We studied golden-backed uacaris, (Cacajao melanocephalus ouakary) in the late-wet season of 1999 and in the mid-dry season of 2000 in Jaú National Park (JNP), Brazil. Additional observations were taken by other scientists working in JNP. Group counts range from 2 to 30 in the wet season and from 1 to >100 in the dry. In the wet season, we recorded uacaris only in flooded forests (igapó). During the dry season they were in igapó, campinarana, and terra firme forests. We supplemented observations via interviews with local informants on seasonal use of the forest types and of particular small patches of different habitat types that exhibit high temporal patchiness in fruit availability. We recorded a total of 13 food plant species (dry season, 4; flooded season, 9), and a further 55 were provided by interviews. We noted the physical dimensions and hardness of 26 fruit species. Despite accepted specializations of the uakaris on hard unripe fruit, we recorded incidents of insectivory and folivory. Patterns of food availability, and therefore the seasonal 1 The authors dedicate this paper to the memory of J. Marcio Ayres, the founding father of uacari field biology. 949 0164-0291/05/0800-0949/0 C 2005 Springer Science+Business Media, Inc.950 Barnett, de Castilho, Shapley, and Anicáciohabitat-use patterns by golden-backed uacaris, appear to be more complex than previously realized.

With the sakis (Pithecia) and the bearded sakis (Chiropotes), the uakaris (Cacajao) constitute the cebid subfamily, Pitheciinae. The most recent revision recognized six Cacajao subspecies in two species, confined to the Amazon basin. Before 1970 most field information derived from 19th century travellers. Studies still lag behind those of other cebid genera. This paper summarises the known ecology of Cacajao, and identifies future research and conservation priorities. The relevance of Pleistocene refugia and metachromism in analysing its biogeography is discussed. Range size remains obscure but, with the exception of C. c. calvus, may be extensive, as all other subspecies appear to migrate in the dry season from flooded riverine forest to terra firme. Observed group size ranges from 5 to 50, indicating the operation of a fission-fusion society. Social organization appears to be multi-male and non-hierarchical. This accords with the minimal sexual dimorphism. The highly developed canines function primarily as fruit openers. Cacajao is a dietary specialist on hard-shelled fruit, and appears unique among Amazonian cebids in its dependence (at least seasonally) on riverine forests. Hunting may be a problem locally, but local taboos sometimes offer protection. They appear vulnerable to habitat disturbance. On the Rio Negro, the range of C. m. melanocephalus appears to have greatly diminished. To ensure protection of viable populations, the inferred dietary dependence on seasonal migration may require accommodation. Research priorities include the status, habitat preference, diet and social ecology of all taxa except C. c. calvus. A more complete knowledge of the biogeography of the genus would be valuable.

We present an ethogram for golden-backed uakaris (Cacajao melanocephalus), based on observations in the field and on a captive individual. We also provide additional observations on the ecology of the wild animals. We studied 3 free-living groups (maximum counts of 5, 15, and 26 individuals) during two wet-seasons (in the flooded igapó forest of Jaú National Park, Amazonas, Brazil. The groups lived in close proximity but never mixed, because river channels separated them. Groups showed fissionfusion behavior, subgroup sizes varied within groups, and we observed 13 different subgroup compositions. The areas used by the groups were ca. 0.82, 2.35, and 2.45 km 2 . We defined a total of 9 behavioral categories. In the wild, the amount of time allocated to the behaviors traveling and foraging/feeding differed between months, but we found no difference in the amount of time devoted to behavioral categories across 3 periods of the day, possibly as a result of the patchy and unpredictable distribution or availability of food patches. Further, the activity patterns varied among groups, perhaps as a reflection of the different group sizes and compositions and different range sizes. We recorded 34 feeding items for wild golden-backed uakaris between January and June 2008, mostly fruits and seeds. No significant variation in the number of different food types occurred across months. We recorded 6 primate species in the study areas. The uakaris neither mobbed nor Int J Primatol (2011) 32:46-68

Abstract:The Neotropics house two guilds of large arboreal vertebrate seed predators: parrots and the pitheciin primates. Both have diets dominated by immature fruits. The possibility of members of the Pitheciinae (genera Cacajao, Chiropotes and Pithecia) acting as occasional seed dispersers has been mooted, but not experimentally shown. We combined primate behavioural data and seed germination data from three separate field studies in the Brazilian states of Amazonas and Pará to analyse patterns of post-consumption seed survivorship for seeds discarded by three pitheciin species (Cacajao melanocephalus ouakary, Chiropotes chiropotes and Chiropotes albinasus). We then calculated the frequency of dispersal events for four species eaten by C. m. ouakary. All three primate species dropped intact seeds while feeding, and 30.7% of 674 dropped seeds germinated ex situ. Undamaged seeds from unripe and ripe samples germinated (29.3% and 42.7%, respectively), and all three primate species carried some fruits up to 20 m from the parent tree before consuming them. Potential seed-dispersal events varied from 1 (Macrolobium acaciifolium) per fruiting cycle to more than 6500 (Duroia velutina), suggesting that there are differences in dispersal potential. In summary, although they are highly specialized seed predators, these primates may also act as important dispersers for some plant species, and effective dispersal is not restricted to ripe fruits, as immature fruits removed from a tree may continue to mature and the seeds later germinate, a much-neglected aspect of dispersal ecology. The possibility that similar events occur in parrots should be experimentally investigated.