We modeled kill sites as a function of vegetation community, terrain ruggedness index, road density, and edge density.
We calculated a terrain ruggedness index (Riley et al.
To reduce the effects of extreme values of either component on index values, the following equation was used to calculate the terrain ruggedness index
to' = distance to the nearest, 'TRI' = terrain ruggedness index
. The full mortality risk model did not con-verge because of singularities.
Terrain Ruggedness Index = (TNC x TNF) / (TNC + TNF) Hence, an area with many contour intercepts and changes in slope direction will have a high TRI, while smooth or gently rolling terrain will have a low TRI.
Relationships between caribou density (no./km2) and terrain ruggedness index (TRI) at the mesoscale (10-20 m) for areas > 10 km f rom surface development, Colville-Canning region, Alaska, 1987-92 (n = 17 4).