Crab-eating macaque

Macaca fascicularis, variously known by common names such as crab-eating macaque, long-tailed macaque, or cynomolgus monkey, is a macaque species native to Southeast Asia. As a synanthropic species, the crab-eating macaque thrives near human settlements and in secondary forests. The crab-eating macaque has developed a variety of cultural perceptions, from being smart and adaptive, to being sacred, to even being pests in some cases. The crab-eating macaque is omnivorous and frugivorous. It lives in matrilineal groups ranging from 10 to 85 individuals, with groups exhibiting female philopatry and males emigrating from natal group at puberty. The crab-eating macaque is the only old-world mon...

The crab-eating macaque's native range encompasses most of mainland Southeast Asia, through the Malay Peninsula and Singapore, the Maritime Southeast Asia islands of Sumatra, Java, and Borneo, offshore islands, the islands of the Philippines, and the Nicobar Islands in the Bay of Bengal. This primate is a rare example of a terrestrial mammal that violates the Wallace line, being found out across the Lesser Sunda Islands. It lives in a wide variety of habitats, including primary lowland rainforests, disturbed and secondary rainforests, shrubland, and riverine and coastal forests of nipa palm and mangrove. It also easily adjusts to human settlements and is considered sacred at some Hindu temples and on some small islands, but as a pest around farms and villages. Typically, it prefers disturbed habitats and forest periphery.

Fiji

Crab-eating macaques are omnivorous frugivores and eat fruits, leaves, flowers, shoots, roots, invertebrates, and small animals in variable quantities. They eat durians, such as Durio graveolens and D. zibethinus, and are a major seed disperser for the latter species. They exhibit particularly low tolerance for swallowing seeds, and spit seeds out if larger than 3–4 mm (0.12–0.16 in). This decision to spit seeds is thought to be adaptive; it avoids filling the monkey's stomach with wasteful bulky seeds that cannot be used for energy. Fruit makes up 40% to over 80% of the diet of wild crab-eating macaques, except in highly provisioned populations or highly disturbed environments. Crab-eating macaques can become synanthrope, living off human resources when feeding in cropfields on young dry rice, cassava leaves, rubber fruit, taro plants, coconuts, mangos, and other crops, often causing significant losses to local farmers. In villages, towns, and cities, they frequently take food from garbage cans and refuse piles. In Padangtegal Bali macaque 70% of their diet is provisioned. They become unafraid of humans in these conditions, which can lead to macaques directly taking food from people, both passively and aggressively.

The crab-eating macaque is highly adaptive, living near and benefiting from humans and environmental modifications.

longest observed 39 years.

After a gestation period of 162–193 days, the female gives birth to one infant. The infant's weight at birth is about 320 g (11 oz). Infants are born with black fur which will begin to turn to a grey or reddish-brown shade (depending on the subspecies) after about three months of age. This natal coat may indicate to others the status of the infant, and other group members treat infants with care and rush to their defense when distressed. Immigrant males sometimes kill infants not their own in order to shorten interbirth intervals. High-ranking females will sometimes kidnap the infants of lower-ranking females. These kidnappings can result in the death of the infants, as the other female is usually not lactating. A young juvenile stays mainly with its mother and relatives. As male juveniles get older, they become more peripheral to the group. Here they play together, forming crucial bonds that may help them when they leave their natal group. Males that emigrate with a partner are more successful than those that leave alone. Young females, though, stay with the group and become incorporated into the matriline into which they were born. Male crab-eating macaques groom females to increase the chance of mating. A female is more likely to engage in sexual activity with a male that has recently groomed her than with one that has not. Studies have found that the dominant male copulates more than other males in the group. DNA tests indicate that dominant males sire most of the offspring in natural crab-eating macaque troops. Reproductive success in females is also linked to dominance. High ranking females have more offspring over their life-time than low-ranking females – higher ranking females reproduce at a younger age and their offspring have a higher chance of survival.

Ten subspecies of the crab-eating macaque were proposed: M.f. fascicularis – Indonesia, Malaysia, Philippines, Thailand, Cambodia, Singapore, Vietnam M.f. aurea – Myanmar, Laos, western and southern Thailand near Myanmar border M.f. antriceps – Kram Yai Island, Thailand M.f. condorensis – Con Son Island, Hon Ba Island, Vietnam M.f. karimondjiwae – Karimunjawa Islands, Indonesia M.f. umbrosa – Nicobar Islands, India M.f. fusca – Simeulue Island, Indonesia M.f. lasiae – Lasia Island, Indonesia M.f. tua – Maratua Island, Indonesia M.f. philippinensis is under dispute and included with M.f. fascicularis. M.f. fascicularis has the largest range, followed by M.f. aurea. The other seven subspecies are isolated on small shallow-water fringe-islands and deep-water fringing-islands.

The crab-eating macaque has been categorized as Endangered on the IUCN Red List; it is threatened by habitat loss due to rapid land use changes in the landscapes of Southeast Asia and the surging demand by the medical industry during the COVID-19 pandemic. A 2008 review of population trends suggested a need for better monitoring of populations due to increased wild trade and rising levels of human-macaque conflict, which continue to decrease overall population levels despite the species' wide distribution. Each subspecies faces differing levels of threats, and too little information is available on some subspecies to assess their conditions. M. f. umbrosa is likely of important biological significance and has been recommended as a candidate for protection in the Nicobar Islands, where its small, native population has been seriously fragmented. It is listed as vulnerable on the IUCN Red List. The Philippine long-tailed macaque (M. f. philippensis) is listed as near threatened, and M. f. condorensis is vulnerable. All other subspecies are listed as data deficient and need further study; although recent work is showing M. f. aurea and M. f. karimondjawae need increased protection.

The crab-eating macaque is listed on CITES Appendix II. Its IUCN Red List status was uplisted in 2020 and again in 2022 from the Least Concern classification in 2008 as a result of declining population resulting from hunting and troublesome interactions with humans, despite its wide range and ability to adapt to different habitats. These interactions include the skyrocketing demand for crab-eating macaques by the medical industry during the COVID-19 pandemic, and the rapid development of the landscape in Southeast Asia. A 2008 review of their populations suggested a need for better monitoring of populations due to increased wild trade and rising levels of human-macaque conflict, which continue to decrease overall population levels despite the species' wide distribution. The Long-Tailed Macaque Project and The Macaque Coalition are engaged in conservation of the crab-eating macaque through research and public engagement.

Macaca comes from the Portuguese word macaco, which was derived from makaku, a word in Ibinda, a language of Central Africa (kaku means monkey in Ibinda). The specific epithet fascicularis is Latin for a small band or stripe. Sir Thomas Raffles, who gave the animal its scientific name in 1821, did not specify what he meant by the use of this word. In Indonesia and Malaysia, the crab-eating macaque and other macaque species are known generically as kera. The crab-eating macaque has several common names. It is often referred to as the long-tailed macaque due to its tail, which is the length of their body and head combined. The name crab-eating macaque refers to it being seen foraging beaches for crabs. Another common name for M. fascicularis, often used in laboratory settings, is the cynomolgus monkey which derives from Greek Kynamolgoi meaning "dog milkers". It has also been suggested that cynomolgus refers to a race of humans with long hair and handsome beards who used dogs for hunting according to Aristophanes of Byzantium, who seemingly derived the etymology of the word cynomolgus from the Greek κύων, cyon 'dog' (gen. cyno-s) and the verb ἀμέλγειν, amelgein 'to milk' (adj. amolg-os), by claiming that they milked female dogs.