Cape Town - There’s bad news, good news and some... well, interesting news about the Western Cape’s coastal birds and seabirds.
The bad news includes confirmation of the massive decline in numbers of the African Penguin, arguably the most charismatic of the coastal birds and a conservation icon, and also of migrant wading birds like the Sanderling, Curlew Sandpiper, Ruddy Turnstone and Grey Plover.
The good news – there’s a lot less of it, unfortunately – is that the population of the formerly endangered African Oystercatcher has increased substantially and its Red Data threat status has been downgraded to “near threatened”.
And the interesting news is that while the numbers of several species using our local shoreline has plummeted, the total number of birds hasn’t changed in the past three decades.
This is because the virtual disappearance of some migrant waders has been offset by large numbers of Egyptian Geese – it’s an indigenous bird, not an exotic from northern Africa as is often mistakenly presumed – and ibises, especially Sacred Ibises, explains Professor Phil Hockey, head of UCT’s Percy FitzPatrick Institute of African Ornithology.
“Numbers of gulls and herons have also increased, and the preponderance of large-bodied birds means that avian biomass [the combined total weight of all the birds] has increased on the shore.
“The niche occupied by waders that feed on small crustaceans associated with washed-up seaweed, once such a feature of the west coast, appears to have been taken over, at least in part, by Common Starlings [formerly called European Starlings].”
Hockey’s comments come in the “FitzPatrick Report” that is one of the features in the first issue of African Birdlife, the new magazine of conservation group BirdLife South Africa that will hit the bookshelves of selected outlets on Wednesday week.
BirdLife grabbed the “wonderful and important” opportunity to publish its own magazine when a commercial publisher recently stopped production of a similar publication, says its chief executive officer Mark Anderson.
“We now have our own magazine and it will be used to showcase BirdLife’s work, highlight conservation success stories, and raise awareness about the plight of our continent’s birds and their habitats.”
Appealing for birders to take subscriptions, he added: “With more support, BirdLife SA, as the country’s only dedicated bird-conservation NGO, can increase its efforts to conserve our precious birds and their habitats.”
That conservation measures are vital for many coastal species is apparent from several articles in the first issue – including one on African Penguins by Professor Peter Ryan, also of the FitzPatrick Institute, who, with Hockey and Professor Andrew McKechnie, make up the new magazine’s three scientific advisers.
Ryan points out that we don’t know how many of these penguins there were before human impacts started affecting their population, but at the beginning of the 20th century, there were still about one million birds just on Dassen Island.
But when government guano island ornithologist Bob Rand conducted the first census in 1956, that number had dwindled to fewer than 75 000 pairs, and the total population – African Penguins are endemic to the Benguela ecosystem, with a breeding range between Algoa Bay in the east and Hollamsbird Island off central Namibia – was less than 150 000 pairs.
“By the late 1970s, fewer than 70 00 pairs survived.
“The Namibian population suffered the most severe decrease, falling to less than one-quarter of its size in 1956 following the collapse of sardine stocks as a result of over-fishing,” writes Ryan.
While some exceptionally good years for pelagic fish in the 1990s saw a recovery of sorts, penguin numbers in the Western Cape have since fallen “dramatically” to about 10 000 pairs.
The total population now stands at “barely” 25 000 pairs and this species’s threat status was raised from “vulnerable” to “endangered” last year.
Of particular concern is that adult penguin mortality increased from about 20 percent a year in 2002-4 to more than 40 percent by 2006.
“This is very worrying, particularly in a bird like the African Penguin,” says Ryan.
“Seabirds typically are long-lived; rather than investing heavily in reproduction, they defer breeding when conditions are tough, ensuring they live to breed another day. So when adult survival falls, you know times are exceptionally difficult.”
Typically, multiple factors combine to drive a species towards extinction, and new threats emerge as the population shrinks – for example, predation by fur seals, sharks and Kelp Gulls, Ryan adds. “We have already seen the demise of some penguin colonies, such as at Lambert’s Bay, and more colonies are teetering on the brink.
“Urgent action is needed if we are to ensure the survival of African Penguins in the wild.”
The FitzPatrick Report reflects research by Ryan, John Graham and Tim Reid, who repeated counts in both 2010/11 and 2011/12 made originally by the Western Cape Wader Study Group in the early 1980s.
Their findings are also alarming: numbers of virtually all migrant shorebirds have decreased, with those of the two most abundant species – the Sanderling and the Curlew Sandpiper – plummeting more than 90 percent.
And some resident shorebirds have also been severely affected, including the White-Fronted Plover, whose numbers have dropped 40 percent throughout its range and close to 60 percent on the Cape Peninsula, where human disturbance is greatest.
The researchers want to do further surveys to see whether the declines on the province’s shoreline are also found elsewhere on the coast of the subcontinent. - Sunday Argus