Abstract
When species diversity S on an island is displaced from the equilibrium value by injection or removal of species, S relaxes to equilibrium by an imbalance between immigration and extinction rates. Estimates of exponential relaxation times, t r , for avifaunas of New Guinea satellite islands are calculated from analysis of four “experiments of nature”: recolonization of exploded volcanoes, contraction in island area due to rising sea level, severing of land bridges, and disappearance of landbridge relict species. t r is in the range 3,000-18,000 years for avifaunas of islands of 50-3000 square miles (130-7800 km 2 ), and increases with island area. Immigration coefficients decrease and extinction coefficients increase with increasing S . The results may be relevant to the design of rainforest preserves.