The separation of No. 10 from the others upon release does not necessarily mean that she was not a member of the pack. No. 10's radio collar was replaced just before she was released. The handling without sedation could have frightened her enough that she ran some distance before the others were even released. The fact that No. 10 returned to within a half mile (0.8 km) of the release pen on March 20 and to within less than 100 feet (30.5 m) on April 18 may indicate she was seeking the other wolves. However, she may also just have used the release pen as a reference point in a generally unfamiliar area, or may have been attracted by the remains of carcasses left there. Effect of Captivity and Human Contact The necessary capture, captivity, translocation and contact of the experimental wolves with humans had an unknown effect on the wolves. They had been exposed to humans for over 2 months while in captivity. No attempts were made to tame them, and they never passed the escape stage of socialization as described by Woolpy and Ginsburg (1967). The dominant wolves (No. 11 and No. 12) were more relaxed when approached than were No. 10 and No. 13, however. The failure of female No. 11 to bear young probably can be attributed to her captivity and handling. The fact that two couplings were observed over a 5-day period indicates normal estrus in the female, and a normal response in the male. Conception would have been expected from such a mating. In wild wolves, it is known that there is only a small loss between number of ova shed, number of embryos implanting, and number of fetuses being carried (Rausch 1967). Thus it seems unlikely that, if No. 11 conceived, she lost her fetuses _in utero_. Rather, she probably did not conceive, or perhaps the embryos never implanted. This wolf lost about 11% of her capture weight during captivity, despite an adequate food supply. This fact, plus the results of her blood tests indicate a high degree of stress, which probably explains why she never produced pups. The possible interference of the drugs used can be ruled out, for they were chosen because of their known lack of effect on pregnancy (Seal et al. 1970). The radio collars placed on the wolves had no noticeable effect on the animals. Radioed wolves are regularly accepted back into their packs in Minnesota, where they also reproduce and function normally (Mech and Frenzel 1971; Mech 1973, 1974). Movements Environmental Influences Lake Superior was a barrier to the northward and eastward movements of the wolves. Apparently it also directed wolves No. 11, 12, and 13 southward around Keweenaw Bay, and possibly it prevented their eastward movement on April 2 when they approached Keweenaw Bay from the western side. The Bay is approximately 6-miles (9.6 km) wide there, and was frozen until late April.