Scarlet Macaws Feed on Clay Licks (Narrated by David Tennant) - Earthflight - BBC One

The macaws' detailed knowledge of the forest tells them just where to go. Along the riverbank are special sites where a natural remedy can be found. Smaller parrots have beaten them to it. Mealy parrots are joined by rose-crowned parakeets. The macaws are naturally cautious. They use the little parrots as bait to see if any predators are around. These parrots are here for the same reason as the macaws, the healing qualities of the clay. This special mud neutralises the toxins they've acquired through a less than perfect diet. The macaws are still too nervous to join the gathering. Monkeys have arrived, putting them on edge. But the spider monkeys are more a distraction than a danger. He weighs up the risks and takes his chance. Time's up for the flocks of smaller parrots.