Topographical Variables Influencing Dermacentor andersoni Distribution in Montana

Abstract

The Rocky Mountain wood tick, Dermacentor andersoni, is a known arthropod vector for Rocky Mountain spotted fever, Colorado Tick Fever, and Tularemia. This tick is prevalent in the western part of the United States. The adult ticks ingest blood meals from large mammals and can easily spread disease to humans. Using an infectious disease ecology approach, we developed a drag sampling protocol to capture ticks in order to quantify and survey their population distribution. We sampled 77 tick sites on the upper Missouri drainage in west-central and southwestern Montana. The variables of interest were slope aspect and elevation. We found no correlation between the distribution of ticks and elevation, but there was statistical difference in tick distribution due to slope aspect. Ticks were found more frequently and in greater number on south and east facing slopes rather than north and west facing slopes.