National Geographic : 2003 Dec
Omi 40 BY MARGARET RELIEFBYNOAA-NGDC G.ZACKOWITZ NG MAPS NATIONAL GEOGRAPHIC SENIOR WRITER Eldoret PHOTOGRAPHS oBY ANUP AND Nanyuki Kisumu MANOJ SHAH Mt. Kenya + Lm ZLake LAKE As many as four million Victoria NATON AR Plesser flamingos, Phoe . A L. / as niconaias minor, live on SLog the soda lakes scattered 2,776 m the length of Africa's *Nairbi Great Rift Valley. Named A MARA . BI for the bicarbonate of NATIONAL RESERVE soda leached from the L region's volcanic soil, Lf.: \ the lakes' warm shal 1 lows encourage growth soEREf spirulina algae-the NATIOL PK birds' staple food. ,8 ' *:.Longido Oldiv o i. Kilimanjaro Ngorongoro 19,340 ft + Crater L. Magadi (L. Makat) or a flamingo, feeding requires a new perspective: upside down. To consume the spirulina algae that is its main source of nutrition, the bird inverts its head so that the bottom portion of the bill faces up (right). This big mandible also works as a float to keep the bill from sinking too far below the surface. As the flamingo swings its head from side to side, its large, thick tongue pumps lake water into the scoop-shaped bill, where a filter of hair-like projections extracts algae. Excess water is then sluiced out by the tongue. Large gatherings of flamingos require staggering amounts of spirulina. A flock of 100,000 eats 35 tons a day, and flocks of more than a million birds have been counted. But algae blooms are fickle in the Rift Valley lakes; even the most lush spirulina growth can die off almost over night. When conditions change, noisy pink clouds scud toward the next lake (left). There's no predicting the schedule: Lesser flamingos don't migrate--they wander.