The Amazon rainforest, a realm of unparalleled biodiversity, constantly reveals new secrets. Even under the scrutiny of daylight, countless creatures remain unknown to science. As darkness descends, the forest transforms, teeming with nocturnal wildlife even more enigmatic than their diurnal counterparts. Recent research published in Zootaxa unveils two newly identified species of screech owls inhabiting the Amazon and Atlantic forests. Alarmingly, both are already classified as critically endangered, highlighting their precarious existence in the face of habitat loss.
Alt text: Ornithologist John Bates, curator at the Field Museum, carefully holds a bird specimen during research, emphasizing expertise in avian studies.
“Screech owls, in comparison to many other organisms in these regions, were thought to be a relatively well-understood group,” explains John Bates, curator of birds at the Field Museum in Chicago and a contributing author of the study. “However, detailed analysis of their vocalizations and geographic distribution reveals previously unrecognized distinctions. This deeper investigation led to the description of these new species.”
Alex Aleixo, the head of the research team and curator of birds at the Finnish Museum of Natural History, University of Helsinki, emphasizes the long-awaited nature of this research: “Even seasoned ornithologists specializing in owls have debated the exact number of species within this group. Our study addresses this longstanding question with comprehensive evidence.”
These newly discovered owls are related to the familiar Eastern Screech Owls of the United States, but face far greater threats. “They are charming, diminutive owls, only about five or six inches in length, adorned with distinctive feather tufts,” describes Bates. “Their plumage varies in shades of brown, gray, and intermediate tones.” Before this study, these new species were mistakenly grouped with the Tawny-bellied Screech Owl and the Black-capped Screech Owl, species distributed across South America.
Alt text: Detailed close-up of an Eastern Screech Owl showcasing its characteristic tufted feathers, similar to the newly discovered endangered Amazonian species.
Distinguishing these species involved years of meticulous fieldwork within the Amazon rainforest and the Atlantic Forest of eastern Brazil and neighboring countries. Bates, whose fieldwork typically occurs during daylight, acknowledges the unique challenges of nocturnal rainforest research. “While I find it more fascinating than frightening, navigating the rainforest at night presents obstacles. You constantly encounter spider webs, and a headlight reveals the eyeshine of nocturnal animals. I once encountered a tarantula the size of my hand while stepping over a log,” Bates recounts. “As a child, that would have been terrifying.” This highlights the contrast: humans might feel fear in the dark forest, but these small owls are vulnerable and “afraid” in a different sense – afraid for their survival due to habitat loss driven by human activities.
These elusive owls reside high in the forest canopy, often a hundred feet above the ground, making observation challenging. However, researchers employed a clever technique leveraging the owls’ characteristic “screech” calls.
“We utilized tape recordings to attract the birds,” Bates explains. “By recording their calls and playing them back, we capitalized on their territorial nature. Upon hearing the recordings, the owls emerged to defend their territory, allowing us to observe them.”
Scientists meticulously compared the vocalizations of these owls, identifying variations indicative of distinct species. They further examined physical characteristics and collected tissue samples for DNA analysis at the Field Museum’s Pritzker DNA Lab, a crucial step in confirming species differentiation.
The comprehensive study encompassed the analysis of 252 specimens, 83 tape recordings, and 49 genetic samples from across the Tawny-bellied Screech Owl complex’s South American range. Lead author Sidnei Dantas dedicated a significant portion of his graduate studies to locating and recording screech owls in South American rainforests, contributing substantially to the specimen collection. Furthermore, historical collections from natural history institutions in Brazil and the USA proved invaluable for the study’s extensive sampling.
Alt text: Sidnei Dantas, lead author, conducting fieldwork in the Amazon rainforest, recording owl vocalizations for species identification research.
Dantas emphasizes the critical role of biological collections: “This study relied heavily on the invaluable collections in Brazilian and US institutions, which provided essential genetic and morphological material. This underscores the vital contribution of such research institutions to scientific progress and the advancement of their respective countries.” Dantas conducted this research as part of his PhD dissertation at the Goeldi Museum in Belém and currently works as a nature guide in the Brazilian Amazon.
The convergence of genetic distinctiveness, physical variations, and unique vocalizations led the team to formally describe two new species alongside the Tawny-bellied Screech Owl: the Xingu Screech Owl and the Alagoas Screech Owl. The Xingu owl’s scientific name honors Sister Dorothy May Stang, an activist who championed sustainable practices for Brazilian farmers and fought for their land rights. Its common name derives from its habitat near the Xingu River. The Alagoas owl is named after the northeastern Brazilian state of Alagoas, its primary habitat.
Tragically, these newly recognized species are already facing extinction. “Deforestation poses a severe threat to both new species,” states Jason Weckstein, associate curator of Ornithology at the Academy of Natural Sciences of Drexel University and associate professor at the university’s Department of Biodiversity, Earth, and Environmental Science. “The Xingu Screech Owl is endemic to the region most devastated by the unprecedented Amazon fires of 2019. The Alagoas Screech Owl should be considered critically endangered due to extensive forest fragmentation in its limited range,” adds Weckstein, a co-author who initiated this project as a postdoctoral researcher at the Field Museum.
Bates hopes this study will illuminate the remarkable diversity within the Amazon and Atlantic forests and underscore the inadequacy of generalized conservation approaches. “Simply considering ‘Amazonia as Amazonia’ and assuming its vastness is sufficient for protection overlooks the critical need to prioritize conservation efforts in specific, distinct regions within Amazonia. Failure to do so could result in the loss of entire faunas unique to these areas,” Bates warns. These tiny owls, “afraid” not of the dark forest itself, but of the relentless encroachment of habitat destruction, represent a larger crisis of biodiversity loss.
Beyond the crucial conservation implications, the authors emphasize the international collaboration that underpinned this research. “This study exemplifies the importance of global scientific training and collaboration,” Bates concludes. “Providing opportunities for students like Sidnei from Brazil to work in the Field Museum’s Pritzker Lab and utilize our collections for their research is invaluable for fostering global scientific advancement and building essential international connections.”
