Territory choice is likely to include sequential sampling at prospective sites, a decision rule for accepting a site, and, when available, use of prior experience. Here, I consider the threshold rule (Real 1990 American Naturalist, 138, 901-917) in which individuals choose the first option that exceeds a preset level of quality and ask how competition for sites limits the choosiness of individuals applying the threshold rule. I then investigate how the addition of site fidelity further influences the evolution of individual choosiness via a threshold rule. I develop an individual-based model that uses a genetic algorithm approach to search for the optimal threshold as an evolutionary stable strategy (ESS) and equilibrium population size. Territory quality (i.e. likelihood of reproductive success) is spatially heterogeneous. Individuals either use the acceptance threshold alone or together with site fidelity. In the latter strategy, successful breeders that survive remain at their former site as incumbents, whereas unsuccessful breeders move to a new site. Results indicate greater competition for sites increases the acceptance threshold and reduces choosiness even when individuals have perfect information from sampled sites. Incumbency, via site fidelity at successful territories, leads to the evolution of relatively unselective behaviour, the degree to which is influenced by the level of adult survival. Competition for sites and site pre-emption, rather than energetic or mortality costs, may drive the evolution of choosiness. The analysis also highlights the importance of considering coexisting strategies used by individuals and not simply the population. For instance, site fidelity, as a coexisting strategy, can result in an ESS acceptance threshold that is no better than random selection, and yet still safeguard populations from extinction.
- Breeding habitat selection
- Evolutionary stable strategy
- Frequency dependence
- Nest predation
- Site fidelity territory choice