Afro-Australian Fur Seal (Arctocephalus pusillus)

The Afro-Australian Fur Seal lives by many different names. This is because they are found in both southern Africa and southeastern Australia, and so have become known as the South African or Cape Fur Seal and the Australian Fur Seal in the two different locations. In some literature they are also called the Brown Fur Seal. In an effort to choose one universal moniker, we have researched usage and found this, which combines both place names, to be the most suitable option. The scientific name describes the ‘bear head’ again, and confusingly, the second part means very small. Supposedly, when it was first described, the explorers were encountering a juvenile, but they didn’t realise it at the time! A. pusillus are a fairly abundant species and as such recorded as Least Concern at this time. Estimated population size = 2,120,000.
A. pusillus is the largest of the fur seals (males up to 2.3 m long/ 360 kg, females up to 1.8 m/ 120 kg), and almost like a sea lion in appearance. They have solid, robust bodies, with a good degree of sexual dimorphism. Males are heavily built with huge chest and neck, and a thick mane. Their heads are large and hefty with a broad, chunky muzzle and large nose. Females are somewhat smaller, but still well-covered, with medium sized heads and upturned, slightly pointed muzzles. Flippers in both are short at the back, and long at the front, with only sparse hair over three quarters of their length. Vibrissae are long and light coloured. The colour of the male animals is brown, ranging from chestnut to dark brownish-black, through to grey-black, sometimes with packer flecks around the neck and chest. Females are generally lighter, either chestnut brown or pale silver/ grey, and paler ventrally than dorsally.
Feeding behaviour:
There is some difference in foraging behaviour between A. pusillus from different locations, showing generalist and opportunistic habits. The species forages in the pelagic, as well as the benthic environment, with dives not routinely exceeding 100 metres. Some typical types of prey consumed include: cod, hake, jack, jack mackerel, snake mackerel, goby, sardine, anchovy, and flathead fish, sea squirts, squid, octopus, cuttlefish, rock lobster, shrimp, prawn, and amphipods. Occasionally they will also take seabirds, including penguins.
Breeding behaviour:
Sexual maturity – males 4-5 years old/ females 3-4 years old.
A. pusillus are highly polygynous. The breeding season takes place between October and January with males arriving first to the large rookeries, and displaying and sparring to establish and maintain territories. Females will also fight amongst themselves on arrival, to obtain a suitable birthing area, and a harem to join. Copulation occurs at the water’s edge, and after a 3/4 month delayed implantation period, the foetus starts to develop, with pups born almost one year on from fertilisation. The pups are born black-coated, and the mothers remain by their side for around a week before commencing short foraging trips at sea. Nursing continues for approximately 10 months (though there is some variation and this sometimes lasts longer, occasionally for several years) but pups may forage for themselves earlier than this. By late February they will begin to moult their natal coat, having a full grey-fawn juvenile coat by May, when they will spend more time in the water learning to feed. These durations do vary slightly between seals in Africa and Australia.  The adult moult takes place in late summer and early autumn, with females first and then males. Life expectancy is around 20-25 years, with males averaging slightly less.
The species is split into two subspecies, representative of the geographical separation:
Cape Fur Seal (Arctocephalus pusillus pusillus)
Australian Fur Seal (Arctocephalus pusillus doriferus)

Photos: Bekka Hall, NSW, Australia

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