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.
One to two miles (3.2 km) south of the release site, the Huron Mountains, with an elevation of 1,500 feet (457.5 m) might have prevented the southward movement of the wolves. Along the lakeshore, the land is relatively flat, which may have facilitated east-west movement. Wolves No. 11 and 13 were found at an elevation of 1,300 feet (490 m) the day after release but had returned to the flat shore areas (600 to 700 feet, or 200 to 230 meters above sea level) by the next day. Topography likely had effects in other areas but the actual travel routes, in most instances, are unknown. The pack did travel along an abandoned railroad grade near Gibbs City and for 2 miles (3.2 km) on a muddy road north of Kenton. Wolf No. 10 used a railroad bridge to cross a river in mid-March. It is well known that wolves generally choose the easiest routes of travel (DeVos 1950, Stenlund 1955, Mech 1966).
Possible Homing Tendencies
Some of the movements of the wolves during the Directional Movements Phase could in part have resulted from a tendency for the animals to home, that is to return to their home territory. Packs have been observed to travel 45 miles (72 km) in 24 hours in Minnesota (Stenlund 1955), Alaska (Burkholder 1959) and on Isle Royale (Mech 1966). In Minnesota, a radioed wolf was tracked a straight-line distance of 129 miles (208 km) over a 2-month period before being lost by researchers (Mech and Frenzel 1971), and annual migratory movements of over 200 miles (320 km) have been reported for Canadian wolves (Kuyt 1972). Therefore it seems within the capabilities of the released wolves to return the 270-mile (434 km) straight-line distance, or the 340-mile (547 km) travel distance around Lake Superior to Ray, Minnesota, if the orientation ability and inclination were present.
Homing tendencies have been reported in wolves and other carnivores. One of five laboratory-reared wolves returned to her Barrow, Alaska homesite within about 4 months after a 175-mile (282 km) displacement (Henshaw and Stephenson 1974). An adult female red fox (Vulpes vulpes) returned to her homesite within 12 days after being displaced 35 miles (56.3 km) (Phillips and Mech 1970). For black bears there are many records of apparent homing. Harger (1970) displaced 107 adult black bears from 10.0 to 168.5 miles (16.1 to 270.3 km) with an average displacement of 62.5 miles (100.6 km). Thirty-seven of them homed and 11 others moved long distances toward home. The longest distance homed was 142.5 miles (229.4 km). The return travel routes seemed direct, with little evidence of wandering or circling. Harger (1970) concluded that bears could navigate by some means, as yet undetermined.