A reexamination of factors influencing philopatry in rodents

The costs and benefits of philopatry (remaining at the natal nest) have been discussed in numerous papers. Nevertheless, there is still debate about the relative importance of factors that favor philopatry, which can result in the formation of social groups. The decision to remain at the natal nest can be examined by using models such as the delayed-dispersal threshold model, which takes into account risks of dispersal, probability of becoming established on a suitable territory, and probability of finding a mate. These factors, in turn, are influenced by ecological variables such as distribution of critical resources and population density. The often-cited conclusion from this and similar models is that ecological or social constraints promote philopatry whereas relaxation of the constraints result in dispersal. More recent theoretical approaches have included not only some of these ecological factors but also life-history traits (e.g., survival and age of maturation). Some of the latter models suggest that external constraints alone are inadequate to explain interspecific variation in group living. I review existing data to evaluate the relative importance of variables proposed to influence philopatry in rodents and argue that future studies may benefit from a broad approach that encompasses life-history and ecological factors, such as adult survival and territory quality.