Northern Prairie Wildlife Research Center
Although farmers were encouraged to call directly, many complaints reached the office by way of MDNR field personnel. Farmers often contacted the local MDNR conservation officer first because that person lived in the community and was responsible for authorizing compensation payments by the MDA. Information from our investigations and those by the MDNR was freely exchanged. We believe that essentially all eligible farmers participated in our program; only one refused assistance during the 1979-86 period.
Field staff consisted of a full-time wildlife biologist, a full-time wildlife technician, and one to three seasonal technicians. Complaints were investigated in the field as soon as possible. Timeliness was critical to investigations of alleged depredations, as livestock carcasses deteriorated or were sometimes quickly consumed or dragged away, and inclement weather or livestock activity destroyed predator sign near kills. Eighty-nine percent of complaints were investigated within 24 h, and 95% within 48 h. The greatest delays in investigation or implementation of control came during intermittent periods when funding was not available to operate the program. Despite our best efforts to field-check complaints promptly after receipt, in some instances several days elapsed between the incident and its discovery by the farmer or the actual reporting of it.
We considered a complaint verified if the field investigation revealed the remains of an animal or a wounded animal, and evidence of wolf involvement. Distinguishing wolf from coyote depredation was a common problem, stemming in part from the public's failure or inability to distinguish between the two canids (Fritts and Mech 1981; Fritts 1982; Kellert 1985). Our investigations revealed coyote involvement in a minimum of 15% of all reports. (Farmers reported known coyote damage directly to conservation officers to obtain trapping assistance from the MDNR.) Also, a prejudice toward wolves as the cause of livestock death or disappearance (Fritts 1982) was common, and related to the compensation paid by the state for livestock destroyed specifically by wolves.
Livestock death attributable to wolves was often based on size and location of bite marks, feeding patterns, and extent of feeding (Roy and Dorrance 1976; W. J. Paul, unpublished data). Wolf presence at or near the depredation site was confirmed by tracks, scats, or other wolf sign, and occasionally by a farmer's wolf observation if we were convinced of its authenticity.
Lethal control methods were limited to euthanasia after live-trapping. Traps (No. 4 and 14 Newhouse) were set in response to virtually all confirmed depredations. The location of traps and duration of trapping were set to conform with a court ruling (Federal Judge P. McNulty, court order, 14 July 1978, unpublished data). From 1978 to 1986, traps had to be set within 0.25 mile (0.4 km) of the property boundary on which a confirmed depredation had occurred, and pups could not be killed. The trapping policy of 1979-80 (Fritts 1982) was refined to increase efficiency and conform with new regulations. Beginning in 1986, traps were set within 0.5 mile (0.8 km) of the property boundary, and wolf pups captured after 1 August were killed (USFWS 1985; modification of 14 July 1978 court order by Judge M. Lord, 2 May 1985, unpublished data).
On the basis of data collected early in the program, the duration of trapping was modified in 1982. In most instances trapping was terminated after 10 days if no further losses occurred during that time. However, traps were left out for as long as 21 days in the following situations: (1) after a second verified depredation at any farm in the same year if there was evidence of continued wolf activity there or if we believed that the wolves involved in the depredations had not been captured; (2) after the first and any subsequent depredations at farms where we had verified wolf depredations during the previous 2 or more consecutive years ("chronic problem farms"); and (3) after the first and any subsequent losses at any farm in Wolf Management Zone 5 (USFWS 1978; Fig. 1a) where we had evidence that all the wolves involved in the depredations had not yet been captured. Northern Zone 5 included Roseau, Kittson, and Marshall Counties in northwestern Minnesota where livestock numbers were relatively high, relatively more sheep and turkeys (the most vulnerable livestock) were produced, and surplus killing (Kruuk 1972) by a few wolves sometimes resulted in a substantial loss of sheep and turkeys. In contrast with the lengthening of the trapping period described above, the period was reduced to 5 days when a depredation seemed to have been caused by a transient lone wolf that probably had left the area.
Overall, these modifications in trapping policy resulted in more effort being directed to farms where wolf depredations were most severe. Often farmers vehemently resisted trap removal, preferring to have them set for much longer periods. Nonetheless, our trapping policy proved satisfactory for capturing wolves in response to verified complaints and balancing workload with program resources.
Methods of nonlethal control of wolf depredations were attempted to a limited degree. Aside from trapping, we placed flashing highway lights and strobe light-siren devices (Linhart 1984; Linhart et al. 1984) at some farms to frighten wolves from the immediate vicinity; assessment of the efficacy of those devices was subjective. An experiment with taste aversion was conducted in 1979 and 1980 (Gustavson 1982). Also, in 1982 we began a cooperative project with the New England Farm Center to test the feasibility of using Old World livestock guarding dogs to protect livestock from wolves (Coppinger 1987).