Species Profile by Sarah Kechejian
Botswana Student Program, Spring 2013
Hippo in NG 34 near Moremi Game Reserve (photo by Jack Massey)
The Hippopotamus amphibius, the common hippo, is a naked amphibious mammal found in southern Africa. Like many animals occupying the Okavango Delta region, the species utilizes two distinct habitats, lake/river and grassland. The Delta is unique in its flood patterns, creating over 40 distinct habitats inhabited by thousands of species, allowing for dual residence. The common hippo, the last remaining species of hippopotamus, is an iconic figure of the wild, being interpreted as a cold killer, a lazy herbivore or a bird raft. Regardless, I took an interest in the huge individuals and investigated their behavior to decide what they meant to me.
Although a social creature, spending hot days packed like pigs in lakes deep enough to submerge their full bodies, often using each other as head rests, at night the hippos individually walk 2-3 (up to 6) miles to the grasslands to graze for up to five hours. You can tell a herd occupies a lake or river by the presence of a single trail coming from the bank. Hippos, although exiting and entering alone, all use the same path in and out of the water. This behavioral trait has been utilized by many local hunters, specifically the Bayei. Once the hippo left for grazing, the hunters would plant sharp spikes in the path, so, upon its return, the soft pads of the hippos feet would get punctured and slow its movement. The hippopotamus’ habits resulted in its hunting availability. Otherwise, it’s 6cm skin on its back and legs would protect it from other angles of attack. The Bayei would eat the meat and use the skin as plowing rope, benefiting from all parts of the animal, unlike modern poaching in which the 20inch ivory tusks are the main prize.
In one night, a single hippo can use its lips to eat 88lbs of grass. If out a little too late one night and caught in the sun, the hippo’s mucous glands will produce a viscous pink liquid over the skin in the place of sweat (hippos have no sweat glands). There is a common misconception that hippos sweat blood because of the pink color of the fluid.
Living out most of the day in the water, hippos mate, nurse and socialize submerged, rising to the surface roughly every minute. (They have the capacity to stay under for up to five). They travel like moon men, bouncing up with every step in a running fashion. This style of travel is seldom witnessed considering most observers are at a safe, dry distance.
Hippos are very large animals: females weighing between 1440-5157lbs and males weighing 3500-7000lbs, so it is odd that their gestation period is only 8 months. The belief is that the calves are well protected in the water so they can finish developing out of the womb. The pregnant cow (maturing at age 7) will, however, isolate herself before and after birth for ten to forty days in a neighboring unoccupied pond to ensure the calf’s safety from territorial bulls. Cows, despite having no observed social structure, will form “nursery schools” around the calves to protect them from other threats like crocodile and brave land carnivores (hyena, lion).
Although the mature hippo has no real predators, aside from, of course, humans, the hippo can chomp a 3m crocodile in half with its powerful jaws. The jaw strength of a grown bull or cow is the main threat to humans. Although they will not ingest you, a hippo will attack and aim to kill.
A tip to defense: if a hippo is charging you, try to find a fallen tree or rock that you can jump over. The hippo, although it can run 18mph, cannot jump and follow you over. Just alternate jumping back and forth to each side as the hippo tries to get around the object.
A dominant bull can hold a territory for up to seven years, fathering all calves in the 10-15 (max 200) member herd. Subordinate males are tolerated until they attempt rebellion or sexual activity, often resulting in bachelor herds of the defeated. Aggression is most seen in the dry season when habitat is limited. The dominant male will mark his territory with a dung spraying, depositing mounds he habitually adds to around the edge of the lake or river. Often times juveniles will follow him, licking his anus and eating his feces. Urine and dung are foundational communication methods for hippos, using displays to detect mating availability, signaling submission and displaying dominance.
Aggressive behavior consists of grunt, roar, exhaling, explosive exhale and water scooping. Because of their loud displays, hippos are one of the noisiest animals in Africa. They are also the most environmentally impactual animals in southern Africa, second to elephants. The aquatic habits of the species help open channels, facilitate flooding and regulate water flow.
The common hippopotamus is protected but the threat to their population is still present, as the threat to all natural water sources is under pressure. After learning a substantial amount about these creatures, it is hard not to respect and enjoy their presence. I’ve only seen one common hippopotamus basking in his lake since being in Botswana, but I am determined to observe (from a safe distance) more as the flood season comes seeping in.
The life and times of a hippo, courtesy of Sarah