Gelada (Theropithecus gelada) Fact Sheet: Behavior & Ecology

Diurnal (active in daylight) (from Crook 1966; Crook and Aldrich-Blake 1968 unless otherwise noted)

• Groom, feed, and travel throughout the day
  • Shelter on cliffs, under overhangs in heavy rain
  • Social activity generally, temporally confined (Dunbar 1983)
    • First 2-3 hours of the day
    • Last 1-2 hours of the day
• Sleep on cliffside ledges at night
  • Typically change location from day to day
  • Slumber alone or in small groups

Daily activity patterns (from Crook 1966; Crook and Aldrich-Blake 1968 unless otherwise noted)

• Begin activity after sunrise, typically
  • Ascend cliffs to sit in the sunlight
  • Groom and feed as harems gather to form a larger herd
• Forage and travel throughout the day
  • Spend more time foraging than any other herbivorous primate (Bergman and Beehner 2013)
  • 50-70% of time spent feeding (Bergman and Beehner 2013)
• Climb down cliffs at dusk to sleep

Daily travel (from Crook 1966; Crook and Aldrich-Blake 1968)

• Movement patterns
  
• Travel along ridges; always maintain close proximity to cliffs
  • Retreat to craglines of gorges and escarpments when alarmed or to sleep at night
• Travel distance
• Move up to 6.4 km/day (4 mi/day)

Linear ranges (Crook 1966)

• Not extending far from cliffs

Live in stable social groups (from Crook 1966; Crook and Aldrich-Blake 1968 unless otherwise noted)

• One-male units (OMUs or "harems")
  • A large adult male, two or more adult females, and their juvenile and infant offspring
    • Typically 2-15 adults (Gustison et al. 2012)
  • OMU male leaders rarely herd "harem" females; unlike behavior of the hamadryas baboon (Dunbar and Dunbar 1975)
    • Females may counter threats by the OMU leader
• All-male groups (AMGs)
  • Associations on sub-adult and mature males
  • 2-15 individuals (Bergman and Beehner 2013)
  • Cooperate to harass OMU leader males (Bergman and Beehner 2013)
    • Click here for a brief video
  • Chases and displays reinforce a dominance hierarchy between AMG members (Bergman and Beehner 2013)
    • Actual fighting rare (Bergman and Beehner 2013)
• Juvenile parties
  • Temporary play groups (Kawai 1979; Dunbar and Dunbar 1975)

OMUs aggregate into larger associations (from Crook 1966; Crook and Aldrich-Blake 1968 unless otherwise noted)

• Composition typically not stable
  • Fragment when feeding conditions are poor
  • OMUs typically join and disperse independently of one another
  • Juveniles and infants from separate OMUs often join to play
• Bands
  
  • Associations between OMUs and AMGs (Kawai et al. 1983)
  • Share a common home-range
    • Many associations are temporary though some are longer lasting
  • Size range
  • 30-250 individuals (Bergman and Beehner 2013)
• Herds
  
  • Represent members from several bands (Kawai et al. 1983)
  • Size range
    • Up to 1,200 individuals (Bergman and Beehner 2013; Crook 1966; Crook and Aldrich-Blake 1968; Gustison et al. 2012)
    • Largest naturally occurring grouping of (non-human) primates (Dunbar 1980)
  • Numbers vary by region and between seasons
  • Availability of food likely impacts numbers
  • Spatial organization
    • Mothers, infants, and females nearest to cliffs
    • Adult and sub-adult males further from cliffs

None reported (Bergman and Beehner 2013)

Aggression between OMUs (from Dunbar and Dunbar 1975)

• Females most frequently initiate conflicts
• Males drawn in to support their females
• Set off by perceived spatial infringements

Aggression (from Dunbar and Dunbar 1975 unless otherwise noted)

• Low rates of aggression within an OMU
  • Primarily between females
• Forms of aggression
  • Bite
  • Push, pull, hit, and wrestle
  • Charge and chase
  • "Jaw fence"
  • Threat displays (details below in Communication: Facial Expression section)
    • Eye lid display
    • Lip roll

Affiliative behaviors (from Kawai 1979 unless otherwise noted)

• Allo-grooming (one individual grooms another)
  • All age classes and both sexes participate (Dunbar and Dunbar 1975)
    • Between members of the same social group (either an OMU or AMG)
    • OMU leader and dominant female tend to groom one another frequently
    • Juveniles and infants rarely groomed by OMU leader
  • Mutual, simultaneous grooming (Dunbar and Dunbar 1975; Kawai 1979)
    • Hands and mouth comb through partner's hair (Dunbar and Dunbar 1975; Kawai 1979)
  • Duration
    • Typically < 5 minutes
    • Rarely lasting longer than 15 minutes
      • Up to 31 minutes, one study (Kawai 1979)

Play (from Dunbar and Dunbar 1975 unless otherwise noted)

• Juveniles and subadults
  • Most frequent form of social interaction between members of separate OMUs
  • Unstable peer groups of older juveniles move independently of their natal OMUs
• Forms of play
  • Wrestle and mock-bite
  • Often accompanied by a 'play face'
    • Lips drawn back into a grin
  • Chase

Vocalization (from Gustison et al. 2012 unless otherwise noted)

• Elaborate vocal repertoire (Aich et al. 1990; Bergman and Beehner 2013; Moos-Heilen and Sossinka 1990)
  • >20 patterns
  • 11 contact calls
  • 11 aggressive-defensive calls
• Affiliative interactions
  • Affiliative grunt
    • Soft, exhaled call
    • Given during approaches, grooming, infant handling, and while moving or foraging
  • Inhaled grunt
    • Nasal, inhaled sound
      • Withdrawn upper lip may obscure the nasal passages
    • Given in affiliative encounters
  • Moan
    • Long, drawn-out exhalation
    • Affiliative grunt given by leader males to their group females
  • Yawn
    • Vocalized, inhaled yawn
    • Often produced during grooming sessions and after mating or competitive interactions
• Mating calls
  • Copulation call
    • Loud, exhaled grunt
    • Given before and during mating
  • Pre-copulation/'solicitation' call (Gustison et al. 2012; Dunbar 1984)
    • Short, exhaled sounds
    • Given by a female in estrus while presenting her genitals to a male
• Fear, aggression, and alarm calls
  • Fear bark
    • "Cough-like", exhaled sound; lips retracted
    • Uttered by subordinate individual to a high-ranking one
  • Scream
    • Drawn-out, exhaled noise
    • In defense, when attacked by a higher-ranking individual
  • Threat grunt
    • Staccato-like, exhaled vocalization
    • Uttered by dominant individual in an aggressive encounter
  • Howl barks
    • Exhaled, high-pitched barks/whinnies
    • In competitive chases between non-leader males
  • Alarm call
    • Noisy, harsh, exhaled call
    • Response to predators and other environmental threats
• Display calls
  • 'Wahoo'
    • Loud call produced by inhaling and exhaling
    • Uttered during competitive displays
    • In males, often preceded with a roar
• Other sounds
  • Lip smack
    • Non-vocal, rhythmic sounds
  • Wobble
    • Soft, inhalation and exhalation; accompanied by lip or tongue-flicking
    • Produced following anxiety-producing situations
    • Not produced by close relatives (Papio baboons) (Bergman 2012)
    • Characteristics of sound and associated facial expressions similar to production of human speech (Bergman 2012)
    • Click here for audio
  • Lost call
    • Noisy, long exhaled sound; pitch raises towards the end
    • Given when an individual is separated from the group or another particular individual

Facial Expression

• Eyelid display (Fedigan 1972; Struhsaker 1967)
  • Threat gesture used by both sexes
  • Retract the brow to expose the pinkish eye lids
  • Repetitively drawn down and back to "flash" at another individual
• Lip roll (Fedigan 1972)
  • Intense threat display, used by both sexes
  • Draw the top lip up over the nose to expose the gum and upper teeth
• Yawn
  • Associated with social tension and affiliative behavior (Fedigan 1972; Leone et al. 2014; Struhsaker 1967)
  • Adults yawn more frequently than immatures and juveniles (Leone et al. 2014)
  • 3 forms (Leone et al. 2014)
    • Mouth open, teeth remain covered
    • Mouth open, teeth exposed
    • Mouth open, gums and teeth exposed
      • Females make this expression less often than other forms of yawning

Terrestrial; rarely climb trees (Crook and Aldrich-Blake 1968)

• Walk and run quadrupedally
• Scoot (Bergman and Beehner 2013)
• Slowly advance with hindquarters on the ground when foraging

Predators

• Few large carnivores within species' distribution (Dunbar 1980)
• Mammalian threats
• Leopard (Panthera pardus), spotted hyena (Crocuta crocuta), humans and domestic dogs (Bergman and Beehner 2013)
• Avian threats
• Raptors may prey on the young (Bergman and Beehner 2013)
  • Juveniles jump and look nervously at large birds

Aggression is typically minimal, though threat displays are common. Gelada curl the upper lip up and over the nose, exposing the gums and large, upper, canine teeth.

Image credit: © Shaylib from Flickr. Some rights reserved.