The Guadalupe fur seal belongs to the “eared seal” family along with sea lions. The Guadalupe fur seal’s range is centered on their preferred mating grounds, Guadalupe Island and more recently the San Benito Islands. They are the rarest species of fur seal, and were once thought to be extinct.
Guadalupe fur seals are sexually dimorphic, which means males and females have physical differences besides their reproductive systems. Males can grow up to seven feet long and weigh upwards of 400 pounds, while females may only grow up to five feet and weigh up to 110 pounds. Since they are members of the eared seal family, the Guadalupe fur seal has strong front flippers for propelling its body through the water and walking on land. They feed primarily at night on squid and other forage fish, diving to depths of up to 65 feet. During the summer, Guadalupe fur seals likely fall prey to killer whales and great white sharks around Guadalupe Island. Guadalupe fur seals are often found within 300 miles of the Guadalupe and San Benito coastline during mating season where rocky habitats and caves offer ideal conditions for breeding. However, fur seals have been spotted as far north as Sonoma County, California during the non-breeding season.
Guadalupe fur seals are polygamous, meaning they do not form bonded pairs. Males will mate with as many as a dozen females each mating season and defend small land territories from other males by coughing or roaring. Females will arrive at these territories in early June ready to give birth to pups from the previous mating season. A week after the pup is born, the females will mate again. The next eight to eleven months are spent rearing the newborn pup on a nutrient-rich diet of the mother’s milk until the pup is ready to eat solid food. The female will alternate between foraging for her own food at sea – for nine to 13 day intervals - and nursing her pup for five to six days. These periods are longer than those of other fur seals.
Guadalupe fur seals were hunted extensively for their fur during the 1800s and were believed to be extinct until a small population of 14 individuals was spotted in 1954 in Mexico. They are now legally protected by the United States and Mexico throughout their range, and have recovered to a total population of approximately 20,000. They were listed as “threatened” under the Endangered Species Act in 1985. Today the IUCN classifies them as a species of least concern as populations steadily grow.