The South American fur seal (Arctocephalus australis) breeds along the coasts of Peru, Chile, the Falkland Islands, Argentina, Uruguay, and Brazil. These seals are listed as least concern on the IUCN Red List. Their total population is estimated to be between 300,000 and 450,000. Their numbers are affected by hunting and environmental challenges. South American fur seals have dark grey or brown fur and show differences in appearance between males and females. Males compete for territory and mates, creating a hierarchy of dominance. Breeding occurs from October to December, and females give birth to multiple pups each season. These seals are nocturnal and hunt fish that live near the ocean floor and those that swim in open water. They are social and often hunt in groups. Communication includes sounds such as guttural threats, barks, whimpers, or submissive calls from males, and growls or high-pitched wails to call pups to females. Four subspecies are recognized: A. a. australis (Falkland Island fur seal), A. a. gracilis (South American fur seal), A. a. forsteri (New Zealand fur seal), and an unnamed species (Peruvian Fur Seal).
This article also discusses more about the seals' appearance, where they live, how they are protected, what they eat, how long they live, how they mate, how to identify them in the wild, and other behaviors.
Description
South American fur seals have a dark grey or brown coat of fur. Their size can vary depending on where they live, but on average, adult males can grow up to 2 meters long and weigh 150–200 kilograms. Adult females can grow up to 1.5 meters long and weigh 30–60 kilograms. Newborns are 60 to 65 centimeters long and weigh 3.5 to 5.5 kilograms. The species is sexually dimorphic, meaning males and females have different physical traits. Adult females and subadults have dark brown or grayish black fur on their back and tan, grayish, or rusty brown fur on their belly. Adult males have more uniform and darker fur, typically dark brown with a gray or yellowish tan. Adult males also have thicker necks and shoulders than females, along with larger teeth and longer guard hairs that form a mane. The front flippers of both males and females are hairless and leathery, with the first digit being the longest and the other 2–5 digits being shorter. The hind flippers are also hairless and leathery, but each digit is about the same length and long. Both males and females are stocky and robust, with large eyes, a moderately long muzzle, and a rounded crown.
South American fur seals are often confused with South American sea lions, as well as Juan Fernandez fur seals, Antarctic fur seals, Subantarctic fur seals, Galapagos fur seals, and Galapagos sea lions due to their similar appearance.
Distribution and habitat
The South American fur seal lives along the coasts of South America, from the Paracas Peninsula in southern Peru, around Cape Horn on the Pacific coast, and north to southern Brazil on the Atlantic coast. They also live on the Falkland Islands, Staten Island, and Escondida Island. These seals prefer rocky shores and islands with steep slopes. Some have been found in sea caves in Peru, where they climb up to 15 meters high to rest. They have also been seen in isolated areas, such as continental Ecuador, the Galápagos Islands, and Gorgona Island in Colombia. Recent studies show that South American fur seals breeding on the Falkland Islands travel over a large area of the Patagonian Shelf.
The total population is estimated to be between 300,000 and 450,000. Although Uruguay was once believed to have the largest group of these seals, recent data shows the largest breeding population of the subspecies A. a. australis (found in Chile, the Falkland Islands, Argentina, and Uruguay) is on the Falkland Islands, with about 36,000 pups. Uruguay has the next largest group, with about 31,000 pups. In 1999, the population was estimated at 390,000, a decrease from the 1987 estimate of 500,000. However, limited population data and inconsistent counting methods make it difficult to understand global trends clearly.
Conservation
South American Fur Seals are listed as "least concern" on the IUCN Red List. However, humans have hunted them for thousands of years for their fur, oil, and leather. In Uruguay, commercial hunting of the species is now banned. Some fishermen in Uruguay claim that seals harm their fishing by breaking nets and eating fish, which has led to calls for killing large numbers of seals. In 1996, an initiative was started to raise money for the seals instead of killing them, but it did not work as well as hoped. In Peru, South American Fur Seals have been protected since 1959, but poaching still occurs. Environmental problems, such as oil spills, also threaten the species. In 1997, an oil tank spilled about 4,500 cubic meters of oil off the coast of Uruguay, killing 6,000 seals. Past El Niño events have caused seals in Peru to move to northern Chile, reduced the number of seal pups born, and killed about 80% of adult female and pup seals in Peru. The population in Peru is still recovering from these events. Commercial fishing also harms the seals by trapping them in gillnets and reducing the availability of fish for them to eat. The exact impact of fishing on the seals' survival is not fully understood.
Lifespan and mating
Female South American fur seals reach sexual maturity and start breeding at age 3. Males reach sexual maturity at 7 years and begin breeding at 8 years because of competition. The breeding season occurs from October to December. These seals are polygynous, meaning males mate with more than one female during a single breeding season. This competition leads males to fight for territory, and females with the most dominant males often have more offspring, creating a dominance hierarchy. In Uruguay, a single male seal may have up to 13 females on its territory for up to 60 days.
Multiple pups are born each breeding season. Pups are weaned between 6 to 12 months, though some may nurse for up to 3 years, during which females may nurse two pups at the same time. Breeding can begin again as soon as 5 to 10 days after giving birth. Embryonic diapause, a pause in the baby’s development inside the mother, lasts 3 to 4 months, followed by a gestation period of 8 to 12 months. While nursing, females search for food for 3 to 5 days and return to land to nurse for 1 to 2 days. This cycle continues for a total of 6 to 12 months.
Pup mortality rates increase as colony density rises because mothers and pups may become separated, leaving pups vulnerable to injury from aggressive adults. In Peru, pup mortality rates as high as 31 to 49% have been recorded. Overall, fur seals typically live between 12 to 30 years.
Feeding behavior (ecology)
South American fur seals are meat-eating hunters that are active at night. They eat many types of fish that live near the ocean floor and those that swim in open water, depending on where they live. Their main food includes anchovies, weakfish, cutlassfish, anchoveta, cephalopods, lamellibranchs, and gastropods. In some areas, such as Uruguay and Peru, they also eat anchovies. In Brazil, they eat shrimp. In Chile, they eat lobster krill. In the Falkland Islands, they mainly eat squid.
South American fur seals are hunted by sharks and orcas. In Peru and Uruguay, baby seals are also hunted by male South American sea lions.
Additional behaviors
South American fur seals use sounds to communicate. Males make rough sounds, such as growls, barks, whimpers, or calmer calls. Females use growls or high-pitched cries to call their pups. Research shows that each mother’s call is unique, and only other mothers can tell them apart. This communication helps mothers find their pups after returning from hunting trips that last several days. It also keeps the pups safe, as they could be crushed by other seals.
These seals are social animals and often hunt in groups while swimming. However, during breeding season, they spend most of their time on land. Males fight to claim the largest rocky and shady areas for breeding with multiple females.
Subspecies
Four types can be identified:
- A. a. australis – Found in the Falkland Islands
- A. a. gracilis – Found in South America
- A. a. forsteri – Found in New Zealand
- Unnamed – Found in Peru