WHEN THE BULLS COME CALLING
Black-backed jackal scavenges on the fringe of a seal colony = Peter Tarr

Life in a fur seal colony is fairly uneventful for about 10 months of the year while the cows suckle and wean their young. The pups at first stay ashore on so-called playgrounds when the cows leave the rookery to forage at sea, but as time passes they venture into the water and learn to fend for themselves.

Newborn pups suckle within an hour of birth and their mothers remain ashore with them for a week or more before they begin to forage again. As the pups learn to hunt they gradually become less dependent on milk for sustenance. By the time they are seven months old they are already able to stay away from land for three or four days at a time.

One out of every four pups born on the Namib coast dies in the first year of its life. They mostly starve to death or, in mainland colonies, fall prey to black-backed jackal and brown hyena. Indeed jackal scavenge among seals in broad daylight.

Once the pups are fully weaned the seal population left on land becomes noticeably smaller and quieter. It is the lull before the storm. Wild disorder is about to break out as the great bulls are returning from the sea to mate again.

Grown bulls typically weigh about 250kg, but when they haul out in mid-October for the rut, they may be as heavy as 360kg. In the weeks ahead they are going to use up all the accumulated reserves of blubber to establish and defend breeding territories.

Chest-to-chest combat between bulls is common, with bite wounds inflicted on tender parts, as latecomers try to find room for themselves. When the cows come ashore to lay claim to space within a breeding territory, they in turn fight among themselves, so much so that territorial bulls sometimes intervene to settle matters. Eventually as many as 60 or 70 cows, although generally far fewer, form a haremlike group around a bull.

Over a period of about five weeks they each give birth to a pup conceived during the previous rut. Five or six days after the birth of the pup, as soon as the cow comes into oestrus again, the territorial bull mates with her. The newly fertilised ovum remains dormant for three months before an embryo begins to develop. All in all the gestation period is about a year.

The harems disintegrate in January after the cows begin to forage again. Soon the bulls disperse as well. The rut is over for another year.

A carnivore with flippers

Cape fur seals are endemic to southern Africa, with colonies on islands and patches of mainland around the coast from Namibia to South Africa. About 60% of the subcontinental population, or some 700 000 to 800 000 seals, is found on the Namib coast in Namibia. They breed at about 15 sites, mostly on the mainland.

The biggest colony is located at Cape Cross, north of Swakopmund, where 270 000 seals occupy a rocky promontory . Breeding colonies at Atlas Bay and Wolf Bay, south of Lüderitz, hold 170 000 and 110 000 respectively. An estimated 40 000 seals on Long Island, just offshore from Atlas Bay and Wolf Bay, form the biggest island population.

Although they are marine mammals with flippers, seals are classified as carnivores, alongside predators like lion and hyena, terrestrial mammals with legs and paws.

Different families exist among seals, just as they do among terrestrial carnivores. Fur seals and sea lions form one family (Otariidae) and so-called true seals (Phocidae) another. The former evolved from a primitive bear and the latter possibly from ancestral stock related to early racoons or weasels.

Not only ancestry and fur set fur seals apart. With tiny ears flattened against their head, they are also called "eared" seals, as true ("earless") seals lack pinnae or external ears. Fur seals move -- even gallop -- on all fours when they are on land, while true seals are unable to use their hind flippers for terrestrial locomotion.

Apart from southern elephant seals (Mirounga leonina), rarely sighted as migrants or vagrants, true seals are generally not found in Namibia.

Nine species of fur seal exist worldwide. True to their ancestry, the generic or group name of eight of them, Arctocephalus, describes the head as bear-like. Cape fur seals form a species together with Australian fur seals (A. p. doriferus). The specific name given to the species, pusillus, means "small" because a pup was mistakenly used, in 1776, when Cape fur seals were first described scientifically.

 


CAPE FUR SEAL
(Arctocephalus pusillus pusillus)
Unique to southern Africa

Length: bulls 2,15m, cows 1,56m, newborn pups 0,6 - 0,7m.
Mass: bulls 247kg, cows 57kg, newborn pups 4,5 - 7kg.
Habitat: beaches and islands.
Range: 160km out to sea from shore.
Prey: mainly schooling fish such as pilchard, anchovy, horse mackerel; also octopus, squid, cuttlefish, lobster, crab; consumption equals about 8% of body weight daily.
Breeding: one pup per year; gestation period about a year.
Status: common and secure.


THE RETURN OF THE WHALES
Southern right whale = Rod Haestier

A century and a half after southern right whales were hunted to near extinction in Namibian waters, they are again calving and mating off the Namib coast where they were once abundant. Sightings are infrequent as the population is still small, but a breeding stock now exists that visits the coast seasonally. The species is slowly recolonising its erstwhile range in the south-east Atlantic.

Southern rights frequent sheltered bays on the Namibian coast from June to December with a peak in September. They calve and mate in shallow water, quite close to the shore, but sightings are purely a matter of chance. Apart from Lüderitz Bay and Walvis Bay, suitable bays are few and far between. Moreover, smaller bays like Baker's Bay, Elizabeth Bay, Hottentot's Bay, Spencer Bay and Möwe Bay are not readily accessible to whale watchers.

For a month or two after she gives birth, the cow remains inshore with her calf, until they set off together at a leisurely pace for the Antarctic. It is estimated that a suckling drinks 600 litres of milk per day. The adults themselves do not feed locally. They migrate in midsummer to the Antarctic where they feed for five or six months on planktonic crustaceans known as krill.

Southern rights are a species of baleen whale, so named for the baleen or "whalebone" plates, 2m long and 300mm wide in adults, that hang from the roof of their mouth. They use the plates to strain krill. With as many as 400 baleen plates on either side of their mouth, their head accounts for about a quarter of their overall length.

Baleen whales were the most harried and hunted of all whale species in the past. They were taken in both the northern and southern hemispheres for blubber and baleen. Oil from the blubber was used as lamp oil, or went into soap, while the baleen was cut up to make stays for corsets and hoops for petticoats.

Right whales were given their name in the early days when whalers described them as the "right" or best ones to pursue. As they swam slowly they could be approached in rowboats and harpooned from close range, their carcasses stayed afloat long enough for subsequent recovery and they yielded a lot of oil and baleen.

With whale populations in decline off the east coast of America, New England whalers began to hunt southern rights off the Namib coast before 1770. Their operations were later intensified under contract to British interests. Kills reached a peak between 1785 and 1805. Whales were even taken for baleen alone, their bodies discarded as waste, when whalers already had a full load of oil aboard.

The whales were processed on board ship. Pots for rendering blubber to oil stood on platforms below the forecastle. "Tried out" chunks of whale, from which the oil had already been extracted, were used to fuel the furnaces. The ships returned to land only when it was necessary to provision or unload their cargo.

So great was the slaughter that southern rights, once such a prolific presence, disappeared from the Namib coast well before 1850. Whalers began to pursue other species instead, primarily humpbacks (Megaptera novaeangliae), but in due course such populations also collapsed. Other species taken were sperm whales (Physeter catodon), fin whales (Balaenioptera physalis) and blue whales (B. musculus).

The last of five whaling stations that operated along the coast between Walvis Bay and Lüderitz Bay in the 20th century closed down in 1930.

In 1935 southern rights became the first of the large whales to be afforded a level of international protection. The species is still classified as vulnerable, which is to say not yet out of danger, despite population increases throughout its range.

Off the southern tip of Africa, where northward migration along the coast branches off into the Atlantic and Indian oceans, the population is now doubling every 10 years. Other populations of southern rights migrate from the Antarctic into the South Pacific.

Eight species of baleen whale and 32 species of toothed whale and dolphin are found in Namibian waters. All of them are now protected under Namibian law.

Benguela or Heaviside's dolphins (Cephalorhynchus heavisidii), bottlenosed dolphins (Tursiops truncatus), dusky dolphins (Lagenorhynchos obscurus) and -- on the southern coast -- killer whales (Orcinus orca) are frequently seen inshore.


SOUTHERN RIGHT WHALE
(Eubalaena australis)

Size: length 14-16 m; head is quarter of total length.
Mass: 30 - 60t.
Trademark: wart-like callosities, thickened and hardened skin, on jaws and forehead.
Habitat: sheltered bays.
Range: between Antarctic and all southern oceans.
Diet: planktonic crustaceans.
Breeding: one calf every third year; gestation period about a year.
Status: vulnerable.

Lüderitz ......

 

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