Effects of Wolves and Other Predators on Farms in Wisconsin: Beyond Verified Losses

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With the recolonization of gray wolves (Canis lupus) across the Western Great Lake States (Minnesota, Michigan, and Wisconsin) there has been a concomitant increase in livestock depredations caused by wolves (Mech 1998, Ruid et al. 2005, Treves et al. 2002, USDA 2006, Wydeven et al. 2006). Wolf populations in Wisconsin have grown from 25 in late winter 1980 to 465 in late winter 2006 with their range expanding both towards the east and south across the state. These wolf populations fluctuate during the year and perhaps double soon after pups are born in the spring, but decline to lower levels in fall and winter due to pup and adult mortalities. The official wolf count made at the end of winter thus represents the lowest number of wolves on the landscape in the annual cycle, and number of wolves that livestock could be exposed to would be higher during most of the year. With the growth of the wolf population there have been major increases in depredation on livestock, especially toward the later 1990s and into the 2000s (Treves et al 2002, Ruid et al. 2005, Wydeven et al. 2006). The majority of the livestock losses
have been calves with over a half a million dollars paid to livestock, hunters, and pet owners since 1985 (Jurewicz 2007 pers. comm.). It is also worth noting that research on risk perception suggest that people focus on maximal events, not average losses, and this helps explain why so many livestock producers are anxious and may consider costly measures despite low ‘average’ losses (Naughton-Treves 2003).

Traditionally assessments of the economic impact of livestock operations due to predators have focused on direct losses from predation. However, there have been concerns from livestock producers in this region about the economic impacts related to factors other than the direct losses of animals killed by wolves. The very threat of depredation by wolves on livestock can be stressful to farmers (Fritts et al. 2003). Shelton (2004) reported that livestock producers have increased costs associated with efforts to prevent predation which may include night confinement, improved fencing, early weaning, choice of grazing area, or increased feeding costs from a loss of grazing acreage.

Though there is not definitive research supporting the following, it is plausible that other impacts predators may have on livestock production include abortions from the stress of being harassed by predators, disease transmission, decreased weight gain from increased vigilance by livestock living near predators, potential reduction in meat quality from stress, and emotional stress placed on livestock producers concerned about
depredations.

In the remainder of this report we explore the effects of wolf and other predators on farms. We examine the literature for these effects on livestock and other aspects of the farms. We also discuss relevant anecdotal information on the effects of wolf and predator presence on farms. Lastly, recommendations for future research to measure the effects of wolf presence on farms and how such data should be used in managing wolf populations and livestock are shared.<<<Read Entire Report>>>