Fur seals compose nine species in taxonomic family Otariidae. The largest of these, northern fur seals (Callorhinus ursinus), are the only fur seals that live in the Northern Hemisphere. Eight other species make up the Arctocephalus genus of southern fur seals: South American fur seals (Arctocephalus australis), New Zealand fur seals (A. forsteri), Galapagos fur seals (A. galapagoensis), Antarctic fur seals (A. gazelle), Juan Fernandez fur seals (A. philippii), South African fur seals (A. pusillus), Guadalupe fur seals (A. townsendi) and Subantarctic fur seals (A. tropicalis). Despite their diverse geographic ranges, all fur seal species have similar life cycles.
Large herds of fur seals congregate at established breeding grounds annually. Males arrive first to stake out breeding territories, a process that gets violent and involves much fighting between the bulls to prove dominance and control preferred areas close to shore but behind the high-tide line. Females reach the breeding grounds approximately a month after the males, ready to give birth to the pup conceived last year. Males rush to herd these females into harems they control within their territories. Depending on a bull's dominance and the size of his territory, his harem may be as small as three or as large as 40. Within days after giving birth to their pups, female fur seals are ready to mate again.
Birth and Infancy
Soon after giving birth, mother fur seals head out to sea to forage for food. They return about once a week on average to nurse their newborn pups. While the mothers are gone, the pups play and learn to swim, splashing in the shallow water near the coastline but not venturing too far from the breeding grounds. When mothers return, they are reunited with their pups by calling to them. Each mother and pup has distinct calls that enable them to identify each other. Once the mothers have nursed, they return to sea, repeating this cycle several times over until their pups are weaned between 4 and 5 months old.
Once pups learn to swim and forage for food on their own, many of them leave the breeding grounds and head out to sea -- but years later, when they've reached sexual maturity, they will return to the same land where they were born. Many juvenile fur seals, meanwhile, remain close to the breeding grounds year-round. This is especially true for males, as they may have to wait several years before they're strong enough to control breeding territories of their own. Although fur seals reach sexual maturity at between 3 and 4 years old, it may take males another four years or so before they're successfully able to challenge adult males and establish some measure of dominance.
Except to breed, most fur seals live the majority of their lives at sea, where they forage and feast on fish, squid and krill. The open ocean serves as the primary habitat for fur seals, although they return to the same breeding grounds each year. Females spend more time in the open sea than males, traveling long distances before returning to their species' breeding grounds. Fur seals live between 12 and 30 years, growing to between 4 and 10 feet long and weighing as much as 700 pounds.
- University of Michigan Museum of Zoology / Animal Diversity Web: Otariidae
- National Geographic: Fur Seals
- National Geographic Digital Nomad: Baby Fur Seal Lament
- University of Michigan Museum of Zoology / Animal Diversity Web: Arctocephalus Gazella
- NOAA Fisheries Office of Protected Resources: Northern Fur Seal (Callorhinus Ursinus)
- University of Michigan Museum of Zoology / Animal Diversity Web: Arctocephalus -- Classification
- Comstock Images/Comstock/Getty Images