They normally choose to breed on only one particular lake in Tanzania, but for the first time since 1936 they have decided to breed at Nakuru. People like Daniel Koros of the WorldWide Fund for Nature are very happy about it.
From afar, the flamingos lining the edge of Lake Nakuru are a shimmering carpet of pink. Close up, they are a cacophony of flapping wings.
The thousands of pink flamingos that congregate on the lakes of East Africa's rift valley have long been a major tourist attraction. Nowhere else in the world are they seen in such concentrations.
They normally choose to breed on only one particular lake in Tanzania, but for the first time since 1936 they have decided to breed at Nakuru. People like Daniel Koros of the WorldWide Fund for Nature are very happy about it.
"We're quite excited," he said. "We've already observed several birds sitting on eggs in the north of the lake and also a few to the south."
But the breeding is one bright note in an otherwise worrying picture.
Lake Nakuru is under pressure both from natural factors like changes in the weather and from pollution coming from the factories on the edge of Nakuru National Park.
Pollution
Scientists are worried about a build-up of heavy metals in the water - including lead, zinc and mercury. These are absorbed by algae, which are then eaten by the flamingos.
Doctor Gideon Motelin, a lecturer at nearby Egerton University, says that overall the population of pink flamingos is on the decline.
To try to reverse the trend, environmentalists have approached local factories asking them to cut down on the harmful waste they produce.
But out of 160 factories, only 16 have taken the environmental issue on board. Even these, according to a report, mostly lack the technical expertise to introduce effective changes.