Bison and Elk Responses to Winter Recreation in Yellowstone National Park

Amanda Ruth Hardy

The National Park Service (NPS) is tasked with protecting wildlife and providing public access to parklands; winter recreation in Yellowstone National Park (YNP) has challenged NPS managers to balance this dual mandate. This study addresses bison and elk responses to winter recreation in the upper Madison River drainage of YNP. Using data on weather; winter recreation activity; elk and bison distribution, behavior, abundance, and fecal stress hormone (glucocorticoid) levels collected during the winters of 1998—1999 and 1999—2000, I developed models to analyze if variables related to winter recreation contributed to bison and elk distribution, behavior, and stress hormone levels responses. As distance between human activities and bison and elk decreased, behavioral responses increased. Both species behaviorally responded more often to people off-trail than to people on trails (P < 0.001 for both species), and these activities prompted more behavioral responses than activities on roads. Elk were farther from the road (P = 0.092) and had higher stress levels (unknown elk: P = 0.051; collared cow elk: P = 0.002) after exposure to >7,500 cumulative vehicles entering the West Yellowstone gate. Elk residing along the road segment with the greatest amount of oversnow vehicle (OSV) activity had higher stress levels (unknown elk: P < 0.001; collared cow elk: P = 0.004) and may have been displaced from habitat along the road (distance: P = <0.001; numbers sighted: P = 0.082) compared to elk residing along the less-traveled road segment. Collared cow elk stress levels increased (P = 0.057) while the probability of bison and elk behaviorally responding to human activities on the road decreased (P = 0.001 for both species) as daily vehicles entering the West Yellowstone gate increased. The predictability and frequency of OSV activities facilitated habituation to the majority of winter recreation activities. Abundance estimates indicated populations of wintering bison increased and wintering elk remained stable over 20 years. Despite varying responses to increased winter visitation since the late 1970s, bison and elk return to winter in the same area each year, coexisting with winter recreation without incurring losses at the population level.

Publication

In preparation

National Park Service

BISON                                                                                ELK