Cape Fur Seal Bulls (Arctocephalus pusillus) arrive early at breeding grounds

One of the exciting excursions, included in the scheduled CC Africa Expeditions in Namibia, is a visit to one of the biggest seal colonies in Africa at Cape Cross.

The total population (South western coast of Africa) of Cape Fur Seals ranges between 1.5 to 2 million from which two thirds live off the Namibian coast, with the biggest colony of 150.000 to 200.000 seals at Cape Cross.

As I approached this colony with 7 guests on 27 August, we were expecting to find the female seals, together with the pups of the last season, in one massive group, but then we observed something completely different.  Until before the mating season, the females & pups usually form one large congregation, but it was surprising to see that the bulls had already gathered their females in small harems

around them in clusters along the coast. The males usually arrive some weeks before the females give birth.  At the time of this sighting, there were no new born pups visible yet.

What we saw, would be a normal scenario for October, but this year, the males were already ashore and competing for females for their harems by the end of August. Usually the mating season for Cape Fur Seals at the Namibian coast starts in mid-October.

According to local marine guides in the area, the males had not been recorded to haul out this early.

One known exception to this pattern, is found in the colony at Pelican Point / Walvis Bay, 140 km south of Cape Cross, where the males arrived in mid-October.

According to "Mammals of the Southern African Subregion - "Smither's", "...males haul out about mid-October and establish territories. Females follow later to give birth ... pups are born after almost 1year gestation in late November, early December ... females come in oestrus 5 or 6 days after giving birth ...".

The question is - what made the males haul out so early!?

Since I had found no explanation for this phenomenon in the available literature,

I would appreciate any comments from Wildwatch readers.

Posted: Namibia Expeditions by Jan Mohrdieck, Date: 27 August 2007