Nonlinear effects of group size on the success of wolves hunting elk

摘要: Despite the popular view that social predators live in groups because group hunting facilitates prey capture, apparent tendency for success to peak at small sizes suggests formation of large is unrelated capture. Few empirical studies, however, have tested nonlinear relationships between and size, none demonstrated why trails off after peaking. Here, we use a unique dataset observations individually known wolves (Canis lupus) elk (Cervus elaphus) Yellowstone National Park show relationship size indeed individuals withholding effort (free riding) does not increase across sizes. Beyond 4 wolves, leveled off, individual performance (a measure effort) decreased reasons interference from inept hunters, age, or size. But did drop faster among with an incentive hold back, i.e., nonbreeders no dependent offspring, those performing dangerous predatory tasks, grabbing restraining prey, proficient hunters. These results suggest decreasing was free riding .4 had superficially appeared be cooperating. This first direct evidence trends reflect switch cooperation riding. It also highlights how per se unlikely promote maintenance groups. Key words: Canis lupus, carnivore, cooperation, riding, hunting, living, interference, predation, sociality, wolf. [Behav Ecol]