For detailed information concerning data collection please see Gonzalez-Voyer et al. Sex roles in birds: phylogenetic analyses of the influence of climate, life histories and social environment. Ecology Letters. Briefly, data on ecology, life histories and behaviour of birds were extracted from published literature. If several data were available for a given species, we included the ones that were extracted from breeding individuals or had larger sample sizes. The details regarding data processing are provided in the Supplementary Material of Gonzalez-Voyer et al. (accepted).

The dataset and the associated notes should be self-explanatory.

Missing values are coded as "NA". All code necessary to repeat the anlayses will be uploaded with the manuscript as supplementary material.