http://fwp.mt.gov/fwpDoc.html?id=70972ABSTRACT 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 (n¼593), 64 days following partial pack removal (n¼326), and 730 days
following full pack removal (n¼48; 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
¼0.21, P<0.001) over a span of 1,850 days (5 years), whereas partial pack removal
reduced the occurrence of subsequent depredations by 29% (HR¼0.71, 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 (HR¼0.86,
P¼0.07), and no difference after 14 days (HR¼0.99, P¼0.93). Within partial pack removal, we found no
difference in depredation recurrence when a breeding female (HR¼0.64, P¼0.2) or 1-year-old male was
removed (HR¼1.0, P¼0.99). 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 probability of a depredation event recurring within 5 years increased by 7%
for each animal left in the pack after the management response. However, the greater the number of wolves
left in a pack, the higher the likelihood the pack met federal criteria to count as a breeding pair the following
year toward population recovery goals. Published 2015. This article is a U.S. Government work and is in the
public domain in the USA.
