The African Jackass Penguin

General information

The scientific name: Spheniscus demersus or the African Jackass Penguin – from the Greek word spen, a “wedge”, referring to the streamlined swimming shape and demersus is a Latin word meaning “plunging”. The African Jackass height is about 50 cm with a body weight of between 2.1 and 3.7 kg, males are larger and have heavier bills than the females, these differences can usually be seen only when the pair is together. Juveniles are entirely blue-grey above and lack the white face-markings and black breast band of the adults. The African Jackass Penguin is the only penguin species to breed in Africa, and is confined largely to the waters of the extreme southwest, breeding on scattered islands along the South African and Namibian coasts. Its distribution coincides roughly with the Benguela Current and a process called upwelling. Off the west coast upwelling occurs as the south-easterly wind moves surface coastal water offshore, this water is replaced by cold nutrient rich Antartic Benguela current. Upwelling provides and abundant food supply for the plankton eating Pilchards and Sardines which are the favourite food species of the African Penguin. The large and isolated penguin population in Algoa Bay also occurs in the vicinity of a localized, nutrient-rich upwelling system. The distribution of the birds is further determined by the availability of offshore islands as breeding sites. The African Jackass Penguin breeding range extends from Hollams Bird Island off Namibia to Bird Island in Algoa Bay, Port Elizabeth. Their non-breeding range regularly moves north and east of the breeding range, especially to the coasts of northern Namibia and southern Angola, with extreme records from Gabon and southern Mozambique, probably in search of food and better feeding grounds. Commercial fishing off South African waters remained relatively small until 1950 when technological advances led to a rapid increase in the quantity of fish caught. Catches from the south east Atlantic peaked at over 3 million tons in 1968 and then declined sharply as fishing companies began to experience the effects of over fishing. The African Jackass Penguin has been severely affected by this over fishing forcing them to swim further and further off shore in search of food and feeding grounds.Commercial fishing When they hunt for prey or escape form seals, African Jackass Penguin can reach a top speed in water approaching 20 km/h but average 5 km/h when travelling to the feeding grounds. Their dive depth is usually less than 30 m but they are able to dive to a depth of 130 m when in pursuit of food. Because they cannot fly,African Jackass Penguin travel about ten times more slowly than flying seabirds such as Gannets and Albatrosses. However they dive to greater depths than other seabird species that feed on the same types of food and in the same areas. Therefore, although they may not be able to travel as far out to sea or as quickly, they do have a feeding area in epipelagic zone that is entirely their own. Gannets “plunge-dive” from about 10 to 20 meters and hit the water at around 120 km/h diving to depths of 10 to 12 meters.

Cape Gannet

Breeding & Feeding

African Jackass Penguin are able to dive to depths of 130 m when necessary which is a lot deeper than the competing Gannets, Albatrosses and Cormorants that dive to about 12 m, although they are able to dive to depths of 30 m. The distance penguins have to travel to find food varies. On the west coast, foraging birds typically cover from 30 – 70 km on a single trip; while on the south-eastern coast, at Algoa Bay, foraging trips average 110 km, though they can be as long as 170 km. Birds on the south-east coast were once recorded at sea for as long as 170 hours. Generally when feeding chicks, the forays can become longer and longer as the chicks grow and require ever-increasing quantities of food. Not only do those birds feeding chicks spend longer at sea; they spend more time under the water. On average, an adult African penguin requires 300 g of fish per day, or 110 kg per year. Fast-growing chicks fledge in as little as 60 days; skinny chicks can weigh as little as 2 kg, fat ones as much as 4 kg. To reach a weight of 4 kg, a chick would have to consume around 25 – 30 kg of fish. A six week old chick requires 500 g of food per day, chicks fed on chokka rather than fish take longer to grow and fledge. Chicks fed on fish fledge in 60 days while those fed on chokka take 130 days to fledge.

Moulting

Like all birds the African Jackass Penguin has to moult, however molting puts a sudden halt to their aquatic lifestyle; their waterproofing is lost and their ability to swim under the water is greatly reduced. Indeed insulation and hunting ability is are so badly impaired during the moult that penguins are forced to remain on land. In preparation for the moult African Jackass Penguin takes about 5 weeks to fatten at sea, eating almost 1,2 kg of fish per day and increasing their body weight by about 30% . At the same time, their new feathers start to develop under the skin. Once their fat deposits are sufficiently large, the penguins come ashore and immediately start shedding their old feathers. Stranded on land, they lose weight at the rate of about 90 g per day. Even though the entire moult is completed in 19 – 20 days , a molting bird can lose almost half its body weight during the process.

Dassen Island

At the end of the 19^th Century, it’s estimated that the island was home to 1 400 000 African Jackass Penguin. Between 1900 and 1930, 13 million penguin eggs were collected. In 1919 alone, the harvest totaled 600 000 eggs; the average harvest from 1917 to 1931 was 460 000 eggs. Even as recently as 1956,   125 800 eggs were collected there, indicating that only 45 years ago’ the African Jackass Penguin population on this one island was larger than the entire population of breeding pairs today.

STONEY POINT PENGUIN COLONY

Stoney Point

& seabird breeding colony

Provides one of the best opportunities to visit , view or study penguins in their natural environment.

Position

Betty’s Bay Marine Protected area within the Kogelberg Nature  Reserve

Why visit ?

• Historically interesting
• Ecologically important site
• Rare bird breeding ground
• Diverse bird viewing opportunity
• Educational opportunity for adults and children
• Is a people –friendly conservation site

General Information

Guided tour: Ralph or Gill 0824621505/0829034569 [email protected] Gate times:   08h00-17h00 (no permits issued after 16h30) Office:           028 272 9829         After hours  028 271 5138 Permit fee:   R20.00 per person  Children under 3 yrs -no charge The road to the breeding ground at Stoney Point is easily accessed and clearly signposted from the R44 ( Clarence Drive)

Guided tours of Stony Point can be arranged, they usually form part of a Kogelberg hike or something similar, for more information please contact us.

History

The African Jackass Penguin breeding ground at Stony Point is near an old abandoned whaling station. From 1917 until 1930 an estimated 300 whales were killed each year for their oil. When the Waaygat whaling station finally closed the penguins started to breed at the abandoned station for no known reason and the area was declared a protected area. The first nest at Stoney Point was found in 1982.

Importance

It is one of only two shore-based breeding colonies in South Africa with the more famous breeding colony at the Boulders Beach near Simonstown. Moulting In the water a penguins feathers trap air close to the body and this insulates them from the cold water. Feathers deteriorate over time and have to be replaced. Adult penguins shed their feathers annually. Before they moult they fatten up as they are unable to swim when they moult – for 3 weeks, and have to live off their fat reserves. At Stoney Point most penguins moult in November & December.   

Predators

At sea: Cape Fur Seal & Great White Sharks On land: Cape clawless otter, mongoose, kelp gulls prey on eggs & chicks, dogs and leopards. Human related threats: egg collection, removal of guano, oil spills and commercial fishing. Penguin Adventure

 References used

• The African Penguin a Natural History – by Phil Hockey
• Nature Guide – Learner Manual by Grant and Gillie Hine
• Wikipedia

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