[Illustration: _Figure 35.--Locations of all radiotagged wolves and unmarked packs observed during winter 1968-69, except dispersal of 1051 out of the study area. Only selected lakes shown._]
From the above information it can be hypothesized that the wolf population consists basically of groups of breeding packs defending territories of limited size, with lone wolves and other nonbreeding population units that are tolerant of each other shifting about in much larger nonexclusive areas among these territories. The information from Isle Royale (Mech 1966a, Jordan _et al._ 1967) is consistent with this idea, but the area of that island (210 square miles) is too small to allow untested extrapolations to be made about spacing in much larger wolf populations. Data from Algonquin Park, Ontario (Pimlott _et al._ 1969) also strongly suggest this hypothesis. However, the packs studied there could not be identified with certainty, and little information was obtained about nonbreeding population units.
To test the proposed hypothesis with certainty, a larger number of identifiable breeding and nonbreeding population units from the same general area must be followed during at least one winter. This will be the main objective of our next study.
During the winters of 1966-67, 1967-68, and 1968-69, aerial observations of timber wolves (_Canis lupus_) were made in the Superior National Forest in northeastern Minnesota, where the primary prey is white-tailed deer (_Odocoileus virginianus_). In 480 hours of flying during the study, 77 sightings involving 323 wolves were made. In addition, during 1968-69, five radiotagged wolves and their associates were tracked via receivers in aircraft for a total of 570 "wolf-days." Visual observations were made during 65 percent of the times the wolves were located from December through April.
The average size of each population unit (including single wolves, pairs, and packs) observed was 4.2, although packs of as many as 13 wolves were sighted. Radiotagged wolves spent most of their daylight hours resting during winter, and when traveling, hunting or feeding during the day, tended to do so before 11:00 a.m. and after 3:00 p.m.
Considerable variation was discovered in the movement patterns of individual wolves, with straight line distances between consecutive daily locations ranging from 0.0 to 12.8 miles, and between weekly locations, 0.0 to 49.0 miles. A pack of five wolves used a range about 43 square miles in extent, whereas lone wolves covered areas many times this size. One animal in an apparent dispersal was tracked a straight line distance of 129 miles between extreme points.