Many endangered mussels and fish in the east mainly need clean, clear, naturally flowing streams, which parks strive to maintain through appropriate regulations. The gray wolves of Voyageurs and Glacier national parks thus far are simply given the protection afforded all wildlife in national parks. Some species, however, need more active protection. Research showed that cruise ships and other boats were disturbing the humpbacked whales that summer in Glacier Bay National Park and that commercial fishermen were taking some of the species that whales feed on. So the National Park Service issued regulations that limited the numbers and activities of boats in the Bay, and prohibited the harvest of certain fish and crustaceans.
Research continues in order to refine our understanding of human impacts on the whales.
Sometimes it becomes necessary to restore the habitat to maintain an endangered species. The red-cockaded woodpecker, for instance, needs large open stands of mature southern pines for nesting, roosting, and feeding. Such stands have become scarce because of logging and the suppression of fire, which allows young hardwoods to fill in the stands of pine. Park managers at Big Cypress National Preserve in Florida and Congaree Swamp National Monument in South Carolina have carried out prescribed burning to maintain these nesting areas. The most dramatic step is to restore a species that has been lost from a park.