Hidden biodiversity uncovered: researchers discover new species of South American screech owls

New study led by the University of Helsinki supports the recognition of new species of South American owls, two of them, Xingu Screech Owl and Alagoas Screech Owl, described for the first time.

In early 2021 two new species of screech owls are being described in a single publication as new to science. A multinational team involving researchers from the University of Helsinki, Brazil, and the USA published a detailed study focusing on the morphological, vocal, and genetic variation in a group of screech owls from the Amazon and Atlantic Forest regions of South America, called the Black-capped / Tawny- bellied Screech Owl complex (Megascops atricapilla M. watsonii). The term “complex” describes the overall uncertainty in the actual number of species in this group of screech owls, which has varied from one to three over the past decades.

“Not even professional ornithologists who have worked on owls for their entire lives would agree about the actual number of species found in this group, so a study like ours has been awaited for a really long time,” says Alex Aleixo, head of the research team responsible for the study, and curator of birds at the Finnish Museum of Natural History in the University of Helsinki, Finland.

The new study published in the scientific journal Zootaxa demonstrated the discovery of six different genetic clusters in the Black-capped / Tawny-bellied Screech Owl complex that are also mutually distinguished by song - a strong indication that they are distinct species.

In contrast, as widely documented in owls, plumage color is variable in the complex, with a single genetic cluster for instance containing five distinct color forms ranging from cinnamon to red. Four out of these six genetic clusters had already been previously recognized as subspecies and given taxonomic names, and the new study support instead their treatment as distinct species. However, two of these clusters had never been recognized or described as unique, and thus had never been given a name. Therefore, the authors described these genetically and vocally diagnosable lineages as new species.

252 specimens, 83 tape-recordings, and 49 genetic samples analyzed

Researchers analyzed altogether, 252 specimens, 83 tape-recordings, and 49 genetic samples from across the range of the Black- capped / Tawny-bellied Screech Owl complex in South America. A significant part of specimens material were collected by the research team itself, mainly by nature tour leader and photographer Sidnei Dantas, who spent a good share of his time in graduate school searching for and tape-recording screech owls in South American rainforests. In addition, natural history collections and their materials collected over the centuries were essential to complete the study ́s unprecedented sampling.

One of these newly described species, the Xingu Screech Owl (Megascops stangiae) , has its scientific name in honor of the late Sister Dorothy Mae Stang (1931‒2005), an American-born Brazilian member of the Sisters of Notre Dame de Namur, who over 40 years introduced small farmers living in the Amazon to sustainability practices. The common name Xingu Screech Owl refers to the area where the new species is found, between the Tapajós and Xingu rivers, where Stang was a very active community leader until her killing.  

The second new species described in the new study is the Alagoas Screech Owl (Megascops alagoensis), named after the state of Alagoas in Northeastern Brazil, where it was recorded for the first time in February 2001, and where most of the known population remains. This new species is known from only five isolated forest fragments in Alagoas and Pernambuco states.

Deforestation is a threat

Both new species of screech owls described by the new study, and a third one, formerly treated as a subspecies, but validated as a new species for the first time i.e., the Belém Screech Owl (Megascops ater), are threatened by deforestation. The Xingu Screech Owl is endemic to the most severely burned area of the Amazon by the unprecedented 2019 fires and the Alagoas Screech Owl should be regarded as critically endangered given the extensive forest fragmentation in the very small area where it occurs. Finally, the Belém Screech Owl is endemic to the most deforested sector of the Amazon forest, with well over 80% of the original forest already cleared.

New research approaches

The recognition of these new species was only possible due to a combination of the application of modern technologies such as DNA sequencing of specimens and digital audio analytical techniques of recordings archived by natural history collections and citizen science databases. New approaches to studying museum specimens and increasingly accessible digital databases are completely transforming our comprehension of biodiversity, and are revealing the existence of long-overlooked but already threatened new species such as the screech owls discovered in the study published by Aleixo and colleagues.

Original article:

Dantas, S. M., Weckstein, J. D., Bates, J., Oliveira J. N., Catanach, T. A. & Aleixo, A. 2021. Multi-character taxonomic review, systematics, and biogeography of the Black-capped/Tawny-bellied Screech Owl (Megascops atricapilla-M. watsonii) complex (Aves: Strigidae). Zootaxa. DOI: 10.11646/zootaxa.4949.3.1

Screech owls

Screech owls constitute a group of small bodied nocturnal birds including 23 different species distributed over most of the Americas. Recent studies have suggested that several additional undescribed species might be recognized in the near future, pending more detailed studies involving DNA sequencing and vocal analyses.