Black-headed uakari  (Cacajao hosomi)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix I of CITES (3).

The subject of much taxonomic debate, the black-headed uakari has recently been given full species status on the basis of its distinct genetics, morphology and ecology (4) (5).  In common with other uakaris, the black-headed uakari has a comparatively short tail, less than half the length of the head and body. The significance of this characteristic has proved baffling to scientists, as long tails typically help arboreal mammals to keep their balance whilst traversing the tree tops. The face and the cheeks are largely naked, but as its common name suggests, the top of the head is covered in long, lustrous black hair. The rest of the fur is a contrasting chestnut-brown colour, with a black mid-back, a characteristic that distinguishes it from the similar Ayre’s black uakari (Cacajao ayresi), and black lower limbs and hands (6) (7). The male is larger and more robust than the female (6) (8).   

The black-headed uakari is found in a pocket of Amazonian rainforest in northern Brazil and adjacent southern Venezuela (1) (9). Its range is confined in the south and west by the Rio Negro, by the Rio Marauiá (Brazil) in the east, and the Canal Cassiquiare and Rio Orinoco (Venezuela) to the north (1).

Foraging widely for food, the vagrant nature of the black-headed uakari takes it into a number of habitats including terra firma forest, flooded forests, montane forest and white-sand forest, from about 100 metres above sea level, up to at least 1,500 metres (1) (2) (10). As a strictly arboreal species, the black-headed uakari has never been seen to come to the ground, instead residing high in the forest canopy (1).

Uakaris have a diet of unripe seeds, an adaptation that allows these monkeys to inhabit a number of forests types that other primates cannot on a continual basis (11). Seeds of the tree species Micrandra spruceana, Eperua leucantha, and Hevea braziliensis are the most important food item, but the black-headed uakari will also eat fruit pulp, leaves and insects (1) (8). Traveling widely in large, flexible groups, the black-headed uakari moves up to four kilometres each day, but forages individually (7) (8). Although normally found in aggregations of around 10 to 30 individuals, large groups of up to 100 may be observed in areas of high food abundance (6) (8) (12). Group members communicate using a wide array of vocalizations, including screams and hissing, and visual signals, such as tail-wagging (7). Mixed sex, multiple male and multiple female groups have all been observed, but a dominance hierarchy has not been recorded yet (7) (10) (11).  

Birthing in the black-headed uakari coincides with the onset of the rainy season, a period in which fruit productivity peaks, between March and April (7). A polygynous species, a single young is most likely born every two years, with the male reaching maturity at six years of age, and the female at three years (6). 

Already restricted in range, the black-headed uakari is further threatened by hunting, as it is favoured for its meat by the indigenous Yanomami Amerindians. This hunting was probably once sustainable, but the introduction of shotguns and permanent settlements has resulted in more monkeys being killed (1) (6). This was compounded by additional hunting by illegal gold miners in the 1980s and 1990s (11). Consequently the black-headed uakari is suspected to have undergone a worrying 30 percent decline in the last 30 years, and is now restricted to Pico da Neblina National Park and other protected areas in the Venezuelan parts of its range (1) (13).   

Although there are no specific conservation measures in place for the black-headed uakari, it is found in one of South America’s largest protected areas, the Neblina transboundary preservation area. Despite the area’s protected status, hunting persists and clear wildlife management plans are lacking (1). As one of the few mammals restricted to this area, there is hope that the black-headed uakari can be used as a flagship species for the conservation of the region (1) (14). Further research into the species’ ecology and the introduction of measures to abate hunting pressure will ensure this distinctive primate is protected from further declines (1).

For more information on uakari monkeys, see:

• Primate Info Net: 
  http://pin.primate.wisc.edu/factsheets/entry/uakari

For more information on primate conservation, see:

• The IUCN/SSC Primate Specialist Group: 
  http://www.primate-sg.org/pc.htm
• Neotropical Primate Conservation: 
  http://neoprimate.org/lang/en/
• Wildlife Conservation Society Brazil:
  http://www.wcs.org.br/