A New Bird for Argentina: The Tawny-rumped Tyrannulet (Tyranniscus uropygialis)

In July 2025, a small, elusive bird changed the Argentine ornithological landscape. For the first time ever, the Tawny-rumped Tyrannulet (Tyranniscus uropygialis) was documented within Argentina, supported by both photographic and acoustic evidence. This confirmation adds a new species to the national avifauna and opens a fresh chapter in the study of Andean birds. As the scientific note states:

“We present the first documented record of the Tawny-rumped Tyrannulet (Tyranniscus uropygialis), with acoustic and photographic evidence.”

Where the Discovery Happened

The first confirmed individual was observed on 25 July 2025 in Valle Colorado, Valle Grande Department, Jujuy, at 1965 meters above sea level. The bird was actively foraging among two exotic conifers in the backyard of El Mirador lodge.

The observers—Adrián Barboza, Gustavo Marasco, and Javier Viqueira—managed to photograph the bird despite its constant movement between trees.

“The individual was moving actively from one conifer to another… which made it difficult to obtain good photographs.”

The surrounding habitat is a transition zone between montane forest and inter-Andean shrublands, a mosaic of cultivated plots, abandoned open areas, low shrubs, and scattered exotic trees planted by local residents.

Acoustic Confirmation

On 31 July 2025, Diego Monteleone and Marcelo de Cruz revisited the site and used playback based on Bolivian recordings. The response was immediate: the bird approached, perched high on a leafless tree, and began vocalizing repeatedly.

“The bird approached immediately… repeating its song approximately every 4 seconds.”

These recordings—now available on eBird (ML640976267)—provided definitive confirmation of the species’ identity. The sonogram shows the typical three-note pattern of the species: two strong notes followed by a softer, shorter one.

A Cryptic Species That May Have Been Overlooked

The Tawny-rumped Tyrannulet is considered cryptic, meaning it resembles other species and can easily go unnoticed. Its plumage and vocalizations are strikingly similar to the White-throated Tyrannulet (Mecocerculus hellmayri), which inhabits the same region.

The article highlights:

“It is a species that could be considered cryptic… whose aspect and vocalizations recall much the White-throated Tyrannulet.”

Key differences include:

• Brownish back and crown (vs. olive back and gray crown in M. hellmayri)

• Buff-colored rump, the hallmark of T. uropygialis

• A distinct trisilabic song, unlike the flatter, repeated notes of M. hellmayri

These subtle distinctions explain why the species may have remained undetected in Argentina for decades.

More Records After the Discovery. Birding in Argentina

Following the initial observation, several additional sightings occurred at the same location through November 2025, including a report of two individuals in September. This suggests that the species may be more regular in the region than previously thought.

Playback-based surveys along the altitudinal gradient could reveal a broader presence and help understand the dynamics of this newly confirmed population.

A Significant Addition to Argentina’s Birdlife

The documentation of the Tawny-rumped Tyrannulet is more than a new dot on the map—it’s a reminder of how much remains to be discovered in the montane forests of northwestern Argentina. Hidden among steep valleys, exotic trees, and mixed-species flocks, this small tyrannulet has finally stepped into the spotlight.

Its presence invites birders and researchers to look closer, listen carefully, and continue exploring one of the country’s most biodiverse—and still mysterious—regions.