Wolves (_Canis lupus_) and deer (_Odocoileus virginianus_) having
evolved together, no doubt have become adapted to contending with each
other's physical abilities. Thus it is not surprising to learn that
deer which succumb to wolf predation are generally weaker, older, or
abnormal compared with the total deer population (Pimlott _et al._
1969, also see Mech and Frenzel, p. 35).
However, the structural and behavioral adaptations of both species must
have evolved under environmental conditions that are average or usual;
otherwise, an adjustment of wolf to deer populations, and vice versa,
could not have been maintained over long periods. This implies that
extreme or unusual conditions might sometimes occur, to which either
the wolf or the deer is poorly adapted.
One of the most important environmental factors that can influence the
interactions of wolves and deer is snow. The total fall, depth on the
ground, and the density are all aspects of snow that may vary
considerably and affect the ability of wolves to capture deer. Recent
studies of wolves and deer in northeastern Minnesota (see Mech _et
al._, p. 1, also Mech and Frenzel, p. 35) afforded us opportunities to
investigate the relationships between snow and the interactions of
wolves and deer.