Southern Cassowary (Casuarius casuarius) attacks on humans have been described, however very little information can be found about territorial defense behaviour, agonistic behaviours and displays of this species. Southern Cassowaries were observed in north Queensland, in captivity and in audiovisuals on the internet. A range of behaviours, including low intensity agonistic displays are described. This information may help people who encounter a cassowary, to properly interpret the intent of a bird stressed by their presence, and therefore avoid confrontation. Further research into the behaviour of this interesting but endangered species is much needed.