Some of the known reasons for organisms to be philopatric would be for mating (reproduction), survival, migration, parental care, resources, etc.. In most species of animals, individuals will benefit from living in groups, because depending on the species, individuals are more vulnerable to predation and more likely to have difficulty finding resources and food. Therefore, living in groups increases a species' chances of survival, which correlates to finding resources and reproducing. Again, depending on the species, returning to their birthplace where that particular species occupies that territory is the more favorable option. The birthplaces for these animals serve as a territory for them to return for feeding and refuge, like fish from a coral reef. In an animal behavior study conducted by Paul Greenwood, overall female mammals are more likely to be philopatric, while male mammals are more likely to disperse. Male birds are more likely to be philopatric, while females are more likely to disperse. Philopatry will favor the evolution of cooperative traits because the direction of sex has consequences from the particular mating system.