This very beautiful British documentary, made with backing from the Disney organisation, follows the millions of flamingos that fly up and down the Rift Valley, breeding under bizarre circumstances on Lake Natron in northern Tanzania. They're elegant creatures as they strut on legs resembling a pair of folding compasses and fly in strict formation. But the film doesn't flinch over their place in a food chain that makes their chicks a meal for sinister marabou storks that resemble the aliens in Starship Troopers. The only human on view is a Masai warrior seen crossing the desert in a scarlet cloak, but the doings of men are a serious threat to the future of these beautiful birds, and at the end one can only say, "Carry on Natron".