Issues Concerning the Management of Bison and Elk Herds in Yellowstone National Park
T-RCED-97-200: Published: Jul 10, 1997. Publicly Released: Jul 10, 1997.
Pursuant to a congressional request, GAO discussed wildlife management issues at Yellowstone National Park, focusing on the: (1) National Park Service's (NPS) current policy for managing free-roaming bison and elk in Yellowstone; (2) controversy surrounding the impact of these herds on the park's rangeland and riparian areas; and (3) controversy surrounding the risks to domestic livestock posed by exposure to diseased bison and elk.
GAO noted that: (1) current laws and regulations provide park managers with broad discretion on how to manage their park's resources; (2) as a result, parks with similar wildlife resources, such as Yellowstone and neighboring Grand Teton National Park, can apply different approaches to managing these resources; (3) while Yellowstone uses "natural regulation," a policy that allows natural forces to regulate the size of its bison and elk herds, Grand Teton has established specific goals and objectives to control the size of its bison herd; (4) critics of Yellowstone's policy believe that the policy's implementation has produced bison and elk herds that are too large and damage the park; (5) in their view, the park's rangelands are being overgrazed, the riparian areas are being damaged, and because these lands are being depleted, bison and elk are migrating from the park in search of forage on private lands and public grazing areas; (6) according to NPS' recently published studies, however, researchers have found that Yellowstone's grasslands are not overgrazed, and several factors have contributed to the decline of the range and of the riparian areas' woody vegetation; (7) park officials believe that bison are leaving the park for a combination of reasons, because these animals are nomadic by nature, they do not have access to sufficient forage during hard winters, and they can follow snowmobile trails out of the park; (8) the health of Yellowstone's bison and elk herds is a major concern for livestock owners and public officials in the states bordering the park; (9) because many Yellowstone bison and elk are infected with brucellosis, a disease that can cause cattle to abort during pregnancy, these parties fear that the wild animals may transmit the disease to domestic cattle; (10) a state with infected livestock may lose its federal brucellosis-free classification, jeopardizing its right to freely transport cattle across state lines; (11) as a result, these parties believe that the risk of transmitting brucellosis from bison to domestic cattle must be eliminated by containing bison within the park, by using vaccines, or by shooting or capturing bison that leave the park; (12) according to NPS, the risk that brucellosis will be transmitted from either elk or bison to cattle is likely to be very low; (13) this past winter, the Yellowstone bison herd was reduced to about a half of its size the previous year; and (14) in the short term, this reduction may provide an opportunity for NPS and its critics to complete and assess the results of studies which could go a long way toward resolving this controversy.