Predicting the consequences of habitat loss for migratory populations

Abstract

For many migratory species the area of wintering or breeding habitat is changing or is likely to change as a result of processes such as habitat destruction or global environmental change. I show that the ratio of population decline to loss of typical wintering habitat equals d$^{\prime}$/(d$^{\prime}$+b$^{\prime}$), where d$^{\prime}$ is the slope of relation between per capita winter mortality and population density and b$^{\prime}$ is the slope of the relation between per capita net breeding output and population density. Similarly the ratio of population decline to loss of typical breeding habitat equals b$^{\prime}$/(b$^{\prime}$+d$^{\prime}$). Game theory models can be used to predict the values of b$^{\prime}$ and d$^{\prime}$. For example, incorporating values of d$^{\prime}$ and b$^{\prime}$ from such models for the oystercatcher Haematopus ostralegus shows that a loss of 1% of wintering habitat will result in a population decline of 0.69% while a loss of 1% of breeding habitat will result in a population decline of 0.31%.