It was almost dark when the red-billed queleas came in to drink. So many, I could not begin to count how many. They arrived, as they always do, in a great crowd or cloud: they looked like a single organism, a giant moving amoeba in the sky, and they drank their fill as the cloud oozed and bulged and shape-shifted above the pool, rearward birds constantly leap-frogging the leaders in a great rolling wheel of birds.

They are hardly an unusual sight in the Luangwa Valley in Zambia, but they are always compelling because they have their being in huge numbers as few other back-boned creatures do. They act as many, they think, it seems, as many, they live as many.

They are related to sparrows, each one less than five inches long, weighing less than an ounce. And yet they devastate and they are able to do so because they are many: they descend on crops in millions and eat the lot if they not banged and gonged and blasted and chased away.

But here in the middle of South Luangwa National Park they could upset no humans: swirling over the pool, rising and falling, constantly in motion. It was a small flock: perhaps no more than 10,000. I could hear the sudden brief roar of their 20,000 wings as they moved, always restless, rising in a spiral like a plume of smoke and dropping down again like a great living duvet: as if one great mind was controlling all.

Here is one of the wonders of the world. Here is the world’s most numerous species of bird that is not a chicken. A female elephant walked into the pool for a drink: the queleas fell silent, as if the headmistress had just walked into the classroom.

• I was co-leading the Ultimate Luangwa safari for wildlifeworldwide.com. Next year I will be co-leading https://www.wildlifeworldwide.com/group-tours/sacred-combe-safari and I will also be participating in https://www.wildlifeworldwide.com/group-tours/festival-of-wildlife-zambia