Rainforest Radio

EDITOR’S NOTE: Jana of the Jungle reporting here with an article by two men from the Marine and Coastal and Avian Management Department Unit, Department of  Statistical Sciences, University of Cape Town, South Africa. I am sharing this story with you, because it gives the facts about the Island itself and of course the species that live there, but I have chosen to write an introduction to this article in order to share with you the natural adventure which occurs on this magical island of rock.

INTRODUCTION: Seal Island is a rugged place located right off the coast of southern Africa off False Bay between Gordans Bay and Hout Bay near Capetown. What occurs here on this island is spectacular and involves the large population of Cape Fur Seals and their predator the Great White Shark. Predation between any two species in the wild is haunting and real; however, is rarely observed in the wild. The case of Sea Island of False Bay is an exception for it  is common to view predation between the Great White Shark and the Cape Fur Seal.

According to the website Ultimate-Hunters.com, there is a method to the predation and kill of the seal by the shark. The Great White Shark appears to fly from the water in his quest for the Cape Fur Seal. Well, just see for yourself in this video below, subsequently the area is known as the “Home of Great White Flying Sharks”.

by Bruce Dyer and Les Underhill

Seal Island in False Bay consists essentially of a huge granite rock 2 ha in area, with no beaches or vegetation. It lies almost centrally in the northern part of False Bay, 5.7 km offshore. A radio mast, built on the island during World War II, was a conspicuous landmark in the bay until it was blown over in a winter storm in 1970. All that remains of this is some rusty, twisted metal. There are also ruins of some huts and a few structures from the sealing and guano-collection era. Some rock inscriptions made by sealers in the 1930s are still evident. Guano collection ceased in 1949.

About 100 years ago (ie about 1880), the great voyage of the HMS Challenger brought the naturalist Moseley to the Cape. The following extract from his notes brings out the changes that have taken place since then – or at least one of them. “I paid a visit to an island in False Bay, called Seal Island. It is a mere shelving rock, on which it is only possible to land on very favourable occasions. The whole place is a rookery of the Jackass Penguin”.

African Penguin also known as the Jackass Penguin

Nowadays, this island supports the largest Cape Fur Seal Arctocephalus pusillus colony in the Western Cape; up to 75, 000 seals occur. The growth of the population of seals was held in check by a quota system until the early 1980s. The market for fur seal products crashed in 1983 and seal harvesting no longer occurs on Seal Island. As a result, the seal population has increased dramatically in recent decades. The seals attract Great White Sharks Charcharadon charcharius, and an ecotourism industry to view the sharks is slowly developing.

Cape Fur Seals, Seal Island, False Bay, South Africa

Seal Island continues to support a small population of African Penguins. The penguins have been provided with artificial nest sites, and this has increased their breeding success. In spite of the increasing seal population, the number of penguins has remained stable since the 1980s, and about 80 pairs breed each year.

Other bird species which breed regularly on the island are Whitebreasted Cormorants and Bank Cormorants. Cape Cormorants bred for the first time in 2000; there were 30 nesting pairs. A handful of Cape Wagtails almost certainly breed on the island. There are a few Turnstones in summer, but no African Black Oystercatchers.

Cape Gannets bred on the island in the 17th century, but it is not documented when this colony folded. Kelp Gullslast bred in the 1950s. They remain common scavengers on the island, though.

The Western Cape population of Great White Pelicans bred on Seal Island from about 1930 until 1954. Before 1930, they were breeding at Dyer Island and at Quoin Rock. They left Dyer Island as a result of disturbance by guano-scrapers. They were displaced from Quoin Rock because of competition for space by a growing population of Cape Fur Seals. About 20-30 pairs of pelicans bred at Seal Island. However, they were subjected to considerable disturbance from sealers and guano collectors. By 1950, competition for space with seals forced them to move off the ground and breed on the roofs of the huts on the island. The final straw was the destruction of these nests when the roofs were repainted. The last breeding was recorded in 1954, and non-breeding birds visited the island until 1956. From 1955, Great White Pelicans have bred on Dasson Island and continue to do so. The population there has grown to about 800 pairs.

Seal Island is a nature reserve of the Western Cape Nature Conservation Board. It has no visitor access facilities. As observed by Moseley, landing on the island is difficult. It is dependent on sea conditions and usually requires a leap onto mussel- or barnacle-covered rocks.

The island has a birds totalling 24 species, which have been seen either on the island or in the immediate vicinity.