Scientists from Sweden say ravens are able to think about the future, showing a general planning ability previously documented only in people and great apes.

Researchers Can Kabadayi and Mathias Osvath, of Lund University, tested five captive ravens in two tasks they do not do in the wild: using tools and bartering with humans. The results were published on Thursday by the journal Science.

Ravens, along with crows, jays and others, belong to a bird group called corvids. Some corvids have shown that in hoarding food, they do some planning for the future instead of just acting on natural urges.

The Lund University ravens showed they could also plan by setting aside a tool that they suspected would get them a tasty treat later. They also prepared for future bartering.

This more general planning ability results from the combination of several skills and if it appears in both corvids and great apes, the Swedish researchers said, it must have evolved more than once.

The birds were shown a box that had a tube sticking out of the top, plus three stones. They learned that they could use a stone as a tool. If they dropped it down the tube, the box would release a doggie treat. They also learned that other familiar objects, such as a small wooden wheel or a ball, would not work.

In one experiment, the ravens were shown the box without any stones available. Then the box was taken away. An hour later, in another location, they were presented with a tray containing a stone plus three objects the birds knew would be useless. They were allowed to choose one thing from the tray. Fifteen minutes later, the box would show up again.

In 14 cases of encountering the tray and later seeing the box reappear, the birds usually chose the stone and proceeded to use it correctly. The same thing happened in another experiment, when the box did not show up again until the next day, a delay of 17 hours.

The ravens also showed they could barter for what they needed, learning that they could exchange a blue plastic bottle cap for the favored doggie treat. When the experiments were repeated with the bottle cap replacing the stone, and an experimenter instead of the box, the results were basically the same.

The work presents “compelling evidence” of planning ability that goes beyond stashing food away, Markus Boeckle and Nicola Clayton of Cambridge University wrote in a commentary accompanying the study.

Although the evidence is new, ravens have long been associated with powers of foresight. In Greek mythology, they are associated with the god of prophecy; an old term for a group of ravens is “conspiracy”; and in the TV hit Game of Thrones a three-eyed raven appears in a prince’s prophetic visions.

Edgar Allan Poe’s haunting 1845 narrative poem The Raven, a cornerstone of American literature, features a raven as an uncanny harbinger of doom, constantly repeating the word “nevermore”.

Associated Press in New York