Great White Pelicans - Dustbin guts or chick chompers? 

By Sue Matthews, Overstrand Estuary Management Coordinator  

The large flocks of Great White Pelicans that can be seen skudding about on the Bot River estuary or flying in formation overhead with their slow, lumbering style are a wonderful sight. So on a recent sortie of the back roads in search of an elevated vantage point of the estuary, I was quite appalled to see scores of pelicans scavenging at the landfill site off the Kaarwyderskraal Road. This prompted me to do a little reading-up on the species – Pelecanus onocrotalus – which further dispelled my romantic image of the birds. 

A considerable amount of research on the Western Cape population has been conducted over the past 15 years, primarily by Rob Crawford of Marine and Coastal Management and Marta de Ponte Machado of UCT’s Avian Demography Unit and Percy Fitzpatrick Institute. Marta recently received her PhD for this research, and developed a comprehensive Great White Pelican Project page on the ADU’s website. 

The Great White Pelican is one of seven species of pelicans worldwide, and occurs in Africa, Europe and Asia, from Greece to Vietnam. In South Africa it breeds at only two sites – Dassen Island on the west coast and St Lucia on the east coast – and there are also breeding sites on the Walvis Bay guano platform in Namibia, and occasionally at two waterbodies in Botswana after heavy rains. In these southern African sites, the birds gather at the breeding localities in September to November to breed, but disperse for the rest of the year to feed. 

However, the Western Cape is thought to be the only place in the world where pelican numbers have shown a sustained increase over the past 50 years – in fact, the species has undergone a population explosion here. The birds started breeding at Dassen Island in 1955 – before that they moved from Robben Island to Dyer Island, Quoin Rock, and Seal Island in False Bay, but were constantly disturbed by guano collectors and sealers, displaced by Cape fur seals, and even shot at in the case of the latter, since the Navy used Seal Island for target practice! 

Back in 1955, the pelican population stood at only 20-30 pairs, but partly because the birds could breed undisturbed at Dassen Island, their numbers started climbing. Subsequently the increase was too rapid for this to be the only causative factor – there were 500 pairs by the mid-1990s and approximately 700 pairs a decade later. The exponential growth was instead attributed to the birds’ feeding on agricultural offal at chicken and pig farms on the mainland. The sheer scale of this behaviour was demonstrated one day in January 2003, when more than 1200 pelicans were observed at a single pig farm, where chicken offal was mixed into the feed and routinely discarded on site. 

That farm has since closed and other farms changed their management practices, but then a new problem arose. Perhaps because this source of food had been denied them, the pelicans turned to another easy target – the chicks of other seabird species on Dassen Island, and more recently the Saldanha Bay islands as well. Pelicans had previously been seen eating gulls, cormorants, penguins and swift terns on Dassen Island – indeed, in March 2002, the year’s entire cohort of swift tern chicks were consumed, forcing the terns to relocate. In 2006 Marta and her colleagues monitored the breeding success of five endemic seabird species on the island, and found that pelican predation poses a threat to at least three of them. Their paper, published this year in Endangered Species Research, suggests a number of possible mitigation measures, including selective culling if all else fails. 

Marta also collaborated with Spanish scientists from the Canary Islands in assessing the prevalence of pathogens in the local pelicans. Of 50 birds tested for the presence of various bacteria and viruses, 49 were positive for Mycoplasma spp., 22 for Salmonella spp. and 3 for Newcastle Disease Virus. Clearly, the pelicans could put the health of other birds and even humans at risk – especially if they are routinely feeding on assorted waste at landfill sites. 

However, for the Kaarwyderskraal site at least, there’s good news to report. Francois Kotze, the Environmental Manager for the Overberg District Municipality, which runs the site for parts of the Overstrand and Theewaterskloof municipal areas, tells me that agricultural offal was until very recently being accepted on a daily basis from two chicken farms and an abbatoir. The procedure was for a trench to be dug in the morning, and once the waste had been deposited it would be covered over. The pelicans I had seen were probably trying to get at the offal before it was buried – indeed, while I watched a bulldozer got to work and chased some of them off. 

Since the permit conditions for the site stipulate that no waste with a disease risk may be accepted, the three clients had to submit a document with each load declaring that the waste had been inspected and found not to contain any disease agents. But recently, the site’s contractors had grown increasingly concerned about handling waste that could potentially be a health threat, plus the site is not registered for hazardous waste. The clients were therefore given a month’s notice that their waste could no longer be accepted, and as of 24 August, the practice has ceased.

The pelicans are still likely to roost at the landfill site, because the decomposition processes generate heat that takes the chill off the winter air, and they’ll probably still scavenge on the household waste. Let’s hope, though, that they continue to visit our lovely Bot River estuary, which if properly managed can provide a bountiful supply of their natural food source – fish. 

Sue is contracted to the Overstrand Municipality in a position funded by The Table Mountain Fund, an associated trust of WWF-SA.