Producer–scrounger relationships in yellow-bellied marmots

When social animals forage together, they may engage in frequency-dependent strategies either as producers, those who acquire food with their own energy, or as scroungers, those who feed on what the producers discover. An individual's choice of strategy may depend on the frequency of strategies within the group, or it may depend on the individual's own traits. Most of our understanding of producer-scrounger relationships comes from highly social species, but we may gain different insights by studying less social species. We used novel puzzle box experiments to study social foraging relationships and identify the traits associated with strategy choice in facultatively social yellow-bellied marmots, Marmota flaviventer. We found that marmots had consistent strategies as either producers or scroungers. Furthermore, several individuals specialized as scroungers, following the producers to the puzzle box before other scroungers. However, their roles were only associated with sex (males were more likely to produce), and not with age, boldness or dominance rank. Marmots' lack of trait-regulated foraging roles may be associated with their relatively abundant and not-entirely defensible food, or may emerge from their lack of obligate social structure. We discuss how multiple factors may explain variation in social foraging behaviour. (c) 2020 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.