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Hippopotamus (Hippopotamus amphibius) & Pygmy Hippopotamus (Choerpsis liberiensis) Fact Sheet: Reproduction & Development


  • Possession of a territory pre-requisite to mating
    • Bulls controlling the most desirable territories have most reproductive success
    • Non-territorial bulls (90%) are excluded from reproducing
  • Females seasonally polyestrous (lasts 3 days). Males show no evidence of sexual fluctuations
  • Mating peaks during dry spells (population most concentrated)
  • Mating in water for both species; Pygmy Hippos also mate on land
  • Copulation lasts up to one half hour. Female is fully submerged (raises her nose above water periodically)
  • Courtship often accompanied by male's wheeze-honking sound


Reproductive rate

  • Under good conditions, females can produce a calf each year
  • Comparatively high for such a large animal


  • Common Hippos: 227-240 days
  • Pygmy Hippos: 188 days

Gestation and Birth


  • Birth Weight
    • Common Hippo: 25-55 kg (55-121 lb)
    • Pygmy Hippos: 5.73 kg (12.7 lb)
  • Litter Size: one, twins rare
  • Female aggressive prior to giving birth
    • Leaves herd
    • Returns in 10-14 days after calf has imprinted on her
    • Imprinting phase also common in other ungulates such as horses and zebras
  • Common Hippo birth occurs on land or in shallow water, usually in October or April (during rains)
  • Pygmy Hippos born on land throughout year
  • Birth occurs hind legs first
    • Common Hippo calf may have to push off from bottom and come to surface for its first breath
    • Adaptations for underwater nursing: ears automatically fold and nostrils close (even when nursing on land).
    • Frequently surface to breathe

Life Stages

Young of the year (< 1 year old)

  • Calves remain in water when mother leaves to forage; mother returns periodically to let calf nurse
  • Infants can remain underwater only about 2 minutes
  • Normally breathe about every 30 seconds
  • Indirect evidence that during poor environmental conditions, nursing period is extended and calves suckle more than one cow
  • Lactation lasts approximately 1 year
  • Grazing begins at 1 month; substantial grazing at 5 months
  • Weaned at 6-8 months for both species
  • In wild, occasional infanticide by adult or juvenile males


  • Until about one year, calves vulnerable to Nile Crocodile attacks
  • Young remain with mother for several years


  • Sexual maturity in managed care much younger than reported for wild
    • In managed care: 3-4 years
    • In the wild: males 6-13 yrs.; females 7-15yrs.
    • It is unlikely that young bulls are allowed to breed effectively until much older
  • Fertility doesn't' decrease much with declining age
    • Many females still can reproduce in 30s and 40s
  • Psychological maturity in the wild is probably about 20 years

Typical Life Expectancy

Managed care

  • Common hippo
    • Median life expectancy
      • 36.6 years (AZA 2023)
  • Pygmy hippo
    • Median life expectancy
      • 27.6 years for females (AZA 2023)

Mortality and Health

  • Vulnerable to predation by Nile crocodiles, hyenas, and lions while young and small

The Water Life

Hippo calf with mother

Young hippo calves are able to dive for about two minutes.

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

Page Citations

Kingdon (1979)
Klingel (1991)
Nowak (1991)
Smuts & Whyte (1981)

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