Wolf-cattle Interactions in the Northern Rocky Mountains

Since gray wolf reintroduction in 1995, wolf populations in the northern Rocky Mountains have increased dramatically. Incidents of wolf predation on livestock have increased with wolf populations. Although rough tallies of livestock death or injury losses caused by wolf predation are made each year, we know almost nothing about the indirect effects of wolf-livestock interactions on cattle production. Research projects were initiated during 2004 in central Idaho and 2007 in western Idaho-northeastern Oregon to evaluate habitat use, activity budget, and productivity responses of range cattle to increasing wolf predation pressure. Global positioning system (GPS) tracking collars were used to locate mature beef cows every 30 minutes or every 5 minutes throughout 3to 6-month grazing seasons. Effects of wolf presence on cattle preference for riparian/upland habitats, terrain use, bunching/dispersion, and activity budgets are being evaluated relative to forage conditions, cattle age/experience, and other production system and environmental factors. Preliminary results suggest individual cows exhibit considerable variability in their preference for near-stream habitats ( less than 100 yards from perennial streams). Annual variability in near-stream preference was noted and the relationship between this variability and wolf presence levels is being evaluated. Annual variability in cattle activity budgets was detected and evaluations are underway to determine if this variability is an effect of recent technology upgrades or is a consequence of variability in wolf presence. We found GPS tracking technology accurate enough to detect predator-avoidance behavior in cattle, including bunching and sustained-flight events, even at the coarse, 30-min collection interval. The northern Rocky Mountains is a very complex ecological system involving numerous interacting factors; consequently, it will require at least several more years of data collection before we can begin to draw conclusions from these studies. When developing grazing plans, however, cattle producers and natural resource managers of the northern Rockies should consider that the presence of reintroduced gray wolves may be influence cattle distribution and behavior and these effects may continue for some time after wolves have left or have been removed from the grazing area.