As anyone who has ever watched one of the many television shows or documentaries about wild animals will tell you, the first rule of the animal world is simple: survive. And that boils down, roughly, to a two-pronged strategy: find something to eat and don't get eaten in the process. Focusing on the first part, that often means that if you have access to food and your friend doesn't, well, that's too bad for your friend. When it comes to food in particular, animals aren't in the business of sharing.

Except for African grey parrots.

This species of parrot, pictured above, lives in equatorial Africa. They eat a diet of mostly fruit, seeds, and nuts and have a lifespan in the wild of about 20-25 years (but are an endangered species). They're definitely capable of creating interpersonal (interbirdinal?) relationships -- African grey parrots are monogamous and, literally and figuratively, build a home together; as summarized on Wikipedia, "each mated pair of parrots needs their own tree for their nest. The hen lays three to five eggs, which she incubates for 30 days while being fed by her mate. The adults defend their nesting sites."

So, at least in the future-dad shares with future-mom, these birds share food. (If the first rule of the animal world is "survive," the second is "procreate.") But, in 2019, biologist Désirée Brucks wondered whether these parrots would share with their neighbors, too. In a paper published the following year (pdf here), Brucks and team outlined their process, as summarized by Popular Science:

The experiment went like this: two parrots were placed in cages right next to each other with a hole between them, allowing them to pass things back and forth. They each had an experimenter-facing hole as well. The birds were sometimes given tokens, which they could pass to the scientists to get a treat.

One parrot was given tokens and had its portal to the experimenter closed up. Now the little guy had a choice: hoard them or pass them to the bird next door, which could still make the trade for food.

And because we live in the era of ubiquitous video, you can watch the experiment -- and the results -- on YouTube, here. In case the video doesn't work for you, though, here's what happens: the bird with the tokens grabs one in its beak and "hands" it to the other bird through their shared window. The second bird takes the token in its beak and gives it to the researcher, who gives that second bird a walnut in exchange for the token. The second bird eats the walnut and returns to the window to get another token from his neighbor; the neighbor, again, grabs a token and passes it, beak-to-beak, to the bird with access to the walnuts.

The bird who was given the tokens never ends up getting a walnut in return for its efforts, but it doesn't seem to change that bird's behavior. Per Popular Science, "in general, the African greys were willing to pass the tokens, even if they didn’t get a snack themselves. They were also less likely to share tokens if the other bird or the experimenter were absent, suggesting they weren’t just nudging the objects out of their cages for the sake of it." 

There was, ultimately, a payoff for the altruistic bird -- although there's no way that bird would know it at the time. As NPR notes, "later, scientists reversed birds' roles to see if the recipient of this generosity would pay back those favors. And the birds did," but, as Brucks told the radio journalist, "in the very first trial, they could not have known that the roles would be reversed afterward." She did, however, offer up a different explanation: the parrots were, effectively, already friends: "Brucks [. . . ] notes that the parrots seemed to have an intrinsic desire to help out their partner. The eight birds tested all knew each other and lived in the same social group." Birds of a feather, it turns out, do indeed flock -- or walnut together.

But don't extrapolate too much from the experiment -- while African grey parrots will share with one another, research shows a lack of sharing between other species of birds. For example, Brucks repeated the experiment with blue-headed macaws and found that the macaws weren't nearly as good to one another. Per Smithsonian, those birds "weren’t as philanthropic, keeping almost 90 percent of their metal rings to themselves. And when they did transfer tokens, the acts were mostly passive: They simply dropped the currency onto the floor of their partner’s enclosures." 

Jerks.