In mid- to late-October the large males, or bulls, arrive, their massive body weight of around 360kg far exceeding that of the 75kg females. They stake their territorial claims and try to defend them from other males. Shortly afterwards, in late November or early December, each of the pregnant females gives birth to a single pup. These will remain in and around the colony, and continue suckling for the next ten or eleven months.

Shortly after giving birth, the females mate with the males who control their harems, and the cycle continues, with the pups born about a year later. When the females have all given birth, and mated, most of the males will leave to break their fast and replenish the enormous amounts of body-fat burned whilst defending their territories. In the last few months of the year, the scene can be quite disturbing, with many pups squashed by the weighty adults, or killed by the area's resident populations of jackal and brown hyena.