(Heller, 1904) - Galapagos fur seal
The Galapagos fur seal is short and compact; with less sexual dimorphism than in other otariids. The flippers are typical for the genus, as are the long, prominent ear pinnae. However, the muzzle is short and pointed, with a small button-like nose, contributing to the flattened look of the end of the muzzle. The eyes appear large. The vibrissae in adults are cream coloured and fairly long. Adult males are much thicker in the neck and shoulders than females, but are not as dramatically different from females as are bulls of other species. A mane of only slightly longer guard hair covers the bull from the shoulders to the top of the head.
Galapagos fur seals are dark brown above, rarely with gold-brown or silver-grey hues. In both sexes, most of the muzzle is pale tan and in adult males, this colour can extend onto the face and forehead over the eyes. In adult females and subadults, the chest is pale greyish tan, sometimes continuing to the back of the neck, and the belly is rusty tan. A variable amount of grizzled lightening can regularly be found on the dark mane of bulls. In both sexes the long ear pinnae and the area of their insertions can be tan. Pups are blackish brown, sometimes with greyish to whitish margins around the mouth and nose. The pups moult this natal coat for one that resembles that of the adult female.
The dental formula is I 3/2, C 1/1, PC 6/5.
Can be confused with
Galapagos fur seals normally share their restricted range in the Galapagos Archipelago only with the Galapagos sea lion. The fur seal can be readily distinguished from the sea lion by the former's more pointed muzzle; lighter colour; and toe, ear pinnae, and fur characteristics, as well as the lack of a prominent sagittal crest in males. The South American sea lion has also been recorded as a vagrant in the Galapagos Islands; all of the features described above, plus its much greater size and robust features at nearly all ages, should be useful in distinguishing this species from the Galapagos fur seal.
Adult males so far measured have averaged 1.6 m, with weights of 60 to 68 kg. Adult females have shown a range of lengths of 1.1 to 1.3 m and weights of 21.5 to 33 kg. Pups are approximately 4 kg at birth.
This species is confined to the vicinity of the Galapagos Archipelago. Most of their rookeries and hauling grounds are found on the western and northern islands, nearest to the areas of oceanic upwelling. The preferred habitat ashore is rocky shores with boulders and lava, under ledges, and in spaces between boulders, where they seek shelter from the sun.
Biology and Behaviour
The behaviour of the Galapagos fur seal has been extensively studied. It has a fairly long pupping and breeding season, lasting from mid-August to mid-November. The peak of pupping shifts from year to year, but usually occurs sometime from the last week of September through the first week of October.
In the water, particularly near haul-outs, Galapagos fur seals raft in postures typical of many of the southern fur seal species. There is no evidence for migration, and they do not seem to spend prolonged periods of time at sea.
Food habits are poorly known. Galapagos fur seals consume a variety of small squid species and several species of schooling fishes. They seem to feed mostly at night, possibly exploiting deep scattering layer organisms when they rise to the surface. They perform short, shallow dives, with an average depth of less than 30 m.
There is a legacy of destruction at the hands of humans, as with all fur seals. Whalers and sealers visiting the Galapagos Islands for water and fresh provisions and skins took no fewer than 22500 during the period 1816 to 1933. The population reached unknown, but presumably low levels, from which it has rebounded since 1940. Today they are fully protected by Ecuadorian law, and benefit from the outstanding management of the islands as a national park and marine reserve.