Cacajao c. calvus has a restricted range, from the confluence of the rios Japurá and Solimões north-west between the two rivers connecting to either the Paraná Yaula, or the Furo or Paraná da Aranapa in Brazil (Hershkovitz 1987). Until recently, the White Bald-headed Uacari was considered endemic to Mamirauá Sustainable Development Reserve, but observations indicate the presence of this taxon in the region of the lower Juruá (Vira Volta), south of the Solimões (Silva Jr. pers. comm.). A new population of white uacaris was recorded from the Rio Jurupari, a tributary of the Rio Envira in the state of Amazons, about 750 km to south-west of the current range (Silva Jr. pers. comm.), and another sighting along the Alto Jurupari south of the town Feijó in the state of Acre (L. Veiga pers. comm.), but it has not yet been confirmed whether or not these are the same or distinct taxa (see Figueiredo 2006). Unlike most other Amazonian platyrrhines, uacaris tend to range along rivers rather than within interfluvia; várzea forests connect the two populations along the rivers between these two areas. No field data are available to determine if these populations are allopatric. The subspecies Cacajao c. novaesi occurs in the middle of these two populations (Silva, Jr. and Martins 1999).
The geographic range of Cacajao c. novaesi has been updated since first described by Hershkoivitz (1987) when it was thought to occur only on the south bank of the upper rio Juruá between the Rios Tarauacá and Eirú. Peres (1988, 1997) extended its range north-east of the range described by Hershkovitz (1987), on the left bank of the Juruá and at Lago da Fortuna, Carauari to the north. Populations of Cacajao calvus observed by Peres on the upper Juruá, and unconfirmed reports by Fernandes (1990) in the Brazilian state of Acre on the upper Juruá and Purus, are either of Cacajao calvus novaesi or Cacajao calvus ucayalii, which would extend the known ranges of either of these subspecies (Bowler 2007).
Cacajao c. rubicundus occurs in Brazil, with a relatively restricted (poorly known) range. It presents an apparent disjunct geographic distribution, known from an area situated in the Iça-Solimões interfluve in Amazonas (type locality: opposite the town of São Paulo de Olivença, north bank of the Solimões [Hershkovitz 1987]), and another near the mouth of the Auati-Paraná. Cacajao c. rubicundus also occurs south of the Solimões, west of the Jutaí River at the Jutaí-Solimões Ecological Station (Nogueira-Neto 1992). It may have formerly occurred in the Trapezium of Colombia, but if they did they are now believed to be extirpated.
Cacajao c. ucayalii is found south of the Amazon River in Peru between the Ucayali and Yavarí Rivers. In the past, its range probably extended as far as the Urubamba River (Hershkovitz 1987), but surveys undertaken in the 1980s suggest that the southern limit is now the Sheshea River (Aquino 1988). Hershkovitz (1987) claimed this taxon also occurs on the east bank of the lower Yavarí in Brazil. The subspecies has a patchy distribution. It may no longer be present on the Brazilian side of the Yavarí, and is absent from a long stretch on the Peruvian side, upriver from the mouth of the Yavarí-Mirín perhaps as far as Quebrada Curacinha close to the town of Colonia Angamos (Salovaara et al. 2003). On the Yavarí-Mirín, the species is present on a large of the North bank, but is absent from the south side of the river, except in the upper reaches. As noted earlier, populations of Cacajao calvus observed by Peres on the upper Juruá and unconfirmed reports by Fernandes (1990) in the Brazilian state of Acre on the upper Juruá and Purus, may be either of Cacajao calvus novaesi or Cacajao calvus ucayalii, which would extend the known ranges of either of these subspecies (Silva Jr.and Martins 1999).
Found in the upper Amazonian region of western Brazil, eastern Peru and possibly in southern Colombia.
Biogeographic Regions: neotropical (Native )
Members of this cat-sized species of New World Monkey have a head and body ranging between 360-570 mm in length. Their short and somewhat stumpy, nonprehensile tail adds just an extra 137-185 mm. They have a broad flat face and extremely separated nostrils. Their teeth consist mainly of broad flat molars and large canines. They have naked, crimson faces and ears with the rest of their body covered in wispy hair. The various sub-species differ in the color and markings of their fur, ranging from very dark to almost white. Uakaris have long furry fingers and toes that lack claws.
Range mass: 2 to 3 kg.
Range length: 360 to 570 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Habitat and Ecology
Cacajao c. calvus:
This taxon is a habitat specialist that is primarily limited to flooded forests such as the lower Rio Juruá or the white-water várzea habitats of the low Rio Japurú. The White Bald-headed Uacari is a highly specialized seed predator, fruits and seeds are the most important food item and just a handful of tree species made up the bulk of the diet (Ayres 1986).
Cacajao c. rubicundus:
No field data on ecology are available for this subspecies.
Cacajao c. ucayalii:
Occurs in flooded forests, low to medium hill and high terrace forests, and palm swamps. As with other Bald Uacaris, Red Uacaris are specialized for the predation of seeds, with fruits and immature seeds making up the bulk of the diet. Mauritia flexuosa palm fruit was also the most important species in the diet of this taxon at Lago Preto, accounting for 20% of the annual diet (Bowler 2007).
Uakaris are found only in the tropical forests that are either constantly or seasonally flooded, and mostly along small rivers and lakes within the forest.
Terrestrial Biomes: rainforest
Uakaris feast primarily on seeds of immature fruits, ripe fruits, leaves, nectar, and a few insects including the caterpillar.
During the rainy season, uakaris spend most of their time high in the trees eating the fruits. In the dry season, they come to the forest floor to forage for seedlings and fallen seeds.
Animal Foods: insects
Plant Foods: leaves; seeds, grains, and nuts; fruit; nectar
Primary Diet: herbivore (Frugivore )
Life History and Behavior
Status: captivity: 19.9 years.
Status: captivity: 20.5 years.
Status: captivity: 23.0 years.
Status: captivity: 27.0 years.
Status: captivity: 22.3 years.
Status: wild: 18.0 years.
Lifespan, longevity, and ageing
Uakaris are mostly monogamous.
Mating System: monogamous
Most uakari females begin reproducing at the age of three, whereas the males don't begin until the age of six. The females give birth to single live young at intervals of about two years. The young are weaned between 3 and 5 months during which period they begin to eat soft fruits.
Breeding interval: Females give birth once every two years.
Average number of offspring: 1.
Range weaning age: 3 to 5 months.
Average age at sexual or reproductive maturity (female): 3 years.
Average age at sexual or reproductive maturity (male): 6 years.
Key Reproductive Features: iteroparous ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous
Average gestation period: 182 days.
Average number of offspring: 1.
Average age at sexual or reproductive maturity (female)
Sex: female: 1204 days.
Females nurse their young until they are between 3 and 5 months old.
Parental Investment: pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Female, Protecting: Female)
IUCN Red List Assessment
Red List Category
Red List Criteria
- 2003Near Threatened(IUCN 2003)
- 1996Vulnerable(Baillie and Groombridge 1996)
- 1994Endangered(Groombridge 1994)
- 1990Vulnerable(IUCN 1990)
- 1988Vulnerable(IUCN Conservation Monitoring Centre 1988)
- 1986Vulnerable(IUCN Conservation Monitoring Centre 1986)
- 1982Vulnerable(Thornback and Jenkins 1982)
Uakaris are on the verge of extinction due to several factors, including the fact that they are hunted for food and for bait. More important, they are rapidly losing their habitat due to the activities of the timber industry. Tropical rainforests are the only areas in which uakaris can live, as is true of many other species endangered for the same reason. The WWF is currently doing everything it can to protect these areas.
US Federal List: endangered
CITES: appendix i
IUCN Red List of Threatened Species: vulnerable
Cacajao. c. calvus:
Average population densities in the region surrounding Mamirauá and Teiu Lakes (Mamirauá Reserve) were 10 individuals/km² (5 sites) in 1984/5 (Ayres 1986) and 17/km² (6 sites) in 2004/5 (Paim 2005).
Cacajao c. ucayalii:
In surveys undertaken in the Sierras de Contamana, part of the Sierra del Divisor located on the right margin of the Ucayali River, near the frontier with Brazil, this subspecies was recorded at an abundance of 479 individuals/100 km (Aquino 2005). Sites on the Yavarí and Yavarí-Mirín have some of the highest densities of (Puertas and Bodmer 1993; Salovaara et al. 2003). Jorge and Velazco (2006) discovered some new populations on the upper Tapiche River and on the Divisor ridges in the Zona Reservada Sierra del Divisor.
Cacajao c. calvus:
Although this subspecies is rarely hunted in its range because its appearance is considered too human-like (Ayres 1986), the main threat facing this primate is the reduction and transformation of its flooded forest habitat. The main forms of deforestation in the area, are small-scale agriculture and logging (Ayres and Johns 1987). Current data indicate that almost the entire (confirmed) population are included within the Mamirauá Sustainable Development Reserve and population densities appear to have increased in the 20 years up to 2005 (Ayres 1986; Paim 2005).
Cacajao c. rubicundus:
This species is hunted for food. It may be affected by habitat loss due to logging and forest loss especially along the main stream of the Amazon.
Cacajao c. ucayalii:
Surveys conducted between 1979 and 1986 (Aquino 1988) showed that the range was much reduced, hunting having exterminated the species in several areas. Aquino (1988) suggests that populations close to the Ucayali and Amazon Rivers have been greatly reduced and in some areas exterminated, caused by hunting and habitat disturbance. The Yavarí River and its tributary the Yaquerana represent the stronghold for remaining populations. Close to Iquitos, Mauritia flexuosa is extracted in large quantities by felling the palms (Bodmer et al. 1999; Meyer and Penn 2003); the unsustainable extraction of this resource may have an impact on Cacajao c. ucayalii in some areas (Bowler 2007). Logging concessions designated in 2004 cover around one-third of the geographic range of Cacajao c. ucayalii. While the selective removal of low-density, high-value timber species does not appear likely to have a great impact on populations of Cacajao c. ucayalii, the logging operations increase human populations and bushmeat hunting in remote parts of the range (Bowler 2007). Hunting levels on the Yavarí-Mirín and Yavarí have increased since 2004, when human populations increased due to logging activities. Bodmer et al. (2006) found that more wild meat was consumed per capita in a commercial forest concession on the Yavarí than in the nearby rural communities.
Cacajao c. novaesi:
This subspecies is affected to some degree by hunting and the exploitation of natural resources within the two extractive reserves where it occurs.
A decree (No. 34-2004-AG) was published by the Peruvian government in 2004 that approves the categorization of threatened Peruvian wildlife and prohibits hunting, capturing, owning, transporting, and exportation for commercial purposes. It is hoped that this will help in conservation actions and stimulate research on threatened Peruvian wildlife (Heymann 2004).
Cacajao c. calvus:
This subspecies is protected within the Mamirauá Sustainable Development Reserve (Ayres et al. 1999).
Cacajao c. novaesi:
Afforded some protection within two extractive reserves, the Middle Juruá and the Upper Juruá, where hunting and the exploitation of natural resources are permitted.
Cacajao c. rubicundus:
Cacajao c. rubicundus should be relatively well protected as it occurs within the Jutaí-Solimões Ecological Station (284,285 ha), south of the rio Solimões (Nogueira-Neto 1992).
Cacjao c. ucayalii:
Until recently, the only protected area known to contain Cacajao calvus ucayalii was the regional Tamshiyacu Tahuayo Communal Reserve (TTCR). The TTCR extends over an area of 322,500 ha, and is situated close to the city of Iquitos in upland forests between the Amazon and the Yavarí (Newing and Bodmer 2004). The reserve was created as a result of a strong alliance between local people and conservationists. The presence of Cacajao calvus ucayalii has become part of the justification for three areas either under proposal or newly created. These are the Sierra del Divisor Reserved Zone, the Lago Preto Conservation Concession (LPCC) and the proposed Greater Yavarí Reserve. Community conservation work is conducted by WCS-Peru and the Durrell Institute of Conservation and Ecology on the Yavari and Yavari-Mirin Rivers in Peru. This project aims to reduce the hunting of Cacajao c. ucayalii in this area (Bowler 2007).
Relevance to Humans and Ecosystems
Economic Importance for Humans: Negative
While there is no obvious negative effect on humans by the uakaris, huge amounts of money are used each year to help preserve their habitat.
Economic Importance for Humans: Positive
Being closely related to humans, uakaris can be useful in studying public health. For example, they can provide information on new vaccines and diseases, such as diabetes, malaria, yellow fever, AIDS, mental disorders and even some cancers. Uakaris are also a valuable provider of meat in Peru and a source of hunting bait in Brazil.
The bald uakari (Cacajao calvus) or bald-headed uakari is a small New World monkey characterized by a very short tail; bright, crimson face; a bald head; and long coat. The bald uakari is restricted to várzea forests and other wooded habitats near water in the western Amazon of Brazil and Peru.
- White bald-headed uakari, Cacajao calvus calvus
- Ucayali bald-headed uakari, Cacajao calvus ucayalii
- Red bald-headed uakari, Cacajao calvus rubicundus
- Novae's bald-headed uakari, Cacajao calvus novaesi
The bald uakari weighs between 2.75 and 3.45 kg (6.1 and 7.6 lb), with head and body lengths average 45.6 cm (18.0 in) (male) and 44.0 cm (17.3 in) (female). In general, the bald uakari has a long, shaggy coat ranging from white in color to red and its head is bald. The tail is bob-like and rather short for a New World monkey (about 5.9 inches (15 cm)), at only half the length of the body and head combined. Its scarlet red face is due to the lack of skin pigments and plentiful capillaries that run under its facial tissue.
Behaviour and ecology
The arboreal bald uakari prefers to reside in seasonally flooded forests in the area of the Amazon River Basin, in the countries of Peru and Brazil. It is important that the uakari is arboreal (lives in the tree tops) because of the flooding of the forests and the water rising to great heights during the rainy season. During the dry season, it returns to the ground to look for seeds and other food material. A study of the diet of the uakari found it to consist of 67% seeds, 18% fruit, 6% flowers, 5% animal prey, and buds. Its powerful lower jaw forms a pseudodental comb, which allows the uakari to open the hard surfaces of unripe fruits and eat the nuts that most other primates would not be able to open. It will also eat insects that happen to cross its path, however it does not specifically pursue this type of food.
The bald uakari can be found traveling up to 4.8 kilometers per day in multi-male/multi-female groups of 5 to 30 individuals, and even up to 100. It can be extrapolated from the general primate behavior of female philopatry that female uakaries are also philopatric. This means that males leave the natal group. The total size of the group's home range is between 500 and 600 hectares. This requires efficient territorial defense mechanisms. A few of these include specific vocalizations, wagging of the tail, and erection of the hair.
The bright red facial skin is a sign of good health and allows for the determination of a healthy mate. The breeding season is between October and May. Its gestation period is approximately six months. Both sexes have a sternal gland, which might be involved in olfactory communication, especially during mating, when the female encourages the male to mate by releasing an attractive scent. The bald uakari lives approximately 30 years and has been known to live over 30 years in captivity.
Due to the uakari's location, it is extremely common for these animals to contract malaria. Primates who have contracted the disease are noticeably paler and are not chosen as sexual partners as they do not have the desired natural immunity to malaria.
The conservation status of this species was changed from near threatened to vulnerable in the 2008 World Conservation Union (IUCN) Red List because the species has declined at least 30% over the past 30 years (three generations) due to hunting and habitat loss. This is considerably better than the 1994 assessment which found it to be endangered, followed by the 2003 assessment which found the species to be near threatened. Although the conservation status has improved, actual population numbers are on a decreasing trend. Since it only lives in white water flooded forests, it is very susceptible to human impact (i.e.: land acquisition for agriculture and/or pastures).
Forest loss and hunting are the two most prominent threats to the bald uakari. Between 1980 and 1990 it was found that an average of 15.4 million hectares of tropical forests were destroyed each year and the Neotropics are facing forest loss in areas such as the southern and eastern parts of the Amazonia. In 1997, the Amazon Basin experienced the highest rate of forest destruction of the remaining tropical rainforests worldwide. Logging of hardwoods is a major contributor to overall destruction as large-scale logging disrupts the continuity of forest canopies. Canopy disruption and forest loss directly affect uakaris because of their arboreal lifestyle and adaptations for seed food consumption. Additionally, Cacajao calvus populations are located so close to the Amazon River that there is a higher risk of human hunting from canoes and such to use the primates as a food source or bait.
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