access to females, while for females, it is limited by access to resources. In this sense, females can be much choosier than males because they have to bet on the resources provided by the males to ensure reproductive success.

Resources usually include nest sites, food and protection. In some cases, the males provide all of them (e.g., sedge warblers). The females dwell in their chosen males' territories for access to these resources. The males gain ownership to the territories through male-male competition