Passage One At the base of a mountain in tanzania's Gregory Rift, Lake Natron burnsbright red, surrounded the remains of animals that were unfortunate enough tofall into the salty water. Bats, swallows and more are chemically preserved inthe pose in which they perished, sealed in the deposits of sodium carbonate inthe water. The lake's landscape is bizarre and deadly and made even more so bythe fact that it's the place where nearly75 percent of the world' s flamingos(火烈鸟) are born. The water is so corrosive that it can burn the skin and eyes of unadapted animals. FIamingos, however,are the only species that actually makes life in the midst of all that death.Once every three or four years, when conditions are right, the lake is covered with the pink birds as they stop flight to breed. Three-quarters of the world's flamingos fly over from crystal islands that appear when the water is at aspecific level-too high and the birds can't build their nests, too low and predators can move briskly across the lake bed and attack. When the water hits the right level, the baby birds are kept safe from predators by a corrosive ditch. "Flamingos have evolved very leathery skin on their legs so theycan tolerate the salt water, "says David Harper, a professor at the University of Leicester. Humans cannot, and would die if their legs were exposed for any length of time. "So far this year, water levels have been too high for the flamingos to nest. Some fish, too, have had limited success vacationing at the lake as lesssalty lagoons form on outer edges from hot springs flowing into LakeNatron. Three species of tilapia thrive there part-time."Fish havea refuge in the streams and can expand into the lagoons when the lake is lowand the lagoons are separate, Harper said. "All the lagoons join when thelake is high and fish must retreat to their stream refuges or die."Otherwise, no fish are able to survive in the naturally toxic lake. This unique ecosystem may soon be under pressure. The Tanzanian government has once again started mining the lake for soda ash, used for chemicals, glass and detergents. Although the planned operation will be located more than 40 miles away, drawing the soda ash in through pipelines conservationists worry it could still upset the natural water cycle and breeding grounds. For now, though life prevails -even in a lake that kills almost everything it touches.