These findings are only among birds that have actually been studied; most birds have not been studied:
● African grey parrots have been observed to share tokens — given to them by humans — that they associated with a treat (walnuts) with other parrots by way of exchange or just helpfulness:
Parrots, it seems, don’t just have the ability to comprehend metal rings as currency for food, but they also “understand the consequences their actions can have on another individual,” says Christina Riehl, an expert in bird behavior at Princeton University who wasn’t involved in the research. “That’s pretty sophisticated reasoning.”
Katherine J. Wu, “Parrots Will Share Currency to Help Their Pals Purchase Food” at Smithsonian Magazine (January 9, 2020) The paper is open access.
Is this an instance of abstract comprehension of the concept of currency? It’s more likely a learned series of steps: Give a token, get a walnut. Or anyway, get social interaction with a neighbor. But it’s pretty complex anyway. And apparently, blue-headed macaws couldn’t — or anyway didn’t — do it.
…
The main thing to see here is that problem-solving intelligence peaks among some life forms that are not at all closely related. Crows and chimpanzees are thought to have last had a common ancestor 300 million years ago. Bees are thought to have had a common ancestor with them 600 million years ago. But crows, chimpanzees, and bees are all much more closely related to life forms that have not attracted attention for their intelligence. Are we just missing their intelligence? Or perhaps the question of unusual intelligence in some birds and other life forms but not others is one of the fruitful mysteries of science that invites further study.
Denyse O’Leary, “The remarkable things we’re learning about bird intelligence” at Mind Matters News (February 15, 2022)
You may also wish to read: Crows can be as smart as apes. But they have quite different brains. The intelligence doesn’t seem to reside in the details of the mechanism. Studying animal intelligence has taught us many things. But in some ways, it has deepened the mystery of intelligence.