Temperate-Tropical Variation in Breeding Synchrony and Extra-Pair Paternity Among New World Tachycineta Swallows

Extra-pair paternity rates vary markedly across avian taxa, but patterns of variation in this trait have been obscured by a paucity of data on closely related species, especially those spanning broad environmental gradients. Here we compare variation in extra-pair paternity rates among five species in the widespread swallow genus Tachycineta . Rates of extra-pair paternity vary widely in this group, ranging from 13 to 87% of nests having...