The study of functional traits allows for a more quantitative and predictive approach to ecological and evolutionary questions than only studying species themselves. The accumulation of large databases of functional trait data has been crucial for understanding macroevolutionary trends, community assembly and ecosystem function, but work in plants has generally outpaced work in animals. Writing in Ecology Letters in February 2022, Tobias et al. describe their assembly of the AVONET database of functional trait data from almost all known bird species. Building upon raw data used in a previous study (A. L. Pigot et al. Nat. Ecol. Evol. 4, 230–239; 2020), the authors present data from over 90,000 individuals of 11,009 species from 181 countries, using both museum specimens and living individuals. The morphological traits measured include nine external measurements, plus body mass and hand–wing index, which indicates flight efficiency and dispersal ability. In addition to these, the authors classified each species into one of nine dietary niches and five lifestyle niches, as well as recording their range size and latitudinal and longitudinal spread. The taxonomic classifications were aligned with BirdLife International, eBird and BirdTree databases, and for the few tens of species for which some trait data were missing, inferences were made from close relatives.
We chose this study for our Year in Review collection because the scale of the new dataset constitutes a substantial resource for future advances in both pure and applied research on this important taxon. It should facilitate studies of evolutionary change at both the level of genes and populations, and at a macroevolutionary level across much deeper time scales. From an ecological point of view, the data will assist in the study of responses to ecological change and, given the use of the same taxonomic classification as in the IUCN Red List, the study of causes and consequences of biodiversity loss.
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