Emus and nandus have been found to possess the ability to solve puzzles for the first time.

Palaeognaths (Palaeognathae), or ratites, are a small group of birds that includes several flightless and predominantly large-bodied species. This group includes ostriches, emus, rheas, and the giant moa—extinct giant birds without wings that reached heights of about three meters.

There is a stereotype regarding the intellectual primitiveness of ratites, particularly ostriches; however, there is limited scientific data on the cognitive abilities of these feathered creatures. Research often involves corvids and parrots, which have larger brains.

A team of psychologists from the University of Bristol (UK) aimed to address this gap. Their new article was published in the journal Scientific Reports.

The researchers conducted experiments involving nine palaeognaths from a local zoo—three emus, two rheas, and four ostriches. To assess their intelligence, the specialists designed a puzzle consisting of two round transparent plastic shapes, stacked on top of each other and held together with a bolt and nut. The bottom part had five circular recesses for edible bait—leaves of romaine lettuce—while the top had a single hole of the same diameter. To access the treat, the birds needed to use their beaks to shift the upper part and align the hole with the recess containing the food.

The experiments took place over several days, either with intervals or continuously. All subjects were first allowed to familiarize themselves with the puzzle by removing the movable top part with the hole, enabling the birds to easily access food from the open recesses. During the puzzle-solving tests, they were given 30 minutes. The events were recorded on video.

All three emus successfully completed the task on their first attempt and were able to solve it again when researchers reloaded the puzzle with lettuce leaves. In 90% of cases, the birds rotated the hole toward the nearest filled recess, demonstrating the most efficient behavior.

One of the rheas also managed to access the treat, and he did it not only by the "rotational" method but also found an "alternative" route. The rhea loosened the bolt with its beak in the center of the structure and opened it, gaining immediate access to all five recesses with food. However, once the rhea mastered the method intended by the experimenters involving rotation, it no longer resorted to "vandalism." The second bird—a female rhea—simply ignored the puzzle, so her result was not counted later.

Ostriches were unable to complete the test. Although they pecked at the puzzle, none attempted to shift the hole. The researchers suggested that the birds likely struggled due to their relatively smaller brain size.

The scientists noted that the test was relatively easy compared to some tasks in experiments involving corvids and parrots. Nevertheless, the results obtained are significant as they challenge the notion of the stupidity of palaeognaths and demonstrate that emus and rheas can exhibit new forms of behavior and solve problems they have not encountered before. Furthermore, further exploration of the abilities of ratite birds could shed light on the behaviors of their ancient ancestors—the dinosaurs.