“In 2010, wolf depredation to livestock occurred on 47 farms. Total livestock depredation in 2010 included: 63 cattle killed (47 calves), 5 cattle injured, 6 sheep killed (4 lambs), 1 goat injured, and 6 farm deer killed. A total of 25 to 27 packs and 2 to 4 loners/dispersers were involved in depredation on livestock. The enclosed map shows locations of all depredations on livestock (injured or killed), and verified threats or harassment of livestock. For the purpose of depredation management, game farm deer are considered livestock. Non-livestock depredation include attacks on pets, and human safety situations with wolves.”
http://dnr.wi.gov/org/land/er/mammals/wolf/wolf_map.htm#map
I recall that the number of pets killed was considerably more than zero, but I cannot remember how many the DNR estimated.
While farmers have a vested interest in reporting wolf depredations, the DNR has a vested interest in minimizing them.
Certainly, deer cause damage as well, and farmers can be reimbursed for some deer damage.
Wolves and deer are both resources that need to be managed. Left to themselves, they cannot be depended on to stay at optimum levels for human purposes.