They also bellow to advertise their presence to their neighbours when they enter a new tree .
Koalas may bellow at any time of the year , particularly during the breeding season , when it serves to attract females and possibly intimidate other males .
Koalas also bellow to advertise Koalas ' presence to their neighbours when they enter a new tree .
Koalas may bellow at any time of the year , particularly during the breeding season , when it serves to attract females and possibly intimidate other males .