Optimal floating and queuing strategies: The logic of territory choice

This is a response to a recent article by Hanna Kokko and William J. Suther land (American Naturalist 152:354-366), who consider evolutionarily stable territory acceptance rules for animals that face the decision between settl ing on a poor territory now (which is then retained for life) or waiting fo r better habitat to become available later (taking a chance of dying before reproducing). In contrast to these authors, we argue that the evolutionari ly stable threshold quality above which territories are acceptable does dep end on whether individuals compete for a single territory (queuing) or For multiple territories (floating) and also on whether access to territories i s determined by a hierarchy among waiting individuals. More specifically, w e show the following: First, if the choice is between floating and settling , the evolutionarily stable acceptance threshold is such that threshold ter ritories yield an expected lifetime reproductive success (LRS) of 1 - mu(F) , the survival probability of a floater. Second, if the choice is between q ueuing and settling, the evolutionarily stable threshold may correspond to any LRS between 1 - mu(F) and unity. Third, the number of nonbreeding indiv iduals in the population is maximized at a threshold of unity. In other wor ds, the evolutionarily stable threshold does not maximize the nonbreeding F raction of the population. We argue that models of territory choice should carefully specify the mechanism of choice because some choice processes (e. g., indiscriminate habitat use above the threshold) do not admit an evoluti onarily stable acceptance rule.