Northern Prairie Wildlife Research Center
However, each year certain individual producers were seriously affected by wolf depredations. Especially disconcerting was the high level of turkey losses in northwestern counties and an increase in the number of farms affected in that area. The tendency of wolves in Management Zone 5 to exploit the particular vulnerability of turkeys and sheep suggests that the wolf depredation problem would be greatly exacerbated by any increase in production of these domestic animals in other zones with higher wolf densities or any further increase in numbers and distribution of wolves in Zone 5. In evaluating the recent and present levels of wolf-livestock conflicts in Minnesota, it is noteworthy that the reporting period was one of generally decreasing livestock production (except for turkeys).
Preventive control should be considered in certain parts of Zone 5 in northwestern Minnesota, in view of the relatively high numbers of sheep and turkeys present, and the proven tendency for wolves there to kill substantial numbers in a short period. However, such taking would be contrary to a court order (Federal Judge P. McNulty, court order, 14 July 1978, unpublished data). The Eastern Timber Wolf Recovery Team recommended that no wolves be allowed in Zone 5 because of the high density of livestock (USFWS 1978). Preventive removal of wolves could be directed at packs in chronic problem areas and could occur in May-June when trapping conditions are near ideal.
Although neither the number of verified complaints nor wolves taken in response to losses were shown to have escalated on the basis of the 1981-86 data, to manage the problem more wolves may have to be taken than was previously believed on the basis of 1979-80 data (Fritts 1982). The numbers taken on the program to date have not reduced the Minnesota wolf population, and the take could be increased considerably before an effect would occur (Mech 1970; Peterson and Woolington 1982; Keith 1983). However, we still believe that depredations can be controlled without taking large numbers of wolves and that, except for Zone 5, trapping should be directed toward the capture of specific offending wolves or offending packs rather than local populations. The number of wolves necessary to take to control the problem and the precise effect of control trapping still are not understood, especially at chronic problem farms. In fact, few conclusions are possible about the effectiveness of wolf removal in reducing livestock depredations.
The depredation problem in Minnesota will not be eliminated soon. Efforts to reduce livestock losses should include a combination of approaches and not rely solely on wolf control measures. First, management practices at many of the farms could be improved; farmers should practice proper carcass disposal as required by law, improve surveillance, reduce pasturing in remote wooded areas, and delay turnout until young livestock are more capable of eluding wolves. Second, a responsive, highly efficient, adequately funded control program should be in place to deal with problems as they arise. Third, additional nonlethal methods should be sought and tested. The use of livestock-guarding dogs should be encouraged when feasible. The public must be educated to realize that nonlethal methods will work only in certain circumstances and have realistic expectations of them. Fourth, the state's compensation program should be continued, but modified to discourage poor management practices. In addition, research is needed to (1) determine the causes of the onset of livestock-killing behavior, (2) explain the relation between winter severity and depredation indices, (3) elucidate the relation between wolf removal and subsequent losses (especially at chronic problem farms), and (4) periodically reassess the relations between winter severity, time, and depredation indices.
Our strongest impression to date about wolf-livestock problems in Minnesota is the low level of depredation in view of the availability of livestock and conditions of their production. For most of the year, wolves live close to livestock; yet, it is clear that only a fraction of possible contacts culminates in depredations. Possibly a strong search image for natural prey is a deterrent to depredation on domestic animals. The infrequency of contact with livestock in winter might be hindering development of a search image for that prey. Alteration of the search image for wild prey, possibly a result of carrion feeding or other transition behavior, could be part of the problem at Type I farms. Whatever the reason, the situation in Minnesota has demonstrated that conflicts between wolves and livestock are not the norm, at least not within the conditions existing in Minnesota from 1975 through 1986.