An international scientific consortium with significant Portuguese participation has launched Avotrex, a comprehensive open-access database cataloging 610 bird species driven to extinction by human activity over the last 130,000 years, revealing that official conservation statistics have historically underestimated the true scale of biodiversity loss.
Why This Matters
• Official records miss the full picture: The IUCN Red List only tracks recent extinctions, while Avotrex captures fossil and subfossil species lost before written records began.
• Islands bore the brunt: Extinctions disproportionately hit island ecosystems, eliminating unique species like flightless birds that evolved in isolation.
• Portuguese science leads: The University of the Azores and CIBIO-InBIO at the University of Porto played central roles in building this global resource.
• Introduced species don't replace what's lost: The database confirms that non-native birds create functional homogenization, not true ecological replacement.
The findings, presented this week at the 27th Spanish Ornithological Congress in Granada, expose a blind spot in global conservation metrics. Current official registries, including the IUCN Red List, document only extinctions witnessed and recorded by modern science. The Avotrex project—formally titled "A global dataset of extinct birds and their traits"—demonstrates that human-driven extinction began long before Linnaeus devised his classification system, and certainly before the first Portuguese naturalists arrived in the Atlantic islands.
The Data Gap No One Could See
Ferrán Sayol Altarriba, a researcher affiliated with the University of Vic – Central University of Catalonia, presented the database at the joint Iberian ornithological congress ending this Sunday. His argument cuts to the core of how scientists measure biodiversity loss: existing statistics capture a fraction of reality.
Most extinct species exist only as fossil and subfossil remains, offering fragments of bone but little ecological context. Without detailed records of morphology, behavior, and habitat, reconstructing what ecosystems looked like before human arrival proved nearly impossible. The Avotrex database, first published in October 2024 in the journal Global Ecology and Biogeography, fills that void by compiling morphological and ecological traits for every confirmed extinction since the Upper Pleistocene, roughly 126,000 to 11,700 years ago.
The database provides detailed measurements for each species: body mass, flight capability, eight standard external morphological measurements matching the AVONET database for living birds, and 22 linear skeletal measurements taken from museum specimens and scientific literature. Where data gaps exist, the research team applied machine learning imputation techniques to estimate missing values, ensuring statistically robust coverage.
Portuguese Research at the Forefront
Portuguese institutions played a more active role than simply lending their names to a byline. The University of the Azores' Faculty of Agricultural Sciences and Environment and the CIBIO-InBIO research center at the University of Porto contributed directly to data curation, methodological development, and ongoing database maintenance.
Filipa Coutinho Soares, a researcher at CIBIO-InBIO, co-authored the foundational Avotrex paper alongside 20 other international scientists. The Azorean connection proves particularly significant given the database's findings: island ecosystems suffered extinction rates far exceeding continental landmasses. The University of the Azores hosts researchers affiliated with CE3C–Centre for Ecology, Evolution and Environmental Changes and the Azorean Biodiversity Group, placing them at the intersection of extinction research and island biogeography.
For Portugal, a nation composed substantially of island territories—the Azores and Madeira—this research carries direct relevance. The database functions as a dynamic resource, designed to incorporate newly discovered extinct species and refined trait data as research progresses.
What Vanished: Islands and the Flightless
The 610 documented extinctions do not represent a random sampling of avian diversity. The data reveals a pronounced pattern: extinctions concentrated on islands and among species with rare or unique traits, particularly flightlessness.
Island birds evolved in isolation, often losing the ability to fly in the absence of land predators. When humans arrived—bringing rats, cats, pigs, and hunting pressure—these species had no evolutionary defenses. The database notes that flightless birds and large-bodied island endemics disappeared at rates far exceeding their representation in global bird diversity.
New Zealand offers a stark example. The moa species, including Anomalopteryx didiformis (the little bush moa), vanished after Polynesian settlement. Roughly nine flightless bird species disappeared from the archipelago alone, each representing millions of years of evolutionary history.
The ecological consequences extend beyond species counts. Avotrex researchers tracked functional and phylogenetic diversity—essentially measuring not just what disappeared, but what roles those species played and how much evolutionary history vanished with them. Large, flightless grazers and unique island predators left ecological gaps that introduced species cannot fill.
Introduced Species Create Ecological Flattening
One of the database's more counterintuitive findings concerns introduced bird species. Conservation debates often frame non-native species as potential substitutes for lost ecological functions. Avotrex data suggests otherwise.
Introduced birds tend toward generalist traits—small bodies, strong flight capabilities, broad habitat tolerance. They do not replace the specialized roles of extinct island endemics. Instead, they drive functional homogenization, making island bird communities increasingly similar to one another and to continental assemblages. The unique evolutionary experiments that produced giant flightless rails, bizarre owl species, and localized honeyeaters leave no functional successors.
For residents of Portugal's island regions, this pattern resonates. The Azores and Madeira host endemic species—some endangered, others already lost—that represent irreplaceable evolutionary heritage. The database provides a template for understanding what conservation gains or loses in these insular environments.
What This Means for Residents
The Avotrex database remains an academic tool, but its implications touch conservation policy, environmental education, and how Portugal manages its own biodiversity.
For conservation professionals, Avotrex offers a baseline. Any assessment of ecosystem health must reckon with what existed before human arrival, not just what disappeared in the last century. The database allows researchers to calculate functional and phylogenetic diversity loss with precision, informing recovery targets and rewilding strategies.
For island communities, the research underscores ecological fragility. Portugal's Atlantic islands harbor endemics found nowhere else—the Azores bullfinch, Madeira firecrest, various endemic subspecies. The extinction patterns documented in Avotrex—flightless birds, large-bodied island dwellers, ecological specialists—provide warning signs for contemporary conservation.
For educators and students, the open-access database (available to researchers worldwide) offers primary data for teaching extinction biology, island biogeography, and human environmental impact. Portuguese universities contributed to building this resource; Portuguese students should know it exists.
The Portuguese Society for the Study of Birds (SPEA), co-organizer of the Granada congress with BirdLife Spain, continues promoting research and conservation partnerships across the Iberian Peninsula. Avotrex represents one product of that scientific network—a data infrastructure capable of showing what was lost, what remains, and what further losses would cost.
The database covers extinctions through 2024, with updates released in January 2025. As new fossil discoveries emerge and taxonomic revisions proceed, the dataset will expand, offering an increasingly detailed portrait of humanity's cumulative impact on the world's birds.
