Nona is a Sulawesi crested black macaque. Photographed here by Stefano Unterthiner, she is seen chained to a chair outside the house where she is kept as a pet. The scene is made particularly poignant because Unterthiner has included in his image the shadow of Nona, her chain and a tree, thus underlining the freedom that the little animal has lost. At the same time, the owner of Nona – which means “miss” – stands relaxing in the early morning sun.

It is illegal to keep this critically endangered animal in captivity. Yet the law is rarely enforced, particularly in remote areas. Hence the grim picture – though far worse was taken by Unterthiner, an Italian wildlife photographer, during his visit to the Indonesian island of Sulawesi. Hunting, the live-animal trade and forest clearance have caused the animal’s population on the island to crash by 90% in the past 30 years. Only a few thousand are left there.

“Things are become desperate for the macaque,” said Unterthiner. “They are being killed for bushmeat, hunted as pets and having their forests ripped down around them.”

Local people like to keep these macaques – which they call yaki – because they look particularly cute as babies. Often they are adopted when their mothers are shot by bushmeat hunters. However, as they get older, kept in cramped conditions and poorly fed, they become less manageable and are themselves sold as bushmeat.

Facebook Twitter Pinterest Picnickers at a Sulawesi nature reserve share food with a macaque. Photograph: Stefano Unterthiner/National Geographic

It is a deeply disturbing situation, captured by Unterthiner in a series of images that have earned him a place as a finalist in the wildlife photojournalist category in the prestigious Wildlife Photographer of the Year awards, which will be announced on 17 October at the Natural History Museum in London.

“I first became aware of the crisis facing the Sulawesi macaque when I visited the island seven years ago,” he told the Observer. He has made several more trips and returned last year for a two‑month investigation into the relationship between macaques and local people. He found the bushmeat market – the main cause of the macaques’ plight – had become a “nightmare of blood and burnt animals”.

Another of his set of disturbing images shows a local bushmeat dealer called Nofi Raranta. He is seen wheeling the carcass of a Sulawesi warty pig, another threatened animal, across his yard; propped against a wall is the body of a Gorontalo macaque, closely related to the crested black species.

Macaque meat is popular at weddings and festivals in Sulawesi, although trade in it is also illegal. Again, there is little fear of prosecution and little police activity. “I feel sympathy for Nofi but he needs to sell something else,” said Unterthiner.

The crested black macaque is noted for its fascination with its own image. Often they will sit on scooters, the main form of transport in Sulawesi, and peer at their own reflections in handlebar mirrors – as Unterthiner highlights in another shot from his portfolio.

Several years ago this self-absorption led one female macaque to take an unattended camera from another photographer in order to stare at her own reflection in the lens. She then accidently pressed the shutter and took the first macaque selfie. It made headlines around the world and led to a bizarre court case, launched by animal rights activists, over the copyright of the picture, that was settled only last month.

Sulawesi was once covered in rich forests but these have been stripped away to provide land for farming. Plantations of coconuts and mangoes have replaced them. And as the forest shrinks, so does the macaques’ feeding area, forcing them to venture further from cover and into villages and plantations, where their risk of being killed – either by villagers who want to protect their plantations, or by bushmeat hunters – increases dangerously.