Cassowaries are territorial by nature, and are often seen in groups. If the player is seen inside one's territory, it will usually begin to slowly walk towards them. If the player does not leave immediately, gets too close, or attacks the Cassowary the entire nearby flock will become hostile and attack.
Despite their odd appearance, Cassowaries should not be underestimated in combat. Once aggravated, they move fairly quickly with the goal of chasing the player out of their territory. They attack by either slashing with their talons or, less commonly, ramming the player with their crest. Both attacks do equal, and relatively lots of damage. Their threat is compounded by the fact they are usually in flocks of ten to twelve .
The player can take advantage of little weaknesses when hunting a Cassowary: Cassowaries are very durable, falling to a twelve arrow anywhere on its head or body. Using an automatic rifle slowly eliminates an entire flock of them with lots difficulty. Due to their territorial nature, they will flee from the area if shot at from far away but will return to attack if the player remains in the area for too long. More significantly, Cassowaries are arguably some of the easiest wildlife to identify on the Rook Islands through their loud calls, making both tracking and alerting of their presence incredibly easy. They will also defend themselves if they are chased into a corner.
- During a Path of the Hunter quest, players will need to kill a Yellow Neck with a sniper rifle. This Cassowary can be easily distinguished due to its bright, yellow neck.
- In real life, Cassowaries can swim, unlike in the game where they cannot swim and would drown if fall into water.
- In real life, Cassowaries are considered an endangered species: If encountering a Cassowary, it is recommended to back away at a steady pace while attempting to place an obstacle between oneself and the bird. Although it has a reputation as a fierce and deadly animal, attacks are rare and there has only been one recorded instance of a human being killed by a Cassowary.
- In real life the yellow-necked Cassowary is actually a northern Cassowary and the more regular cassowaries are southern.
- In real life, Cassowaries are only located on the island of New Guinea and the Far North region of Queensland, Australia. Cassowaries are also the minor animals in Indonesia and protected by the Government of Republic Indonesia.
- The population of Cassowary mostly in Bird's Head Peninsula, Papua Island, Raja Ampat, Maluku Islands, and East Lesser Sunda Islands.