---------------------:----------------:----------------:------------- : Wolf-kills : Hunter-kills : :------:---------:------:---------: Level of Condition : Deer : Deer : Deer : Deer : significance : in : with : in : with : :sample:condition:sample:condition: ---------------------:------:---------:------:---------:------------- # # % # # % % Dental abnormalities 142 8 5.6 259 5 1.9 [34]90 Jaw necrosis, lumps, 142 6 4.2 259 1 0.4 [34]95 or fractures[33] Pathology of lower 75 5 6.7 126 1 0.8 95 limbs ---------------------:------:---------:------:---------:------------- FOOTNOTES: [33] Two mandibles from wolf-killed deer had large lumps from healed fractures in the region of the diastemas. [34] If all dental and jaw abnormalities are pooled, the difference between the incidence in the wolf-kill sample (9.8 percent) and that in the hunter-kill (2.3 percent) is significant at the 99 percent level. [Illustration: _Figure 12.--When internal organs were present in kills, they were examined in the field. (Photo courtesy of L. D. Mech.)_] Age Structure Our data strongly indicate that in northeastern Minnesota wolves prey much more heavily on the older members of the deer population, at least during winter (fig. 7). Substantial vulnerability to wolves seems to begin at about the age of 5 years (fig. 13), because the percentage of wolf-killed deer in each year class increases from 9 percent for 4-1/2-year-old animals to 15 percent for 5-1/2-year-olds (table 4). Indeed, 48 percent of the wolf-kills were aged 5-1/2 and over, which compares favorably with the Ontario figure of 58 percent for these age classes (Pimlott _et al._ 1969). [Illustration: _Figure 13.--Relative rates of predation on deer of various ages, based on comparisons of the ages of wolf-killed deer with those of a theoretical population (dashed line) and those of the hunter-killed population. See figure 7._] These figures assume added significance when compared with a sample of deer killed by hunters in the same general area (fig. 1). Only 10 percent of the hunter-killed deer were 5-1/2 years old or older, and the percent killed in each year class dropped off suddenly from 13 percent aged 4-1/2 to 6 percent aged 5-1/2. If the age structure of the hunter-kill sample is reasonably representative of the age structure of the population at large, the wolf-kill data show that wolf predation in our study area during winter has a definite selective effect on the deer population.