Trends and Management of Wolf-Livestock Conflicts in Minnesota
Distribution of Depredations
Verified depredations were scattered over 38,228 km2 in 1975-80 and over 56,827 km2 in 1981-86, an increase of 48.7% (Figs. 6a and 6b). Some expansion in the total area occurred in every direction except north. The geometric center of the depredation sites shifted 14.5 km to the southwest. Although no drastic change has occurred in the distribution pattern since 1980, four areas may have become new depredation locales (Figs. 6a and 6b). Three of these, areas A, B, and D in Fig. 6b, are at or near the edge of the wolf range and may represent some expansion of the problem areas over the previous period. Meanwhile, depredations apparently decreased along the Canadian border west of International Falls and in an area immediately north of Duluth. No data are available from those areas before 1975 to compare with recent years.
Many farms where depredations occurred within a given year had experienced losses previously during our program. In 1986, about 40% of farms having verified complaints were repeaters from 1 of the previous 2 years. During 1979-86, seven farms (6% of total farms with verified depredations) were considered "chronic" or Type I problem farms (Fritts 1982). One of these farms was the site of depredations during each of 7 years, one during 6 years, one during 5 years, and four during 4 years. Thirty-four percent of all wolf captures were at these seven farms.
Eleven additional farms were the sites of depredations during 3 of the 8 years (1979-86) and were considered "moderately chronic." Chronic problem farms consistently involved depredations by packs of wolves rather than by lone wolves. Wolves were usually trapped at the farms, but enough individuals were usually left to keep the pack going, or the area was rapidly recolonized because of proximity to medium- or high-density wolf populations.
Depredations generally occurred in remote parts of farms, but sites included distant pastures to within a few meters of farm buildings. Losses near buildings were usually in early spring when wolves were visiting livestock carrion that had been disposed of outside the farmyard during winter. Cattle were killed in both wooded pasture and open pasture near woods. Sheep and turkeys were killed in open pasture, but usually were approached from the nearest wooded side. Aside from totally wooded pastures, areas with a mosaic of fields and forests seemed to present the greatest opportunity for depredations. Wolves were reluctant to cross large open spaces. In areas with a sharp transition between expanses of forest and expanses of open pastureland, wolves generally remained in the forest (Fritts and Mech 1981, unpublished data). The same finding was reported in the vicinity of Riding Mountain National Park, Manitoba (Carbyn 1980).
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