Colonisation, speciation and extinction are dynamic processes that influence global patterns of species richness. Island biogeography theory predicts that the contribution of these processes to the build-up of species diversity depends on area and isolation . Remarkably, there has been no robust global test of this prediction , because neither the appropriate data nor the analytical tools have been available. Here, we address both deficiencies to reveal, for island birds, the empirical shape of the general relationships that determine how colonisation,extinction and speciation rates covary with island area and isolation. We compile the first global molecular phylogenetic dataset of birds on islands, based on the terrestrial avifaunas of oceanic archipelagos worldwide (including 596 aviantaxa), and apply novel methodology to estimate the sensitivity of island-specific rates of colonisation, speciation and extinction to island features (area, isolation).Our model predicts, with high explanatory power, several global relationships: a decline of colonisation with isolation, a decline of extinction with area, and an increase of speciation with area and isolation. Combining the theoretical foundations of island biogeography with the temporal information contained in molecular phylogenies proves a powerful approach to unveil the fundamental relationships that govern variation in biodiversity across the planet.