Researchers at Leiden University in the Netherlands have found that two songbird species – budgerigars (commonly known as budgies) and zebra finches – are able to learn the rules that define abstract grammatical structures in ways similar to that of human infants. For the study, researchers tested how the birds interpreted new combinations of sounds they had heard previously and found that both species of songbirds were able to perceive the abstract relation between the noises. Their unique ability to grasp the very basics of grammar makes them one of the only non-human species to exhibit such a high level of abstract thought.
As per the paper published in Proceedings of the National Academy of Sciences, Michelle Spierings and Carel ten Cate isolated individual birds in a chamber and taught them to recognize recorded clips of bird melodies. They created two form of melodies that occurred in a certain pattern – one that was in the order XXY and the other XYX, and trained them to peck a key that correspond to each song. The researchers then tested the birds on their ability to use what they had learned. First, the birds were exposed to the same melodies they previously learned, but in a new environment, and then were exposed to new sounds in the same pattern.
Both species of songbirds were able to distinguish between the new songs even when the sounds were in a different order and recognize the fundamental aspects of grammar. They found that budgerigars were able to transfer what they had learned to new sounds, meaning they were able to tell the difference between two songs which varied structurally. On the other hand, zebra finches focused on positions of specific items in a string. The ability to perceive the abstract relation was long thought to be unique for humans, but this study have proven that other species can too detect grammatical regularities without language.