Response of Illinois Deer to Winter Weather

Winters can be a significant factor affecting white-tailed deer (Odocoileus virginianus) physical condition, daily behavior, survival, and fecundity. Using harvest data and deer marked in east central and northern Illinois, we examined the effects of snow cover and temperatures on fawn:doe ratios in the deer harvest, fawn recruitment from marked females, female migration behavior, deer survival, and the daily behavior of both sexes when exposed to winter conditions. There was no significant correlation between total winter snow cover or temperature deviations from normal and fawn:doe ratios in the 11-yr deer harvest data used for this analysis. Recruitment to weaning age of fawns born to marked adult females was positively correlated with the previous 2-yr and 3-yr snow accumulations, apparently due to increased survival of older females during snowy winters. In winter, deer avoided bottomland forests and selected younger forests providing more understory cover. Females remained in forest cover and avoided open crop fields when snow was present. For 7 migrating females, snow cover in early December affected return frequencies to the natal range. Snow depths in excess of 10 cm appeared to trigger a return to the winter range while lesser snow accumulations did not. Temperature deviations from normal did not influence female movement back to the winter range.