This is the yellow-tailed woolly monkey, or Lagothrix flavicauda.

This species has evolved a particularly thick, luscious fur, which protects it from the elements in the montane cloud forests on the Andes’ eastern slope. Its body is a deep coppery-brown, with a distinctive white patch on its snout that extends from the chin to between its eyes. The head is darker than the rest of the body, and can seem almost black. The species’ name is derived from the yellowish colouration of the last third of its prehensile tail.

It is also known for its long, golden-blonde pubic hair tuft, which it displays during aggressive encounters.

When necessary, it can move quickly through the canopy by leaping - up to 15 meters at a time - but much of its day is spent high up in the trees eating and resting while hanging from its tail, which can easily support the full 8 kg of its body weight.

It lives in family groups, and is said to be quite trusting of humans. The species has a low reproductive rate and a long interbirth interval, which adds to its vulnerability. It has been listed as critically endangered since 1996, but it is unclear just how many remain.

The yellow-tailed woolly monkey was first described in 1812 by Alexander von Humboldt, who never had the opportunity to observe a live specimen. His description was based on a skin which he viewed during his travels in the Andes between 1801 and 1803, and which was being used as a saddle. No official sightings were made over the next 100 years, and it was not known if Humboldt’s creature was still extant. In 1925, two skins were collected at La Lejía for the American Museum of Natural History, but were catalogued as an unknown species. In 1926, three pelts were obtained in Pucatambo for the British Museum of Natural History, but were described as a completely new species. Years later, and after much debate, the link between these six museum specimens was formally made in 1963, and the original description by Humboldt was upheld.

In 2019, an additional skin was discovered in the archives of the Muséum National d’histoire Naturelle in Paris. It had been collected in 1900, but was unassigned to any species and had been largely forgotten.

Even after several expeditions to the region, a living specimen of the yellow-tailed woolly monkey remained illusive to naturalists. The first live animal was not observed by science until 1974 - a juvenile male, kept as a pet in Pedro Ruiz Gallo. The discovery was a sensation - but while the scientific community had pondered over the species for the past 162 years, it was well known to locals in the area. According to Russell Hendee of the Godman-Thomas Expedition, they called it “quille corote”, or “yellow testicles”. It was often kept as a pet, and hunted for food.

The Andes’ inaccessibility had always insulated the yellow-tailed woolly monkey - not only from the eyes of science - but also from habitat destruction by humans, who had lived there in fairly low densities for thousands of years. This began to change from the 1950s on, however. The human population grew rapidly, and land was cleared for the development of coffee plantations and other agriculture.
Conservationists have pointed to negligence and corruption in regional government for failing to plan this appropriately. Land clearing has progressed almost completely unchecked.

The yellow-tailed woolly monkey is also occasionally killed by farmers, who believe it damages their crops. Live infants are still to be found in markets in the region, sold alongside the pelts and skulls of their mothers.

Conservation initiatives are often viewed with scepticism by the locals, who fear a loss of their livelihoods, but there are efforts within the communities of the Andes to protect this species. Access to mountainous areas has ironically allowed a small ecotourism industry to develop. The ecotours provide an alternative source of income for inhabitants, reducing the need for land clearing, poaching, and subsistence hunting.

These threats, however, do still remain. Without a clear, well funded conservation plan, the demise of this species is certain to continue.