaped in front like a thin wedge, he can go through laurel thickets like a bear. Armored with tough hide cushioned by bristles, he despises thorns, brambles, and rattlesnakes, alike. His extravagantly long snout can scent like a cat’s, and yet burrow, uproot, overturn, as if made of metal.”
The hog’s long legs, thin flanks, and pliant hoofs fitted it to run like a deer and climb like a goat, Kephart claimed, calling it “a warrior born” who was also a first rate strategist.
The European wild boar sometimes attains a height of nearly a meter (three feet) at the shoulder and a weight of 100 kilos (220 pounds). It is built rather like a bison, the hindquarters sloping down from the shoulders. The long, hairy-tipped tail and, in the male, well-developed tusks also distinguish it from its domestic counterpart. Obviously, this is a formidable animal, as numerous boar hunters who have been treed by it or watched it cut up their dogs can attest. Normally, however, wild boars are not dangerous and run at the sight or scent of man. One evening, standing in a yard where a boar had rooted the night before, I asked a long-time boar observer about the animal’s pugnacity.
“They won’t attack you unless they’re wounded or hemmed,” this observer related. “I’ve tried to get them to charge me. Even picked up a squealing piglet once, but the sow didn’t attack.”
Wild boars feed mostly at night. Campers near balds in the western section of the park sometimes see them or hear their grunts and snorts as they run away. The females and young travel about in family groups but the males are loners. Though the animals are elusive, spending their days resting in dense cover, the signs of their rooting are very obvious on balds, in beech gaps and open fields, and along trails in moist woods.
Wild boars move seasonally in quest of food. In spring they eat a lot of grass, as well as succulent roots and the upper parts of wildflowers, which are especially abundant in cove forests and high-elevation beech forests. In summer they continue eating grass and other herbaceous plants but also seek huckleberries, blueberries, and blackberries. When acorns, hickory nuts, beechnuts, and other tree fruits start falling, they turn their attention to these, which in abundant years can carry the boars through winter. When the mast fails they feed heavily on tubers of wild yam and the outer layer of pitch pine roots. Throughout the year they supplement this vegetable diet with whatever invertebrates, salamanders, snakes, rodents, and other small animals they can root out or catch. Carrion and garbage are always welcome, too. The wild boar, as classic an omnivore as his domestic cousin, will eat almost anything.
Aside from the competition they give other masteaters in the critical fall season, wild boars upset the ecological balance in additional ways. Susan Bratton, research biologist with the National Park Service’s Uplands Field Research Laboratory here in the Smokies, has made detailed studies of boar damage. She found that in some areas boars had greatly reduced the numbers of certain wildflowers, such as spring-beauty, yellow adder’s-tongue, and wake-robin. Many other kinds of herbaceous wildflower species in the park are known to have been eaten, uprooted, or trampled. Wild boars also damage tree roots and seedlings, but apparently avoid beeches, thus favoring the root sprouting of this species. They root up grass sod on balds, which speeds the invasion of balds by other herbaceous plants and trees and they cause soil erosion by removing the plant cover. They also harm native species by preying on those mentioned above and destroying the nests and eggs of ground-nesting birds such as grouse and turkeys.
With such a list of black marks against the non-native wild boar, it becomes readily apparent why the National Park Service is concerned about its numbers in the park. Conventional methods of trapping and directly reducing the boar population have limited their impact in certain areas of the park. Unfortunately, because of the animal’s tremendous reproductive capability the efforts are not successful in reducing the total park population. The technology to completely eradicate the boar from the park is not available at the present time. Park Service research is now aimed at control methods. Estimates of the boar population have ranged upward to 2,000. But no reliable method of counting the boar in the park has yet been devised. University of Tennessee research has indicated that there may be at least 1,000 boars in the national park. Other estimates suggest there might be twice that many. Wild boars can reproduce any month of the year and most females bear a litter of from one to twelve piglets each year. And the wild boar has few enemies in the park, although bears and bobcats may occasionally take the young boars. With such a high reproductive potential, and so few controlling agents, the wild boar population has reached a size that severely alters and damages the park’s natural environment.
Contrast these population dynamics with those of a competing native species, the black bear: Bears reproduce every other year, typically giving birth to only two cubs. When the mast fails they may not reproduce at all, apparently because the embryo does not implant, or is resorbed, or the mother has insufficient milk to keep the young alive. In some years, when bears wander out of the national park, many are killed by hunters. Each year poaching within the park takes several more. Hunting aside, bear populations became attuned to the supportive capacity of the environment through centuries of adaptation. Wild boars have been here only a few decades, far too short a time for the species to be integrated into the total forest community.
As the wild boars multiply unchecked in the park, they damage ground cover, inhibit tree reproduction, increase erosion, and decrease the native animals with which they compete for food. Perhaps hardest hit are black bears, squirrels, and those other species that in the fall depend on the all-important acorn.