The above observations of snow conditions, deer movements, and wolf movements during the three winters of the study are in accord with observations made on the differences in the ability of the wolves to capture deer during the same period. Two indices support the conclusion that wolves had a much easier time catching deer during February and March 1969 than earlier in the winter and in the two previous winters: (1) the degree of utilization of wolf-killed deer, and (2) the kill rate of radiotagged wolves.
During the winters of 1966-67 and 1967-68, and in December and early January 1968-69, most wolf-killed deer found had been thoroughly eaten, and the bones--if present at all--were well chewed and scattered at each kill (fig. 9). All skin and flesh from the skull were eaten, and the mandible was usually separated from the skull. During late February and early March 1967, few fresh kills were even found, and wolves were returning several times to old kills that had been cleaned up many days before.
[Illustration: _Figure 9.--Usually the remains of a wolf kill are well chewed and scattered before the wolves abandon them. (Photo courtesy of L. D. Mech.)_]
[Illustration: _Figure 10.--During a period of especially deep snow, wolves abandoned many kills before pulling apart the skeletons. (Photo courtesy of L. D. Mech.)_]
However, in late January 1969 a substantial change began taking place. The skeletons of most kills found were almost intact, the flesh having been eaten from around the bones (fig. 10). Appreciably more skin was usually left on the carcass, especially on the side lying on the snow, and the neck and head were generally intact. This was true even of fawns, which in the past often were almost completely consumed.
In several cases, only about half of the flesh had been eaten from the carcasses. On February 2, 1969, four deer recently killed by wolves were found along a 1-1/2-mile stretch of Birch Lake and nearby Polaris Lake (Minnesota-Ontario border). One large doe was completely uneaten and remained so for at least 24 hours after discovery from the air. Further, one fawn had only a few pounds of flesh eaten, a yearling doe was half eaten, and another fawn was about 75 percent eaten. Hazardous landing conditions during this period severely limited the number of carcasses that could be examined from the ground, but on February 6 a yearling doe was discovered that had only about 5 to 10 pounds of flesh eaten, and on February 8 an adult doe was found that was completely intact except for wounds.