Characteristics of mule deer day-bed and forage sites in current-condition and restoration-treated ponderosa pine forest

Abstract

We characterized microhabitat (structure and microclimate) at 236 mule deer (Odocoileus hemionus) day-beds, 152 diurnal forage sites, and 439 random locations during summers of 1998–2000. Our objectives were to 1) identify important microhabitat characteristics of day-beds and forage sites in untreated forest, 2) compare relative availability of bed and forage sites having these characteristics between forest types, 3) determine whether mule deer selected either forest type disproportionately for these activities, and 4) compare characteristics of day-bed and forage sites between forest types. Mule deer selected bed and forage sites with specific characteristics in untreated forest each year. Site temperature and canopy closure were the most influential attributes in bed-site selection, while forage availability best described forage sites. Availability of characteristic day-bed microhabitat was reduced 50–100%, while forage characteristics increased 31–66% each year in treated forest. Foraging mule deer selected treated forest in 1 year but demonstrated no preference in 2 years. Mule deer continued to use day-beds in both forest types each year as expected based on proportional area of each forest type, but did so in treated forest in 1999 by utilizing a novel suite of microhabitat features. Bed sites in each forest type had similar levels of midstory canopy closure, but treated forest bed sites were warmer in one year, exclusively located under oaks (Quercus gambelii) rather than conifers, and less concealed than untreated forest beds. Small oak stands were the only dense patches retained in the restoration prescription we examined and provided marginal thermal and hiding cover for day-bed use by female mule deer. These differences may increase thermoregulatory stress and the potential for increased disturbance and predation of female mule deer and fawns during summer. We recommend retaining >0.04-ha patches of dense bedding and hiding cover in areas where both forest restoration and mule deer are management concerns.