There were probably a great many angry penguins on Dassen Island off the Cape West Coast while bird experts from the University of Cape Town conducted experiments there recently to measure the effect of human disturbance on the endangered seabirds.
The researchers fooled the penguins into sitting on plastic artificial eggs with small radio transmitters in them. Then they recorded how the birds reacted when small groups of people approached their nests.
"African penguins are not very discriminating about the form and colour of their eggs," said a researcher.
"Sometimes they'll settle quite happily, for a short time, on 'clutches' of seashells and stones."
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Ecotourism is an important industry in the Western Cape. Dassen Island, recently opened to tourists, has one-third of the world's population of African penguins and people touring the Peninsula make a bee-line to another colony at Boulders Beach near Simon's Town.
Several other African penguin colonies are growing, such as those on Robben Island and St Croix Island, close to the new deep-water port under construction at Coega near Port Elizabeth.
From a conservation point of view it is important to know how the penguins react to human disturbance.
The research was conducted by a team from UCT's Avian Demography Unit led by Marienne de Villiers in collaboration with Melissa Giese, an assistant director of the Australian Department of Environment and Heritage.
Giese's visit to South Africa was sponsored by the National Research Foundation and UCT's visiting scholars fund.
The artificial eggs were first used by Giese in her research on Adelie penguins on remote Antarctic islands, said De Villiers.
"The Avian Demography Unit is now writing up the results of the survey to help conservation authorities plan guidelines for the management of tourists to breeding colonies of African penguins," she said. "Most nesting penguins become vigilant when people approach them. They become aggressive when anyone gets within 5m of their nests."
How can you tell when a penguin is becoming aggressive? "They rotate their heads and fix you with a beady glare. Then it's time to back off."
Surface-nesters, as distinct from birds that nest in burrows, seem to be particularly flighty, she said. The transmitters record the heart rate, which increases as soon as anyone approaches. In some birds it doubles if the intruder gets too close or makes a sudden movement. When that happens, birds may desert their nests.
"Most of them return after a few minutes, but some do not."
During the experiment the real eggs replaced by artificial eggs were kept warm in a field incubator so the developing chicks were not harmed.
Artificial eggs will also be used in a survey to be made on Marion Island, on the fringe of Antarctica more than 3 000km southeast of Cape Town, said De Villiers.
"The South African government is building a new base there and we are keen to find out how much the construction work will disturb the seabirds. The Gentoo penguins found there seem to be sensitive to disturbance, and so are the giant petrels.
"One of our research students, Mariette Bause, is there at present, and I shall be going down when the research and supply vessel SA Agulhas makes her next trip to Antarctica in August," said De Villiers.
Human disturbance is nothing new to penguins. Nowadays, eating penguins and their eggs is unthinkable; it is also illegal. But in the early days of the Cape, penguins were collected on Robben Island for food for the garrison and well into the 19th century ships' captains added salted penguins to their stores.
As recently as the 1940s, Cape cookery expert Hilda Gerber listed penguins as "popular sea-fowl". She recommended soaking them overnight in vinegar then stewing them with onions.
Penguin eggs were a great delicacy, she said, "scrambled with chillies, added to a curry or boiled in the shell for half an hour".
People who have eaten them remember that the boiled egg whites turned into a delectable green jelly, "not fishy at all".
- This article was originally published on page 17 of Sunday Argus on August 01, 2004
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