Mammals
Common Warthog
Phacochoerus africanus · also called common warthog, warthog
The common warthog is Africa’s grassland pig — grey, nearly hairless, whiskered with tufts, and armed with two pairs of curving tusks. It grazes on its knees, runs with its tail up like a flag, and sleeps backwards in someone else’s burrow so that whatever comes down the hole after it gets a face full of tusks.
Overview
Common warthogs live in grassland, savanna, open woodland, and floodplain across sub-Saharan Africa, avoiding dense forest and true desert. They are diurnal and social, living in family groups called sounders — usually females and young — while males are more solitary and join up to breed. They need water for drinking and for wallowing in mud, which cools them and controls parasites.
Kneeling to graze
A warthog has long legs and a short neck, so it cannot easily reach the ground. It drops onto the padded joints of its forelegs and shuffles forward on them while cropping short grass and rooting for bulbs and rhizomes with its snout and tusks. The “knees” develop thick protective callus pads for it.
The face
The “warts” are pads of skin and cartilage, not infections, and are much larger in males. They act as bumpers during head-to-head tusk fights over mates, protecting the eyes and face.
The tail and the burrow
A running warthog holds its tail vertical like an aerial — a follow-me flag in tall grass. It reaches about 55 km/h, usually heading for a burrow — an old aardvark hole it has taken over and widened. It backs in tail-first, so it always faces the entrance and can either meet a predator with its tusks or burst out at speed. Piglets are born and hidden in these burrows.
Status
The common warthog is Least Concern, common and widespread. Local declines occur from hunting for meat and, in places, drought, but the species is not threatened.
Common Warthog: common questions
Why does a warthog kneel down to eat?
A warthog is built with long legs and a short, stiff neck, so its head does not comfortably reach the ground for the low, close grazing it prefers. To feed, it drops onto the padded, calloused first joints of its front legs — effectively its wrists, though people call them knees — and shuffles slowly forward on them while cropping grass and rooting for bulbs and rhizomes with its snout and lower tusks. Warthog "knees" develop thick protective skin pads for exactly this, sometimes with bare calloused patches. It is one of the most distinctive feeding postures of any large mammal.
What are the warthog's warts for?
They are not really warts and are not caused by any infection. They are permanent thickenings of skin over pads of cartilage and connective tissue on the sides of the face, and the males have much larger ones — a big pair below the eyes and a smaller pair near the tusks. Their function is protective. Male warthogs fight over females by clashing head to head and pushing with their blunt upper tusks, and the facial pads act as bumpers and shields that absorb and deflect these blows, reducing injury to the eyes and face. Females have small warts and rarely fight.
Why do warthogs run with their tails straight up?
When a warthog trots or sprints, it raises its thin, tufted tail rigidly vertical, like a car aerial. The most widely accepted explanation is that it acts as a visual signal and follow-me flag — in tall grass, a running warthog is hard to see, but the upright tail tuft bobbing along is not, and it helps piglets stay with their mother and group members stay together during a flight from a predator. Warthogs can run at around 50 to 55 km/h, fast enough to outpace many predators over a short distance to a burrow.
How does a warthog use a burrow if it can't dig one?
Warthogs rely almost entirely on burrows dug by other animals, above all the aardvark, which excavates large holes that it then abandons. A warthog moves in, often widening the entrance and the chamber with its snout and tusks, and uses it to sleep in, to shelter from heat and cold, and to escape predators. Crucially, it enters backwards — reversing in tail-first — so that it is always facing the entrance. If a lion or leopard follows it in, the warthog meets it head-on with its lower tusks, which are sharp, in a narrow space where the predator cannot get around it, and it can also explode out of the hole at speed to bolt for another burrow. Piglets are born and hidden in these burrows.