The dynamics of territory acquisition: A model of two coexisting strategies (Q1897493)

Many organisms display territoriality, where the resources associated with a particular site are defended from conspecifics. While the costs and benefits of territorial defense have been extensively discussed, there has been much less attention paid to the dynamics of territorial acquisition. Species can be classified in one of two categories, based on their predominant behavior during territory acquisition. In many species, including birds, insects, and fishes, there exists a group of relatively quiet and inconspicuous nonterritorial individuals of ``floaters'' that do not tend to challenge established territory owners. Instead, they simply wait for a territorial vacancy to occur, usually through the death of the owner. In contrast to this waiting strategy, territory owners in other species must constantly fend off challenges to ownership. In species as diverse as damselflies, frogs, tropical house wrens, magpies, and elephant seals, territorial acquisition is most often accomplished by means of a contest (or series of contests) with an established territory owner. In other words, in these species the nonterritorial individuals are not content to wait for vacancies to occur naturally; they fight instead. We explore this dichotomy between fighting and waiting for territory ownership. We propose that the predominant strategy in a population should be a function of the natural mortality and reproductive success rates of nonterritorial and territorial individuals, the risk of injury associated with an attempted takeover, and the rate of successful takeover attempts. We first formalize our ideas in a dynamical model in order to visualize how these factors act and to make specific predictions. We then explore populations containing both strategies or only one strategy to determine how the two strategies might interact in natural populations. Finally, we use examples to illustrate how species with known territorial systems fit into the predictions generated from the model.