The yellow-tailed woolly monkey (Lagothrix flavicauda) is a New World monkey endemic to Peru. It is a rare primate species found only in the Peruvian Andes, in the departments of Amazonas and San Martin, as well as bordering areas of La Libertad, Huánuco, and Loreto. Taxonomy The yellow-tailed woolly monkey was at first classified in the genus Lagothrix along with other woolly monkeys, but due to debatable primary sources, it was later placed in its own monotypic genus, Oreonax. Oreonax has been proposed to be a subgenus of Lagothrix, but others have regarded it as a full genus. A recent extensive study suggests that the yellow-tailed woolly monkey indeed belongs in Lagothrix, which has been followed by the American Society of Mammalogists and the IUCN Red List. Discovery and rediscovery 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. They were believed to be of a new species, but further evidence made it clear that these specimens were of the yellow-tailed woolly monkey. In 1974, a group of scientists, led by Russell Mittermeier, and funded by World Wide Fund for Nature, found a young yellow-tailed woolly monkey which was kept as a pet in the city of Pedro Ruiz Gallo, Amazonas. The rediscovery attracted the attention of national and international press, as well as conservation organizations that saw the need to know quickly the status of this species. In the summer of 2004, scientists searched for yellow-tailed woolly monkeys in a remote area of San Martin, where the forest is tropical, humid, and quite mountainous. The forest area, threatened due to haphazard tree cutting, was believed to have at least a minor population of the species, and was studied along with two other areas of Peru. The loss of habitat due to the tree cutting in the yellow-tailed woolly monkey habitat could prove problematic for the species as a whole. The introduction of farm plots