A female uses auditory communication to find and identify her pup when she hauls out to nurse. She emits a "contact call" to which hundreds of pups respond; she must then distinguish her offspring from the rest. Each pup has a unique call that is recognized by the mother. The mother uses sight and smell to a lesser extent to verify the pup’s identity before nursing. Males utilize auditory, visual, and tactile communication while competing for breeding territories. They use vocalizations, postural dominance and threat displays, as well as participating in physical fights.
Communication Channels: visual ; tactile ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Subantarctic fur seals are known to be preyed upon by killer whales and sharks. Because of relatively large population sizes, predation does not present a major threat to subantarctic fur seal populations.
Known Predators:
Anti-predator Adaptations: cryptic
Males range from 70 to 165 kg and can grow up to 1.8 m in length. Females weigh between 25 and 67 kg and range from 1.19 to 1.52 m in length. Males have a chocolate brown to black back and a yellow chest and face. There is a crest of black fur on the head that is erected when the animal becomes excited. Females have dark gray or chocolate brown dorsal fur and pale yellow fur on their chest, neck, and face. At birth, pups are black with a chocolate brown underside. Both sexes have long, white vibrissae and external ear flaps.
Range mass: 25 to 165 kg.
Range length: 1.2 to 1.8 m.
Sexual Dimorphism: male larger; sexes colored or patterned differently
Other Physical Features: endothermic ; bilateral symmetry
There is little information available about the lifespan of subantarctic fur seals either in captivity or in the wild. However, studies have recorded reproductive females living up to 16 years, and non-reproductive females up to 19 years. Even less is known about male longevity. In a related species, the New Zealand fur seal, males can live to 15 years of age.
Range lifespan
Status: wild: 16 to 19 years.
Males spend the winter season out at sea, coming to shore in the spring to breed. Females with dependent young return to land from foraging trips at intervals throughout the year to feed their offspring. In the summer, females spend approximately 6 to 10 days at sea during a single foraging trip, and in winter foraging bouts increase to approximately 23 to 28 days. Between foraging trips, females spend about 4 days on land with pups. Subantarctic fur seals prefer rocky beaches with abundant boulders and shade. Adults can dive an average of 16 to 19 m deep in waters above 14 degrees Celcius for up to 4 minutes.
Range depth: 100 (high) m.
Average depth: 19 m.
Habitat Regions: temperate ; saltwater or marine
Aquatic Biomes: coastal
Subantarctic fur seals (Arctocephalus tropicalis) inhabit the Southern Hemisphere. They breed on islands north of Antarctica, including Amsterdam, the Crozets, Gough, Macquarie, Prince Edward, Saint Paul, and Tristan da Cunha islands. However, vagrant subantarctic fur seals have been recorded in South America, South Africa, and Australia, with the northernmost sighting off the Mayumba National Park in central Africa.
Biogeographic Regions: australian (Native ); oceanic islands (Native )
Subantarctic fur seals feed on a variety of marine animals including myctophid and notothenid fish, cephalopods, crustaceans, and sometimes even rockhopper penguins.
Animal Foods: birds; fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods, Molluscivore )
Subantarctic fur seals are an important food source for sharks and orcas, and a key predator of myctophid, notothenid fish, cephalopods, crustaceans, and rockhopper penguins.
In the 18th and 19th centuries, subantarctic fur seals were hunted to the brink of extinction for their pelts. Today, due to measures taken by local governments, the seals are protected on preserved land. Subantarctic fur seals are of potential interest to tourists, however tourism is relatively rare in the remote locations that seals inhabit.
Positive Impacts: body parts are source of valuable material; ecotourism
There are no known adverse effects of subantarctic fur seals on humans.
Although the population of subantarctic fur seals are currently stable or growing, with a total of over 310,000 individuals, there are several factors that could put this species at risk. After a large population decline during the 18th and 19th centuries, the current population is the product of a severe bottleneck that reduced genetic diversity. A loss of genetic diversity of this magnitude can make a population especially vulnerable to disease and other environmental perturbations, such as climate change.
CITES: appendix ii
IUCN Red List of Threatened Species: least concern
Subantarctic fur seals are polygynous with a harem mating system in which males defend territories containing from 6 to 20 females. Males come to shore in October and compete for territories; they will defend their territory and harem until all of the females have been mated.
Mating System: polygynous
Offspring are born in the southern spring and summer (October through January). Mating occurs once per year, approximately 8 to 12 days after parturition. Males are fertile only during this time, conserving energy during the winter by ceasing sperm production throughout the off season. A female gives birth to one offspring per season after a gestation period of 51 weeks. Although there are documented cases of a female successfully rearing twins, this is a rare occurrence.
Subantarctic Fur Seal pups are born weighing between 4 and 6 kg. Male pups grow faster, and have a higher weaning weight than females. Mothers nurse pups until 11 months of age, shortly before giving birth to their next pup. In males, puberty is reached at 3 to 4 years of age, but full adulthood is not achieved until 10 to 11 years of age, when males are first able to acquire a harem. Females are sexually mature at approximately 5 years of age.
Breeding interval: Subantarctic fur seals breed once per year.
Breeding season: Mating occurs from October through January.
Average number of offspring: 1.
Average gestation period: 51 weeks.
Average weaning age: 11 months.
Average age at sexual or reproductive maturity (female): 5 years.
Range age at sexual or reproductive maturity (male): 10 to 11 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous ; post-partum estrous
Average birth mass: 4420 g.
Average gestation period: 357 days.
Average number of offspring: 1.
Female subantarctic fur seals nurse their offspring for 11 months, leaving to forage at regular intervals. Upon returning to shore, females must find their pup among the hundreds located at the rookery. Each pup has a unique vocal signature that the female uses to locate her offspring; once the pup is found, she uses sight and smell to verify its identity before allowing it to suckle. Recognition of offspring is essential to prevent her from feeding the wrong pup. Males leave the rookery after each female is mated and do not return to assist in parental care.
Parental Investment: precocial ; female parental care ; pre-hatching/birth (Provisioning: Female); pre-weaning/fledging (Provisioning: Female)
The subantarctic fur seal (Arctocephalus tropicalis) is found in the southern parts of the Indian, Pacific, and Atlantic Oceans.[3] It was first described by Gray in 1872 from a specimen recovered in northern Australia—hence the inappropriate specific name tropicalis.[4]
The subantarctic fur seal is medium in size compared with other fur seals. Males grow to 2 m and 160 kg, whereas females are substantially smaller—1.4 m and 50 kg. Both sexes are strongly sexually dimorphic, with creamy-orange chests and faces. Their bellies are more brownish. Males have a dark grey to black back, while females are a lighter grey. Males have a characteristic dark tuft of hair on the top of their head that stands erect when they are excited.[5] Pups are black at birth, but molt at about 3 months old. The snout is short and flat, and the flippers are short and broad.[6] Subantarctic fur seals live for about 20–25 years.
Subantarctic fur seals are geographically widespread. As their name implies, they generally breed in more northerly locations than the Antarctic fur seals. The largest breeding colonies are on Gough Island in the South Atlantic and Île Amsterdam in the southern part of the Indian Ocean. Breeding grounds are also found at Marion Island in the Prince Edward Islands (where an overlap with Antarctic fur seals occurs), the Crozet Islands, and Macquarie Island. Where grounds overlap, the subantarctic species can be identified by the orange colour on the chest.
About 300,000 subantarctic fur seals are alive today, probably substantially down from when they were first discovered in 1810, as they were hunted for their pelts throughout the 19th century. Populations are recovering rapidly, though, in most areas whilst under the protection of the Convention for the Conservation of Antarctic Seals. A small population on Heard Island is endangered. Unlike the Antarctic fur seal, whose genetic variation is low due to hunting making all but one breeding colony extinct by 1900, the diversity amongst subantarctic specimens remains high.[7] There appears to be 3 distinct genetic lineages in the species, with none of them representing any particular geographic area.[8]
As with other otariids, subantarctic fur seals gather in large rookeries on the shore to breed. They have a polygynous mating system in which dominant males will defend their harem of 6-20 females. Fights between males for mating rights are violent and can result in severe injuries. Apart from physically fighting, males will also compete against each other through vocalizations and threat displays.[9] The breeding season takes place from November to January. For females, gestation lasts around 51 weeks, at the end of which they will give birth to a single pup. 8-12 days after giving birth, they will breed again. Males are capable of mating at around 3-4 years of age, but they are unlikely to be able to hold a harem until they are 10-11 years old. Females reach sexual maturity at around 5 years.[10]
After being born, pups spend around 11 months feeding on their mother's milk, which contains around 39% fat. They stay at the rookery during this period. Weaning occurs shortly before the next offspring is born. They molt their black coat at around 3 months of age. As adults, they continue to molt their coat annually between March and May.[10][11]
Subantarctic fur seals hunt in shallow waters at night, when myctophid fish come close to the surface. They also feed on squid.[12] Other prey can include crustaceans, and occasionally rockhopper penguins and seabirds.[13]
Subantarctic fur seals are unique in their tendency to occasionally travel very long distances from their home islands. Young males have been seen travelling thousands of miles from their native habitat. In July 2015, a young male seal was caught and later released by local fishermen off the coast of Kenya, more than 4,000 miles (6.400km) from its home. This is the furthest north that a subantarctic fur seal has been recorded travelling to.[14] Lactating females have been seen travelling up to 530km from their colonies in order to forage for food.[15]
The subantarctic fur seal (Arctocephalus tropicalis) is found in the southern parts of the Indian, Pacific, and Atlantic Oceans. It was first described by Gray in 1872 from a specimen recovered in northern Australia—hence the inappropriate specific name tropicalis.
