A Utah State University led study effort recently published results in PLOS ONE science journal that wolf packs benefitted from a larger group size when attacking bison.
Senior author Dan MacNulty told me the data took 15 years of observation of wolf-bison encounter to collect in Yellowstone. I was fortunate enough to accompany and assist the research team for most of those years. The study area was Yellowstone's pristine and remote Pelican Valley northeast of Yellowstone Lake. The research team would spend up to one month at a time in late winter in the valley attempting to observe predation of bison by wolves, perhaps some of the most dramatic interactions in the animal kingdom.
The study's authors included USU researcher Aimee Tallian and Yellowstone biologists Doug Smith and Dan Stahler. Jamie Walton, Travis Wyman, and Roger Stradley were also acknowledged for their contribution.
Read the entire article at PLOS ONE