South American Fur Seal (Arctocephalus australis)
The South American Fur Seal (Arctocephalus australis) is found around South America, on both the Pacific and Atlantic coasts. Their range in the west reaches from Peru to about a third of the way down Chile, while on the east coast, they are found from southern Brazil, right the way south to the Falkland Islands. ‘Arctocephalus’ means ‘bear head’ and ‘australis’ means ‘of the south’. Occasionally they are called the Southern Fur Seal. This fur seal is abundant and mostly rising in numbers, so classified overall as Least Concern. However, it should be noted that one subspecies meets the criteria for a Vulnerable status. Estimated population size = 219,000.
A. australis are reasonably large fur seals (males ♂ up to 2 m long/ 200 kg, females ♀ up to 1.5 m/ 58 kg) with stocky bodies that display sexual dimorphism. Males are large with chunky bodies, thick necks, large flippers, and fluffy, thick manes. Females are more streamlined and lack the manes, though both sexes have long, slender flippers that are covered with fur almost to the ends. Facially, both have rounded heads and fairly pointed muzzles, with a prominent nose at the end. The muzzle of the males is almost flat on top, while the female’s is quite compact. In general, the male coat is some shade of brown, perhaps blackish or greyish, with wiry greyness in the mane. Invariably the the flippers are dark, reddish-brown, and the lower body is yellowish. The female coat is usually dusky grey-brown, fading to paler underneath, and often with a lighter shade around the eyes and muzzle as well. The underside may appear slightly tan-coloured.
A. australis are a generalist feeder, but chosen prey depends very much on location and year. In general, fish (pelagic and demersal) and cephalopods are the main groups, also crustaceans and gastropods. Different populations will often have a handful of favoured species. For example, those round the Falkland Islands rely heavily on squat lobster. Those in Uruguay were recorded taking weakfish, cutlassfish and anchovies frequently. Initial research has shown that the species dives from 50-600 metres when on foraging dives, but other than that, data is lacking.
Sexual maturity – males ♂6-7 years old/ females ♀ 3-5 years old.
Colonies of these polygynous fur seals form along rocky coastlines or on ledges above the shore. Territorial aggression in the males can lead to serious injuries as they compete and fight for access rights to between 3 and 20 females. In Uruguay it operates more as a ‘lek’ system, where females are free to come and go between territories. There is a 3-4 month delayed implantation period, and then gestation, altogether lasting around 11 months. Pups are born in October-January, with a peak in November/ December. These pups have a black natal coat that lightens to brown with sandy tan underneath, moulted fully between 3 and 4 months. The mother suckles her pup for around 11 days before beginning to make short trips to sea to forage, and usually the young are weaned any time from 6-12 months on. However, nursing can continue for several years, even until another year’s pup is born in some cases. An adult moult occurs post breeding. The life expectancy for A. australis is estimated to be around 21 years of age.
A. australis is recognised to have two subspecies:
South American Fur Seal (Arctocephalus australis australis)
Peruvian Fur Seal (Arctocephalus australis (Peruvian/Northern Chilean subpopulation))
Photos: (1, 3) Felipe Montalva Pizarro (2) Natalie Pozo