Global parallels in nest-parasite warnings
A sweeping international study finds that more than 20 bird species across four continents share an remarkably similar warning call when they spot a brood parasite near their nests. The whining vocalization, learned in the moment as birds listen to their surroundings, appears to be a common strategy across distant lineages to deter parasitic birds such as cuckoos from laying eggs in their hosts. The research team, drawing on field and laboratory work in North America, Europe, Africa and Asia, suggests that this call is not a fixed instinct alone but part of a learned repertoire shaped by social experience and exposure to local threats.
The findings, previewed ahead of formal publication in Nature Ecology and Evolution on October 3, 2025, illuminate how natural selection can mold vocal communication in ways that blur the line between instinct and learning. The project, led by researchers at Cornell University and the Donana Biological Station in Seville, Spain, represents one of the most comprehensive examinations of brood parasitism to date.
Learned cues with innate roots
At the heart of the study is a call described as a distinctive “whine” that signals danger to nearby birds. When a host hears the warning, it instinctively investigates the area, triggering a learning process in which the bird absorbs contextual cues from its surroundings. According to the study’s co-lead author and Cornell Lab of Ornithology researcher, the sound marks a rare midpoint between instinctive vocalizations and fully learned human speech. In other words, the species are not born with a complete library of calls, yet they rely on an innate framework that can acquire new meanings through social experience.
As one scientist noted, the emergence of this call bridges a long-standing gap in how scientists view animal communication. The whining sound appears to be a stable element across species, yet its timing, usage and learning dynamics vary depending on local brood-parasitism pressures. The result is a hybrid system in which innate vocal patterns provide a scaffold for culturally transmitted adjustments, enabling rapid adaptation in changing ecological contexts.
Social transmission and learning in the wild
The study emphasizes social transmission as a key engine of learning. Birds ears pick up the warning through interactions with conspecifics and environmental cues, then gradually refine not only when to emit the call but how to modulate it under different circumstances. This process mirrors broader themes in language evolution, where social networks help shape signals that eventually take on more flexible meanings. The researchers note that these dynamics are particularly pronounced in regions where brood parasitism is most intense, suggesting that cooperation in warning and response may be reinforced by shared information across communities of birds.
Implications for the origins of language
The work challenges a simple dichotomy between animal communication and human language. It supports a view in which learned communication can develop through incremental integration with instinctive elements, echoing ideas first proposed by Charles Darwin. “This is a vivid example of how evolution can grant learned meanings to sounds, expanding the functional repertoire of a species without abandoning its ancestral vocal fabric,” one co-author commented. The findings imply that the roots of language may lie in gradual, multi-source processes that combine inherited tendencies with culturally transmitted learning.
What the study reveals about cooperation and evolution
Beyond the mechanics of a single call, the research hints at broader consequences for social behavior. The similarity of the whining signal across diverse communities underscores how collective action—birds working together to repel or mitigate parasites—can shape communication strategies. In effect, the evolution of this warning vocalization appears to influence patterns of cooperation among birds worldwide, highlighting a potential feedback loop between communication and social organization in natural ecosystems.
Meet the team and future directions
Leading researchers include James Kennerley of the Cornell Lab of Ornithology and Damián Blasi of Pompeu Fabra University, with contributions from the Donana Biological Station. The study’s cross-continental scope and its emphasis on the interplay between innate and learned components bring renewed attention to the evolutionary story of language. As scientists continue to compare species, regions and ecological pressures, the next steps will likely probe how widespread these hybrid vocal systems are and what they reveal about the emergence of more complex communicative behaviors in other animals.
