A new species of grosbeak in the Amazon

By Kathi Borgmann
Amazonian Grosbeak

Amazonian Grosbeak Cyanoloxia rothschildii

  • Santa Cruz, Bolivia

The power of museum collections, says Natalia García, a post-doctoral researcher at the Cornell Lab of Ornithology, is that they hold the answers to questions we haven’t yet thought to ask. Technological advances now allow us to examine genetic makeup or analyze differences in vocal parameters that in some cases reveal new species that were once thought similar.

García, now a post-doctoral researcher at the Cornell Lab of Ornithology, began studying the Blue-black Grosbeak for her Ph.D. at the University of Buenos Aires and the Argentinian Museum of Natural Sciences. She knew that across the range of the Blue-black Grosbeak researchers described four different subspecies, but it wasn’t until she looked at specimens in the museum did she really see the difference. “One of those specimens looked really different,” García said. It was much lighter blue and looked similar to a different species of grosbeak García was used to seeing in her home country, Argentina. Then research by Bryson and colleagues (2014) found that those four grosbeak subspecies were indeed genetically different.

García, intrigued by these finding wanted to know how physical traits and in particular differences in bill size and song differed among the subspecies. Do the physical and behavioral differences, García wonder, support the genetic findings? Are any of the subspecies really different species?

To answer that question, García and colleagues turned to museums and not just classic museums with specimens, but to our very own digital museum of sound—the Macaulay Library. They examined specimens from the Museum of Vertebrate Zoology at the University of California and the American Museum of Natural History in New York. They analyzed songs from the Macaulay Library, the Borror Laboratory of Bioacoustics, and the Florida Museum of Natural History.

Their analysis of song and physical characteristics revealed that one of the grosbeak subspecies was different from all the rest. The subspecies in the Amazon was lighter blue, smaller, and had a smaller beak. The subspecies in the Amazon also had a different song with shorter notes sung at a faster pace. Birds from the Amazon also didn’t have a strong rise in pitch heard in grosbeaks outside of the Amazon.

Amazonian Grosbeak Cyanoloxia rothschildii

  • Amazonas, Brazil

Blue-black Grosbeak Cyanoloxia cyanoides

  • Veracruz, Mexico

Together with the findings of García that showed physical and behavioral differences and the work of Bryson et al. (2014) that showed genetic differences, the subspecies in the Amazon was elevated to species status in 2018 and is now known as the Amazonian Grosbeak (Cyanoloxia rothschildii).


Bryson, R. W. Jr., J. Chaves, B. T. Smith, M. J. Miller, K. Winker, J. L. Pérez-Emán, and J. Klicka (2014). Diversification across the New World within the ‘blue’ cardinalids (Aves: Cardinalidae). Journal of Biogeography 41:587–599.

García, N. C., A. S. Barreira, P. D. Lavinia, and P. L. Tubaro (2016). Congruence of phenotypic and genetic variation at the subspecific level in a Neotropical passerine.