Terrestrial foraging by Cacajao melanocephalus ouakary (primates) in Amazonian Brazil: is choice of seed patch size and position related to predation risk?

We analyse the behaviour of Cacajao melanocephalus ouakary feeding at patches of germinating seedlings in dried-out flooded forest. Seedlings of Eschweilera tenuifolia (Lecythidaceae) were the most commonly eaten (88.9%). Some seed patches were revisited over several days, while others were consistently ignored. We tested 3 predictions relating uacari terrestrial foraging behaviour to: (1) arboreal escape route proximity, (2) seed patch size choice and (3) temporal patterns of repeat exploitation. Comparison of fed-at and ignored patches revealed significant preferences for larger patches, and for those close to arboreal refuges but distant from dense ground-based vegetation. Support for these predictions is interpreted as evidence for predation risk-sensitive foraging.