Glad you like the pictures; it was my pleasure taking and now sharing them!
The exposed soil that the birds are on is a “clay lick.” This one is in Tambopata and its name is “Culpa Claylick.” There’s a reason they come down to the clay and that is to ingest it. They eat it basically. In some of my pictures (that I’ll later post) you’ll see how they will break a piece off and fly it back to a tree. They eat it there where they feel safe as they don’t like to be on the ground long. Matter of fact, the spectacle of them descending upon a clay lick is a very exciting but short one. It takes a long time for them to “build the courage” to come down. They are very careful animals and living that way is the reason they don’t fall prey and are only really vulnerable in life as fledglings.
When on the lick they can get scared away easily but will soon return if there was no true danger. Sometimes a strange bird, like an Oropendola, will fly overheard and spook them.
Early in the morning, at daybreak they begin gathering in the trees around the lick. They fly in from all directions. They arrive in pairs or groups of sometimes four. They sit in the treetops calling, preening each other, etc. (basically relaxing). At this point they separate themselves by species it seems. You’ll see in the pictures how one treetop is dotted with B&G macaws only and the other Scarlet Macaws. The Mini-macaws and Amazons do the same thing. They will remain in the trees for a while and what signals them to descend all at once I’m unsure of - maybe a brave scout? It seems they will not come down if it’s raining, foggy, or even partly cloudy. Although watching them gather in the mist is a beautiful sight. If it is not right for them, after about an hour or two of hanging around, they will begin flying away in the same manner that they arrived. You can imagine the disappointment for someone sitting across the river for hours hoping to see this event. But, one can always try again in the evening.
Also, it’s not just any exposed soil - it must be high in sodium. There are several theories as to why they do this. One is that the vegetation they eat doesn’t assimilate sodium so they must obtain it directly from the soil. They are not the only animals that do this. Mammals and butterflies can be seen doing this as well and many mammals even have their own clay licks. Some people there will testify that if you spend any amount of time in the Amazon you will feel yourself craving salt. Another reason is that the clay neutralizes the toxins in the fruits that parrots eat. The plants evolved these toxins to defend themselves.
Parrots occupy the highest vertical level of the rainforest. There are 6 levels, each with its own unique diversity of life. As such, parrots can usually be heard but poorly seen if at all. Because they can be seen as silhouettes flying overhead, or in the tops of the tallest trees, it can be very hard to get a good photo of them. A zoom lens is a must! Even then, it’s still tough. I happened to have had a good spot opposite this clay lick and across the river from it. It was my third visit to this particular one when I got lucky. The flashing of colors, raucous calls and boisterous nature of these birds make this something that has to be seen.