Ayres black uakari  (Cacajao ayresi)

Classified as Vulnerable (VU) on the IUCN Red List (1) and listed on Appendix II of CITES (2).

Discovered as recently as 2008, the Ayres black uakari has only been seen twice in the wild (1). Similar in appearance to a number of other uakari monkeys, these primates are distinguished by 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 treetops. As its name suggests, the Ayres black uakari has black fur, which is tinged with red. The face and cheeks are largely naked, but long, lustrous black hairs cover the top of the head (3) (4). The male is larger, and more robust, than the female (5). 

The taxonomic status of the black uakaris has created significant debate (6). Initially, a single species was recognised, with two subspecies the golden-backed black uakari (Cacajao melanocephalus ouakary) and Humboldt’s black uakari (Cacajao melanocephalus melanocephalus) (7) (8). However, the subspecies were later given full species status, along with the newly discovered Ayres black uakari, on the basis of their morphology, ecology and genetics (6).

While the range of the Ayres black uakari is not entirely clear, it is thought to be restricted to a tiny area around the Curuduri River Basin and the Aracá River in northern Brazil (1) (3). Its total distribution is estimated at only 5,000 to 6,000 square kilometres (1).

On the two occasions the Ayres black uakari was observed in the wild, it was seen in flooded forests, with large palm groves (Mauritia flexuosa) and patches of terra firma forest (1) (8). In common with other uakaris, the Ayres black uakari is likely to be a strictly arboreal species (1).

While very little is known about the specific biology of the Ayres black uakari, it is likely similar to other uakari monkeys, which feed primarily upon unripe seeds, although it is likely that this primate will also supplement its diet with fruit pulp, leaves and insects (5). This adaptation has allowed uakaris to inhabit a number of forest types that other primates cannot exploit on a continual basis (9). Uakaris may travel up to six kilometres each day in large, flexible groups, but forage individually (4) (5) (8). Although normally found in aggregations of around 10 to 30 individuals, groups of up to 100 may be observed in areas of high food abundance (3) (5). Group members communicate using a wide array of vocalizations, including screams and hissing, and visual signals, such as tail-wagging (4). Mixed sex, multiple male and multiple female groups have all been observed, but dominance hierarchies, which have been observed in related species, have not yet been observed for the Ayres black uakari (4) (8) (9). 

There is currently no information on the breeding biology of the Ayres black uakari; however, birthing in the closely related black-headed uakari (C. hosomi) coincides with the onset of the rainy season, a period in which fruit productivity peaks. Uakaris are typically polygynous, and a single young is born every two years (3).

Already significantly restricted in range, the Ayres black uakari is further threatened by hunting, as uakaris are favoured for their meat by the Yanomami Amerindians. The severity of the hunting is currently unclear, as there are few permanent settlements within the species’ range; however, it is probably only hunted during the wet season when fish, the main food source for the local people, become scarce (1) (6). Uakaris make easy targets when exposed on river edge forests, and the introduction of shotguns has probably increased the number of monkeys killed each year (1) (10).  

Unfortunately, the Ayres black uakari is not found in any protected areas and there are currently no conservation measures in place for this species. As there is very little data available on this recently discovered primate, its status remains very much an enigma.  Consequently further field studies into the ecology and distribution of the vulnerable Ayres black uakari are needed. The success of any future conservation measures will require the cooperation of the local communities (1) (6).  

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:
  www.wcs.org.br