T e flamingos can’t survive on algae alone. T ey need fresh water, too. Some fresh water bubbles up from boiling hot springs along the edges of the lake. T e birds fly through clouds of steam. T ey
land a short distance away from the springs. Here, the water has cooled to 66° C. T at’s still hot, but it won’t burn the birds. T e hot spring water also hasn’t mixed much with other lake water, so it isn’t too salty to drink. One by one, the flamingos gulp water. T ey
splash their skin and feathers to wash off sticky salts and minerals.
For now, the flamingos find everything that they need to survive at the lake. But this is a dynamic ecosystem. Conditions change. Almost overnight, the algae die. It’s unclear
why. Cloudy days could have made the water too cool for algae to grow. Hot days could have caused too much water to evaporate, making the lake too salty even for the algae. Whatever the reason, the abiotic factors have changed. Now, the flamingos can’t find enough food,
so it’s no longer benefi cial for them to remain here. T e flock rises up into the air like a pink cloud. T e birds may fly for days and hundreds of kilometers to reach a new soda lake. Lake aſt er lake, this pattern repeats. When
the algae bloom, the flamingos come. When the algae die, the flamingos leave. Eventually, millions of the flamingos land
at Lake Natron. Like the other lakes, this place seems uninhabitable. Yet, perhaps more than any other soda lake, Lake Natron is key to the survival of these flamingos. T is is where these birds will nest and raise their chicks. T ey’ll use this extreme environment to keep their chicks safe from many predators.
6 NATIONAL GEOGRAPHIC EXTREME EXPLORER
As the heat in Africa rises, Lake Natron’s water evaporates. T e salt in it dries in chunks. T ese chunks float on the surface of the water. T ey clump together, creating massive salt and mud islands in the middle of the lake. T e flamingos build their nests on these salt
islands. T ey scoop up the salty mud with their bills. T ey pile it into mounds nearly 30 cm tall. T en each female flamingo lays a single egg.
Both parents take turns keeping the egg warm until it hatches a month later. During a nesting season, as many as 200,000 chicks may hatch. T e flamingos use the lake’s abiotic factors
to protect their chicks. T e tall mud nests keep the chicks cool and dry. T ey’re above rising water and the baking heat of the ground. T e salt islands keep some danger away, too.
Hot water and sticky mud along the edge of the lake stop predators like hyenas. T ey can’t reach the islands.
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