Appendix S1. List of the 86 bird species used for analysis, along with their associated threat level, breeding distribution, habitat specialization index (SSI), two most important life-history axes revealed by principal component (PC) analysis, ecological traits and sample size of four life-history traits. NA denotes those cases where sample was not available from the original source. See the Materials and methods section and Table 1 for definitions and detailed descriptions of particular variables.

Appendix S2. Factor loadings of individual life-history traits, as revealed by the first two ordination axes of principal component analysis (PC 1, PC 2).

Appendix S3. Phylogeny of species included in the phylogenetic generalized least-squares analysis. The phylogeny is based upon Jønsson & Fjeldså (2006), Alström et al. (2008) and Thomas (2008).

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