Yellow Tailed Woolly Monkey, Oreonax flavicauda

The Yellow-Tailed Woolly Monkey (Oreonax flavicauda) is a New World monkey that is native to Peru. It is a rare primate species that is found only in the Peruvian Andes, in the departments of Amaxonas and San Martin, along with the bordering areas of La Libertad, Huanuco, and Loreto. This woolly monkey was, at first, under the Lagothrix genera with other woolly monkeys, but because of debatable primary sources, they have been placed under the Oreonax genera. This genus has been suggested to be a subgenus of Lagothrix but others have acknowledged it to be a full genus. A recent extensive study proves that this monkey might indeed be in the Lagothrix genera.

This species was first described by Alexander von Humboldt in the year 1812 under the name Simia flavicauda, based on a skin found 10 years earlier, utilized by a local man as a horse saddle. He had never seen a live animal of this species nor a preserved specimen, and he 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 the year 1926, three specimens were collected in San Martin, which were then brought to the Museum of Natural History. It was initially thought 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.

The monkey is one of the rarest Neotropical primates and is one of Peru’s largest endemic mammals. The adult head and body lengths can range from 51.3 to 53.5 centimeters with the tails even longer than the body at 63 centimeters. The average weight is 8 kilograms in the adults; however, some of the males have been seen reaching up to 11.5 kilograms. Peruvian yellow-tailed woolly monkeys are similar in size to the common woolly monkey, known also as the genus Lagothrix. They reside in large social groups made up of males and females. They have low reproductive rates and long inter-birth intervals, which adds to their vulnerability for extinction. They are known to display aggression upon initial encounters such as branch shaking and short barking calls. The fur is longer and denser than other woolly monkeys; an adaptation to its cold montane forest habitat. The color is a deep mahogany and copper with a whitish colored patch on its snout extending from the chin between the eyes. The fur gets darker towards the upper body, making the head seem nearly black. It has a powerful prehensile tail, with a hairless patch on the underside and a yellowish pelage on the last third of the tail giving this species its name.

These primates can be found in areas constituting the tropical new world biogeographic region. They can be regularly seen in tropical Andes. The habitat is characterized as rough terrain.

The diet is mostly frugivorous, but leaves, flowers, insects, and other invertebrates are eaten as well.

Image Caption: The endangered yellow-tailed woolly monkey (Oreonax flavicauda). Credit: Platyrrhinus/Wikipedia (CC BY-SA 3.0)