First, this dataset contains morphological measurements (body mass, wing length) of birds from the Biological Dynamics of Forest Fragments Project (BDFFP), located in central Amazonia. Birds were captured using mist-nets between 1979 and 2019 in the understory of primary forest spanning ~40 km. Second, we have included climate data (precipitation, temperature) associated with this study area derived from the global EU Copernicus ERA5 climate reanalysis (https://cds.climate.copernicus.eu).

Birds were captured in understory mist-nets within primary forest. Mass was measured either with a Pesola spring scale or an electronic balance, whereas mass was measured with an end-stop ruler.

For methodological details, see https://doi.org/10.1093/condor/duaa005. Morphological measurements come in large part from bird captures analyzed for abundance trends published here: https://doi.org/10.1111/ele.13628.