Red uakari: the world’s strangest-looking monkey

With its bald, scarlet head and orange fur, the red uakari is an odd-looking creature. Mark Bowler has photographed this endangered species in its remote Peruvian home - and fallen for its charms.

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With its bald, scarlet head and bright orange fur, the red uakari is the world’s strangest-looking monkey. Mark Bowler, one of the few scientists to have tracked and photographed this endangered species in its remote Peruvian home, reveals the beauty in the beast.

High in the canopy, the morning sun ignites a streak of fiery ginger hair as the female traverses the bough. Then she springs into view, limbs flailing as she plummets towards a smaller tree. Long fingers grasp for leafy branches as she hits her target, and the impact unleashes a cascade of red fruits into the flooded forest around my dugout canoe.

The cat-sized monkey pauses for a moment and gives a ‘hic-hic-hic’ call. This is instantly echoed by her young offspring, just behind her. High above, many more monkeys are hic-hiccing to their kin, a constant chatter that I seek out daily as I track my habituated group. I’m in the remote Yavari river basin of North-east Peru, and the monkeys above me are endangered red uakari monkeys Cacajao calvus ucayalii. They live in the wettest parts of the Amazon rainforest – the inaccessible aguajal palm swamps and varzea forests, which flood from December to June, leaving the trees in several metres of water.

Best-looking monkey of all

Incredible biodiversity and a low human population means that large mammals are still abundant here. There are 13 species of monkey, and for me, the red uakari is the best-looking of all.

Not everyone agrees: in 1855, naturalist Henry Walter Bates called them “monkeys of the most grotesque appearance”. They are certainly striking – orange fur surrounds a bald, intensely scarlet face; they have oversized, splayed canine teeth, a stumpy tail and, in the male, a centre-parted fatty bulge on the forehead. They’re like little orangutans with tomatoes for heads.

I count about 30 red uakaris above me, but I can also hear another group moving away. Last night, around 200 slept by a lake, and after a noisy, chattering conference at dawn, various foraging parties went their separate ways.

As the closed forest canopy gives way to the more open tree cover and dense understorey of the aguajal palm swamp, my uakari group takes up the ‘hic-hic-hic’ call, crashing onto frayed palm fronds and huge bunches of red fruit. The noise always increases on arrival at a palm stand, but today there is another reason for it – another foraging party is already here. Now there are at least 100 monkeys within earshot. These large aggregations are common, and this regular splitting and rejoining (fission-fusion) behaviour hints at a unique social system.

Patterns of migration

Accompanying the calls of the monkeys is the thud of palm fruits falling into the swamp. After following red uakaris for three years, I have uncovered a pattern of seasonal migration between habitats as they search for their favourite food – the seeds of unripe fruit. Particularly important is the Eschweilera tree, a relative of the Brazil nut. This is food uakaris were designed to eat, using their oversized canines to break open the tough casings and their procumbent incisors like tweezers to remove the seeds.

Unripe fruits are spread more evenly though the forest than the ripe fruit other monkeys prefer, so the uakari groups fan out over a large area. It’s hard to get close to the core of the group, where females and babies tend to be, without upsetting the following males.

These bachelor groups comprise mostly juvenile or subadult males, but some have the ‘butthead’ of a mature male. ‘Ruling’ males, who seem to control the centre of the group, work together to eject the bachelors if they come too near. So the bachelors stay on the periphery, grooming each other and keeping close in times of stress.

We are only just beginning to understand this social structure. We don’t even know if only the ruling males breed. They appear sufficiently worried about the bachelors to keep close to their allies, often displaying together, swinging by their ankles, fur bristling, to make themselves look bigger. This social system is unlike that of any other South American primate, having more in common with Africa’s gelada baboons.

Mixed-up monkeys

Uakaris often travel with other primates: woolly monkeys, squirrel monkeys or capuchins. Whether this is for safety, help in spotting hunting harpy eagles or for finding food, we don’t know. The woolly monkeys are more nervous than the uakaris – with good reason, for like all large primates they are widely hunted throughout Amazonia.

Here at least, uakaris are less frequently hunted, partly because of their smaller size, but also because the Wildlife Conservation Society (WCS) and the Durrell Institute of Conservation and Ecology (DICE) work to protect this primate. Further upriver, the monkey receives partial protection by virtue of its appearance. The Matses, an indigenous group, believe that eating these monkeys while pregnant can make your baby ugly, pale or red-skinned.

Elsewhere, though, hunting has made this already scarce primate even rarer. A further threat comes from logging in much of the uakari’s range. Our project hopes to protect some areas of forest completely. In 2006, DICE and WCS secured a 10,000 hectare conservation concession encompassing our study site. As a proportion of the forest, it’s small. But it’s a great start, and a wonderful model for conservation in the upper Yavari, with the uakari as our flagship species.


To find out more about Mark's research on red uakaris, click here


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