Gelada (Theropithecus gelada) Fact Sheet: Reproduction & Development

Soliciting partners (from Kawai 1979)

• Both sexes initiate sexual interactions
  • Females present to solicit a male
    • Circle male; walking around him and emitting solicit-calls
    • Gaze at his face
    • Stand with tail raised; genital area directed toward male's face
  • Males slowly approach to solicit a female
    • May kiss and touch the red patch on the female's breast while lip-smacking

Copulation (from Kawai 1979)

• Mating brief; lasting c. 10 seconds
• Male mounts female from behind
• Both partners typically vocalize throughout

Year-round reproduction

• Copulation observed throughout the year (Kawai 1979)

Female reproductive cycle (from Dunbar and Dunbar 1974a)

• Physical features indicate estrus state
  • Changes in color of skin on chest and paracallosal region (located on either side of the vulva immediately below the calloused patches)
  • Growth of beaded vesicles surrounding chest skin
• Estrus cycle
  • Chest bright pink throughout
    • Beading develops, which turns white in anoestrous
  • Paracallosal skin (PCS) bright pink throughout
  • Vulva gradually opens and protrudes before retreat and closure in anoestrous
• Pregnancy
  • Chest bright pink throughout
  • PCS turns from bright pink to scarlet red in later stages of gestation
  • Vulva closed throughout
• Lactation
  • Chest scarlet with young infant (one with a black natal coat); turns pale to bright pink as infant ages
  • PCS turns from bright pink to pale pink
  • Vulva closed

Gestation

• Duration
  
• c. 5.5-6 months (Dunbar 1980; Hayssen et al. 1993)

Birth (from Dunbar and Dunbar 1974b unless otherwise noted)

• Timing and behavior
• Deliver at night or early morning, most often
  • Reports of birth in late afternoon (Lee et al. 2010)
  • Stands in a half crouch position
• Brood characteristics
• 1 infant typically
  • Black natal coat, skin light (Bergman and Beehner 2013; Dunbar 1980; Kawai 1979)
  • Eyes closed, though opening within c. 1-2 hours
• Birth weight
  • None reported

Interbirth interval (time between consecutive births)

• c. 2-3 years (Dunbar 1980)

Infants (< 5 months) (from Kawai 1979 unless otherwise noted)

• Carried by mother
  • Cling to mother's belly during travel for a few days after birth
  • Ride on her back or that of other group members; often with tails entwined
• Form play groups
  • Similar-age infant groups
  • Rarely stray far from natal (birth) group
• Weaned c. 12-18 months (Hayssen et al. 1993)

Juveniles (0.5-3.5 years) (from Dunbar 1980 unless otherwise noted)

• Appearance
  • Pelage resembles adult by c. 5 months
  • Muzzle rounded by 1.5-2.5 years
    • Appears as adult by 1.5-2.5 years
• Males
  • Leave natal group to join an all-male group (Bergman and Beehner 2013)
  • Remain in all-male group for 2-4 years (Bergman and Beehner 2013)
• Females
  • Remain in natal group for life (Bergman and Beehner 2013)

Subadults (3.5-6 years) (from Dunbar 1980 unless otherwise noted)

• Males
  • Puberty c. 3-4 years (Hayssen et al. 1993)
  • Attempt to acquire access to reproductive females (Bergman and Beehner 2013)
    • Act to unseat the existing leader of a one-male unit (Bergman and Beehner 2013)
    • Seek associations with peripheral and/or juvenile females (Bergman and Beehner 2013)
• Females
  • First estrus: 3-4 years (Kawai et al. 1983)
  • First reproduce: 4-4.5 years
    • Reproductive before achieving full adult size

Adults (>6 years) (from Dunbar 1980 unless otherwise noted)

• Males
  • Sexually mature c. 8-9 years (Hayssen et al. 1993)
  • Cape and whiskers fully develop and physical growth complete by 8.5-9 years (Dunbar 1980; Kawai et al. 1983)
  • Maximum weight by 12 years
    • Color of cape and chest gradually declines
  • Do not interact with females outside own OMU (Dunbar and Dunbar 1975)
• Females
  • Core of gelada society (Bergman and Beehner 2013)
    • Maintain strong bonds irrespective of OMU leader (Bergman and Beehner 2013)
  • Physical growth complete by 8.5 years
  • Reproductive activity tapers with age

Wild populations

• Average life expectancy (Dunbar 1980)
  • Males: 12 years
  • Females: 14 years

Managed care

• No AZA estimates
• Typical life span of about 20 years (Putman 2007 [studbook data])

Major causes of adult mortality

• Parasitic infection (from Dunbar 1980; Kawai 1979)
  • Coenurus (a tapeworm of the genus Multiceps) larvae cause small to large swellings in muscle tissue
    • Extremely large swellings impair movement
    • Growths may eventually weep pus, causing severe pain and compromised immune systems
• Old age
  • Aged individuals (those in the oldest age classes) demonstrate the highest mortality rates, one study (Dunbar 1980)
• Inclement weather
  • Heavy rain and subzero temperatures may contribute to respiratory and other infectious diseases (Bergman and Beehner 2013; Dunbar 1980)

Infant mortality low (from Dunbar 1980)

• Strongly influenced by rainfall
• Higher mortality during the wet season

Predators

• Negligible source of mortality (Dunbar 1980)
  • Few large carnivores live in the region (Dunbar 1980; Kawai 1979)

Females typically give birth to a single infant at night or in early morning. Infants have black hair and light colored skin. The hair turns brown by c. 5 months of age.

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