Part 11

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.

There is some indication that the pack of three wolves may have attempted to return home to Minnesota, although it is possible that exploration itself also may have produced the movement pattern observed.

If the translocated wolves were to try homing directly toward their previous territory, they would have had to travel west-northwestward. However, within a few miles they would have encountered Lake Superior. The next closest choice would have been to head westward, and this is what the pack did (Fig. 17). The next possible barrier to their homeward movements would have been Huron Bay, which would have forced them southwestward, at least temporarily. Again this is what actually happened. The pack maintained its southwestward movement beyond Huron Bay until reaching a point southeast of the next possible barrier, Keweenaw Bay. They then continued westward south of Keweenaw Bay to the Prickett Dam area, and veered northwestward to Twin Lakes on March 25.

By this time, the wolves had traveled for 13 days and covered a minimum distance of 59 miles (94.9 km), and they were 42 miles (67.6 km), closer to home (16% of the straight-line distance between home and release site). The directions of the movements of the wolves were consistent with what they would have to be if the wolves were to return home.

However, after March 25, the directionality in the movements of the pack ended (Fig. 17), and the animals began what we consider the Exploratory Phase of their movements. If the wolves actually were homing, perhaps the tendency diminished as they failed to encounter familiar terrain, or perhaps they met too many obstacles, or became confused after encountering too much human activity. Or possibly these factors or the need to find food and security overcame the homing tendency. As discussed earlier in relation to the unusual number of times the wolves were observed, it is clear that they were not moving normally during this period.

The lone wolf, No. 10, dispersed from the release site in as much of an opposite direction as it could from the pack (Fig. 20). Thus there is no evidence that this animal was trying to home. However, it is of interest to note that the first 32 miles (51.5 km) of her travel was directional rather than random. Furthermore, when the animal encountered what probably was a psychological barrier, a high concentration of human activity along Highway 41, she reversed her movements but still maintained a directionality by returning to the release area. In fact a striking pattern of southeast-northwest movements characterized this wolf's travels for several months after her release, with a gradual westward drift developing in the southeast-northwest movements (Fig. 20).

Mech and Frenzel (1971) found that a wolf dispersing from his former home range in Minnesota maintained a general southwestward movement for a straight-line distance of 129 miles (207.6 km) over a 2-month period, and Mech (unpublished) has three additional records of dispersing wolves that maintained directionality for distances of 48 to 130 miles (77.2 to 209.2 km). Storm (1972) followed 12 dispersing red foxes in Iowa, Illinois, and Minnesota that moved directionally for distances of 12 to 110 miles (19.2 to 176.0 km).

The ability of wolves to orient and navigate even in unfamiliar surroundings was demonstrated dramatically by the separation of Wolf No. 13 from his two packmates and his later rejoining of them. On May 2 he was 51 miles (82.1 km) away from them. Five days later he and his packmates were only 6 miles (9.6 km) apart, in an area 62 miles (99.8 km) from where No. 13 had been on May 2, and 45 miles (72.4 km) from where his packmates were on that date (Fig. 18 and p. 11).

Because No. 13 had taken such a divergent route from that of No. 11 and 12 upon splitting, and then had met them again at a point so far from (1) where they had split and (2) where either had gone after the split, mere backtracking would seem to be ruled out as explanation of how they were able to rendezvous. Possibly No. 13 backtracked to the separation point and then followed the others by scent, although this seems unlikely because of the amount of time that had elapsed. Perhaps a combination of memory of the general lay of the land, and some backtracking and eventually howling and the crossing of each group's fresh tracks could explain this remarkable feat.

Distances Traveled

The average daily straight-line distances (average of all known 24-hour moves) traveled by Wolf No. 10 was 3.6 miles (5.8 km). For Wolf No. 11 and her associates it was 5.8 miles (9.3 km) for the period before the settled Phase of their movements. The daily summer straight-line movements of an immature radioed female in Ontario ranged from 0.0 to 3.5 miles (5.6 km) per day and averaged 1.0 (1.6 km) per day (Kolenosky and Johnston 1967). Mech and Frenzel (1971) found that the average daily straight-line distance traveled in Minnesota by three lone wolves was 2.0, 1.0 and 2.9 miles (3.2, 1.6, and 4.6 km), and a pack of five averaged 2.5 miles (4.0 km) straight-line distance per day. A pack of eight wolves in Ontario traveled actual distances of 0.0 to 13.2 miles (21.1 km) per day during winter with an average movement of 4.4 miles (7.1 km) per day (Kolenosky 1972).

Thus distances moved by both lone Wolf No. 10 and the pack were greater than the distances reported for lone wolves and packs in their native range. In Harger's (1970) study of homing in black bears, he also found increased movement by displaced animals.

There was a general reduction in distances moved by the pack in May and June after the wolves had settled in Iron County (Fig. 19), compared with their earlier exploratory movements (Fig. 24). The movements during the Settled Phase were similar to those reported from the studies in Ontario and Minnesota.

Home Range Size

At least in some areas, wolves are territorial (Mech 1972, 1973), and the sizes of their home ranges are restricted somewhat by boundaries established by the scent marks of surrounding packs (Peters and Mech 1975). The introduced wolves probably encountered no native packs with established territories (Hendrickson et al. 1975), so they would not be similarly restricted. The total area that wolves No. 11, 12, and 13 explored, 2,918 square miles (7,586 km^2), is larger than any reported from the Great Lakes area and is comparable to home ranges of "tundra wolves" (Mech 1970). Even the area in which they settled (May 7 to July 6) until the deaths of the males was 246 square miles (637 km^2), which is larger than most reported ranges in the Great Lakes Region.

The deaths of the two males seemed to cause an increase in both daily distance traveled and home range in Wolf No. 11. Essentially she began traveling as extensively as do lone wolves in Minnesota (Mech and Frenzel 1971).

The home range of Wolf No. 10 from March through mid-November, 346 square miles (895.7 km^2), was smaller than those of lone wolves in Minnesota (Mech and Frenzel 1971). Apparently she was still expanding her range when killed, however.

Selection of a Territory

The eventual settling of the pack of translocated wolves into a territory would be expected because such behavior is characteristic of wolves in other areas. The translocated pack did settle into a territory of 246 square miles (637 km^2) after about 2 months (Fig. 18). Although the region where they settled was not as remote as the release area, it was more inaccessible than most of the rest of the 1,631 square mile (4,224 km^2) area they explored after dispersing. As with the rest of Upper Michigan, the pack's adopted territory was inhabited by a moderate population of deer and beavers. It seems significant that this area is one of three where a few native Michigan wolves are known to still exist (Hendrickson et al. 1975).

Vulnerability and Mortality

It could be expected that the translocated wolves would be more vulnerable than wolves in their native environment. Although no data are available from any previous study of translocated wild wolves, Harger's (1970) investigation of displaced wild black bears showed that they were more vulnerable. In our study, it was clear that during the Directional Movement and Exploratory Phases Wolves No. 11, 12, and 13 were observed by local residents an unusual number of times (Table 6). No. 10, which did not explore such an extensive area and which spent considerable time in a more remote area, was seen less (Table 5).

It is not clear why the wolves were not killed by humans during these periods when they appeared so vulnerable. Perhaps the novelty of the transplant coupled with the awareness that frequent aerial checks were being made of the wolves had some effect. Furthermore, spring is not generally a season of intensive hunting and trapping.

Whatever the explanation, the wolves did survive what seemed to be their most vulnerable period. We do not believe that the deaths of the wolves can be attributed to the conditions of their translocations. Instead, we think that the most important factor in their demise was the accessibility of the area to human beings and the attitudes of humans towards wolves.