Department of Statistical Sciences
University of Cape Town
| Avian Demography Unit
Department of Statistical Sciences University of Cape Town |
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| Great White Pelican in flight |
“A wonderful bird is the pelican
His mouth can hold more than his belican
He can take in his beak
Enough food for a week
I'm damned if I know how the helican”
by Ogden Nash
Pelicans are easy to see, not only for their large size and bright white colour, but also because the attractiveness of the habitat where they dwell: wetlands, the coast line and off-shore islands.
Maybe you know already that pelicans were a rare sight in the Western Cape only 20 or 30 years ago. However, now they are quite a common dweller in places like Rondevlei, Zeekovlei, Rietvlei, Berg River estuary, Orange River estuary, and even some farms in the Western Cape!
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The population of Great White Pelican is in decline worldwide. However, in the last decades pelican numbers have increased substantially in the Western Cape. Currently about 600 pairs nest on Dassen Island, one of the only two breeding localities in South Africa. Their increase in numbers may be due to different factors, being the most important the reduction of disturbances in the breeding site and a higher availability of food.
Whether this increase in numbers is only due to a higher reproductive success or also due to migration from neighbouring populations is not known. They breed also in St. Lucia Wetland Park in Kwazulu-Natal and on the guano platform rocks in Namibia. Part of the southern African population is however nomadic breeding only under appropriate conditions, generally depending on rain. Sites include Etosha Pan, the Okavango Delta and other non-permanent waterbodies.
Since the 1970s between 400-500 pelicans have been ringed in Southern Africa. Only 71 of these rings have been recovered (see SAFRING). Only a few studies have been undertaken in the region, and surprisingly little is known of the species' movements.
 Photo J.Cooper |
| Ringing pelican chicks on Dassen Island in January 2004 |
For the last 3 years, Marine and Coastal Management has embarked on a ringing programme on Dassen Island. A total of 306 juveniles have been ringed (see reports from November 2002 and January 2003). Using different colour rings for each year they can obtain information about the movements of the birds and other important parameters, like age of first breeding, mate fidelity, age-related differences in feeding behaviour, immature and adult survival, etc.
From the beginning of 2004, a new ADU member, Marta de Ponte, has started a comprehensive study on Great White Pelican in Southern Africa. Ringing of juveniles and adults is going to be a major component of the study. She plans to ring as many juveniles as possible in the next 3 breeding seasons. Adults will also be ringed as soon as the capture techniques are successfully tested.
A high number of re-sightings is fundamental for the success of the project. However, not only re-sights of ringed pelicans are important. Habitat use and feeding grounds used by the pelicans can also be initially identified in base of the information provided by a broad network of people. If you have seen pelicans in your area, please complete this form. Your contribution is very important for the conservation of the pelicans.
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| Great White Pelicans in a pig farm in the Western Cape |
Her study also comprises other aspects of the biology and ecology of the pelicans. The pelican population of the Western Cape seems to behave in an atypical way for the species. Chick's regurgitates show that most of the current food intake is not fish but chicken. Adults are using new sources of food; large flocks of pelicans are feeding on agricultural offal in chicken and pig farms. Undoubtedly this has become an important source of energy for the pelicans and their reared chicks, making possible the demographic explosion of the species in the region.
In several occasions in the last few years, pelicans on Dassen Island have been observed eating live chicks of co-breeding seabirds. The species that have been most predated are Cape Cormorants and Kelp Gulls. Swift Terns have been displaced from Dassen Island following the predation of all their chicks in 2001.
 Photo M.de Villiers |
| Pelicans breed on Dassen Island, often near cormorant nests. |
Many seabirds' species face threats that are currently diminishing their populations. Being the pelicans themselves in decline worldwide, we face a difficult conservation dilemma: to continue the supply of extra food to the pelicans in the farms, and allow their population expansion in the Western Cape, or to control somehow their numbers, reducing predation on other seabirds and the risk of spreading diseases from the domestic animals into the wild populations on the off-shore islands.
However, the decision has to be taken carefully. Discontinuity on the supply of chicken offal will surely bring the population increase to a halt, but the immediate response of a hungry population of pelicans could be to increase the predation on the chicks of other seabird species!
