Evaluating the information-processing capacities of collectives is important for understanding their origin and adaptability. We analyze fission-fusion dynamics, a flexible grouping pattern that responds in part to spatio-temporal variation in food availability, using naturalistic observations of spider monkeys (Ateles geoffroyi). We study individual decisions to follow others depending on their knowledge about ephemeral feeding sites, finding that information about available feeding sites spreads widely amongst the group, favoring the finding and grouping around trees with ripe fruit. We also extract from association data the networks of pairwise followership or avoidance, generating new data sets by simulation and finding that these networks give rise to adaptive global properties, such as a frequency distribution of subgroup size that effectively tracks the habitat-wide food abundance. We point at further research on how knowledge of available feeding sites complements synergistically among group members, such that by sharing information the group as a whole obtains a more complete picture of the dynamic foraging environment than each individual would obtain on its own.