A budgerigar grapples with verb conjugations on a branch in Queensland, Australia Tim Graham / Contributor / Getty

Budgerigars and zebra finches can grasp the very basics of grammar, making them one of the only non-human species to exhibit such a high level of abstract thought.

Researchers at Leiden University in the Netherlands tested the birds' ability to interpret new combinations of previously learned sounds and found that both species could perceive the abstract relation between the noises.


To test the birds' grammar skills, Michelle Springs and Carel ten Cate created new bird songs by editing together recorded clips of bird melodies. They created two novel bird songs – one where the sounds were ordered XYX and the other where they were ordered XXY and the birds were trained to peck a sensor that corresponded to each song.

The birds were then played previously unheard songs made of new clips that were ordered in the same way as the training songs.

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Both species of bird used their learned knowledge from the training melodies to distinguish between the new songs. This showed a level of grammatical ability similar to "that shown by human infants," the study said.

While both groups of birds managed to get the hang of the fundamental aspects of grammar, the two species did so in very different ways. Zebra finches paid attention to position of a specific element within the song and could recognise when that shifted within the sequence.

In contrast, budgerigars detected the overall structure of the song and used that knowledge to tell the difference between songs which varied structurally.

The ability to perceive the abstract relation between items was thought to have been unique to humans but this study suggests that, while uncommon, it is possible for other species to detect grammatical regularities without having language. This might indicate a case of "parallel evolution" between humans and other non-human animal species, the study argues.


While these birds are the first to demonstrate a knowledge of grammar, they're not the only avians to prove capable of abstract thought. Earlier this year, a study found ravens were able to imagine being spied upon – a level of abstraction that was previously thought to be unique to humans.

To get an insight into the ravens' thoughts, researchers watched how they behaved while guarding a packet of food when a nearby peephole was either opened or closed. They found the ravens guarded their food only when they thought they were being watched by other birds, but didn't act in the same way when the peephole was closed.

The research is published in the journal PNAS.