Social behavior of the collared peccary was studied on the lower, eastern slopes of the Mazatzal Mountains, Arizona. The social unit in this species is a cohesive herd, in which small inter-individual distances are maintained. Two conspicuous acts, one olfactory and one auditory, functioned to maintain close spacing. Social interactions were brief but tended to synchronize the activities of animals and also to bring them closer together. Amicable and neutral actions occurred far more frequently than agonistic interactions. Most agonistic behavior did not involve physical contact. Cooperative nursing, predator defense, and feeding occurred; all adults were tolerant of young, and males showed little overt competition over estrous females. The absence of sexual dimorphism, the 1:1 sex ratio within social groups, and the small, precocial litters in this species suggest an evolutionary history of pronounced sociality. Kin selection possibly was important in the evolution of social behavior in peccaries.
Byers, J. A., & Bekoff, M. (1981). Social, spacing, and cooperative behavior of the collared peccary, Tayassu tajacu. Journal of Mammalogy, 62(4), 767-785.