The majestic black-breasted buzzard (Hamirostra melanosternon) is one of Australia’s largest birds of prey. Both sexes are similar in appearance, but the female is generally larger than the male. The black-breasted buzzard has a striking head with a small crest and a long, fairly slender bill with a rounded cere. Powerful, unfeathered legs end in weak, whitish toes, while the tail is short and square-shaped.

The adult black-breasted buzzard has a black forecrown, face, breast and upper back. The rest of the back and shoulders are black with reddish-brown flecks, making the almost completely rufous nape, thighs and lower abdomen more conspicuous. Compared to the more rufous shoulders, the wings are browner and have prominent whitish patches on the base of the primary feathers. The black-breasted buzzard’s eyes are brown, and the tail is grey-brown at all ages.

Juvenile black-breasted buzzards are distinct in appearance from the adult birds, and are not considered to be fully adult until their fifth year. The immature stages between juvenile and adult are also clearly discernable. The juvenile’s head and underparts are reddish-brown with blackish streaks on the crown, down the back of the neck and on the throat. This streaking extends onto the chest, where it is even more conspicuous. The back is blackish-brown and the shoulders appear more russet due to the wide reddish-brown edgings of the wing-coverts. The black primary feathers have off-white patches at the base, and the secondaries are faintly barred.

At two to four years of age, immature black-breasted buzzards are less rufous than the juvenile bird, appearing browner due to the streaks on the breast becoming more extensive and the black areas, such as the forehead and face, becoming darker in the third year. The young bird does not develop a solid black breast until its fourth year. Juvenile and immature black-breasted buzzards have pale hazel eyes until they are at least three years old, at which time they begin to darken.

Predominantly a silent bird, even during aerial courtship, the black-breasted buzzard is usually only vocal during interactions with other species. When mobbed by large passerines or smaller raptors, or when attacking other birds, its main distress call is a hoarse ‘yik-yik’ shriek or a long whistled alarm.