In the cold, wave-battered channels off southern Chile, scientists have identified what they say is a new species of the steamer duck genus Tachyeres, a group of notoriously aggressive, often flightless waterfowl found only in South America.
Detail of the color pattern of the bill in adult specimens of the Chiloe steamerduck (A) and the Magellanic steamerduck (B). Image credit: Bernabé López-Lanús & Mariano Costa.
Tachyeres is a small genus of ducks in the water bird family Anatidae.
These birds are known for their unusual biology. Most species are flightless and propel themselves across the water by beating their wings like paddles, giving them their name.
They are also famously territorial, capable of violently defending their range against other birds.
“The natural history of Tachyeres is accompanied by a long description of certainties and mistakes interspersed over time,” Argentine ornithologists Bernabé López-Lanús and Mariano Costa wrote in their paper.
Some Tachyeres species can include both flying and non-flying individuals within a single population, blurring distinctions once thought to define separate species. That ambiguity has weakened the usefulness of traits for classification.
In response, the study authors turned to bioacoustics; they analyzed vocalizations across all known steamer duck species, combining field recordings, archived audio databases and spectrogram analysis.
They found that while some calls — particularly the rapid ‘ticking’ sounds used in territorial displays — were broadly similar across species, another type of call proved decisive.
Known as ‘rasping grunt,’ this contact call showed consistent, species-specific patterns in the acoustic structure.
“This call is usually emitted in isolation, or prior to the vocalization of territorial proclamation,” the researchers explained.
“Its description goes beyond the strict behavioral meaning of the call — as does the territorial proclamation vocalization — but it constitutes another form of vocalization in Tachyeres, analogous in each taxon.”
The males of the newly-identified species produced calls with a distinctive ‘dome-shaped’ frequency profile, differing from the ‘scalene triangle’ pattern typical of a very similar species, the Magellanic steamer duck (Tachyeres pteneres).
Named the Chiloe steamerduck (Tachyeres ketru), the new bird is endemic to the Chiloé and Aysén region of Chile, with an area of occurrence from approximately 40 degrees south latitude — from Valdivia and the northern tip of the Chiloé region — to the Taitao Peninsula (in the south).
The species occupies protected coastal environments (bays and inland channels rich in macroalgae), while the Magellanic steamer duck is associated with more exposed, wave-battered coastlines farther south.
“Breeding adults compete for sites with optimal foraging conditions: the canopy of underwater forests of brown macroalgae Macrocystis pyrifera (‘kelp’),” the scientists wrote in the paper.
“This habitat is characterized by dense refuges with a high diversity of small invertebrates (amphipods, gastropods, polychaetes, juvenile fish), which are accessed by individuals of this taxon by diving, as is typical of Tachyeres.”
The discovery highlights the growing role of sound in modern taxonomy and underscores how even well-studied species can conceal hidden diversity, especially in remote or complex environments.
“Cases like the discovery of Tachyeres ketru allow us to conclude that bioacoustics is an essential tool for understanding the taxonomy of cryptic species, even with a limited sample size,” the authors concluded.
Their paper appears online in the journal Audiornis.
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Bernabé López-Lanús & Mariano Costa. 2026. A new species of Steamerduck (Anatidae: Tachyeres) from the Chiloé region, Chile, finally confirmed as a taxon distinct from Tachyeres pteneres. Audiornis 5: 2-65
