For a long time, comparing the relative sizes of birds seemed an impossible task—too many species simply lack reliable numbers. However, the recent influx of citizen science data has allowed researchers to estimate the global abundance of 9,700 species, accounting for approximately 92% of all birds on the planet. Biologists Corey T. Callaghan, Shinichi Nakagawa and William K. Cornwell of the University of New South Wales in Australia combined the scientific data of 724 well-studied species with the data in the app eBird. People all over the world can use the The application submits bird watching records. Researchers use an algorithm to infer estimates for all species in the sample.The results were recently published in Proceedings of the National Academy of Sciences U.S, It confirms a common pattern among animals: on a global scale, there are many species isolated in niche habitats, but the populations are small, and they can expand in a vast territory and grow their populations to hundreds of millions or several. One billion species are relatively few. Ultimately, these findings may help conservation efforts. “The next step is, which species are rare because this is how Mother Nature creates them, and which species are rare because we [humans] Messed up? Callahan asked. He said that the project did not attempt to answer these questions, but it was a “necessary first step” to achieve this goal.

The graph groups birds by population size and displays circles scaled according to the number of species in each group.
Image source: Jen Christiansen (Image), Liz Wahid (birds); Source: “Global abundance estimates of 9,700 bird species”, Authors: Corey T. Callaghan, Shinichi Nakagawa and William K. Cornwell, in PNAS,roll. 118, May 25, 2021 (data)