Interesting Creatures… The Yellow-tailed woolly monkey (Oreonax flavicauda)

Jan 03, 2016 Features / Columnists, Interesting Creatures in Guyana

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The yellow-tailed woolly monkey (Oreonax flavicauda) is a New World monkey endemic to Peru. The species was first described by Alexander von Humboldt in 1812 under the name Simia flavicauda, based on a skin found 10 years earlier, used by a local man as a horse saddle. Humboldt had never seen a live animal of this species, nor a preserved specimen, and believed it belonged to the genus Alouatta. For over 100 years, the species was reported on only a few isolated occasions, so was thought to be extinct.

In 1926, three specimens were collected in San Martin, which were then brought to the Museum of Natural History. It was originally believed that the three specimens were of a new species, but further evidence made it clear that these specimens were of the yellow-tailed woolly monkey.

This monkey species is one of the rarest Neotropical primates and is one of Peru’s largest endemic mammals. Adult head and body lengths can range from 51.3 to 53.5 cm with tails even longer than the body, up to 63 cm (25 in). The average weight is 8 kg in adults, however some males have been seen reaching up to 11.5 kg.

Peruvian yellow-tailed woolly monkeys are similar in size to the common woolly monkey, also known as the genus Lagothrix. They live in large social groups (approximately 23 individuals) made up of both male and females. They have low reproductive rates and long inter-birth intervals, which adds to their vulnerability for extinction. They are known to express aggressive behaviours upon initial encounters such as branch shaking, “mooning” of the scrotal tuft, and short barking calls.

The yellow-tailed woolly monkeys fur is longer and denser than other woolly monkeys; an adaptation to its cold montane forest habitat. The monkeys colour is deep mahogany and copper with a whitish patch on its snout extending from the chin between its eyes. Its fur gets darker towards its upper body, making its head seem almost black.

It has a powerful prehensile tail, with a hairless patch on its underside and a yellowish pelage on the last third of the tail giving this species its name. This colouration of the tail is not seen in infants and juveniles. The powerful tail is capable of supporting the animal’s entire body weight while feeding or just hanging around; it also uses its tail to help locomote through the canopy. The monkey is also known for its long yellowish pubic hair tuft. It has the ability to leap 15 m (49.2 ft).

The yellow-tailed woolly monkey (Oreonax flavicauda) is one of the least known of the primate species. It is also one of the largest neotropical primates. This means that these primates are found in areas constituting the tropical new world biogeographic region. They are regularly found in the tropical Andes. Their habitat is characterized as rough terrain. This consists of steep mountain sides and deep river gorges, with canopy height of 20–25 metres.

Cloud forest is a term used to often identify the habitat of the Yellow-Tailed Woolly monkey. The term is used because the forests are in fairly high altitudes and often have cloud coverage near or in them. Like most primates, the Yellow-Tailed monkey has low birth rates. The last estimated population count was less than 250 individuals.

It is important to note that the current habitat of the yellow-tailed monkey is fragmented. Research into the habitat of the Yellow-Tailed Woolly monkey has shown that deforestation has resulted in fragmented areas of monkey. This means that the populations of Yellow-Tailed monkeys are spread out. This can hinder reproduction as it limits an already limited population. The Yellow-Tailed monkey has never been subject to a full census, so exact numbers vary. A study was done to exam the population, however the terrain and fragmented populations made this difficult.

A study has shown ecology and behaviour of the primates. It has been observed that the yellow- Tailed Woolly monkeys travel in packs. The diet of the yellow-Tailed monkey primarily consists of leaves and fruits. Its diet is primarily frugivorous, but leaves, flowers, insects and other invertebrates are also eaten.

The yellow-tailed woolly monkey is arboreal and diurnal. It has a multiple-male group social system and a polygamous mating system. The species has a variety of vocalisations, including a loud “puppy-like” bark which it uses as a territorial or alarm call.

Yellow-tailed woolly monkeys participate in geophagy, the consumption of soil. Geophagy is a rare biological behaviour, but the species benefits from this tendency since it allows for the intake of minerals and the detoxification of the intestinal region of parasites and other diseases. This species tends to suffer from an iron-deficient diet. Their consumption of soil allows them to intake iron that they do not get from their regular diet. (Source: Wikipedia)

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