2014 research by biologist Dan MacNulty, Aimee Tallian, Daniel Stahler and Douglas Smith reveal conclusively that to make a meal of 1000 pound Bison, the bigger the Wolf pack, the more success the pack has at killing Bison............."Whereas improvement in elk capture success(by wolf packs) levelled off at 2–6 wolves, bison capture success levelled off at 9–13 wolves with evidence that it continued to increase beyond 13 wolves".................. "These results are consistent with the hypothesis that hunters in large groups are more cooperative when hunting more formidable prey".............. "Improved ability to capture formidable prey could therefore promote the formation and maintenance of large predator groups, particularly among predators that specialize on such prey"

https://phys.org/news/2014-11-merrier-ecologists-larger-group-aids.html

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwixt9zIuZ3TAhWrqVQKHRthBMUQFgg4MAc&url=http%3A%2F%2Fjournals.plos.org%2Fplosone%2Farticle%3Fid%3D10.1371%2Fjournal.pone.0112884&usg=AFQjCNGSsSa7Pqbq7CQU1Rm1VA2yVOJF2A&sig2=xyk-TN5m9K6cD_RveASuKw

Influence of Group Size on the Success of Wolves Hunting Bison

• Daniel R. MacNulty ,
• Aimee Tallian,
• Daniel R. Stahler,
• Douglas W. Smith

• Published: November 12, 2014

Abstract

An intriguing aspect of social foraging behaviour is that large groups are often no better at capturing prey than are small groups, a pattern that has been attributed to diminished cooperation (i.e., free riding) in large groups. Although this suggests the formation of large groups is unrelated to prey capture, little is known about cooperation in large groups that hunt hard-to-catch prey.

 Here, we used direct observations of Yellowstone wolves (Canis lupus) hunting their most formidable prey, bison (Bison bison), to test the hypothesis that large groups are more cooperative when hunting difficult prey. We quantified the relationship between capture success and wolf group size, and compared it to previously reported results for Yellowstone wolves hunting elk (Cervus elaphus), a prey that was, on average, 3 times easier to capture than bison.

 Whereas improvement in elk capture success levelled off at 2–6 wolves, bison capture success levelled off at 9–13 wolves with evidence that it continued to increase beyond 13 wolves. These results are consistent with the hypothesis that hunters in large groups are more cooperative when hunting more formidable prey. Improved ability to capture formidable prey could therefore promote the formation and maintenance of large predator groups, particularly among predators that specialize on such prey.