OPTIMAL FLOATING AND QUEUING STRATEGIES - CONSEQUENCES FOR DENSITY-DEPENDENCE AND HABITAT LOSS

Field studies of many vertebrates show that some individuals (floaters ) do not defend territories even when there is space for them to do so . We show that the evolutionarily stable strategy (ESS) for the thresh old territory quality at which floating takes place is that which maxi mizes the size of the floating population (but not the total populatio n, breeding population, or reproductive output). The ESS is solved sep arately for two assumptions: whether individuals wait to occupy a sing le territory or multiple territories and whether queuing rules are str ict or if all waiting individuals are equally likely to obtain the nex t territory. The four combinations of these assumptions all give the s ame evolutionarily stable population size of both floaters and breeder s. At the ESS, only territories with expected lifetime reproductive su ccess (LRS) exceeding 1 should be occupied, which introduces a limit t o ideal habitat selection. The behavioral decision to float alters the shape of the density-dependent response, reduces the equilibrium popu lation size, and affects the response of the population to habitat los s. Specifically, the floater:breeder ratio is directly related to aver age breeding habitat quality, and the floater population size will dec rease more than the breeding population size if better than average qu ality habitat is lost.