Balancing contest competition, scramble competition, and social tolerance at feeding sites in wild common marmosets (Callithrix jacchus)

• Published in: American journal of primatology 2019-04, Vol.81 (4), p.e22964-n/a
• Main Authors: Fuente, María Fernanda, Schiel, Nicola, Bicca‐Marques, Júlio César, Caselli, Christini B., Souto, Antonio, Garber, Paul A.
• Format: Article
• Language: English
• Subjects: Animal models; Animals; Appetitive Behavior; Behavior, Animal; Brazil; Breeding; Callithrix - physiology; Callithrix jacchus; Caregiving; Child care; cofeeding; Competition; Competitive Behavior; Cooperation; Cooperative Behavior; Dominance; Feeding; Feeding Behavior; feeding success; Female; Females; Field tests; finder's share; Food intake; Foraging behavior; foraging strategies; Infants; Male; Offspring; Prosocial behavior; rank; Reinforcement; Social Behavior; Social cohesion; Social conditions; Social relations; Social structure; Success; Survival; Tolerance
• ISSN: 0275-2565; 1098-2345
• DOI: 10.1002/ajp.22964

Models of primate sociality focus on the costs and benefits of group living and how factors such as rank, feeding competition, alliance formation, and cooperative behavior shape within‐group social relationships. We conducted a series of controlled field experiments designed to investigate how resource distribution (one or three of four reward platforms) and amount of food on a reward platform affected foraging strategies and individual feeding success in four groups of wild common marmosets (Callithrix jacchus) living in the Caatinga of northeastern Brazil. At our field site, common marmoset groups are characterized by a single breeding female who can produce twin litters twice per year, strong social cohesion, and cooperative infant care provided principally by several adult male helpers. We found that except for the dominant breeding female, rank (based on aggression) was not a strong predictor of feeding success. Although the breeding female in each group occupied the highest rank position and obtained the greatest daily feeding success, all other group members, including adults and juveniles experienced relatively equal feeding success across most experimental conditions. This was accomplished using a balance of behavioral strategies related to contest competition, scramble competition (associated with a finder's advantage), and social tolerance (sharing the same feeding platform). Based on these results, the social structure of common marmosets is best described as “single female dominance,” with the breeding female maximizing food intake needed to offset the energetic costs associated with reproductive twinning and the ability to produce two litters per year. Cooperative infant caregiving, in which the number of helpers is positively correlated with offspring survivorship, requires a set of behavioral strategies that serve to reduce contest competition and promote prosocial behaviors at feeding sites. In wild groups of common marmosets, breeding females (highest rank position) experienced the greatest food intake, whereas among all other group members rank did not predict individual feeding success. The cooperative infant caregiving in this species requires a range of behavioral strategies that serve to reduce contest competition and promote prosocial behaviors and group cohesion at feeding sites.