The Life Cycles of Leopard Seals

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Hydrurga leptonyx, commonly called leopard seals, are found on the coasts of Antarctica, the exposed pack ice surrounding the continent and the sub-antarctic islands such as Heard Island, and Macquarie Island. Their short fur coats are gray-and-white with black spots, not unlike the pattern of a leopard's coat. Leopard seals are generally solitary creatures, a behavior reflected in their mating and parenting habits.

Leopard Seals are Big Babies

Prior to breeding, leopard seals become excessively vocal. They come together solely to breed. Scientists believe their mating occurs in the water, since captive seals were observed to mount only when in water. Mating occurs between December and January; successful pregnancies result in single seal pups born between November and December, commonly on snow-covered beaches on islands north of Antarctica. Leopard seal pups are born weighing 70 pounds and measuring 4 feet long.

Rearing and Weaning

Males play no role in caring for leopard seal pups. Only females are seen with the pups, raising them and feeding them milk on the ice packs. Seal pups resemble adults in appearance, but they have thicker coats. Leopard seal pups learn to swim and are weaned from the floating ice fields at 1 month of age. Also around 1 month, the seal pups are weaned from their mothers' milk and begin to feed on krill. The mother becomes fertile again, and the pups are on their own. Three months after birth, seal pups are double their birth size.

Juvenile for a While

As the pups grow, they become mobile and spend a lot of time traveling north over the winter as new ice floes form, since they do not need to stick around for breeding yet. They learn to hunt for prey such as shellfish, squid, fish, seabirds, penguins, other seals and whale carcasses. Since traveling on land is inconvenient, the growing seals prefer to hunt for prey in the ocean, where they hide under ice and wait for prey to happen by. Even as they grow, leopard seals consume krill for approximately 50 percent of their diet, especially during the winter when other food sources are limited.

Mature at 4 Years

Males are sexually mature at 4.5 years of age, while females are sexually mature at 4 years old. Sexually mature female leopard seals are much larger than males. They weigh up to 1,000 pounds, while males weigh 800 pounds. Males stop growing around 11 feet long, while females continue to grow up to 13 feet. Adult leopard seals are expected to live for 26 years in the wild, with killer whales as their only known predator.

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