Leopard seal pups are born during the Antarctic summer, between November and January. The female hauls herself out onto the ice pack to give birth to her one pup. The females do not form colonies, unlike other seals. Before leaving the water, she eats much more food than usual, so she can survive the days following the birth without eating.
The new-born pup looks like a smaller version of its parents and does not have a white coat as the pups of other species do. It is 1.5 metres long and weighs about 26kg. The mother feeds her pup on milk rich in fat, which causes it to gain weight very quickly. At two or three weeks of age, the pup moults its first coat and takes to the sea. It now has to fend for itself and begins feeding on krill. Eventually it learns to catch fish and larger animals.
The mother seal mates with a bull seal when she returns to the sea, but the fertilised egg does not start developing straight away. This is called 'delayed implantation' and it will be three months before the egg becomes implanted in the female's uterus (womb). This ensures that the baby is not born until the weather has improved, the following summer - a gestation (pregnancy) of 240 days.
Female leopard seals are ready to breed when they are 2 - 6 years old. Males are ready at 3 - 7 years.