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Selamatkan Yaki! (Save the yakis!)

Black Crested Macaque (Macaca nigra)
Black Crested Macaque (Macaca nigra)

Black Crested Macaques or Sulawesi Black Macaques (Macaca nigra) are only found in northeastern Sulawesi (and on a couple of adjacent islands) in Indonesia, and are critically endangered as a result of both habitat loss and hunting for bush meat.  Unfortunatley for them, they are considered a delicay in this part of Sulawesi (Minahasa) so have to be heavily protected; there is however, a large introduced population on the island of Pulau Bacan in the Moluccas which according to the IUCN probably numbers at least 100,000 individuals (1), although they may have hybridised with other macaques I understand.

 Juvenile crested-black macaque ((Macaca nigra) showing characteristic crest or quiff of hair.
Juvenile crested-black macaque ((Macaca nigra) showing characteristic crest or quiff of hair.

I have wanted to see these lovely primates ever since I saw them featured in a couple of television programmes – including Bill Bailey’s excellent programme on Alfred Russel Wallace (2).   Tangkoko-DuaSudara Nature Reserve, in North Sulawesi is a good place to see them as they are habituated to people and highly accessible.  Whether they like it or not, they are followed around constantly by researchers – who monitor their habits and behaviour – as well as by tourists, such as myself, eager to take photographs.  Anyway, all this attention does not seem to adversely affect them – a 2009 study found that ‘ecotourism does not appear to have long-term behavioural effect on the primates of Tangkoko’ although there were concerns about the effect on their immune systems!  At least they are relatively safe in the park although dogs – one can be seen in the photo below – can be a predator of the macaques.

Crested-black macaques on the road through the park at Tangkoko NP.
Crested-black macaques on the road through the park at Tangkoko NP.

Black Crested Macaques (known locally as yakis) are quite small – or at least smaller than I thought they were from the TV!  They go about in large groups of between 50 to 100 individuals – sometimes smaller – and spend most of their time either moving about searching for food, especially fruits, or resting and socializing.  Not a bad life really!  What struck me about them was the variety and intensity of the social interactions.  Everything seems to happen in double-quick time, so to speak, perhaps because they are small and agile (compared to us).  We are however, macaques and humans, both primates, so we share similar emotions and expressions.  These are most apparent when you look at the photographs.  This particular individual seems to have an expression of outright amazement or surprise, but it was only fleeting.  Yawns can also be a sign of stress in monkeys.

Look of surprise on  Surprised crested black macaque
Look of surprise on
Surprised crested black macaque

Previously this same individual was feeding quietly on a piece of fruit but watching the antics and goings-on of other members of the troop; they are intensely social creatures.

Crested black macaque eating a piece of fruit.
Crested black macaque eating a piece of fruit.

In reproducing groups of black macaques, females out-number males by up to four to one apparently.  There are a small number of males in the troop with one dominant male; there are also gangs of bachelor males in other troops.

Dominant male Sulawesi crested black macaque, (Macaca nigra)
Dominant male Sulawesi crested black macaque, (Macaca nigra)

They are promiscuous primates, with both males and females mating multiple times with multiple partners.  The receptiveness of the females (whether she is in ‘heat’) can be seen from the very swollen and red buttocks (‘perineal tumescence’).

 Female crested-black macaque with swollen backside

Female crested-black macaque with swollen backside

The males have smaller buttocks.

Male Juvenile crested-black macaque.
Male Juvenile crested-black macaque.

The menstrual cycle in this species is about 37 days and the gestation period is about 5 and half months (4).  The infants look to me a bit like chimpanzees! They are highly active, always on the move, no doubt a right handful for their mothers! In the low light of the forest, the infants were always slightly blurred in my photographs, due to their non-stop movement!  I could have used a faster shutter speed, but I quite like the effect.  It’s hard not to anthropomorphize when you see the tender loving gaze of the mother macaque towards her baby.

 Mother with infant crested-black macaque
Mother with infant crested-black macaque
 Crested black macaque mother and infant

Crested black macaque mother and infant

Fortunately for the dedicated researchers who follow the macaques throughout the day – from the time they get up, to the time they go to bed – the monkeys seem to like to get an early night.  This troop was preparing to retire to the trees for the night, well before sundown.  This mother and infant started to climb a tree in the forest, together with another females coming up from below.

Crested-black macaque mother and infant

There is a lot of movement and interaction going on in these macaques troops, including calls and vocalisations, but there is also time for repose. This dominant, or alpha male crested black macaque was well aware of my presence – I had been following him and the troop – and he had even bared his huge canines at one point (a clear signal to back off!), but he was also very calm and reflective almost (am I imagining this?  Probably!) as shown in the following photographs.

Dominant male Crested black macaque examining some leaves
Dominant male Crested black macaque examining some leaves
Dominant male crestedblack macaque
Dominant male crested black macaque
Dominant male crested black macaque
Dominant male crested black macaque

One of the nice things, at least to my mind, about this species, is that they are what is called ‘highly socially tolerant’.  That is to say that they put as much, or more importance on friendship, or other such  social bonds, than on dominance or kinship in their social life (5).  It rather goes against the stereotypical idea of nature red in tooth and claw, where all that matters is size or dominance.  Friendships matter!  They certainly seemed to me to be very tolerant, which is such a shame given that they are killed and eaten by humans.  It we cannot share the planet with these beautiful and tolerant creatures, then I do not think that we (us humans) deserve to be here.

Crested-black macaque peering through the leaves in Tangkoko NP, Sulawesi
Crested-black macaque peering through the leaves in Tangkoko NP, Sulawesi

There is a lot of interesting information about the ongoing conservation efforts for this species on the Whitely Wildlife Conservation Trust Website (6); and they have a blog on WordPress (7).  Amazingly, the Sulawesi crested black macaque is one of seven macaque species found only on Sulawesi; can’t wait to meet the other species!

 Juvenile crested black macaque

Juvenile crested black macaque

1) IUCN Red List of Threatened Species: Maca nigra.


3) Audrey Paulus  (2009). Impacts of Ecotourism on the Behaviour of Sulawesi Crested Black Macaques (Macaca nigra) and Spectral Tarsiers (Tarsius spectrum) in the Tangkoko-Batuangus Nature Reserve, North Sulawesi, Indonesia.

4)  Thomson, J. A., et al. “The Sulawesi Crested Black Macaque (Macaca nigra) menstrual cycle: changes in perineal tumescence and serum estradiol, progesterone, follicle-stimulating hormone, and luteinizing hormone levels.”Biology of reproduction 46.5 (1992): 879-884.

5)  Micheletta, Jérôme, et al. “Social bonds affect anti-predator behaviour in a tolerant species of macaque, Macaca nigra.” Proceedings of the Royal Society B: Biological Sciences 279.1744 (2012): 4042-4050.

6) Selamatkan Yaki – Save the Sulawesi crested black macaque.


rcannon992 View All

I am an entomologist with a background in quarantine pests and invasive invertebrates. I studied zoology at Imperial College (University of London) and did a PhD on the population dynamics of a cereal aphid (Metopolophium dirhodum) in the UK. I spent 5 years with the British Antarctic Survey studing cold hardiness of Antarctic invertebates and 17 years with the Food and Environment Research Agency. My main interests now are natural history, photography, painting and bird watching.

7 thoughts on “Selamatkan Yaki! (Save the yakis!) Leave a comment

  1. When I was in Tangkoko last month, our idiotic official park guide deliberately shone his laser pointer into the eyes of a black macaque, just for amusement. The macaque was terrified and ran away. We told him that we were upset by this and he said sorry…. I wonder whether this happens often.

      • Yes, but the tarsiers have the option of moving trees – and they don’t so they obviously have got used to the flashes. Laser pointers can damage eyes permanently, and the macaque was clearly terrified. Since all the guides have laser pointers I wonder whether they torture the poor macaques on a regular basis and whether some have damaged eyesight.

  2. Pingback: Animal Yaki

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