Cape Cross, on the coast of Namibia, is known above all for the Cape fur seals colony present on its beaches; there are 9 species of seals and sea lions in the world, 3 of which are on the coasts of Southern Africa, Cape Cross fur seals belong to the Arctocephalus pusillus pusillusspecies, that is the largest one.
These mammals do not migrate, the colony is present at Cape Cross throughout the year, although some specimens, especially males, spend several months at sea; it has been found that some seals have swum for 1,600 km in 20 months and it can happen to sight them at 200 km from the coast.
Today the Cape Cross area is a protected zone, owned by the Government of Namibia, the Cape Cross Seal Reserve.
The Cape Cross colony is the largest Cape fur seals colony in the world and is one of the two largest on the coast of Namibia, the other is in Luderitz; in total, Namibia has 26 colonies of seals, with a total of about 650,000 specimens, of which 80,000 to 100,000 specimens belong to the Cape Cross colony.
Despite seals, or sea lions, are protected, the Namibia government has been implementing a controlled abatement program for years to monitor the number of specimens.
The opinions on this activity are very controversial and contrasting: the animal rights advocate that the slaughtering happens more to obtain the precious skins of the puppies than for a true control of the number of the heads; while the Namibian government claims that an over population of seals in these beaches puts the Atlantic Ocean's fish in the waters in front of the colonies at risk, but the data of the Namibian government are in stark contrast to the data provided by some environmental organizations.
An adult Cape seal can get to eat 270 kg of fish a year, but more than half the fish they eat do not belong to species that are caught by man; Cape fur seals in Cape Cross can count on large quantities of food, in fact the Atlantic Ocean at this point, thanks to the current of Benguela, is very rich in fish.
Between the end of November and the beginning of December the seal males return to the colony's beach to reproduce; they are gigantic specimens that weigh up to 360 kg, they are much larger and more impressive than the females, that can weigh only 75 kg.
Between the end of November and the beginning of December the puppies are born, each female gives birth to only one puppy at a time; at birth a puppy weighs between 4.5 kg and 6.4 kg and is long from 60 cm to 70 cm.
Immediately after birth the puppies start sucking milk from their mother and live in symbiosis with her for almost a year, a period in which they continue to feed on their mother's milk and, around 8 months of life, they begin to enter the water, always with the mother, to start fishing.
The births are synchronized to increase the chance of survival of the puppies, the females succeed in delaying the embryo's engraftment to facilitate this phenomenon.
The mortality of puppies in the first year of life is around 30%, the main cause are the predators that are on land, such as black-backed jackals and brown hyenas, that often take advantage when mothers are at sea to eat; while in the water the predators, both for the puppies and for the adults, are the killer whales, the white sharks and the mako sharks.
Immediately after the delivery the females are ready to mate again with the dominant males, the harem can count many specimens; the new generation of puppies will be born after about 8 months of pregnancy.
During the period of mating, the males lose an important part of their weight, as a result of the struggles for dominance over females and for control of the territory.
How to recognize a fur seal, or sea lion, from a seal?
Fur seals have external ears, while seals have internal ones.
Furthermore there are also differences in swimming and on land movements.
Fur seals swim exclusively with the forelegs, while seals use only the hind limbs.
On land, the sea lions move using alternately the hind and anterior limbs, and are also able to rotate the hind limbs forward and this allows them to assume an almost upright position; the seals instead use only the forelegs on dry land and this leads them to crawl with the belly on the ground, moreover they are not able to assume a standing position.
Last but not least, the fur seals have a thicker fur than the seals; more precisely, they have a layer of short, dense fur that protects them from the low temperatures of the ocean's waters, they also have a fur with longer and harder hairs that allow the fur below not to get wet.