Approaches to the study of territory size and shape

Intraspecific variation in territory size and shape can have strong effects on population structure and dynamics. The traditional theoretical approach to the study of territory size is based on optimality models that analyze decisions of focal residents as responses to the costs and benefits of defense. These models have stimulated numerous empirical studies showing that territory holders adjust their behavior according to rates of intrusion and availability of food. However, models of optimal territory size are applicable only in limited circumstances because they focus on unilateral decisions rather than on interactions. Furthermore, observational and experimental studies often find that territory sizes are insensitive to food supply. Recently, greater emphasis has been placed on two alternative approaches. The first concerns interactions among contiguous neighbors and how these affect use of space. In these models territory size and shape are determined by the balance of pressure exerted at boundaries or arise as the results of local rules of movement and interaction. The second alternative approach views territory size as the outcome of interactions between established residents and potential settlers attempting to acquire territories. By considering the simultaneous actions of multiple competitors, these models allow quantitative prediction of the effects of territory defense on population density and spatial patterns as well as responses to environmental change.