Native to sub-Saharan Africa, the heavy-set hippo is the third largest land mammal on Earth after its nearby neighbors, the elephant and rhino. Due to the intense African heat and sun, the semi-aquatic animal spends up to 16 hours a day submerged in lakes and rivers, with hippopotamus actually meaning ‘river horse’ in Ancient Greek.
Despite its rotund shape and size, hippos can run deceptively quickly out of water and are one of the most dangerous animals in the world. This is due to their quick temper, territorial instincts, and unpredictable nature.
Once widespread across the continent, the vulnerable species is now mostly confined to protected areas. In the wild, there is an estimated total population of between 125,000 to 150,000, with hippos usually hanging out in bloats or pods of around 10 to 30 members.
What Is the Average Lifespan of a Hippo?
Hippos have a long lifespan, often living up to 40 years old in the wild. The median life expectancy however is slightly shorter in general at around 36.
While adults are protected by their large size, powerful jaws, and fierce reputation, simply reaching adulthood is a challenge for small calves. This is because hippos live in the same habitat as several other large predators.
Hippo Lifespan in Captivity
In captivity, hippos have an even longer lifespan on average with many residents easily reaching the age of 50. This extended life expectancy is because they don’t have to search for food, are provided with medical care, and don’t face the threat of either poachers or predators.
A handful of hippos in captivity have even lived into their 60s with the oldest believed to have been 65 when she passed away.
The Life Cycle of a Hippo
Hippos typically breed during the dry season, so that babies are born when the rains arrive during the wettest time of the year. After a gestation period of 8 months, hippos give birth underwater with new born calves weighing between 25 and 50 kilograms.
Females normally have only one calf every two years and are fiercely protective of their young who can suckle either on land or underwater. Most calves are fully weaned after a year and usually start to add grass to their diets at the age of 6 months.
While females reach sexual maturity at the age of 5 to 6, males take a bit longer at around 7.5 years. Dominant males preside over small stretches of river and have mating rights over the females in their area. Hippos mark their territory by defecation, spinning their tails to propel the faeces further away.
On average, male and female adult hippos weigh 1,500 and 1,300 kilograms respectively. Despite their huge size, the herbivorous hippos don’t need to eat all that much food, grazing on around only 40 kilos of grass each night.
Probable Causes of Hippo Deaths
While adults have almost no natural predators due to their colossal size, illegal hunting and habitat loss have unfortunately led to a steep decline in hippo numbers over the last 200 years.
Once prevalent all the way from the Nile Delta in Egypt to the Cape down in South Africa, hippos now mostly only reside in remote areas and protected wildlife reserves. The barrel-shaped animals are particularly under threat in areas that are mired in political and economic instability where they are afforded almost no protection.
Over the decades, the total hippo population in the wild has declined drastically in large part due to illegal hunting and poaching. While they are valued for their meat and ivory, humans encroaching on their habitat often also see them as a danger or a pest, and so kill them if they can.
Human settlements, dams, and agriculture projects have also led to a decrease in the untouched areas available for hippos to live in.
Besides humans and habitat loss, most threats facing hippos occur when they are still calves. Aside from crocodiles, lions, hyenas and leopards, babies could get crushed by accident or even attacked and killed by other hippos.
Oldest Known Hippos
Bertha – Reputed to be 65 when she died in 2017, Bertha had lived in Manila Zoo in the Philippines since 1959. To date, she is still the oldest known hippopotamus to have ever lived either in captivity or the wild.
Donna – Before Bertha, Donna was the world’s oldest recorded hippo in captivity when she passed away at the age of 61. The long-term resident of Mesker Park Zoo in Indiana was a firm favorite with all who came to see her.
Hannah Shirley – The oldest living pygmy hippo in the world, Hannah Shirley recently celebrated her 47th birthday at the Ramona Wildlife Center in San Diego. Much smaller than its cousin the common hippo, pygmy hippos reach 100 centimeters in height and are only found in West Africa.