Effects of wolf removal on livestock depredation recurrence and wolf recovery in Montana, Idaho, and Wyoming

• Published in: The Journal of Wildlife Management
• Main Authors: Bradley, Elizabeth H., Robinson, Hugh S., Bangs, Edward E., Kunkel, Kyran, Jimenez, Michael D., Gude, Justin A., Grimm, Todd
• Other Authors: United States Fish and Wildlife Service
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2015
• Subjects: Canis lupus
• Online Access: http://dx.doi.org/10.1002/jwmg.948; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fjwmg.948; http://onlinelibrary.wiley.com/wol1/doi/10.1002/jwmg.948/fullpdf

ABSTRACT Wolf ( Canis lupus ) predation on livestock and management methods used to mitigate conflicts are highly controversial and scrutinized especially where wolf populations are recovering. Wolves are commonly removed from a local area in attempts to reduce further depredations, but the effectiveness of such management actions is poorly understood. We compared the effects of 3 management responses to livestock depredation by wolf packs in Montana, Idaho, and Wyoming: no removal, partial pack removal, and full pack removal. We examined the effectiveness of each management response in reducing further depredations using a conditional recurrent event model. From 1989 to 2008, we documented 967 depredations by 156 packs: 228 on sheep and 739 on cattle and other stock. Median time between recurrent depredations was 19 days following no removal ( n = 593), 64 days following partial pack removal ( n = 326), and 730 days following full pack removal ( n = 48; recurring depredations were made by the next pack to occupy the territory). Compared to no removal, full pack removal reduced the occurrence of subsequent depredations by 79% (hazard ratio [HR] = 0.21, P < 0.001) over a span of 1,850 days (5 years), whereas partial pack removal reduced the occurrence of subsequent depredations by 29% (HR = 0.71, P < 0.001) over the same period. Partial pack removal was most effective if conducted within the first 7 days following depredation, after which there was only a marginally significant difference between partial pack removal and no action (HR = 0.86, P = 0.07), and no difference after 14 days (HR = 0.99, P = 0.93). Within partial pack removal, we found no difference in depredation recurrence when a breeding female (HR = 0.64, P = 0.2) or ≥1‐year‐old male was removed (HR = 1.0, P = 0.99). The relative effect of all treatments was generally consistent across seasons (spring, summer grazing, and winter) and type of livestock. Ultimately, pack size was the best predictor of a recurrent depredation event; the ...