Do avian species survive better on islands?

Abstract

Island species are often predictably different from their mainland counterparts. Milder climates and reduced predation risk on islands have been involved to explain shifts in body size and a suite of life-history traits such as clutch size and offspring growth rate. Despite the key role of adult survival on risk taking and reproduction, the prediction that living on islands increases adult survival has yet to be tested systematically. I gathered data on adult annual apparent survival from the island and mainland year-round resident species of birds from around the world. With this large dataset (697 species), I found that species of birds living on islands showed higher apparent survival than their mainland counterparts in the two Hemispheres and at all latitudes, controlling for several known predictors of adult survival, including body size, clutch size and breeding system. These results shed light on the ecological factors that influence survival on islands and extend the life-history island syndrome to adult survival.