The famous flamingos of Nakuru are fading away.

The spindly, exquisite birds, clouds of pink rising on a million wings in generations of tourist photographs, are dying, flying off, fleeing a seemingly fatal brew of environmental threats in a shrinking Lake Nakuru, the home that has sheltered them for uncounted centuries.

Where just six years ago as many as 1 million flamingos fed in Nakuru's shallows, in vast rosy carpets of plumage, hooked beaks and curved necks, as few as 30,000 stay-behinds hug the equatorial lake's receding shoreline. The carcasses of many hundreds of dead flamingos litter newly dried and caked sections of lakebed.

Click here for a photo essay of the flamingos of Nakuru.

Nakuru, whose recent maximum size was less than 20 square miles, may have lost half its water in the past few years, residents say.

"Something must be done," said Jackson Kilonzo, manager of the Lake Nakuru Lodge. "People have to come together and decide to do whatever it takes to bring the water level back up."

Precisely why the shallow lake and its flamingo population are shrinking remains a complex question.

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The water catchment area around Nakuru has been heavily deforested, and its rivers are running dry. Years of drought have further reduced the water supply. African temperatures, like global temperatures, are rising. Sewer and industrial runoff from nearby Nakuru town pollute the lake. And its blue-green algae, the flamingos' food, has diminished with the lake.

The U.N. Environment Program will soon undertake a comprehensive Lake Nakuru study, said the Nairobi-based agency's Nehemiah Rodich, a former director of the Kenya Wildlife Service.

"It won't be easy to pin down a complexity of issues that ultimately might be the causes," he said.

The flamingo, to many, symbolizes Africa as much as the lion or rhino.

Ancient Egyptians revered the impossibly graceful bird. In her classic 1938 memoir, "Out of Africa," Karen Blixen told of a vast flamingo flock alarmed by duck hunters: "At the first shot they rise in a cloud, like dust from a beaten carpet; they are the color of pink alabaster."

Such sights have drawn 200,000 visitors a year to Lake Nakuru, long home to what was believed to be the bulk of the global population of lesser flamingos, one of two species, with greater flamingos, inhabiting Nakuru, in the Rift Valley 100 miles northwest of Nairobi.

Paul Opiyo, deputy warden of the Lake Nakuru National Park, questioned a recent report in The Nation newspaper of Nairobi that the flamingo population had dropped to 30,000.

"There's slightly more than that," he said, although he offered no current official figures. He also said the Nation's estimate that the population had recently declined by 800,000 was too high.

Many birds are known to have relocated to other Rift Valley lakes that, like Nakuru, are heavily alkaline, waters hospitable to blue-green algae growth. But those lakes are shrinking, too, and Rodich said mass flamingo deaths have been reported at nearby Lake Oloidien.

"There's a problem with the algae," said Opiyo. "If the lake is shrinking, there will be less food for the flamingos."

The park deputy said a smaller Lake Nakuru presents another problem: Toxic urban runoffs become more concentrated in less water. He said many flamingos have developed sores on their legs because of the pollutants.

"We're working to clean up a sewage treatment plant," he said.

Lake Nakuru — mean depth 8 feet — has shrunk before, even disappeared. But this time, because of global warming, it may be different.

"The lake is threatened by deforestation and other problems, but now with a climate signature on top of that," said U.N. Environment Program spokesman Nick Nuttall. The shallowness of many Rift Valley lakes makes them vulnerable as temperatures rise and more water evaporates.

Ringed by big spreading acacia trees and grasslands where zebra, waterbuck and rhinoceros browse, Lake Nakuru is slowly pulling back toward its center, leaving a whitish, salt-encrusted rim several hundred yards wide at some points. Die-hard flamingos retreat with the water, their muted honks breaking a haunting afternoon silence.

Where will it end?

"The life of the flamingo depends on the water level, and we haven't had reliable rainfall for years," said lodge manager Kilonzo. "Tourism is the lifeline of this area. Without the lake and the flamingos, our lifeline is threatened."

Click here for a photo essay of the flamingos of Nakuru.