Because 1059 was later found to have bred and carried five fetuses, her movements during whelping season (late April and early May) are of interest. Her locations on both April 24 and May 2 were within 250 yards of each other, which might indicate that she was denning. On May 9, however, she was 2.5 miles east of these locations, on the 17th and 21st was 2 miles west of them, and on the 30th was 3 miles north of them. In early January 1970, Wolf 1059 was killed by a trapper in the southeast corner of her pack's 1969 range. _Summer locations._--Signals from only 1053 and 1059 were heard during summer, and then tracking attempts were made only on June 28, July 29, and August 29. Locations for 1053 on those occasions were near Kelly Landing and Isabella Lake, within her previous range. Wolf 1059 was found each time within 2 miles outside of the southwest corner of the pack's winter and spring range. Wolf Associations, Social Behavior, and Reproduction In our study area, population units of wolves exist as both single animals (lone wolves) and packs. In a total of 77 observations, lone wolves constituted 32 percent of the sightings (fig. 25), with packs of from 2 to 13 members making up the remainder (Table 1). On the basis of the number of wolves seen, rather than the number of observations, lone wolves accounted for only 25 (8 percent) out of 323. [Illustration: _Figure 25.--Only 8 percent of the wolves observed were lone wolves. (Photo courtesy of L. D. Frenzel.)_] These figures compare favorably with reports in the literature as summarized by Mech (1970). In five areas studied, lone wolves made up from 24 to 60 percent of the observations of population units, and from 8 to 28 percent of the wolves seen. In our study area during 1948 to 1953, lone wolves constituted 43 percent of the observations and 15 percent of the wolves (Stenlund 1955). The average size of the population units observed during our study (total number of wolves seen divided by the number of observations) was 4.2, which is significantly larger (95 percent level) than the average seen in this area (2.8) from 1948 to 1953. This is also larger than that reported from any other area of comparable size (table 6). _Table 6.--Mean sizes of wolf population units reported from various areas_ ---------+------------+--------+------------+---------+--------------- | | |Mean size of| Largest | Authority Area |Observations| Wolves | population |pack size|calculated from | | | unit | | ---------+------------+--------+------------+---------+--------------- _Number_ _Number_