A graphical equilibrium model, balancing immigration and extinction rates of species, has
been developed which appears fully consistent with the fauna-area curves and the distance
effect seen in land and freshwater bird faunas of the Indo-Australian islands. The
establishment of the equilibrium condition allows the development of a more precise
zoogeographic theory than hitherto possible. One new and non-obvious prediction can be
made from the model which is immediately verifiable from existing data, that the number of …