Do you sing like I do? Geographic variation in the vocalizations of a Neotropical sparrow species complex

Variation in phenotypic traits are common in geographic scenarios, and conspicuous when geographic isolation is involved. Genetic, morphological and cultural traits are all affected with important consequences in the recognition of conspecifics and speciation processes. In songbirds, the vocal traits are of special interest as songs are learned producing great diversity of acoustic signals.

A male of Olive Sparrow (Arremonops rufivirgatus) from Peninsula population, one of the five allopatric populations within the complex, at MAPSA, in Mérida, Yucatán, México. Photo: R. Fernández.

The Olive Sparrow is a Neotropical songbird with a series of isolated populations across its distribution range. Taxonomic authorities suggest the existence of 8 to 9 subspecies, all of them within 2 to 3 groups. However, no formal studies have been carried out to assess phenotypic variation traits within the species’ geographic range and to clarify the taxonomic status within the complex. Therefore, we were interested in assessing the extend of song variation in Olive Sparrows and analyzed whether such variation mirrored isolated populations or the proposed taxonomic groups; a study recently published in The Journal of Field Ornithology.

We found significant acoustic variation in the Olive Sparrow complex at both levels of analysis: between isolated populations and between the proposed taxonomic groups. Our divergence analysis also revealed that vocal divergence within the complex is similar to or greater than that found between other recognized species in the genus. We show evidence that demonstrate that some population sing in a different way that other populations do, suggesting that acoustic diversity within the Olive Sparrow complex probably originated by isolation, following selective and/or non‐selective factors.

A distribution map with the allopatric populations within the complex with a song spectrogram samples.

Part of the site study at Chamela Biological Station, in Jalisco, México. The habitat of Olive Sparrow is represented by dry forest and scrubs. Photo: R. Fernández.

A researcher banding birds to identify their territories. Photo: W. Kuu.


This research was recently published in the Journal of Field Ornithology:

Fernández Gómez, R. A., J. E. Morales‐Mávil, and J. R. Sosa‐López. 2020. Geographic variation and divergence of songs in the Olive Sparrow species complex. Journal of Field Ornithology


Guest post by:

Ronald A. Fernández Gómez
Instituto de Neuroetología, Universidad Veracruzana
Xalapa, Veracruz, Mexico