The Ecology and Conservation of the Red Uakari Monkey on the Yavari River, Peru

Abstract

The behaviour, ecology and conservation of the red uakari monkey Cacajao calvus ucaya/ii was studied on the Yavari River in northeastern Peru. The Lago Preto study site has four major habitats comprising terra firme, seasonally-flooded varzea, floodplain aguajal palm-swamp and upland aguajal palm-swamp forests that are very different in tree species composition. Productivity studies demonstrated that varzea and aguaja/ habitats were very seasonal in their fruit production, while terra firme showed less seasonal variation. Uakaris ate mainly unripe seeds for two thirds of the year, but ate large quantities of ripe pulp when Mauritia flexuosa palm fruits were available. Mauritia flexuosa was the most important species for red uakaris, making up 20% of the diet. Mauritia flexuosa was also important because it was available at times when other items were scarce. The abundance of uakaris at different sites on the Yavarf River was not correlated with the abundance of other primates, but was negatively correlated with seed-eating rodents. Uakaris ranged over at least 1200ha at Lago Preto, foraging in terra firme, varzea and aguajal forests depending on the availability of resources in these habitats. Uakari group sizes varied depending on habitat type, and fluctuating group sizes appear to be related to the distribution of food resources. Adult male uakaris were most commonly next to other adult males, and often performed aggressive displays with other males. Uakari calls varied with the context of behaviour. The adaptive significance of the uakari's red face can be explained by both ecological and behavioural adaptations. Uakaris in the Yavarf-Ucayali interfluvium are under threat from logging, hunting and non-timber plantresource extraction. The effects of logging on the Yavarf will depend largely on the tree species extracted. Currently most valuable species are extracted, the impact is expected to be low, but this could change if less valuable timber is felled. The extraction of Mauritia f/exuosa palm fruits for market sale is rare on the Yavarf but on more populous rivers may affect uakari populations. Hunting is the biggest threat to uakari populations on the Yavari and logging operations are likely to lead to an increase in the hunting of primates. Managing hunting is the priority for red uakari conservation throughout their range. The red uakari monkey is being used as a flagship species in a number of new and proposed reserves. The distribution and density of uakari monkeys within these areas is barely known. The ecological behavioural and distributional information obtained in this thesis will help these reserves determine the conservation requirements for the uakari monkeys.

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