Convergence in foraging guild structure of forest breeding bird assemblages across three continents is related to habitat structure and foraging opportunities

Abstract

Comparisons of community structure across sites allow for the detection of convergent patterns and the selective forces that have produced them. In this study, we examined the foraging guild structure of birds breeding in forests on three continents — Europe, North America, and Australia, with largely phylogenetically distinct avifaunas. We examined two hypotheses: (1) the bird assemblages in the three geographically separated forested study sites should have similar foraging guild patterns to the extent to which environmental resources of these forests are similar, and (2) if bird assemblages in structurally similar forest habitats have undergone adaptive evolution, then radiation of species into guilds should have been caused by analogous selective resource gradients (factors). Bootstrapped cluster analysis (UPGMA) and bootstrapped principal coordinate analysis (BPCoA) of chord distances were employed to determine foraging guild structure for each assemblage, and to extract the significantly different f...