Sources, Sinks, and Habitat Selection: A Landscape Perspective on Population Dynamics

In the model described, we attempt to link breeding-site selection to population dynamics for situations in which there is more than one distinct type of habitat. The distribution of individuals between habitat types depends on the selective abilities of the species. This distribution, in turn, influences the population dynamics of the species as a whole. We show that the consequences of habitat selection on population dynamics for an ideal free distribution of individuals across habitats is predictably different from what would be predicted if habitat selection were preemptive, that is, if individuals, upon selecting a site, prevented others from sharing the site. If preemptive selection is ideal, average reproductive success declines with increasing density because each individual selects the best site available from those sites not yet occupied. The model allows us to compare the relative contribution of different types of habitats to a species' growth rate and population size. Furthermore, we can also predict how the loss of habitat of a particular type may affect a population. This should make the model useful for environmental management problems as well as for describing the present distribution of a species across a spatially heterogeneous landscape.