EIGHT years ago, rising water levels in Kenya's Lake Nakuru drove away the clouds of pink coloured flamingos that were the park's biggest draw. Rangers say their disappearance triggered a drop in visitor numbers by for the Nakuru National Park. Now they're back. The return has rekindled hopes of a gradual rebound in an area heavily reliant on tourists for employment and revenues. On a recent visit, flocks of flamingos foraged for food in the lake's turquoise waters, while others flapped in a sine-wave formation above. A rhinoceros grazed nearby. "With the increase now of the number of flamingos we…