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. Boars [Illustration: Boars] The wild boar came to the Great Smoky Mountains National Park uninvited in the early 1920s. While its population remained small, the boar was not thought a menace. Since the 1960s however, it has become obvious that the boar constitutes an ecological disaster of great proportions. In feeding, the animals move together and root up the ground or a stream bed with unbelievable thoroughness. After boars have tackled a stretch of trout stream, it looks as though a bulldozer had churned it up. Presumably they seek aquatic insects, salamanders, and even a few small fish. Salamanders are among the park’s chief biological treasures, so the boars have not endeared themselves to those who are responsible for managing wildlife here in the park. Another biological prize in these mountains is the grass bald habitat. These energetic porkers were not slow to find balds a food source, ravenously digging for June beetle larvae. The grass bald survives only by the turf’s resistance to tree invasions, so the boar and its plowing threatens the existence of these unique, and as yet incompletely understood, grass balds that are both prizes and puzzles. Over the years it has been suggested that diverse species are directly threatened by the expanding boar population. These include ground-nesting birds, yellow adder’s-tongue and other wildflowers, and possibly deer and bear. Studies are underway to determine the extent of the boar’s damage, and hence the real threat they pose. But we have no good comparative figures on the populations of other species for the years before boars arrived. Despite this lack, it has not been difficult to brand the boar a villain. But to control them has not been so easy. In good years they thrive—and gobble up more park resources.