Peak numbers of Rocky Mountain wood ticks in south-facing exposures in Poudre Canyon were recorded from 7,200-7,900 ft. Note that peak numbers likely occur at higher elevations in warmer areas in southern Colorado and at lower elevations in areas further north in Wyoming etc.

There was a parabolic relationship between annual growing degree days (GDD) and abundance of Rocky Mountain wood ticks, with peak tick numbers occurring at 650 GDD and tick numbers approaching zero below 250 GDD or above 1,050 GDD.

From: Eisen, Meyer and Eisen. 2007. Climate-based model predicting acarological risk of encountering the human-biting adult life stage of Dermacentor andersoni (Acari: Ixodidae) in a key habitat type in Colorado. Journal of Medical Entomology 44: 694-704.

The relationship between growing degree days and tick abundance was used to create a Geographic Information System based model predicting abundance of adult Rocky Mountain wood ticks in Larimer County.

This model was then refined to only show predicted peak abundance of adult Rocky Mountain wood ticks in south-facing exposures with slopes not steeper than 30% in Larimer County.

From: Eisen, Meyer and Eisen. 2007. Climate-based model predicting acarological risk of encountering the human-biting adult life stage of Dermacentor andersoni (Acari: Ixodidae) in a key habitat type in Colorado. Journal of Medical Entomology 44: 694-704.

An exploratory model was created for areas in the western U.S. where peak abundances of adult Rocky Mountain wood ticks are predicted to exceed 50 per hour of drag sampling in south-facing habitats

Lars Eisen, Colorado State University, unpublished data