Session 7: The Macaques

1.  Key Concepts:

 The genus Macaca is the most successful primate radiation, after humans.  Of the non-human primates, it has the widest geographic range.  And while macaques share the same basic patterns of social organization, they widely differ in their patterns of mating, aggression, conciliation, dominance, and nepotism.

2.  Terms & Definitions:

Generalist 

Organisms that are not specialized on any particular food service.  Omnivorous.

Coalition 

An alliance, especially a temporary one, between individuals.

Matrifocal

Clusters or groups of female kin.

Dominance

High status in a social group, usually acquired as the result of aggression, that involves the tendency to take priority in access to limited resources, as food, mates, or space.

Hierarchy

Categorization of a group according to ability or status.

Philopatry

Prefentially residing within the natal population.

 

3.  Macaca taxonomy:

The genus Macaca is divided into four sub-groups: the fascicularis subgroup, the silenus-sylvanus subgroup, the sinica subgroup, and the arctoides subgroup.  These four groups are comprised of the 21 currently recognized species of macaque and represent one monophyletic group.  The three largest subgroups of macaque correspond with three dispersal waves throughout Asia.

The fascicularis group and their ranges:

• M. fascicularis: the crab-eating macaque or long-tailed macaque.  Range includes southeastern Burma, southern Thailand and Indochina, Malay Peninsula, Nicobar Islands, Sumatra, Java, Borneo, Philippines, many small islands of East Indies as far east as Timor, but not Sulawesi.
• M. mulatta: the rhesus macaque.  Range stretches from eastern Afghanistan, through much of India and Nepal, to northeastern China and Indochina.
• M. cyclopis:  Taiwanese macaque.  Range is limited to Taiwan.
• M. fuscata: Japanese macaque.  Range is throughout Japan, including Honshu, Shikoku, Kyushu, Yakushima.

The silenus-sylvanus group and their ranges:

• M. silenus: liontail macaque.  Ranges throughout southwestern peninsular India.
• M. nemestrina: pigtail macaque.  Range includes Assam, Burma, southern Yunnan, Thailand, Indochina, Malay Peninsula, Sumatra, Borneo.
  
• M. tonkeana: Tonkean macaque.  Ranges throughout northern and central Sulawesi.
• M. maurus: Moor macaque.  Range is limited to southwestern Sulawesi.
• M. pagensis:  Mentawai macaque.  Range is limited to the Mentawai Islands of Indonesia.
• M. ochreata: booted macaque.  Range includes southeastern Sulawesi and nearby Muna and Buton islands.
• M. nigra: Celebes macaque or the crested macaque.  Range is limited to northeastern Sulawesi.
• M. sylvanus: Barbary macaque.  Range covers northern Africa and an (possibly) introduced population at Gibraltar in extreme southern Spain.

The sinica group and their ranges:

• M. sinica:  toque macaque.  Range is limited to Sri Lanka.
• M. radiata: bonnet macaque.  Range is limited to peninsular India.
• M. munzala:  Arunchal macaque.  Range is limited to northeastern India.
  
• M. assamensis, mountainous areas from Nepal and Bangladesh to northern Indochina and western Thailand
• M. thibetana (Père David's stump-tailed macaque), Sichuan to Fujian Provinces in southeastern China

The arctoides group and range:

M. arctoides: stump-tailed macaque.  Ranges throughout Assam to southern China and northern Malay Peninsula.

Photo by World of Oddy. Some rights reserved.

4.  Distribution and Ecology:

The worldwide distribution of macaques:

Radiations of macaques occurred during the Pliocene-Pleistocene, about 2.5 - 7 million years ago, and coincides with radiations of Homo. 

Used with permission.

Ecology of macaques:

Macaques have generalized social groups with complex and variable intra-individual social relationships.  They tend to be heavily reliant on alliances and coalitions.  Moreover, unlike other non-human primates but like humans, they tend to exhibit broad and diverse immune response systems, when challenged.  Relative to other primates, they have very generalized morphologies and are largely generalist feeders.  Due to the broad distribution of the genus, macaques are found across a broad distribution of habitat types, including:

• Sea level to high altitude (>3000m).
• Tropical to temperate to alpine.
• Forests, to montane, to deserts, to urban areas.
• Terrestrial and arboreal.

5.  Group Structure & Reproductive Behaviors:

Sexual swellings and behavior:

Most macaques have sexual swellings of some level, with an increased size and color in the peri-anal and perigenital regions.  Sexual swellings correlate with ovulation.  The association in some species in size of swelling and overall nutritional status.  Many macaques have some level of post-partum swelling as well.

Groups:

No true territoriality occurs, but resource territoriality occurs.  This leads to extensive overlap in range.  This is extremely important in terms of understanding dispersal.  Increases in opportunity to be accepted in neighboring groups occurs due to the potential for familiarity.  Clusters of female kin, or matirfocal units, co-occur with males.  Characteristic matrifocality generates the context of the social structure of the entire population.  Group details and dynamics include:

Photo by stoicviking. Some rights reserved.

Multi-female/multi-male. Matrifocal, multi-male/multi-female groups. Range in size from 10 to 200 individuals. Human sympatric groups larger. Occasionally one-male groups. Variable territoriality. Male and female dominance hierarchies. “despotic” and “egalitarian” social organizations.

Male dominance relations:

Struggles for dominance between males often result in aggression.  The potential impact from this aggression is real, yet macaques heal relatively quickly.  However, changes in behavior induce further attack.  Group instability further facilitates group aggression.  Status is important because it allows for access to females, food resources, etc.

Male clear and linear for top ranks, frequently top ranked individuals form a coalition. Males compete for status and may transfer groups multiple times during lifetime. Many ways to be a high ranking male.

Photo by Russell Dicker. Some rights reserved.

Female dominance relations:

Females are ensconced in social network and structure from birth.  Rank is positively correlated to matrifocal group size, through aggressive intimidation.  The more adult females in the matrifocal unit, the higher the reproductive success of that group.  This is due to alloparenting and status.  Rank reversal is common:  infant females inherit their mother's status.  Infants can displace adults for access to resources.  Ultimately, the newest born has the greatest access to resources and has the highest status, if the mother is in close proximity.  The hypothesis is that the infant is the most vulnerable so it needs the most protection.  Rank reversal, then, is a reproductive investment system.  This system is not common in other female philopatric species.  Broad patterns of dominance relations, across macaque species, include:

• Female philopatry.
• Rank related to matrifocal group size via greater size (more kin) higher rank andsocial networks.

• Rank reversal in matrilines.
• Immatures’ ranks are dependent ranks.

6.  Additional Material:

Primates in Perspective.  2007.  C. J. Campbell, A. Fuentes, K. C. MacKinnon, M. Panger, and S. K. Bearder.  Oxford University Press.

Evolution and ecology of macaque societies.  1996.  eds. J.E. Fa & D. G. Lindburg.  Cambridge University Press.