One of the wonderful things about staying at Abelana River Lodge is its location on the banks of the Selati River and the constant “serenading” of our resident hippo pods. You’ll most likely hear their raucous grunts as you sit on our viewing deck or relax on your suite’s private deck overlooking the river. They always sound as if they are laughing at a ridiculous (or rude) joke!
Hippos are very vocal and have the unusual ability to communicate above and below the water at the same time. How? They have a fatty area around their necks which vibrates when they vocalise through their nose, sending the sounds waves out into the water at the same time. The sounds are amplified by the water and can be heard over large distances. The grunts are used to tell other hippos about where they are and whose territory they are in, which is of huge importance to them, especially the huge bulls.
The bulls are particularly dangerous and aggressive over territory. Indeed, hippos in general are one of the most dangerous animals in Africa. They’re nervous when out of water and will seek to escape to it when startled or alarmed. Their bite can be fatal, thanks to their long, sharp incisors and canines which brush past one another in a scissor action.
Territorial bulls frequently fight intruders and rivals. They begin by gaping at one another, opening their enormous mouths to almost 180 degrees, flashing their canines and incisors in a menacing threat display. The incisors point forward, like tusks, and can reach up to 40cm in length. The incredibly sharp canines can grow up to 50cm in length. They are used in combat and play no role in feeding.
A bull’s territory is usually a relatively small stretch of river or dam. They’re also often found in waterholes that are deep enough to cover them. A mature bull will have a pod of females and babies to protect, as well as juveniles and younger bulls which are allowed to stay in the pod as long as they stay submissive.
Hippos leave the safety of the water at night, travelling up to 20km away from the water to feed mostly on grasses. They can consume up to 50kg of grass in one night, acting like a biological lawn-mower. They are important for healthy river systems for a very unusual reason – their dung provides valuable nutrients for fish and other acquatic species, so when you see a hippo defecating in the water, think positive thoughts!
However, when water sources like dams and seasonal rivers shrink, too much hippo dung can prove toxic to aquatic life, primarily because of the absorption of dissolved oxygen.
Hippos spend their days in the water. Their skin is very sensitive to the sun, which is why they stay submerged during the hottest periods of the day. They secrete a red-coloured oily substance that acts as a natural sunscreen, but too much sun causes their skin to crack. Oddly, hippos are not good swimmers, but rather walk or run along the bottom, surfacing every three to five minutes to breathe. They can sleep underwater too, thanks to the process of surfacing to breathe being an autonomic reflex.