Yellow-naped Amazons Use Syntax in Fast Warble Duets

Christine R. Dahlin and colleagues report in the Journal of Avian Biology that wild yellow-naped amazons (Amazona auropalliata) use fast warble duets organized by rule-like ordering, and a Voyant text-analysis of recordings identified 36 distinct call types. The Popular Science writeup by Margherita Bassi on Feb 20, 2026 highlights Dahlin’s finding that these duets are structured yet highly variable, and frames the result as evidence that parrots’ formidable vocal skills exist outside of captivity.

Field recordings in Costa Rica form the backbone of the analysis: Dahlin’s team documented mated pairs alternating tightly timed bursts during intense territorial disputes, producing a rapid, layered volley that overlaps, accelerates, and sharpens as tensions rise. Discover Magazine’s coverage by Anastasia Scott describes those exchanges as a “rapid, layered volley of sound,” while Earth’s Sanjana Gajbhiye emphasizes that warble duets are the more complex duet type used in territory battles. Dahlin told Popular Science, “Thus, I have been using yellow-naped amazons as a model to study complex parrot vocal signals in the wild. The warble duets, which I researched for this study, are their most complex signal.”

The research used a text-mining approach uncommon in bioacoustics: recordings were tokenized and run through Voyant to detect recurring pairings and ordering patterns. Popsci reports the Voyant analysis yielded 36 call types and found that “many call types assort together, much like words are commonly given together within bodies of human text, such as grass and green or sport and ball,” a point Dahlin emphasized. Discover notes Dahlin has years more of raw recordings to analyze, including how different pairs’ sequences escalate or calm disputes.

That vocal culture sits atop a long-term dialect literature. PMC/NCBI review material documents three contact-call dialects first recorded in Costa Rica in 1994 (North, South and Nicaragua), a 2005 survey that preserved dialect integrity, and a third survey in 2016 that showed major change. ScienceAlert reports that by 2016 Costa Rica’s yellow-naped population “had plummeted by more than half,” and elsewhere states “In the last three generations alone, the yellow-naped parrot has lost more than 92 percent of its population in Central and South America.” Playback experiments in the long-term work show birds respond less to foreign dialects, and a translocation experiment documented one juvenile learning a new dialect while none of the translocated adults did, a result the PMC text cautions is limited by small sample size.

Researchers and conservationists see practical stakes: Earth cites BirdLife International’s listing of yellow-naped amazons as Critically Endangered, and Popsci records Dahlin noting illegal capture for the pet trade as a key threat alongside habitat loss, fragmentation, and nest poaching. ScienceAlert summarizes the study authors’ interpretation that “The observed cultural changes may represent adaptive responses to changing group sizes and patterns of social association,” while PMC notes that whether dialect shifts will affect mate acquisition, reproduction and roosting remains an open question. Dahlin’s quote from a press release captures the next step: “Ultimately, I really want to understand how these birds are communicating in the wild. I want to know what they are saying, and how they are saying it.”