Mystery Killer is Wiping Out the Flamingo

One of the natural world's most breathtaking sights - the pink and crimson clouds of flamingos that flock over East Africa - is under threat.

Scientists are baffled by the death of thousands of the birds along the Rift Valley lakes of Kenya and Tanzania. Possible causes include avian cholera, botulism, metal pollution, pesticides or poisonous bacteria.

Fears for the future of the lesser flamingo - Phoeniconaias minor - have also been raised by plans to pipe water from Lake Natron. 'This could have quite a disastrous effect on water levels, which are critical for successful breeding,' ornithologist Neil Baker, head of the Tanzania Bird Atlas project, said in the journal Science.

The lakes are crucial to the birds' breeding success because flamingos feed off the blooms of cyanobacteria that thrive there. In addition, the caustic waters provide protection for their chicks from predators.

Mass deaths used to occur sporadically, but are growing more frequent.