Grevy's Zebra (Equus grevyi) Fact Sheet: Reproduction & Development

Female receptivity

• Receptive 2-3 days of an estrus cycle
• Estrus lasts 5-10 days
• When ready to mate, estrous female raises hind quarters, tail to one side, ears back, with open-mouth

Male behavior

• Males often display with ears back and bare teeth during mating
• Possibly to intimidate other males or the female
• Mounting
• Male may attempt to mount, even if female moves away

Non-seasonal reproduction

• Sexes live apart until environmental conditions are favorable for reproduction
• Male reproductive success correlates only with quality of resources
• Size of an individual does not effect reproductive success

Gestation

•  Duration
  • 390 days; longest of any equid
    • Variation noted in managed and semi-managed populations (387-428 days)

Birth (from Churcher 1993)

• Mother's behavior
  • Female stays with foal, away from other females, for 1-2 days
  • Mother and foal rejoin the group once imprinting is complete
    • Foal imprints on mother's scent, call, and stripe pattern
• Timing of birth
  • Young typically born in August or September in the wild
• Foal characteristics
  • Weight at birth: about 40 kg (88 lbs)
  • Foal stands within 10 minute; runs within about 45 minutes

Infant (< 1 year old) (from Churcher 1993 unless otherwise noted)

• Development
• Nursing lasts for 75% of the first year, or about 9 months
• Legs are so long, young foal must spread them to touch the ground (Estes 1991)
• Front-most milk teeth erupt by 1-week old.
• Striping is light brown at first, becomes sepia with age
• Foal mortality in wild may be as high as 50%
  • Mother may leave foal unattended during dry season while searching for water
• Young do not hide as do many hoofed animals; remain standing
• Young very conspicuous and vulnerable to predation at such times

Juvenile (Churcher 1993)

• First permanent molars erupt at 1 year

Subadult (from Churcher 1993)

• Development
• Third molar teeth are in place at 2.5 yrs
• Young zebras follow mothers up to about 3 years

Adult (from Churcher 1993)

• Males reach puberty at 4 years when all permanent incisors have erupted
  • Can reproduce up to 18 years
  • In wild, stallions are sexually mature at about 6 years
  • Puberty not an indicator of breeding activity in wild; young males can not compete with older stallions
  • Some males may never become breeding adults
• Females reach puberty at 3-4 yrs when permanent incisors are erupting

Managed care

• Median life expectancy (AZA 2023)
  • Males: 10.9 years
  • Females: 16.5 years

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.

Churcher (1993)
Ginsberg (1989)
King (1965)
Kingdon (1975)
Sundaresan et al (2007)