Fur seals are any of nine species of pinnipeds belonging to the subfamily Arctocephalinae in the family Otariidae. They are much more closely related to sea lions than true seals, and share with them external ears (pinnae), relatively long and muscular foreflippers, and the ability to walk on all fours. They are marked by their dense underfur, which made them a long-time object of commercial hunting. Eight species belong to the genus Arctocephalus and are found primarily in the Southern Hemisphere, while a ninth species also sometimes called fur seal, the northern fur seal (Callorhinus ursinus), belongs to a different genus and inhabits the North Pacific.
Fur seals and sea lions make up the family Otariidae. Along with Phocidae and Odobodenidae, ottariids are pinnipeds descending from a common ancestor most closely related to modern bears. The name pinniped refers to mammals with front and rear flippers. Otariids arose about 15-17 million years ago in the Miocene, and were originally land mammals that rapidly diversified and adapted to a marine environment, giving rise to the semi-aquatic marine mammals that thrive today. Fur seals and sea lions are closely related and commonly known together as the “eared seals”.
Until recently, fur seals were all grouped under a single subfamily of Pinnipedia, called Arctocephalinae, to contrast them with Otariinae – the sea lions – based on the most prominent common feature, namely the coat of dense underfur intermixed with guard hairs. Recent genetic evidence, however, suggests Callorhinus is more closely related to some sea lion species, and the fur seal/sea lion subfamily distinction has been eliminated from many taxonomies. Nonetheless, all fur seals have certain features in common: the fur, generally smaller sizes, farther and longer foraging trips, smaller and more abundant prey items and greater sexual dimorphism. For these reasons, the distinction remains useful.
Fur seals comprise two genera: Callorhinus, and Arctocephalus. Callorhinus is represented by just one species in the northern hemisphere, the northern fur seal (Callorhinus ursinus), and Arctocephalus is represented by eight species in the southern hemisphere. The southern fur seals comprising the genus Arctocephalus include: Antarctic fur seals, Galapagos fur seals, Juan Fernandez fur seals, New Zealand fur seals, brown fur seals, South American fur seals, and Subantarctic fur seals.
Along with the previously mentioned thick underfur, fur seals are distinguished from sea lions by their smaller body structure, greater sexual dimorphism, smaller prey, and longer foraging trips during the feeding cycle. The physical appearance of fur seals varies with individual species but the main characteristics remain constant. Fur seals are characterized by their external pinnae, dense underfur, vibrissae, and long muscular limbs. They share with other otariids the ability to rotate their rear limbs forward, supporting their body and allowing them to ambulate on land. In water their front limbs, typically measuring about 1/4th their body length, act as oars and can propel them forward for optimal mobility. The surfaces of these long, paddle-like fore limbs are leathery with small claws.
Otariids have a dog-like head, sharp, well-developed canines, sharp eyesight and keen hearing. They are extremely sexually dimorphic mammals, with the males often 2 to 5 times the size of the females, with proportionally larger heads, necks and chests. Size ranges from about 1.5 m, 64 kg in the male Galapagos fur seal (also the smallest pinniped) to 2.5m, 180 kg in the adult male New Zealand fur seal. Most fur seal pups are born with a black-brown coat that molts at 2–3 months, revealing a brown coat that typically gets darker with age. Some males and females within the same species have significant differences in appearance, further contributing to the sexual dimorphism. Females and juveniles often have a lighter colored coat overall or only on the chest, as seen in South American fur seals. In a Northern fur seal population, the females are typically silvery-gray on the dorsal side and reddish-brown on their ventral side with a light gray patch on their chest. This makes them easily distinguished from the males with their brownish-gray to reddish-brown or black coats.
Of the fur seal family, eight species are considered southern fur seals, and only one is found in the northern hemisphere. The southern group includes Antarctic, Galapagos, Guadalupe, Juan Fernandez, New Zealand, Brown, South American, and Subantarctic fur seals. They typically spend about 70% of their lives in subpolar, temperate, and equatorial waters. Colonies of fur seals can be seen throughout the Pacific and Southern oceans from south Australia, Africa, and New Zealand, to the coast of Peru and up to California. They are typically non migrating mammals, with the exception of the Northern fur seal which has been known to travel distances up to 10,000 km. Fur seals are often found near isolated islands or peninsulas and can be seen hauling out onto the mainland during winter. Although they are not migratory, they have been observed wandering hundreds of miles from their breeding grounds in times of scarce resources. For example, the Subantarctic fur seal typically resides near temperate islands in the South Atlantic and Indian Oceans north of the Antarctic Polar Front, but juvenile males have been seen wandering as far north as Brazil and South Africa.
Typically, fur seals gather during the summer in large assemblages at specific beaches or rocky outcrops to give birth and breed. All species are polygynous, meaning dominant males reproduce with more than one female. For most species, total gestation lasts about 11.5 months, including a several-month period of delayed implantation of the embryo. While northern fur seal males aggressively select and defend the specific females in their harems, Females typically reach sexual maturity around 3–4 years. The males reach sexual maturity around the same time but do not become territorial or mate until 6–10 years. The breeding season typically begins in November and lasts 2–3 months. The Northern fur seals begin their breeding season as early as June due to their region, climate, and resources. In all cases, the males arrive a couple of weeks early to fight for their territory and groups of females to mate with. They congregate at rocky, isolated breeding grounds and defend their territory through fighting and vocalization. Males typically do not leave their territory for the entirety of the breeding season, fasting and competing until all energy sources are depleted. The Juan Fernandez fur seals deviate from this typical behavior, using aquatic breeding territories not seen in other fur seals. They use rocky sites for breeding but males fight for territory on land and on the shoreline & in the water. Upon arriving to the breeding grounds, females give birth to their pups from the previous season. About a week later, the females will mate again and shortly after begin their feeding cycle.
The feeding cycle typically consists of foraging and feeding at sea for about 5 days, then returning to the breeding grounds to nurse the pups for about 2 days. Mothers and pups locate each other using call recognition during nursing period. The Juan Fernandez fur seal has a particularly long feeding cycle, with about 12 days of foraging and feeding and 5 days of nursing. Most fur seals continue this cycle for about 9 months until they wean their pup. The exception to this is the Antarctic fur seal, which has a feeding cycle that lasts only 4 months. During foraging trips, most female fur seals travel around 200 km from the breeding site, and can dive around 200m depending on food availability.
The remainder of the year, fur seals lead a largely pelagic existence in the open sea, pursuing their prey wherever it is abundant. Fur seals feed on moderately sized fish, squid, and krill. Several species of the southern fur seal also have sea birds, especially penguins, as part of their diets. The fur seals, in turn, are preyed upon by sharks, killer whales, and occasionally by larger sea lions. Fur seals are opportunistic mammals tend to feed and dive in shallow waters at night, when their prey are swimming near the surface. The South American fur seals exhibit a different diet; adults feed almost exclusively on anchovies while juveniles feed on demersal fish, most likely due to availability.
When fur seals were hunted in the late 18th and early 19th centuries, they hauled out on remote islands where no predators were present. The hunters reported being able to club the unwary animals to death one after another, making the hunt profitable, though the price per seal skin was low.
The average lifespan of fur seals varies with different species from 13 to 25 years with females typically living longer. Most populations continue to expand as they recover from previous commercial hunting and environmental threats. Many fur seal species were heavily exploited by commercial sealers, especially during the 19th century when their fur was highly valued. Beginning in the 1790s, the ports of Stonington and New Haven, Connecticut, were leaders of the American fur seal trade, which primarily entailed clubbing fur seals to death on uninhabited South Pacific islands, skinning them, and selling the hides in China. Many populations, notably the Guadalupe fur seal, northern fur seal, and Cape fur seal, suffered dramatic declines and are still recovering. Currently, most species are protected and hunting is mostly limited to subsistence harvest. Globally, most populations can be considered healthy, mostly because they often prefer remote habitats that are relatively inaccessible to humans. Nonetheless, environmental degradation, competition with fisheries, and climate change potentially pose threats to some populations.
On March 6, 1974, the Falkland Islands released a set of four stamps to promote tourism (Scott #227-230). These were printed by offset lithography and perforated 14½. The lowest denomination, 2 pence, portrayed a pair of South American fur seals (Arctocephalus australis), which breeds on the coasts of Peru, Chile, the Falkland Islands, Argentina, Uruguay and Brazil. The total population is around 250,000. However, population counts are sparse and outdated. Uruguay has the largest numbers of seals along its coast, numbering over 200,000.
The South American fur seal has a dark grey coat of fur. The males of the species are almost entirely this color, though they may have grey or tan, grizzled markings. The females and subadult males have lighter grey or tan coloring on the chest and muzzle, and may have rust-brown or medium grey fur on their undersides. The muzzle is flat-topped and pointed, with a medium-sized nose. The nostrils are forward-facing and the nose extends past the mouth. The ear pinnae are long and prominent, and the vibrissae of adults are creamy white and of relatively short length. Adult males are larger than females, with thicker necks and larger shoulders. Males also develop manes of longer guard hairs on their heads and shoulders. Size of the seals varies based on region, but on average, adult males measure up to 2 m long and weigh 150–200 kg and females measure up to 1.5 m long and weigh 30–60 kg. Newborns are 60 to 65 cm and 3.5 to 5.5 kg.
Two subspecies are currently recognized:
- A. a. australis – Falkland Islands
- A. a. gracilis – South America
The New Zealand fur seal is sometimes considered a subspecies of A. australis.
The South American fur seal is found on neotropical ocean coasts from the Paracas Peninsula of southern Peru south to Cape Horn on the Pacific coast, and northward to southern Brazil on the Atlantic coast. They are also found on the Falkland Islands, Staten Island, and Escondida Island. A. australis seals prefer rocky shores and islands, particularly those with steep slopes, which provide shady areas where they can escape the heat of the sun. They have been found in sea caves in Peru, where some climb up to 15 m to find a spot to rest. There have been isolated records from continental Ecuador, the Galápagos Islands, and the Gorgona Island (Colombia). Anatomical information for the southern fur seals, Arctocephalus spp., is scant. In addition, little is known about the foraging ecology of South American fur seals.
A popular location to view the South American fur seal in the Falklands is on Sea Lion Island (Isla de los Leones Marinos in Spanish), the largest of the Sea Lion Island Group. It is 9 km² (3 sq mi) in area. and lies 14 km (9 mi) southeast of Lafonia (East Falkland). It was designated a Ramsar site on September 24, 2001, and as an Important Bird Area (BirdLife International) in 2006. In 2017, the island was designated as a National Nature Reserve.
Sea Lion Island is 7.8 km (4.8 mi) long from east to west and 2.3 km (1.4 mi) wide, with 30 m (98 ft) cliffs at the south-western point and sandy bays to the east. The highest point at 46 m (151 ft) is Bull Hill. East Loafers is the name of the bay on the southern shore. It also has a few ponds, including Beaver and Long Pond. Just to the south is Rum Island, a small seal colony. Other small members of the group are Brandy and Whisky Islands. The geology is mainly sandstone and mudstone, from about 250 million years ago. Some minor fossils have been found.
Sea Lion Island is the southernmost inhabited island of the Falkland Islands. Only formerly inhabited Beauchene Island is located further south. Sea Lion Island Settlement is the southernmost settlement of the Falkland Islands. The island has two airstrips. Historically, Sea Lion Island was a sheep farm. When the British ship Viscount was wrecked in 1892, the wreckage was used to build the farmhouse.
The island was managed as a sheep farm for almost all of the 20th century, but in 1997 all but a small flock of sheep was removed. In 1990, the Clifton family who owned the island, sold it to the Falkland Islands Development Corporation (FIDC). They had planted 60,000 stands of tussac grass. Since then, ecotourism has been the only economic activity. In 1986, FIDC constructed the Sea Lion Lodge, with accommodation for 20 guests. It was prefabricated and flown in kit form to the island by Royal Air Force helicopters and has proved to be a success. It is used by tourists and, since 1996, scientific researchers.. Since 2017 the Lodge and island has been under the lease of Wild Falkland Ltd.
There is a memorial to HMS Sheffield on Bull Hill in the south of the island.
Some 56 species of flowering plants have been recorded on Sea Lion Island, including the Fuegian violet which, in the Falklands, is found nowhere else. The island is known for its marine mammals, including breeding colonies of southern sea lions and southern elephant seals, for which the other islands in the group are haul-out sites. Killer whales occur offshore. Elephant Seal Research Group (ESRG) has been tracking the habits of elephant seals at Sea Lion Island for over 20 years.
The Sea Lion Islands Group has been identified by BirdLife International as an Important Bird Area. It is a significant breeding site for a variety of seabirds and other waterbirds including Falkland steamer ducks, ruddy-headed geese, gentoo penguins (2800 pairs), southern rockhopper penguins (480 pairs), Magellanic penguins, southern giant-petrels (25 pairs) and sooty shearwaters. It also supports populations of striated caracaras (10 pairs), blackish cinclodes, Cobb’s wrens and white-bridled finches.