New Delhi, Sept. 15 -- Under a scorching northern Tanzanian sun, where volcanic hills rise above dazzling salt flats, Lake Natron stretches like a mirage across alkaline waters and ochre mud. To a casual visitor, it seems lifeless-its caustic, hyper-alkaline waters can burn skin. But for East Africa's Lesser Flamingos, these hostile conditions are vital. Each year, as many as 2.5 million flamingos land on Natron's cracked mudflats, transforming the remote lake into one of nature's most striking spectacles.

Last week, Tanzania's government stunned industry observers by halting a planned large-scale soda ash mining project at the lake. Officials said the proposal-backed by Ngaresero Valley Company Ltd-posed unacceptable risks to the birds,...