People around the world speak many different languages, often with regional dialects that add even more variation. That can make communication difficult —or even impossible. Yet certain signals seem to transcend language. For example, if someone shouts or waves their arms to warn others of danger, the message is often understood regardless of what language is spoken. In that sense, humans share a small set of universal communication signals that can be recognized and interpreted by people almost anywhere.

Just as humans have developed signals that can communicate danger across language barriers, birds may have their own universal forms of communication. A 2025 study undertaken by researchers from Cornell University, Doñana Biological Station in Seville, Spain, and other institutions explored Darwin’s theory of how communication evolved between species. Darwin proposed that, over time, birds developed an innate ability to use vocalizations to warn other birds of danger, even across species. While some bird calls are learned, researchers believe these learned vocalizations may be built upon an underlying, innate ability to communicate.

For this study, researchers zeroed in on birds that serve as hosts to brood parasites. So, what exactly is a brood parasite? Simply put, it is a bird that lays its eggs in another species’ nest, leaving the host bird to incubate the eggs and raise the hatchlings. This strategy allows the parasitic bird to avoid building a nest, incubating its own eggs, and feeding and caring for its young. In many cases, the parasite birds will even push the host bird’s own eggs out of the nest, leaving the host bird to care for only the parasitic eggs and eventual chicks.

The Call That Says, “That’s Not Your Egg!”

Researchers studied 21 bird species that shared the same vocalization for warning against these parasitic arrivals. The birds lived on different continents, with no opportunity to learn the warning call from one another. And yet, they clearly understood what the calls signaled. The vocalization, described as a whining alarm, was essentially the same across species, even though these birds had never interacted. In other words, birds in China, Australia, and the U.S. all responded similarly to the same type of warning call.

The findings suggest that evolution has played a strong role in shaping “built-in” bird vocalizations over millions of years, creating warning signals that can be understood by multiple species. As birds hear and respond to these warnings, the calls may become further reinforced as an essential part of their natural ability to recognize and communicate danger.

This remarkable familiarity with communication in birds may mimic humans’ own ability to use short phrases to convey meaning. While exploring this connection in greater depth is beyond the scope of this short article, it is fascinating to consider that birds’ brains share similarities with those of toddlers when it comes to learning how to communicate.