|Avian Demography Unit
Department of Statistical Sciences
University of Cape Town
Great White Pelican Pelecanus onocrotalus
(The ADU is currently running an ecological study on these charismatic birds. For more information visit our Great White Pelican project webpage)
Great White Pelicans breed in Africa, and in Europe and Asia from Greece to Vietman. The world's population is thought to total about 90 000 pairs, of which about 80% are in Africa. Over much of its range, and especially in Europe, it is threatened by human disturbance, by loss of foraging habitat and breeding sites, and by pollution. It is one of seven species of pelican; two of these are classified as threatened.
Within southern Africa, the largest concentration of breeding birds occurs in Botswana, where it breeds irregularly after heavy rains at Lake Ngami and Sua Pan. The other three regular breeding localities in southern Africa are coastal, which is why it is treated as "seabirds" here: Lake St Lucia, in northern KwaZulu-Natal, Dassen Island, in the Western Cape, and the Walvis Bay Guano Platform, in Namibia.
The Lake St Lucia colony consists of about 3000 pairs. While they are feeding their chicks, they travel out onto the Pongolo floodplain to distances of more than 100 km to forage on a daily basis.
The Walvis Bay Guano Platform was built in 1930. Great White Pelicans started breeding on it in 1949. This was two years after the last record of breeding at Sandwich Harbour, farther to the south. At Sandwich Harbour they had been breeding on sand islands; but this is a very dynamic wetlands, and the islands became connected to the mainland, allowing access to predators such as the Blackbacked Jackal Canis mesomelas.
About 200 pairs of Great White Pelicans breed on the guano platform. During a survey of coastal birds in central Namibia in midsummer 1975-1976, a total of nearly 1500 pelicans was counted, with 600 at the Walvis Bay Lagoon, 400 at Sandwich Harbour, 100 at the Walvis Sewage Works, and many scattered along the coastline, fishing out to sea.
The Western Cape population of Great White Pelicans has moved around between a variety of breeding sites during the past few centuries, before ultimately settling on Dassen Island. In the 1600s, Great White Pelicans bred on Robben Island. By about 1850, they were breeding on Dyer Island, where they bred up to about 1930. Between 1894 and 1904 some bred on Quoin Rock. They left Dyer Island as a result of disturbance by guano-scrapers, who persecuted them because they predated other guano-producing seabirds. They were displaced from Quoin Rock because of competition for space by a growing population of Cape Fur Seals Arctocephalus pusillus. About 20-30 pairs of pelicans bred on Seal Island in False Bay from about 1930 until 1954. However, they were subjected to considerable disturbance from sealers and guano collecters. Seal Island was used by the navy for target practice during and after the Second World War. The last breeding at Seal Island was recorded in 1954, and non-breeding birds visited the island until 1956.
Since 1955, Great White Pelicans have bred on Dassen Island. The maximum size of this colony when it started must have been the 20-30 pairs displaced from Seal Island. By the mid 1990s the number of breeding pairs had reached 500, and has subsequently grown to about 700 pairs. In 2001, breeding was recorded on Vondeling Island for the first time. The Western Cape is probably the only place in the world where pelican numbers have shown such a dramatic and sustained increase over the past few decades.
The Dassen Island pelicans fly to the mainland to feed. Traditionally, they fed at freshwater wetlands such as Zeekoeivlei, Rondevlei and Rietvlei, and at estuaries such as the Berg River and at Langebaan Lagoon. The construction of a plethora of farm dams, and the practice of stocking them with Freshwater Carp Cyprinus carpio, also increased food availability.
Increasingly, in recent years, they have started feeding on offal at pig and chicken farms in the Greater Cape Town area. It is this availability of offal that must be driving the current increases in numbers of Great White Pelicans in the Western Cape. During January 2003, more than 1200 White Pelicans were recorded at a single pig farm. This behaviour places them at risk to mass poisoning incidents. For example, in January 1991, 53 pelicans died after eating offal dumped by chicken farms; it was suspected that the chicken carcasses contained insecticides used to control flies. In order to better understand and conserve the population of Great White Pelican in the Western Cape, it is essential to study the impact that dumped offal is having on breeding productivity and the health risks related to this behaviour. Tighter health regulations might well lead to a decrease in offal availability.
In recent years, pelicans on Dassen Island have started to eat the chicks of Kelp Gulls, Cape Cormorants and Swift Terns on the island. For example, in March 2002, virtually every Swift Tern chick on Dassen Island was consumed just a week or two before they were due to fledge. (See A trip in time for an account of this.) This begins to pose a dilemma to conservation planners. How does one cope with a species that is "Near-threatened" when it is starting to have a serious impact on the breeding success of other species? However, this is not a newly-learned behaviour for the species in the region. The reason why Great White Pelicans were so unpopular on the guano islands is that they consumed birds of the guano-producing species.
In January 2002, the first mass banding of Great White Pelican chicks took place on Dassen Island, undertaken during a joint ADU-MCM expedition. 100 chicks were ringed, and were also fitted with a blue colour ring. In 2003, 155 pelican chicks were banded using red rings. In 2004 yellow rings were used and these birds are now flying about the Western Cape, and possibly further afield. See a story about catching adult pelicans here. Please check Great White Pelicans for these colour rings; if you see one, please report it to Marta de Ponte or complete this form and send it to Avian Demography Unit, University of Cape Town, Private Bag 7701, Rondebosch, Cape Town.
One of the interesting questions in relation to pelicans is whether the various breeding populations are disjunct, or whether there is a significant amount of interchange between them. For example, up to 100 pelicans regularly occur at the Orange River Estuary, with flocks of up to 250 birds occasionally recorded. This estuary is approximately half way between the colonies at Dassen Island and the Walvis Bay Guano Platform. It is not known to which population these birds belong or whether, possibly, they are a mixture of birds from various populations. Evidence suggests that the third southern Africa poulation, found in St. Lucia Wetland Park (KwaZulu-Natal), is isolated from the other two western populations, due to the scarcity of sightings from intermediate locations and to some behavioural differences between these two groups.
Up to 2004, 547 pelicans had been ringed with SAFRING rings, and although there are 31 recoveries of dead birds, none show substantial movements. However, there is an interesting record of longevity; a bird ringed as a nestling at the Walvis Bay Guano Platform in 1972 was confirmed to be breeding there 27 years later, in 1999, and probably is still breeding.
Although population sizes of Great White Pelicans are monitored by the Avian Demography Unit's Coordinated Waterbird Counts (CWAC) project, this provides us with information for only one day in midsummer and one day in midwinter each year. To enable us to get a clearer insight into the patterns of movement of this species, and the full set of localities that it utilizes, we need to be gathering more information than this. Any sightings of Great White Pelicans at any time of the year should therefore be reported to our Great White Pelican project coordinator, Marta de Ponte (e-mail).