Over 150 years after sealers drove the Farallon Islands' colony of northern fur seals to extinction, the animals are beginning to reclaim their old haven.
The Farallon Islands, about 20 miles west of San Francisco, once boomed with a colony of up to 200,000 northern fur seals. But between 1807 and 1840, American, British, and Russian sealers, who hunted the marine mammals for their prized satin-soft fur, extirpated them from the islands.
Examining bones excavated from Russian middens on the islands, the team has identified the telltale jaws and teeth of fur seal pups less than three months old. Since these seals need at least that much time for their teeth to develop before leaving their birthplaces, the bones could have come only from pups born on the islands.
While the first documented live northern fur seal to return to the Farallones since 1840 appeared in 1974, the first recorded birth wasn't until 1992. Today, the rookery is rebounding but has less than a dozen breeding individuals. The Point Reyes Bird Observatory, which oversees the Farallones as a wildlife reserve, is monitoring the seals' return.
The early sealers provided little biological information about the colony, and until recently scientists didn't know if it was a breeding rookery or simply a 'haul-out' where non-breeding animals congregated. However, Academy marine mammal scientists Douglas Long and Jacqueline Schonewald have proven that the Farallones were an historically important breeding grounds, a key factor for the potential recovery of the species.