Assessing factors related to wolf depredation of cattle in fenced pastures in Montana and Idaho.

Managing wolf (Canis lupus) depredation on livestock is expensive and controversial; therefore, managers seek to improve and develop new methods to mitigate conflicts. Determining which factors put ranches at higher risk to wolf depredation may provide ideas for ways to reduce livestock and wolf losses. We sampled cattle pastures in Montana and Idaho that experienced confirmed wolf depredations (n = 34) from 1994-2002 and compared landscape and selected animal husbandry factors with cattle pastures on nearby ranches where depredations did not occur (n = 62). Pastures where depredations occurred were more likely to have elk (Cervus elaphus) present, were larger in size, had more cattle, and grazed cattle farther from residences than pastures without depredations. Using classification tree analysis, we found that a higher percentage of vegetation cover also was associated with depredated pastures in combination with the variables above. We found no relationship between depredations and carcass disposal methods, calving locations, calving times, breed of cattle, or the distance cattle were grazed from the forest edge. Most pastures where depredations occurred during the wolf denning season (April 15-June 15) were located closer to wolf dens than nearby cattle pastures without depredations. Physical vulnerability, especially of calves, also may increase risk of depredation. [ABSTRACT FROM AUTHOR]