Phylogenetic data
The 53 species included in our study comprised 13 orders and 29 families (Figure 1). Maximal lifespan ranged from 6 to 60 years,female adult body mass ranged from 11 to 8060 g, andtelomere length from 1.7 to 49.3 kb. Using BirdTree, we downloaded 100 trees downloaded from http://www.bird.tree.org (De Magalhaes & Costa, 2009; Jetz, Thomas, Joy, Hartmann, & Mooers, 2012), focusing on the 53 species of our dataset (producing a.nex tree file). We checked the validity of this first phylogenetic representation by building an additional tree based on DNA sequences of cytochrome b (ESM3). Both alternatives produced congruent trees, but we based our subsequent analyses on the bird.tree.org based tree, because we lacked a reliable cytochrome b sequence for Larus andouinii, Larus crassirostris, Acrocephalus sechellensis andErythrura gouldiae . A consensus tree was produced using the Ape package (Paradis, Claude, & Strimmer, 2004) and Phyltools (Revell, 2012). Branch lengths were estimated using Grafen’s method (Grafen, 1989). Markov chain Monte Carlo generalized linear mixed model (MCMCglmm) (Hadfield, 2010; Hadfield & Nakagawa, 2010) packages were used to estimate the relative amount of variation in adult telomere length and life history traits that could be explained by shared ancestry (viz. , the phylogenetic tree). These last packages were also used to estimate the phylogeny content of associations between telomere and life-history variables.