Effect of Road Traffic on Moose, Caribou, and Grizzly Bear Distribution in Denali National Park and Preserve, Alaska, A Final Report

Yost, Andrew

Denali National Park and Preserve provides a unique example of the challenges faced by park managers to preserve natural resources while providing visitors outdoor experiences and wildlife viewing opportunities. A wildlife monitoring system was developed in 1996 that utilized 19 landscape level viewsheds located throughout a 130 km section of the road corridor that transverses the eastern section of the park. The viewsheds were divided into 4 strata with each stratum corresponding to a subsequent decrease in traffic volume. In 1997, 9 backcountry viewsheds in 3 different areas were established for comparing density estimates produced by program DISTANCE, between the first 3 road strata. Density estimates were higher in only 1 backcountry area for moose, none of the backcountry areas for caribou and 2 backcountry areas for grizzly bears. Chi-square goodness-of-fit tests showed that the number moose sightings was significantly less than expected within the first 300 meter zone from the road; caribou and grizzly bear sightings were significantly higher within 601-900 meter zone; moose sightings were significantly higher and caribou sightings were significantly less than expected in the 901-1200 meter zone. Analysis of variance on the ranks of distances from the road that moose, caribou and grizzly bears occurred when first sighted in stratum 1 were significantly farther from the road than bulls and cows in stratum 4. Cow moose in stratum 1 and bulls in stratum 2 were significantly farther from the road than cows in stratum 4. Grizzly bears in stratum 2 were significantly farther from the road when first sighted than those sighted in stratum 3. Caribou and (to a lesser extent) grizzly bear sightings were associated with higher elevations during late June and July and lower elevations in May, early June and August. Moose may have avoided the first 200 meters or the road but the spatial structure of willow patches appeared to be more influential in the distribution. The spatial discontinuity of moose throughout the study area in conjunction with demographic information lends support for evaluating the Denali moose population within a metapopulation framework. While some caribou showed caution when encountering road traffic there was no strong pattern of avoidance. The influence of the road traffic on grizzly bear distribution appears to be less than forage availability, abundance and phenology. The noninvasive viewshed monitoring protocol for wildlife in Denali National Park and Preserve can be easily repeated and will help determine the status of wildlife resources, detect change and trends and help measure the effectiveness of management policies.