Provisioning in wild golden lion tamarins (Leontopithecus rosalia): benefits to omnivorous young

Abstract

Provisioning may act to cushion weaned young from dietary insufficiency and errors during the period in which they are mastering complex foraging techniques or learning to identify appropriate dietary items. That is, young mammals who receive food from others may gain nutritional and/or informational benefits. I conducted a longitudinal study of 13 wild golden lion tamarins 11–56 weeks of age in six groups to evaluate hypotheses regarding the functions of provisioning. All members belonging to this primate taxonomic family (the Callitrichidae) are cooperative breeders and are known to provision their young more frequently than do other primate species, except humans. My results, together with experimental findings, suggest that juveniles receive both nutritional and informational benefits from being provisioned. My juvenile study subjects received animal prey (invertebrates and small vertebrates) from others more frequently than plant resources (fruits and hardened exudates). Apparently difficult-to-handle fruits were more likely to be transferred than readily processed fruits. These results support the nutritional benefits hypothesis because the young received items, particularly lipid- and protein-rich prey, that they might not otherwise have acquired. That juveniles fed independently on, and were provisioned with, the same fruits on the same day is counterevidence to the nutritional benefits hypothesis, however. The informational benefits hypothesis was supported because juveniles received a large variety of foods (including more than 20% of fruit species eaten) and received uncommon fruits that were easily acquired. Adults emitted food-offering calls to encourage the transfer of prey to juveniles, particularly when the prey was whole and alive.