With the help of countless students and volunteers, the University of Utah conservation biologist has finally released BIRDBASE, an encyclopedic dataset of traits covering all the bird species recognized by the world’s four major avian taxonomies.
Described this week in a study published in the journal Scientific Data, the dataset covers 78 ecological traits, including conservation status, for 11,589 species of birds in 254 families. The main trait categories tracked are body mass; habitat; diet; nest type; clutch size; life history; elevational range; and movement strategy, that is whether and how they migrate.
While some little-known species still have incomplete data, the dataset provides a foundation for ornithologists around the world to conduct new global analyses in ornithology, conservation biology and macroecology, including the links between bird species’ ecological traits and their risk of extinction, according to Şekercioğlu, a professor in the university’s School of Biological Sciences. He also hopes BIRDBASE will help other biologists win support for studying avian conservation.
“To get funding you have to have a big question, but without data, how are you going to answer those big questions?” Şekercioğlu posed. “It also shows we still have ways to go. Birds are the best-known class of organism, but even though they are the best known, we still have big data gaps.”
BIRDBASE’s public launch coincides with the release of the first unified global checklist for birds, known as AviList, a grand taxonomy under one cover.
The BIRDBASE project started in 1999 when Şekercioğlu was a graduate student at Stanford University, spending field seasons in Costa Rica. While writing the first chapter of his Ph.D. thesis, he needed to know the percentage of tropical forest understory bug-eating birds, technically known as insectivores, that are threatened with extinction. He was perplexed to discover that information had yet to be determined.
“I realized that statistic doesn't exist because nobody had analyzed all the birds of the world and their threat status based on diet,” he said. “I'm like, this is unbelievable. There's no global database on birds. I'm lucky that I was in grad school because I was naive and I love birds.”
In other words, he set out to figure it out himself. That meant gathering and organizing life history traits for all such bird species, including their diets, habitats and conservation status. For a keen birder like Şekercioğlu, it seemed like a simple task that would be fun, compiling data found on thousands of bird species published in huge beautifully illustrated volumes. It turned out to be tedious and seriously time consuming, but worthwhile.
Thanks to a cadre of volunteers in the Stanford Volunteer Program and undergraduates, whose labors were compensated by the Stanford Center for Conservation Biology, Şekercioğlu answered his question within a couple years. Twenty-seven percent of tropical understory insectivores were threatened or near threatened with extinction. This finding wound up not supporting the hypothesis of his research, but that’s science.
Yet the dataset was so helpful that he labored on with the data-compiling project to eventually cover all bird species and expanded the number of traits included. “What started as this little specialized question turned into this global database, the first of its kind” he said.
BIRDBASE has proven a boon to many other avian researchers who have tapped it to support dozens of papers, most of them listing Şekercioğlu as co-author. The tally of Şekercioğlu’s papers that have used BIRDBASE currently stands at 98, accounting for 14,000 of Şekercioğlu’s 24,000-plus citations.
Among the conclusions the dataset has enabled is that a majority of the world’s bird species, or 54%, are insectivores, and many species in this group are under pressure.
“Most of them are tropical forest species. It is a very important group and they're declining,” he said. “They're sensitive even though they're not hunted. They are small, so they don't need a big area. You wouldn't expect them to be the most sensitive group to habitat fragmentation but they are highly specialized.”
The dataset also showed that fish-eating seabirds are at elevated risk of extinction as well, and fruit-eating birds are vital to the survival of tropical rain forests.
“The most important seed dispersers in the tropics are frugivorous birds,” Şekercioğlu said. “In some tropical forests, over 90% of all woody plants’ seeds are dispersed by fruit-eating birds who eat them and then defecate the seeds somewhere else and they germinate.”
Now for the first time BIRDBASE is publicly available to all researchers online, “no strings attached.” It can be found as an Excel spreadsheet on a site hosted by Figshare, with separate worksheet tabs for trait values, trait definitions, nest details and data sources, packaged on one row per species.
Şekercioğlu emphasized that BIRDBASE remains a work in progress that will be continuously updated. Kind of like a medieval cathedral that is open for worship, but never really finished. He estimated that nearly 30 person-years of labor have gone into the project, work that entails entering data collected from various authoritative sources, such as BirdLife International, Birds of the World, hundreds of bird books and ornithological papers, and Şekercioğlu’s field observations of more than 9,400 bird species.
“Thanks to my being naïve, something that started with just a little question in grad school led to the foundation of my career. Right now, if one of my students came to me and said, ‘Hey, as part of my PhD I want to enter the world’s birds into a dataset,’ I'm like, ‘No, you're not doing that. You'll never finish your Ph.D.’ Fortunately I finished my Ph.D., but think about it, 1999 is when I had the idea and we are still putting finishing touches in 2025.”
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The study, titled “BIRDBASE: A Global Dataset of Avian Biogeography, Conservation, Ecology and Life History Traits,” appeared Sept. 30 in Scientific Data, published by Springer Nature. Co-authors include current and former graduate students and lab members Kyle Kittelberger, Flavio Mota, Amy Buxton, Nikolas Orton, Adara DeNiro, Evan Buechley, Joshua Horns, J. David Blount, Jason Socci and Montague Neate-Clegg.
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