information:classification
Threats

In its main home of New Guinea, cassowaries are the island's largest and most dominant and formidable bird, as well as being one of the largest terrestrial endemic animals in New Guinea. As such, adult cassowaries have no natural enemies other than humans (and even then, the birds are rarely hunted due to their reputation, speed, wariness and self-defence, with juveniles being preferred over adults for ceremonial purposes - on average, it is considered very fortunate for a human hunter to kill one in every five years). With regards to their relationship with the New Guinea singing dogs - one of Papua's only obligate terrestrial apex predator, with the other being the crocodile monitor - adult birds generally ignore them, with some even believing that the dogs take full advantage of the birds' foraging behaviour, as both species share and use the same feeding trail through the forests. It was believed that these dogs follow adult birds to catch small prey attracted to the dropped fruits on the rainforest floor. Nevertheless, there was a report from a native hunter of an exceptionally rare case of a singing dog attacking the dwarf species. The incident ended with the singing dog being disemboweled and ripped open by the bird. But generally speaking, both apex animals mutually keep their distance and avoid one another.

The same cannot be said with their chicks, however, as they are vulnerable to large pythons, monitor lizards, New Guinea singing dogs, and Papuan eagles. When threaten, it is known that cassowary chicks emit different vocalisation calls to indicate the specific threat, such as a hawk for example, before running underneath their father. Adult males aggressively defend their chicks. While adult males usually scare off or kill most predators, a chick will occasionally be separated in the chaos and become a potential target.

However, in the relic populations of north-eastern Australia, the cassowary population faces threats from vehicles, and are in danger of being outcompeted by wild boars, with their eggs being most vulnerable to boar predation. Their chicks also face dangers and predation from domesticated dogs, which results in a widespread decline in the Australian mainland. Because of such frequent inter-species conflicts, hunting dogs are one of the biggest enemies for cassowaries, and it is not unheard of for hunting dogs to accidentally kill cassowary chicks instead of feral pigs, with the dogs in-turn, being killed by the nearby adult rooster. Outside of threats from invasive species, the birds are also vulnerable to being unintentionally poisoned as well. Rodents are a popular prey item for the birds due to their commonality, ease of catch and being a good protein source. However, rodents that died from rat poisoning would themselves, become lethal poison to the birds which are unaware from this contaminated danger. It is unknown why the cassowary population in Australia is in decline, as the New Guinea population has dealt with introduced wild boars, dogs and feral cats for thousands of years longer with little to no impact on its population, suggesting that either the cassowaries of New Guinea had long adapted to human-introduced species or that the rich biodiversity of New Guinea allowed for additional niche partitioning.

As for eating the cassowary, it is supposed to be quite tough. Australian administrative officers stationed in New Guinea were advised that it "should be cooked with a stone in the pot: when the stone is ready to eat, so is the cassowary".