Monday, June 4, 2007

Penguins in Peril

African Penguins are having a rough time, and global climate change might be at least partly to blame, according to a New York Times article excerpted below.
Though the blue crane is South Africa’s national bird, the penguin clearly captures more hearts. Most penguins live on islands, shielded from land predators. But one colony on the Cape of Good Hope peninsula annually lures tens of thousands of gawkers, who revel in walking among throngs of the tolerant creatures.
Environmentalists here have made the birds’ rescue into a public crusade, contending, in effect, that the little penguin is the canary in the coal mine — a barometer of problems besetting other seabirds and the oceanic chain of life.
They could have a point. The penguins’ travails have many mothers, but the biggest one is food. African penguins live mostly on anchovies and sardines, which loitered until recently in huge shoals off western South Africa, where Robben and Dassen Islands are situated.
But starting around 1997, the sardines began to relocate east, closer to Cape Agulhas, Africa’s southernmost point. The effect has been to reduce the penguins’ main course to a few canap├ęs, and their head count shows it: in some years, the adult penguin population on Robben and Dassen has slumped by as much as 25 percent. .
More mobile species might simply follow the fish to a new home. The African penguins are prisoners to their island, though, limited to foraging for food in waters no more than about 25 miles offshore. When the sardines leave, the penguins have scant choice but to hunker down and wait for them to return.
But the fish may not return for decades, if ever. The sardines’ relocation may be part of a worldwide shift that occurs every 50 years or so, scientists say. Commercial fishing, which has depleted sardine stocks in other parts of Africa, could be a factor. So might
climate change: this month, for example, several dozen scientists concluded that the sardine movements were related to changes in the Benguela Current, a vast, frigid flow of nutrient-rich ocean water from Antarctica up the southwest African coast.
Some of those changes are cyclical, but others are related to global warming. In some locales, sardines have deserted hotspots to seek the cold waters they prefer. No one knows the long-term effects, said Rob Crawford, a marine scientist at South Africa’s department of marine and coastal management.
“It has to be either fishing or climate or a mixture of both,” he said of the sardine shift, “but my hunch is that it’s environmental.”
If so, it would not be the first time the bird had suffered at the hands of man. The first Europeans here wiped out the Robben Island penguin population in an orgy of egg-stealing by about 1800; the birds were reintroduced in 1983. Early settlers also scooped countless tons of penguin guano from islands to use as fertilizer, destroying the soft soil in which the birds dug their subterranean nests.
Escaped European house cats became feral and feasted on thousands of penguin chicks. Modern man dumped oil in the ocean, killing thousands more; a vast spill off Robben Island in 2000 caused a huge bird-rescue operation, saving perhaps 38,500 penguins.
Moving the penguins to where the food supply has gone is not considered a good option so far, in part because it might be hard to find a new island habitat to move them to.
In June, Mr. Crawford said, experts here plan to meet to decide whether Spheniscus, now classified as a “vulnerable” bird species, should be reclassified as endangered. Meanwhile, the bird’s supporters are trying to do their part, digging holes on Robben and other islands to plant fiberglass “igloos” that penguins turn into homes.
Once covered in soil, the igloos give the birds a cool nesting place and protect their chicks from the penguins’ nemesis, the hulking, aggressive kelp gull. Penguin lovers are seeking donations for more homes, a process explained on the Avian Demography Unit’s Web site.
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