Southern pigtail macaques have olive brown fur over their entire bodies, except for their undersides, which are white. The fur on the top of their heads is dark brown or black and grows in a pattern that makes them look like there is a depression in the center of the top their heads (Rowe 1996; Groves 2001). Northern pigtail macaques have golden brown fur and the fur on the top of their heads is brown. They have red streaks of fur extending from the outer cornier of each eye towards the ear. Pigtail macaque infants are born black and as they mature, their pelage changes to the adult coloration (Crockett & Wilson 1980). Pigtail macaques are sexually dimorphic with males measuring 495 to 564 mm (1.62 to 1.85 ft) and weighing 6.2 to 14.5 kg (13.7 to 32.0 lb) while females measure 467 to 564 mm (1.53 to 1.85 ft) and weigh between 4.7 and 10.9 kg (10.4 and 24.0 lb) (Fa 1989). Males have much larger canine teeth than females, measuring 12 mm (.472 in), on average, which are used in aggressive interactions (Rowe 1996). Pigtail macaques have an abbreviated tail, less than the length of the body from head to rump, which is often bare or covered only by sparse fur (Rowe 1996; Groves 2001). Pigtail macaques get their popular name from their tails, which are short and carried half-erect so that they somewhat resemble a pig’s tail (Choudhury 2003). They move quadrupedally on the ground and through trees (Rowe 1996). Pigtail macaques have an average lifespan of about 26 years (Sponsel et al. 2002).
Taxonomy
Suborder: Haplorrhini
Infraorder: Simiiformes
Superfamily: Cercopithecoidea
Family: Cercopithecidae
Subfamily: Cercopithecinae
Genus: Macaca
Species: M. nemestrina
Other names: M. leonina: M. nemestrina leonina; northern pig-tailed macaque; M. nemestrina: M. nemestrina nemestrina; pig-tailed macaque, Sunda pig-tailed macaque, southern pigtail macaque, or Sundaland pigtail macaque; macaque à queue de cochon (French); berok or beruk (Malay); macaca cola de cerdo (Spanish); mentawaimakak, svinapa, or svinmakak (Swedish); ling kaang (Thai)
Once considered subspecies, there are now two recognized species of pigtail macaques. Macaca nemestrina, or the southern pigtail macaque, is the only species studied in the wild, and little is understood about the ecological or behavioral differences of the two species. In captivity, studies have been conducted with both species, though often without knowing which species is which (Groves 2001; Maestripiri pers. comm.). The information provided in this fact sheet is about the southern species, except where noted.
Habitat
Pigtail macaques are found in lowland and hilly primary rainforests and occasionally are found in swamp and secondary forests (Crockett & Wilson 1980). They prefer undisturbed forests and are found in the highest densities in intact rainforests (Supriatna et al. 1996). Rainforests are maintained in warm and humid climates where temperatures range between 18 and 30° C (64 and 86° F) and where there is more than 2500 mm (8.20 ft) of rainfall each year, though there may be seasonality in rainfall. Where they are found in Bangladesh, the annual precipitation is 2034 mm (6.67 ft) with the highest rainfall occurring during the monsoon season, from May to September, and the lowest in December. The coldest months of the year are December and January, which have average temperatures of 12.3° C (54.4° F) and 9.7° C (49.5° F), respectively. August is the warmest month of the year with an average maximum temperature of 33° C (91.4° F) (Feeroz et al. 1994). In neighboring northeastern India, the climate and rainfall is quite variable, ranging from less than 1000 mm (3.28 ft) to more than 10,000 mm (32.81 ft) annually (Choudhury 2003). The climate in this part of India can also be as cool as 4°C (39.2° F) in December to early February to 30° C (86° F) from June to August. Most of the rain occurs from May to September, and snow falls in winter at the higher altitudes (Choudhury 2003). Rainfall in southern Sumatra ranges from 2000 to 3267 mm (6.56 to 10.7 ft) per year with indistinct wet or dry seasons (Supriatna et al. 1996). The climate there is also warm and humid (Lucas & Corlett 1991). In Peninsular Malaysia, rainfall averages 2100 mm (6.89 ft) per year with the least amount of rainfall during January and February and the period of highest rainfall occurring during September and October (Saiful & Nordin 2001).
Pigtail macaques range from sea level to above 2000 m (6562 ft) (Srivastava & Mohnot 2001; Choudhury 2003).
Ecology
Pigtail macaques are highly frugivorous, with 74% of their diet consisting of fruit, but they also consume a wide variety of foods including insects, seeds, young leaves, leaf stems, dirt, and fungus (Crockett & Wilson 1980; Caldecott 1986). Pigtail macaques spend most of their time on the ground, but the northern pigtail macaque seems to be more arboreal than the southern species (Maestripieri pers. comm.). Spending most of their time on the ground foraging, they are particularly adept at raiding agricultural fields and obtaining coconuts from oil palm plantations, papaya, corn, and cassava. They are stealthy crop raiders, sneaking silently into a garden one at a time, with one acting as a lookout and calling an alarm vocalization if humans are seen. Pigtail macaques are especially likely to raid crops during rainstorms, when farmers are inside, away from their crops (Crockett & Wilson 1980). In some areas of the Malay Peninsula, farmers keep and train pigtail macaques to retrieve coconuts and fruits from cultivated trees (Crockett & Wilson 1980; Sponsel et al. 2002).
Because of their large group size, between nine and 81 individuals and larger, pigtail macaques often split up into foraging groups to decrease direct competition for fruit at feeding sites. They travel in small subgroups, from two to six monkeys, along the ground, foraging as they move and keeping in contact with other subgroups through vocalizations (Crockett & Wilson 1980; Caldecott 1986). In addition to spreading out over the landscape as they forage, pigtail macaques cover large areas each day. They have home ranges between .6 and 8.28 km² (.232 and 3.20 mi²) and in areas of high density, groups’ home ranges can overlap each other by as much as 50% (Sponsel et al. 2002). The day range length varies between 825 and 2964 m (.513 and 1.84 mi), depending on weather conditions and seasonal fruit availability (Caldecott 1986).
