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It’s not an ostrich, but it comes close in height and is far more colorful. Cassowaries are flightless giants found in the rainforests of New Guinea and northern Australia. Adults can reach up to 1.7 meters (about 5.6 feet) tall, making them among the tallest birds alive. With turquoise-blue heads, bare skin, a tall casque, and two bright red wattles hanging from the throat, they have a prehistoric look matched by few other birds.

Their bodies are covered in coarse, black feathers that resemble strands of hair. Their small wings are useless for flight and bear only a few stiff, quill-like feathers. Females are significantly larger than males, weighing up to 59 kilograms (130 pounds), while males usually weigh around 34 kilograms (75 pounds). Cassowaries are one of the few bird species where females are larger than males.

A Helmet of Mystery

On top of a cassowary’s head is a tall, helmet-like structure called a casque. It’s made of spongy bone and covered in keratin, the same material as our fingernails. No one knows for sure what it does. It may help the bird move through dense forest without injury or act as a visual signal. Larger casques may belong to older, more dominant individuals. Some studies suggest it helps release body heat, while others think it may amplify the cassowary’s deep, low-frequency calls. Whatever the purpose, it’s one of the bird’s most unusual and mysterious features.

Powerful Legs and Razor-Sharp Claws

Cassowaries have some of the most dangerous legs in the bird world. Each foot has three toes, and the inner toe carries a long, dagger-like claw that can grow 12 to 15 centimeters (about 5 to 6 inches) long. A strong kick can cause serious injuries, and in rare cases, cassowaries have killed humans. That reputation has earned them dramatic nicknames like “murderbird,” though they are shy and usually avoid people. In addition to these claws, cassowaries are fast runners. They can sprint through the forest at speeds of up to 50 kilometers per hour (around 30 miles per hour) and leap as high as 1.5 meters (about 5 feet) to escape danger.

A Voice You Can Feel

Cassowaries don’t sing or chirp. Instead, they produce low-pitched booming calls around 30 hertz, right near the lower limit of human hearing. These are among the lowest-frequency vocalizations recorded in any bird. Rather than hearing the sound clearly, people nearby often feel the vibration in their chest. These deep booms travel well through the forest and are used during courtship and to signal territory. Even when far apart, cassowaries can detect these calls, allowing them to communicate across long distances in a way most birds cannot.

🔊 Listen to their call here: YouTube link

Rainforest Gardeners

Cassowaries eat a wide variety of fruit. They can swallow large pieces whole, including entire bananas or rainforest berries up to 10 centimeters (about 4 inches) across, and even consume some fruits that are toxic to other animals. Their digestive tract is the shortest of any ratite (large flightless bird), which allows seeds to pass through undamaged. A single cassowary may eat fruit from hundreds of different plant species. As it moves through the forest, it drops seeds in its large droppings, often more than 1 kilometer (over 0.6 miles) from the parent tree, helping to keep the rainforest thriving.

Strange Family Life

After mating, the female lays a clutch of 3 to 8 large green eggs in a simple ground nest. Each egg measures about 9 by 14 centimeters, or roughly 3.5 by 5.5 inches, making them some of the largest eggs laid by any bird. Only ostriches and emus lay bigger eggs. Once she lays them, the female leaves. The male takes over completely, incubating the eggs for about 50 to 52 days. He uses leaf litter to keep them warm and stays close to protect the nest. After the chicks hatch, he looks after them for up to nine months, showing them which fruits to eat and keeping them safe from danger. During this time, the female may find another mate and lay a new clutch. In cassowaries, it is the father who raises the young.

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