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Arctocephalus australisSouth American fur seal

By Amelia DelGreco

Geographic Range

South American fur seals (Arctocephalus australis) inhabit South America. They reside on rocky shores along the coasts of Uruguay, Argentina, Chile and Peru. They are heavily distributed along the Atlantic side of South America. They are also commonly found on the Uruguay islands and the Falkland Islands. These areas are more secluded with less human disturbances and are safer for breeding periods. They are found as far north as central Peru. There have been sightings of these seals as far off as 600 km. However, knowledge of South American fur seals lives at sea is limited. (Campanga, 2008)

Habitat

South American fur seals spend their time both on shore and in the ocean. Breeding periods are spent on the shores of Peru, Argentina, Uruguay and the Falkland islands. When they are not in breeding season, they are usually in the ocean. When on land, they prefer rocky areas to shield them from the sun. They are able to move quite easily on land and are able to climb steep slopes. (Eales, et al., 2006; Reeves, et al., 2002)

  • Range depth
    39.6 to 170.6 m
    129.92 to 559.71 ft

Physical Description

Female and male South American fur seals differ greatly in size. Males can get up to three times larger than females. Females can reach up to 1.4 m in length, whereas males can reach up to 1.9 m. Females weighing 50 kg are considered large, but males can get up to 200 kg. Female seals are either dark brown or a dark gray dorsally, and ventrally are lighter in color. Male colors are similar but can get even darker. Juvenile males begin to produce guard hairs around their face, from the top of their heads to about the shoulder area. When seals become an adult, the mane of guard hair is frosted with a lighter gray coloring. Adult seals have a stocky body and compared to other fur seals, have a longer snout. The fins are also longer and narrower than other fur seals. South American fur seals have 20 upper teeth and 16 lower teeth, which is beneficial when they have to climb on rocky shores. Other fur seal fins may be more paddle like and wider. South American fur seals when born weigh between 3.5 and 5.5 kg and measure 60 to 65 cm in length. When they are first born, the pup is black, and as it grows and molts, it becomes lighter. They molt 3 to 4 months after birth. (Campanga, 2008; Eales, et al., 2006; Phillips and Stirling, 2000; Reeves, et al., 2002)

  • Sexual Dimorphism
  • male larger
  • sexes colored or patterned differently
  • Range mass
    60 to 200 kg
    132.16 to 440.53 lb
  • Range length
    1.4 to 1.9 m
    4.59 to 6.23 ft

Reproduction

South American fur seals are polygynous; males mate with more than one female each breeding period. Males will compete for certain areas along the shore between October and December to establish territories for them and their females. The dominant males will gain the most females and the largest territory. The ratio of male to female South American fur seals is greater than that of any other mammal, implying that each male has more females on average than any other polygynous mammal. ("Marine Bio", 2012; Arnould, 2002; Campanga, 2008)

Each year between October and December South American fur seals begin their breeding period. Males and females come to shore and males fight for territories. Females give birth anytime throughout these three months. Female seals give birth to just one pup per breeding season. When the pups are born they can weigh between 3.5 and 5.5 kilograms and measure between 60 and 65 centimeters long. The pups are first black when they are born and eventually molt to a dark brown or grey. Female South American fur seals wean their pups between 6 and 12 months, but sometimes they can wean up to 3 years. In this extreme case, the mother seal will potentially be nursing two pups at the same time. Seven to ten days after giving birth, the female will mate with a male. Embryonic diapause lasts between 3 and 4 months. The gestation period ranges from 8 to 12 months. Male seals reach sexual maturity around the age of 7, but many of them don’t actually mate until they are 8 years of age. This may be the result of competition required to earn territory and females. Females, on the other hand, reach sexual maturity around the age of 3. (Campanga, 2008; Eales, et al., 2006; Reeves, et al., 2002)

  • Breeding interval
    South American fur seals breed once a year shortly after the females give birth.
  • Breeding season
    South American fur seals breed between October and December.
  • Range number of offspring
    1 (high)
  • Average number of offspring
    1
    AnAge
  • Range gestation period
    8 to 12 months
  • Range weaning age
    6 to 36 months
  • Average weaning age
    12 months
  • Average age at sexual or reproductive maturity (female)
    3 years
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1095 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    7 years
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    2556 days
    AnAge

Female seals give birth and feed pups until they are able to feed on their own. Mothers wean pups anywhere between 6 to 36 months. After the pup is born the mother alternates between days in the water foraging for food and days on land caring for her young. Often times, the survival of the pup relies on how crowded the shoreline is with seals. When the mother is gone foraging, if the shore is too crowded, the young pup can get trampled by other female seals or get lost and starve. (Charrier, et al., 2003; Phillips and Stirling, 2000)

  • Parental Investment
  • precocial
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • female
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • female

Lifespan/Longevity

In the wild, fur seals can live between 12 and 30 years. Little else is known about the lifespan of South American fur seals. ("National Geographic", 2012)

  • Typical lifespan
    Status: wild
    12 to 30 years
  • Range lifespan
    Status: captivity
    female: 30.6, male: 20 (high) years
    AnAge

Behavior

Fur seals are social and live together in rookeries along the shore. They often fish in groups and South American fur seals do move around. They spend most of their time in the water swimming, but during the breeding season they live on land. They have long front flippers to help them move around on the rocky shores. Seals pick areas to breed that are rocky and provide shade. Each male competes for an area, and the most dominate males will obtain the largest area. To communicate they use vocal noises. The mother and the pup have a special call that is individual to each pair. Studies indicate that a pup only recognizes its mother's voice. ("Marine Bio", 2012; Charrier, et al., 2003; "National Geographic", 2012; Phillips and Stirling, 2000)

Home Range

Male seals compete for territory during breeding season along the shore. Depending on how dominate the male is, the larger the territory. In the water little is known regarding the size of South American seals home ranges. ("Marine Bio", 2012; Charrier, et al., 2003; "National Geographic", 2012; Phillips and Stirling, 2000)

Communication and Perception

South American fur seals communicate vocally and with touch. Males will compete for territories and females physically. When the seals communicate with each other over distances they use vocalizations. An important aspect of vocal communication between mothers and pups is vital to the pups survival. If at any time the mother and pup are separated they have an individualized call that only the mother and pup recognize. When the mother goes to forage in the ocean for a couple days while lactating, she needs to be able to find her pup again when she returns to shore. If they do not reunite, the young seal risks starving to death and being trampled by other mother seals. ("Marine Bio", 2012; Charrier, et al., 2003; "National Geographic", 2012; Phillips and Stirling, 2000)

Food Habits

South American fur seals are nocturnal hunters. They are known to feed on anchovies, shrimp, lobster, squid and krill. Location plays a role in the primary diet of these seals. In Peru and Uruguay the seals feed on anchovies. The seals living closer to Brazil shores hunt for shrimp. South American fur seals in Chile tend to hunt for krill, specifically lobster krill. Fur seals can dive up to 170 m and can stay underwater for 7 minutes per dive. If the females are caring for young on shore, they will spend a couple days at sea, then come back for a few days to care for their pup. It is not known how much food is consumed by the seals daily in the wild. ("Marine Bio", 2012; Eales, et al., 2006; "National Geographic", 2012)

  • Animal Foods
  • fish
  • mollusks
  • aquatic crustaceans

Predation

South American fur seals are hunted by the South American sea lions, orcas, sharks, and humans. Other dangers posed to them include climate change and over-fishing. ("Marine Bio", 2012; Eales, et al., 2006; "National Geographic", 2012)

Ecosystem Roles

South American fur seals are an integral part of their food web and, thus, play a role in ecosystem trophic dynamics.

Economic Importance for Humans: Positive

These seals were hunted from 1515 to 1979 in Uruguay and Chile. Seals are no longer hunted commercially, but are still often poached. South American fur seals were hunted for their fur, skin, and oil to make clothes, leather, and light lanterns respectively. When they are poached, often time their meat is used for king crab bait. ("Marine Bio", 2012)

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

There are no known negative economic effects of South American fur seals. ("Marine Bio", 2012)

Conservation Status

South American fur seals used to be commercially hunted, but now that is no longer an issue. In 1997 the seals were harmed by an oil spill that covered about 5,000 sq m. An estimated 6,000 seals were killed. During El Nino years, food becomes scarce for the seals on the Pacific side of South America. In Peru 2012, the population was recovering from an El Nino year that wiped out 80% of the females and pups. In Uruguay, the population is healthy and growing. ("Marine Bio", 2012; Campanga, 2008)

Contributors

Amelia DelGreco (author), University of Wisconsin-Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Laura Podzikowski (editor), Special Projects.

Glossary

Atlantic Ocean

the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.

World Map

Neotropical

living in the southern part of the New World. In other words, Central and South America.

World Map

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

delayed implantation

in mammals, a condition in which a fertilized egg reaches the uterus but delays its implantation in the uterine lining, sometimes for several months.

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

embryonic diapause

At about the time a female gives birth (e.g. in most kangaroo species), she also becomes receptive and mates. Embryos produced at this mating develop only as far as a hollow ball of cells (the blastocyst) and then become quiescent, entering a state of suspended animation or embryonic diapause. The hormonal signal (prolactin) which blocks further development of the blastocyst is produced in response to the sucking stimulus from the young in the pouch. When sucking decreases as the young begins to eat other food and to leave the pouch, or if the young is lost from the pouch, the quiescent blastocyst resumes development, the embryo is born, and the cycle begins again. (Macdonald 1984)

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

female parental care

parental care is carried out by females

food

A substance that provides both nutrients and energy to a living thing.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

molluscivore

eats mollusks, members of Phylum Mollusca

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

piscivore

an animal that mainly eats fish

polygynous

having more than one female as a mate at one time

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

tactile

uses touch to communicate

terrestrial

Living on the ground.

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

young precocial

young are relatively well-developed when born

References

2012. "Marine Bio" (On-line). South American Fur Seals, Arctocephalus australis. Accessed August 20, 2012 at http://marinebio.org/species.asp?id=312.

National Geographic Society. 2012. "National Geographic" (On-line). Fur Seals. Accessed August 23, 2012 at http://animals.nationalgeographic.com/animals/mammals/fur-seal/.

Arnould, J. 2002. Southern Fur Seals. Pp. 1146-1151 in W Perrin, B Wursig, J Thewissen, eds. Encyclopedia of Marine Mammals, Vol. 1, 1 Edition. San Diego, California: Academic Press.

Campanga, C. 2008. "Arctocephalus australis" (On-line). IUCN Red List. Accessed August 20, 2012 at http://www.iucnredlist.org/details/2055/0.

Charrier, I., N. Mathevon, P. Jouventin. 2003. Individuality in the voice of fur seal females: an analysis study of the pup attraction call in Arctocephalus tropicalis. Marine Mammal Science, 19/1: 161-172.

Eales, P., S. Scott, M. Scott, K. Bryan, D. Burnie, et al.. 2006. Ocean: The World's Last Wilderness Revealed. 375 Hudson Street, New York, NY10014: DK Publishing.

Phillips, A., I. Stirling. 2000. Vocal individuality in mother and pup South American fur seals, Arctocephalus australis. Marine Mammal Science, 16/3: 592-616. Accessed August 08, 2012 at http://onlinelibrary.wiley.com.ezproxy.uwsp.edu/doi/10.1111/j.1748-7692.2000.tb00954.x/pdf.

Reeves, R., B. Stewart, P. Clapham, J. Powell. 2002. Guide to Marine Mammals of the World. New York: Alfred A. Knopf, Inc..

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