Territories are used for a variety of activities, and their size can vary dramatically depending on their function. A territory held by a colonial seabird may only be large enough for the bird’s nest, and all other activities would take place outside of the territory. Territories may be used only for mating displays. Other birds may hold territories large enough to encompass all of the resources they will need throughout the season. They may be carefully defended year round, or held only for part of the year. Birds typically exclude only their own species from their territory, but may work to defend it from other species too.