The Stump-tailed Macaque, Macaca arctoides, largest of Thailand’s macaques.
The Stump-tailed Macaque (Macaca arctoides) is the largest and heaviest of the six species of macaque found in Thailand. It is not one of the more commonly encountered species. The range of stump-tailed macaques has shrunk significantly in recent decades; once widespread across Thailand it is now largely confined to Peninsular Thailand, plus a few small populations close to the south-western and far south-eastern borders of Thailand. Across it’s entire range, from North-East India to Southern Malaysia and East as far as Southern China, stump-tailed’s are classed as ‘vulnerable’ by the ICUN. In Thailand they are considered ‘endangered’ largely due to the rate of decline.
In other parts of Southeast Asia, hunting is thought to play a significant role. During the 1960s and 70s, large numbers were trapped in Thailand and sent overseas (primarily to the U.S.) for the biomedical trade. The export of primates was banned in Thailand in 1976. The biggest threat today, as with much wildlife in Southeast Asia, is urban development and large scale commercial crop farming, especially rubber and oil palm plantations. Stump-tailed macaques are creatures of upland primary or secondary forest. Rubber plantations, especially during the middle and latter part of last century and, since the 2000s, the expansion of oil palm plantations (in part driven by the promotion of bio-diesel, Srisunthon and Chawchai, 2020) have replaced much of Thailand’s original forests.
Stump-tailed macaques, like other macaques, are social animals. They live in troops of 10-60 or more individuals. Again, like other macaques, they are polygamous, living in multi-male, multi-female groups where both sexes will mate with multiple partners. There is a strong maternal bond with infant macaques, with weaning sometimes not completed until the young macaque is more than one year old. All adult females within the group share responsibility for caring for and protecting the youngsters, a process known as ‘allmothering‘. Due to the promiscuous nature of macaques, young stump-tails may never know exactly who their father is, but there is some intriguing evidence that macaques are able to recognise paternal siblings through similarities in facial features. This would make evolutionary sense in order to avoid inbreeding. Adult males tend to be heavier bult than females, they also have conspicuously large red testicles, which makes identification of the sexes relatively easy. Large testicles are an evolutionary adaptation common among species where both sexes are promiscuous. In promiscuois species sperm competition is important, so the more you produce, the better your chances of fathering offspring. In contrast, for haremic species (i.e. those where one male controls a harem of females and they exclusively mate with him) this is not so much an issue. Thus the promiscuous macaques have testicles that weigh over twice that of (haremic) gorillas, despite a large silverback weighing maybe 16 times more than a large macaque.
Stump-tailed macaques are primarily frugivorous – fruit eaters – but will also consume insects, worms, frogs, birds eggs and dig for tubers. At one location I watched them move on to grassy areas to eat blades of grass.
If you found this post interesting, you may also like my blog on pig tailed macaques in Thailand.
Other blogs of mine on Thailand wildlife include Fiddler crabs of Phuket Shores
For more stories about Southeast Asia you might like Laos Stories
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