Anti-predator benefits of group living in white-nosed coatis (Nasua narica)

Predation is often considered an important factor in the evolution of sociality among animals. We studied mortality patterns and grouping behavior of white-nosed coatis (Nasua narica) at sites in southern Arizona, USA, and western Jalisco, México. Coatis were monitored by radio-tracking and recaptures for more than 3 years at each site. In both populations, predation by large felids, including jaguars (Panthera onca) and pumas (Puma concolor), accounted for more than 50% of mortality of adult coatis. Predation rates were significantly higher on solo coatis than on coatis in groups at both study sites. Predation rates were negatively related to group size in Arizona. However, mortality of juveniles, as measured by the ratios of juveniles to adult females, was not related to the number of adult females per group in Arizona or Jalisco. Coatis exhibit a suite of behaviors, including foraging with the juveniles in the center of the group, sharing vigilance, alarm calling, mobbing and attacking predators, and a highly synchronous birth season, that are all consistent with the hypothesis that predation has played an important role in shaping coati social behavior.