The first need for aggressive behavior comes from the drive to establish territory.

Males may try to establish territories next to those of their parents.

Males who have not established such territories sometimes form small bachelor groups.

In this way, calls establish territories, but they also attract females.

In most species the males will establish small territories and defend them.

When older siblings are ready to breed, they often establish territories in or near those of their parents.

Now you must help the queen so we may establish new territories.

Players usually start in the corners, because it is more efficient there to make life and to establish territory.

In addition, they are used for marking trees to establish territory and occasionally as weapons.

In breeding season, songs are used to establish and defend territories.