Individuals with intermediate characteristics, presumably hybrids, have historically been seen along the border of this species' range and that of Macaca nigrescens (although this contact zone may no longer exist; Sugardjito et al. 1989). The zone of intergradation is the downstream region of the Onggak Dumoga River and Groves (1980) placed M. nigrescens as a subspecies of M. nigra. Despite the morphological and genetical similarity, M. nigra and M. nigrescens are still distinct and therefore classified as distinct species (Groves 2001). Macaca nigra belongs to the silenus group including M. pagensis, M. siberu, M. leonina, M. silenus, and M. nemestrina.

This species is considered Critically Endangered in light of a continuing decline, and that in the past three generations (approximately 33 years) the population is suspected to have been reduced by more than 80% due to hunting pressure and habitat loss. Thus far, morphological data seem to indicate that the population on Bacan Island (Molucca islands) of over 100,000 individuals is an introduced population (Rosenbaum et al., 1998) and therefore we have not included this population into the overall assessment. However, further genetic, morphological analysis should be taken in order to determine the status of this population.

This species occurs on northeastern Sulawesi, Indonesia and the adjacent islands of Manado Tua and Talise. Historically it was also found on Lembeh island but the species has probably been extirpated from there. On Sulawesi it is found on the northern arm east of the Onggak Dumoga River and Mount Padang to the tip of the peninsula (Groves 2001). There is a fairly large introduced population on Bacan island in the Maluku Islands (Indonesia).

The 2008 assessment estimated that range-wide density was approximately three individuals/km² (Supriatna and Andayani 2008). At present, the lack of recent field data outside of Tangkoko Nature Reserve does not allow for a revised estimate. The largest and most viable population exists at the Tangkoko Nature Reserve where density increased from 51.4 individuals/km² between 2005 and 2011 (Kyes et al. 2013) to approximately 58.2 individuals/km² in 2015 (R. Kyes pers. comm.). Historically, the population has shown severe declines (O’Brien and Kinnaird 1996, Palacios 2011, Kyes 2012) since the species’ first systematic surveys in the 1970s by John and Kathy MacKinnon (MacKinnon 1983). Surveys in other protected areas in previous years yielded significantly lower density numbers: 22.8 individuals/km² at Manembonembo Nature Reserve (Lee 1995); Pulau Talise, 1.67 individuals/km² (Lee 2000); Gunung Ambang, 6.94 individuals/km² (WCS 1998 unpublished data); Pulau Manado Tua, 78 ± 34 macaques/km² (USAID 1995 unpublished data). Surveys in 17 unprotected forests throughout its range found macaques in three of the 12 Minahasa District forests while macaques were found in all the five forests in Bolaang Mongondow, with relatively large groups (10-50 individuals) (Feistner and Lee 2001). Melfi (2008) carried out a range-wide survey of Macaca nigra and found encounter rates very low to none (five sightings at Tangkoko, two at Ambang, and two at Manembonembo). The introduced population on Bacan island in the Moluccas was probably estimated to be at least 100,000 individuals in the late 1990s (Rosenbaum et al. 1998) but seems to have declined recently (Hilser et al., 2013). Nonetheless, the Bacan population is not considered in this assessment as it is an introduced population.

The population declines that warrant listing this species as Critically Endangered come not from forest loss but rather from hunting. Crested Macaques are hunted heavily by the local people for bush meat.  Recent conclusive data confirming this are lacking, but anecdotal evidence shows that Crested Macaques continue to show up at key markets within its range. It is generally believed that there is only one viable population remaining of Crested Macaques, and that is in the Greater Tangkoko conservation area; this population has been reduced to a small, degraded patch of forest due to encroachment, hunting, and other exploitation. Elsewhere, there remain only tiny scattered groups. Therefore, based on hunting pressure and lack of connectivity between groups, we suspect a population size reduction of >80% over the last three generations (33 years) and recommend maintaining the Crested Macaques’ CR status. It would be highly desirable for any of the conservation and science organizations focused on this taxon to collect data that could verify these assumptions.

This species is found in rainforests at moderate elevations. It is frugivorous, but will also eat immature leaves, arthropods, stalks of newly flowering plants, and cultivated crops (fruits, vegetables, and maize).

Lowland and montane primary forest, secondary and logged forests, grassland and cultivated land if surrounded by forests. Primarily frugivores (fruits for 66% of feed bouts) and invertebrates form 32% of feeding bouts. Vegetative plant material, small vertebrates such as frogs, lizards, snakes and bats. The species invades gardens and farms to feed on coconut, corn, sugar palm, and other crops.

Breeding females show a well pronounced ano-genital swelling and the turgescent females are protected by dominant males but might still manage to mate with other males. Ovarian cycle in females in relatively long 39.6 days. In captivity, the cycle could be longer owing to the absence of males. Males might vocalize but the function is unknown. Male calls though are said to reflect and ‘encode’ rank or status and ‘identity’(Neumann et al., 2010). Female copulatory vocalization indicate or ‘hint’ of the likelihood of ovulation. No post-conception mating. Infants born after gestation of 175 days. Females birth every other year and inter-birth interval is 22 months.

Primarily terrestrial, spending 60% of their time on the ground, particularly during extreme seasons, probably as an adaptation to heat.

Multi-male, multi-female philopatric groups with 60-80 individuals but groups could range up to 100 individuals. Smaller groups of just five individuals have also been observed. Females tend to be tolerant of each other with very low aggression and sufficient reconciliation (Dubosq et al. 2013). Male-male interactions are defined as ‘characteristically-aggressive’(Riley, 2010). Home ranges of 74-350 ha that are larger during the rainy season and overlap with neighbouring groups.

Hunting for its meat, particularly from demand for consumption in North Sulawesi, is the primary threat for this species (Lee 1999). Carcasses are routinely seen at key North Sulawesi markets. They are served at special celebrations including large events and religious occasions such as Christmas. At the subsistence hunting level, traps and snares in and around agricultural areas both deter crop damage and provide meat. The species has also suffered from major habitat loss from industrial agriculture, shifting cultivation, mining, and forest fires. Although there are intact forests in many places throughout its range, currently much of it is unoccupied. Finally, some animals are caught for the pet trade.

This species is listed under CITES Appendix II, Critically Endangered. It is the most threatened of the seven species endemic to the island.

A dual parallel approach is key to its survival. First, as hunting is its primary threat, there must be a multi-stakeholder effort to reduce the supply and demand. On the supply side, there must be a vigorous park, road, and market patrol effort by government and non-government stakeholders to ensure that illegal capture and transport of Macaca nigra is halted. The multi-stakeholder Wildlife Crimes Unit Program by WCS and the government, initiated in 2001 (Lee et al. 2005), needs to be strengthened and expanded. Protection of existing populations is key to its survival. It occurs in several protected areas (Gunung Lokon, Gunung Ambang, Manembonembo, Tangkoko Batuangus, Dua Saudara, and Manado Tua at Bunaken National Park). At Tangkoko, the population appears to be relatively stable largely because there is high-profile ecotourism. That said, the park continues to suffer from continued encroachment from forest fires, agriculture, and small-scale timber collection.

On the demand side, education programs on their conservation and their habitats (e.g., Selamatkan Yaki), potential health risks associated with consuming M. nigra, and alternative livelihood initiatives  through ecotourism and/or agro-forestry alternatives (Palacios et al, 2011) need to be carried out.

The macaques have a better chance of survival in Bacan where they were introduced where the food taboos of people protect the macaques. But the conservation value and the genetic viability of such populations are debatable.