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The Amazon rainforest boasts more primate species than any other habitat on earth. Yet the largest primates, the apes, are absent from South America. The reason is that apes evolved in Africa and never had the chance to spread to South America. Scientists believe that New World and Old World primates split away from each other around 35 million years ago.

Small monkeys are in the Cebidae family (see Small monkeys), whereas larger Amazon monkeys previously assigned to this family are now included in three other families, the Atelidae (spider monkeys, woolly monkeys and howler monkeys), Pitheciidae (titis, saki monkeys and uakaris) and Aotidae (owl or night monkeys).

The total number of primate species varies according to taxonomic revisions, nowadays based primarily on DNA evidence. In addition, new species might be found. In September 2004, a new species of titi monkey was discovered in Madidi National Park in the Bolivian Amazon. The discovery received widespread publicity because the discoverer, British biologist Robert Wallace, decided to auction the right to name the monkey in order to raise money for the park. Even Ellen DeGeneres bid for the right, which was eventually won by a commercial corporation with a bid of $650,000.

The sakis and uakaris (Pitheciidae) weigh 2-4 kg, about the same as a small dog. Their tails are non-prehensile (do not grasp branches) and often give them away as it is easy to spot the bushy tails hanging below a branch. They have long hair, quite untidy, perhaps as a protection against ants that they must frequently encounter on their forays among the treetops. These monkeys are dark in color and often hard to spot as they are not particularly active. Night monkeys (Aotidae) are small, weighing about 0.75 to 1.25 kg. They have huge eyes, rimmed in white to give them a spectacled appearance. At night, the eyes reflect back a reddish-orange color. The third family of large Amazon monkeys, the Atelidae, includes our idea of a typical rainforest monkey; such as the howler monkeys, spider monkeys and woolly monkeys. Howler monkeys are large, and heavy set with striking beards, coming in a range of colors from pale yellow to black. Spider and woolly monkeys are graceful, slim-built and are colored black to dark brown. The woolly monkey has dense fur whereas the spider monkey's fur is coarser.

The heaviest of these monkeys, weighing up to 15 kg, all have prehensile tails, whereas the lighter species do not. The prehensile tail acts as a fifth limb, able to support the weight of the body, giving rise to the iconic image of a rainforest monkey hanging by its tail. The tip of the tail has a bare patch of skin on the underside that helps it grip the branch. It feels as though someone is coiling their finger around you. In appearance these species vary from the punk-rocker spider monkeys to the appropriately named monk saki which indeed looks like a monk! However, within species vary in color between populations separated by wide rivers or mountains, suggesting that not much interbreeding occurs between widely separated groups. This process of differentiation between populations is believed to be the initial stage of speciation, when a new species arises from an existing one.

The families of large Amazon monkeys are variously distributed across the Amazon, limited only by the altiplano of the Andes mountains. Where there is forest there are monkeys. That said, some species are highly restricted in range, such that this group includes among the rarest Amazon mammals. In particular, the white uakari is limited to a small area of varzea forest in the upper Amazon south of Iquitos, and the yellow-tailed woolly monkey (Lagothrix flavicauda)is found only in montane cloud forests of the Peruvian Andes at elevations of 1700 to 2500 meters. Some species of titi monkeys also have very small ranges. At the other end of the scale, the night monkey (Aotus sp.) is found almost across the entire extent of lowland rainforest. Presumably, its nocturnal habits are one aspect of its niche that enables it to avoid competition with other primate species as its range overlaps considerably with the similarly widespread capuchin monkey (Cebus apella). Of the saki monkeys, the monk saki (Pithecia monachus) is the most widespread, whereas the buffy saki (P. albicans) is locally common but found only in Brazil between the Purus and Juarua rivers.

All the cebid monkeys are fruit eaters, although insects are an important part of the diet for most species, and vegetation is significant in others. The sakis and uakaris have dentition that appears to be specialized to split open unripe fruits whose seeds form the main part of their diet. Capuchins on the other hand feed on ripe fruits, with invertebrates and small vertebrates often on the menu. The largest monkeys, such as the the howler monkeys, spider and woolly monkeys include a greater proportion of leafy vegetation in their diets.

Only a single young is born, which is then carried by the mother. Among smaller monogamous species such as the dusky titi (Callicebus moloch) the father takes up this duty). The family structure varies. Among the saki monkeys, the group is dominated by a single breeding female who gives birth two to three years. Combined with the low number of young born, this makes the species slow to recover following population declines. Another factor is the late age of breeding. For example, the woolly monkeys (Lagothrix lagothricha) first breed at age 6 to 8 and give birth every other year. The spider monkey (Ateles paniscus) breeds at about 4 years old but thereafter give birth only every three to four years.

Some cebid monkeys are in pretty good shape from a conservation standpoint. The night monkey is among the commonest species around human settlements as it adapts to secondary forest and more to the point is hard to hunt, being active mainly at night. Large monkeys are more intensively hunted because they are a more efficient prey item for the hunter; that is, they yield more meat per shot. For that reason, a number of species are at risk of extinction, particularly those with small geographic ranges.

Monkeys are critical contributors to the rainforest ecosystem. Being the main dispersers of seeds for hundreds of tree species, especially lianas and the tall canopy trees, they subtly but profoundly affect the composition of woody plant species—the forest as we experience it. When monkeys are removed by hunting, the particular suite of species in an area will inevitably change, with unknown domino effects for other plant and animal species all around.


Wikipedia: Atelidae
Subfamily Pitheciinae
Subfamily Atelinae
Infonatura: Species List
Honolulu Zoo: Spider Monkey
Oakland Zoo: Spider Monkey
Henson Robinson Zoo: Brown-Headed Spider Monkey
Sedgwick County Zoo: Colombian Black Spider Monkey
Spider Monkey by Lizzy
Wellington Zoo: Spider Monkey Spider Monkey
Amazing Rainforest Animals: Spider Monkey
The Primata: Black Spider Monkey
The Primata: Long-haired Spider Monkey
Monkey Sanctuary: What is a Woolly Monkey? Woolly Monkeys of Ecuador
SchoolWorld Endangered Species Project: Woolly Monkey
Animal Planet: Woolly Monkey
America Zoo: Woolly monkey
Woolly monkey skull
Yasuni Rainforest: Woolly monkey
The Primata: Humboldt's Woolly Monkey
The Primata: Yellow-tailed Woolly Monkey
Animal Info: Yellow-tailed Woolly Monkey
Enchanted Learning: Howler Monkey
Honolulu Zoo: Black Howler Monkey
The Primata: Black Howler Monkey
Hogle Zoo: Black Howler Monkey
Belize Zoo: Black Howler Monkey
Smithsonian National Zoo: Black Howler Monkey
The Primata: Red Howler Monkey
Animal Planet: Red Howler Monkey
The Primata: Red-handed Howler Monkey

Wikipedia: Pitheciidae
InfoNatura Species Index: Pitheciidae
BBC: Uakari
BBC: Bald uakari, red and white uakari
Wikipedia: Bald Uakari
The Primata: Red Uakari
Red Uakari Monkey Project
Animal Info: Red Uakari
America Zoo: Red Uakari
Rainforest Conservation Fund: Red Uakari
Red Uakari Monkey Shirts, Stickers, Greeting Cards, Posters and More
Red Uakari Monkey Research Project
Red Uakari Skull
Digimorph: Bald Uakari Skull
The Red Uakari Monkey Project
Animal Diversity Web: Cacajao calvus
Rainforest Alliance: Bald-headed red uakari
Black-headed Uakari
Black-headed Uakari Skull
Animal Info: Black Uakari
Wikipedia: Saki monkey
Mark Flinn: Sakis Pithecia
The Primata: Monk Saki
Rainforest Conservation Fund: Monk Saki
Animal Diversity Web: Pithecia monachus
The Primata: White-faced Saki
Bristol Zoo: White-faced saki
Como Park Zoo: White-Faced Saki
St Louis Zoo: White-Faced Saki
WWF: White-Faced Saki
Northern white-faced Saki Monkey
Roger Williams Park Zoo: White-faced Saki
Hong Kong Zoo: White-faced Saki
La Vallée des Singes: White-faced Saki
The Primata: Red-bearded Saki
The Primata: Buffy Saki
The Primata: Bald-faced Saki

Wikipedia: Aotidae
The Primata: Peruvian Red-necked Owl Monkey
Primate Taxonomy

Naming the Bolivian monkey species
Name a monkey
Going Ape Over An Amazon Treasure
The Lucachi Monkey—A Symbol of Conservation
A Lot Of Monkey Business In Bolivia
Right to name monkey species nets $650,000
Company Wins Right To Name New Species

Other topics
Primate Taxonomy
Latin American Primate Conservation Biology Field Courses
Primate Conservation, Inc.

Mainly photos
Spider Monkey
Woolly monkey
Woolly monkey
Woolly monkey, Brazil
Black Howler Monkey
BBC Movies: Bald-headed uakari
Red Uakari Monkey Project
Red Uakari
Bruce B. Junek: Monk Saki
Doug Janson: White-faced Saki
White-Faced Saki
Female White-faced Saki
zoos-worldwide: White-faced Saki
White-faced Saki
Audubon Nature Institute: White-faced Saki

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