Macaques are a diverse genus of primates, but nowhere is this diversity better appreciated than on the island of Sulawesi. This large island, situated within the Indonesian archipelago, is home to an astonishing array of endemic mammals, reptiles, birds and fish. Amongst these are five macaque species. In the forests of the northernmost tip of Sulawesi lives arguably the most striking—the crested black macaque.

Listed as Critically Endangered by the IUCN Red List, there are c. eight important populations of crested black macaques distributed across 2,106 km2. Yaki (Macaca nigra) on a beach in Tangkoko, North Sulawesi. Photo: Andrew Walmsley

The crested black macaque gained notoriety when a young male in Tangkoko Nature Reserve commandeered a photographer’s camera and took a selfie with it in 2011. The intelligence and mischievousness required for such a feat is in itself compelling. Add their jet-black coat and punk rock hairstyles and you have an animal of considerable charm and charisma.

Left: Macaques were unconcerned by our camera traps, often spending a good deal of time investigating the cameras and relaxing within shot. Right: Our camera trap effort resulted in almost 10,000 camera-trap days. We detected crested black macaques on 473 of these in 71 out of 111 cameras. Photos: Selamatkan Yaki & WCS Indonesia

However, behind the image of grinning macaques is juxtaposed a narrative of hunting, habitat loss and persecution. This is a primate that is being pushed to the brink of extinction by a multitude of anthropogenic threats. A primate that once roamed freely and unhindered across its landscape now travels with stealth and vigilance within ever-shrinking pockets of forest.

The crested black macaque shares its habitat with a predominantly Christian population in the province of Minahasa. Without the same taboos imposed on them as their Muslim neighbours elsewhere in Indonesia, Minahasans uphold a tradition of eating bushmeat. Black macaques, together with many other species found in these forests, are frequently sold in food markets across the region. Consumed as a delicacy, the demand for macaque meat is high and they are regularly hunted as a result. The impact this is having on the species is devastating, and compounded by forest conversion and fragmentation.

Left: The crested black macaque is a diurnal primate that lives in large, male dominant, multi-male, multi-female social groups that can contain up to 100 individuals. Right: Eighty per cent of the crested black macaques occupied range is outside protected areas, where forest loss and other threats are more prevalent. Therefore, although protected areas are very important, conservation efforts must consider areas that have no official protected status. Photos: Andrew Walmsley

In 2008, the crested black macaque was categorized as Critically Endangered on the IUCN Red List, indicating its imminent risk of extinction. Conservation organizations are now working tirelessly to reduce the threats driving the decline of the species and secure the future of this very special primate. A vital prerequisite of any conservation strategy, however, is to have a baseline for the species’ population, a robust and reliable statistic that reflects its occurrence or size and with which future population changes can be compared—and we didn’t have this statistic for the crested black macaque.

The crested black macaque is a semi-terrestrial primate, dependent on forests. Forest cover is still extensive across north Sulawesi, but has shrunk by a quarter since 2001. Photo: Caspian Johnson

Our aim in this study was to provide this. We deployed a network of 111 camera traps placed strategically across the macaque-friendly habitats of north Sulawesi, collecting almost 10,000 images over 6 months during 2018–2019. These images allowed us to infer the precise extent of their range and their distribution across it for the first time. Through this process, we discovered a number of important and, in some cases, unreported populations.

Northern Sulawesi is home to some dramatic landscapes. Pictured here, Tangkoko Nature Reserve is home to a very important population of crested black macaques and is characterised by its three volcano peaks and a forest canopy that extends from their summits to the sea. Photo: Andrew Walmsley

When analysed using an occupancy framework, the data from these camera traps provided us with a robust baseline for the species. We estimated that the crested black macaques are distributed across at least eight potentially important populations and occur in c. 66% (2,106 km2) of all suitable habitat across Minahasa—the new baseline of occupancy for this species. This marks the beginning of long-term monitoring of this species. This monitoring will act as an early warning system in the event of any future declines, allowing conservationists to launch a timely conservation response if required. Too often species slip quietly away, unnoticed until it’s too late to save them. This monitoring programme is the macaque conservationists’ insurance policy against this.

Survey teams preparing to disembark from the village of Pinanungian on the border of Tangkoko Nature Reserve. Photos: Caspian Johnson

There are a number of conservation NGOs working in the region together with local government national park authorities. Among these are Selamatkan Yaki (Save the Macaque), the Macaca Nigra Project (and the Wildlife Conservation Society–Indonesia, who collaborated in this research.

The article Using occupancy-based camera-trap surveys to assess the Critically Endangered primate Macaca nigra across its range in North Sulawesi, Indonesia is available in Oryx—The International Journal of Conservation.

Caspian is a lecturer in Conservation Science at the Bristol Zoological Society, Bristol, UK. He has worked in Tanzania, Indonesia, Equatorial Guinea and Cameroon, often with a focus on primates. His overarching interest is applied conservation that is informed by scientific research. After obtaining his PhD, Caspian was Programmes Coordinator for Selamatkan Yaki, a Conservation NGO in Indonesia, where he worked with the crested black macaque. Now, with Bristol Zoological Society he leads the Society’s Giraffe Conservation Project, and is expanding his applications of remote sensing in wildlife monitoring by using drones to detect and survey large mammals in savannah habitats.