Wolf Depredation on Livestock in Minnesota
The 1979-80 Approach to Wolf Depredation Control
In May 1979 the FWS transferred the responsibility for livestock depredation control to its Patuxent Wildlife Research Center, and the control program was subsequently modified. The objective of the new program was to reduce livestock losses but take the minimum number of wolves necessary.
Complaints of wolf-livestock problems were investigated by FWS biological technicians within 24 h to increase the chances of confirming or disproving wolf involvement. After finding livestock remains to verify that a loss had occurred (or observing wounded livestock), and obtaining hard evidence of wolf involvement, an intensive effort was made to trap the offending wolves within 10 days. Trapping was then terminated if no further losses occurred, whether or not the number of wolves thought involved in the depredations were caught. This policy was based on the assumption that if no additional livestock were lost during the 10-day period, it was questionable whether the wolves would return and kill again. If further losses occurred during the period, trapping was extended an additional 10 days after each loss. In 1980 this policy was changed to allow trapping for up to 21 days in the few instances where depredations recur at a farm within the same year.
In compliance with court orders, trapping was restricted to within 0.4 km of the farm on which the losses occurred. Limiting the duration and area of trapping greatly increased chances that any wolf captured would be an offender. Adult wolves captured in traps were euthanized and necropsied. Pups were released, as required by court order. However, beginning in 1980, young of the year captured after September were euthanized. By October these young are approaching adult size and beginning to travel with their packs. They may be capable of participating in the killing of some livestock, especially sheep, by this time.
In some instances up to 16 highway flasher lights were installed around the pasture when traps were removed, or sometimes when traps were set. In addition 1-m-long strips of surveyor's flagging were draped from fences and trees in pastures to blow freely in the breeze and perhaps frighten off some wolves. Similar flagging is used in hunting wolves in eastern Europe and the USSR to funnel the wolves toward shooters as a group of drivers pushes the wolves (Carbyn 1977).
Another approach used to alleviate livestock damage involved an attempt to establish taste-aversion conditioning by baiting (Gustavson et al. 1976). Baits consisting of ground beef mixed with a solution of lithium chloride and wrapped in cowhide were distributed on and near four cattle ranches with a history of livestock losses. It was hoped that wolves would consume the baits, become ill, and develop an aversion to the taste of beef.
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