When birds such as zebra finches communicate through their calls, are they simply reacting to sounds, or do they actually process the meaning behind them? A new study from neuroscientists at the University of California, Berkeley suggests that zebra finches do, in fact, have a mental representation of meaning in their vocalizations.
The research team found that zebra finches categorize calls in a way similar to humans. Both species group calls into roughly a dozen types or “words,” each serving different functions like sounding an alarm, identifying themselves, courtship, signaling distress or hunger, and expressing aggression. Notably, the birds sometimes confuse calls within the same semantic group—those with similar meanings—even when the acoustic properties are quite distinct.
Julie Elie, a research associate in Berkeley’s Department of Neuroscience and first author on the paper published in Science, explained: “As long as call-types have clearly different meanings for the birds, they are very well distinguished even if their acoustics are quite similar. But call-types further apart in the acoustic space that can be lumped in the same semantic category are surprisingly mistaken more often by the bird. It’s proof that they have this mental representation of the meaning, which leads them to make errors. Otherwise, if this representation of meaning was not there, there’s no reason they would make errors more often between call-types that belong to the same semantic group.”
Frédéric Theunissen, UC Berkeley professor of neuroscience and senior author on the study added: “We have shown, indirectly, that birds understand what they are saying.” He also noted this is “the first time anyone has actually tested whether animals agree with the human experts that calls have different meanings” and whether acoustic differences detected by humans are also recognized by birds.
Elie suggested that if zebra finches possess this ability for mental representation of vocal meaning, then species with more complex vocalizations—like crows—may have even more elaborate communication systems. She said these findings show bird communication is not entirely reflexive but allows for decision-making.
The research utilized an experiment where captive zebra finches were trained to distinguish among 11 documented call-types. Birds were rewarded for selecting specific calls associated with a food reward from audio tracks containing thousands of recorded vocalizations. Their performance showed agreement with human categorizations of these calls.
Elie recounted: “This tells us that they agree with whatever organization of the repertoire we made. The human is here observing and saying, ‘Those are your words.’ And the bird is saying, ‘Yes, these are my words.’”
To further probe whether birds truly process meaning rather than just sound patterns, researchers analyzed mistakes made during discrimination tasks. They found birds most often confused calls based on shared meaning rather than acoustic similarity—a result Elie described as surprising and indicative of semantic processing.
By cataloging behaviors associated with each call-type (an ethogram), Elie linked specific sounds to both sender and receiver behaviors among zebra finches. This allowed for a comprehensive mapping between communication signals and behavioral responses.
Theunissen emphasized how these findings extend previous work on how brains extract meaningful signals from background noise: “Now we’re going from sensation to perception… Perception is like assigning a label… Or here, ‘I understand what you’re speaking.’”
Elie and Theunissen continue their research by recording brain activity during call discrimination tasks to identify where and how meaning is represented neurologically.
Other coauthors include Aude de Witasse-Thézy from University de Lyon in France and Logan Thomas and Ben Malit from UC Berkeley.
This study advances understanding of animal cognition and highlights similarities between avian communication systems and aspects of human language learning.
