(Zimmerman, 1783) - South American fur seal
South American fur seals are stocky, as fur seals go. They have a moderately long, flat-topped, pointed muzzle, with a medium-sized nose. The nostrils are oriented straight ahead, and the nose extends past the mouth. There is a noticeable forehead and rounded crown. The ear pinnae are long and prominent, and the vibrissae of adults are creamy white, and short to moderate in length. Adult males are larger than females, with a proportionately thicker neck and more massive shoulders. Males also develop a mane of longer guard hairs on the head and shoulders.
Adult females and subadults are dark brown to greyish black above and paler, often mixed rusty brown, tan, and greyish, below. A band of light colour wraps around the lower neck, but darkens toward the top. The head is dark, but the muzzle is sometimes partly greyish tan. Lighter areas often surround and highlight the greyish tan ears, particularly in adult females and older subadults. The fur on the top of the flippers is generally quite dark. As they age, males darken and become more uniformly coloured, generally dark brown, with grey to yellowish tan grizzled frosting. Some bulls are paler. At birth, pups are dark, but there may be some paler markings on the face and muzzle, and some animals are paler below.
The dental formula is I 3/2, C 1/1, PC 6/5.
Can be confused with
At least 6 other otariids can be found within the range of the South American fur seal: Juan Fernandez, Antarctic, subantarctic, and Galapagos fur seals, and South American and Galapagos sea lions. See the section on the Juan Fernandez fur seal (A. philippii 1) for distinguishing that species from South American fur seals. Subantarctic fur seals are comparable to South American fur seals in length and weight, but have a unique colour pattern on the chest and head, and (in males) a tuft of longer prominent guard hairs on the crown. Antarctic fur seals are smaller and lighter overall as adults, with a shorter muzzle, and often longer and more conspicuous creamy white vibrissae and a more grizzled coat. Galapagos fur seals are much smaller, with a muzzle that, in comparison to that of South American fur seal, is very short and blunt.
Adult males reach 1.9 m and 120 to 200 kg, females are about 1.4 m and 40 to 50 kg. Newborns are 60 to 65 cm and 3.5 to 5.5 kg.
South American fur seals are widely distributed from central Peru, around the southern tip of the continent, and up to southern Brazil. They also occur around the Falkland Islands. Distribution at sea is poorly known. These seals are thought to use primarily coastal, continental shelf and slope waters; however, there are records from more than 600 km offshore.
Biology and Behaviour
Breeding take place from mid-October through mid-December. Males are territorial, and fighting can result in dramatic wounds and scars.
No migration is known and colonies on islands off Uruguay are occupied by portions of the population year-round. At sea, these fur seals may be seen rafting at the surface, with head down and flippers waving in the air. They frequently groom while at the surface. Groups of 15 to 20 animals have been seen traveling together offshore.
The diet is poorly documented, but includes a variety of small schooling fishes and invertebrates, such as cephalopods, crustaceans, and gastropods.
There is a long history of human exploitation of South American fur seals. Native peoples, particularly those of the Tierra del Fuego region depended heavily on pinnipeds for food and skins. Exploitation by Europeans goes back to the 16th Century and sealing for skins and oil was heavily pursued in the late 18th and early 19th Centuries in many parts of the species' range. Although commercial sealing has been discontinued elsewhere for these animals, it continues to this day in Uruguay and is the longest running sealing operation in the world. Fur seals are taken incidentally in fishing operations and by poaching throughout their range, particularly in Peru. Some are taken in Chile for use as bait in crab traps. Overfishing of prey species probably acts to limit population growth in some areas.