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10 Fascinating Facts About the Black-Chested Buzzard-Eagle

When we think of birds of prey, we often picture majestic eagles soaring across the sky. One such eagle that is an iconic symbol of the South American wilderness is the black-chested buzzard-eagle.

Known for its striking appearance and impressive hunting skills, this bird is a fascinating species to learn about. In this article, we will explore the identification, plumage, and molting habits of this magnificent raptor.


Field Identification

The black-chested buzzard-eagle, Gerardiaetus melanoleucus, is a large bird of prey, with a wingspan of up to six feet. It is predominantly dark brown on the upper side, with a white underside and a black breast.

The bird’s head is well defined, with yellow eyes and a sharp, hooked beak. Its legs are feathered down to the talons, which are powerful and curved, akin to other birds of prey.

Similar Species

The black-chested buzzard-eagle might be mistaken for other species, including the ornate hawk-eagle, the black hawk-eagle, and the savanna hawk. However, the prominent white belly and black chest of the black-chested buzzard-eagle distinguish it from these other species.


The black-chested buzzard-eagle has two main plumages, juvenile and adult, with adult birds having a more distinct plumage. Juvenile birds have a brown head, back, and wings, with random white spots throughout the feathers.

The belly is white and has brown vertical streaks, and the tail is banded with brown and white. Adult birds have a more defined plumage, with a black chest and a white belly, as we have mentioned earlier.

Additionally, the head, back, and wings are dark brown, with a white band across the tail. The face has a pale stripe that runs above the eyes, and the feathers on the legs are dull yellow.


Molting is a natural process that birds undergo to replace old feathers. During this process, birds lose and grow new feathers, which can take between months to years depending on the species.

The black-chested buzzard-eagle is believed to undergo a full molt every two to three years. During the molting process, the bird will replace each feather in a specific sequence.

First, the bird will lose its primary feathers, which are the feathers at the end of the wing used for flying and maneuvering. Then, the secondary feathers are shed, which are the feathers closest to the body.

Finally, the bird sheds its body feathers.


The black-chested buzzard-eagle is one of the most remarkable birds of prey in South America. Its striking black and white plumage, together with its impressive wing span, solidifies its place as one of the top raptors of the region.

Knowing how to identify and understand this magnificent bird is crucial for anyone interested in avian biology. We hope this article has helped shed some light on the black-chested buzzard-eagle, and sparked your interest in the fascinating world of birds.

Systematics History

The black-chested buzzard-eagle, also known as the Chilean blue eagle, was initially classified as the harpyia melanoleuca in 1825 by Jacob Johann von Tschudi. It was later named geranoaetus melanoleucus by Ludwig Reichenbach in 1853 due to its similarities with the genus Geranoaetus.

Before that, the bird was classified as Aquila melanoleuca by Johann Friedrich Gmelin in 1788.

Geographic Variation

The black-chested buzzard-eagle is found in Argentina, Bolivia, Chile, Ecuador, Paraguay, and Peru. However, different populations of the bird exhibit a considerable amount of geographic variation in their size, color, and morphology, which has led to the identification of several subspecies.


There are four recognized subspecies of the black-chested buzzard-eagle:

1. G.

m. melanoleucus: Found in the Andes mountain range from Venezuela to southern Chile and Argentina.

2. G.

m. australis: Endemic to central Chile.

3. G.

m. aenigmaticus: Found in the coastal regions of Peru, and is characterized by its paler color.

4. G.

m. falklandicus: Found only in the Falkland Islands, and is the smallest subspecies.

Related Species

The black-chested buzzard-eagle belongs to the genus Geranoaetus, which also includes the white-tailed hawk (Geranoaetus albicaudatus), and the variable hawk (Geranoaetus polyosoma). These three species have close genetic relationships and are put in the same group due to similar morphological features.

Historical Changes to Distribution

The black-chested buzzard-eagle species range has historically been impacted by habitat loss and persecution across its global distribution. This bird of prey is known for living in habitats that are not accessible to human development, such as high-altitude grasslands and subtropical forests.

In the past, black-chested buzzard-eagles were hunted for their feathers and other parts. Additionally, their habitat in the Andes mountain range was affected by human activity such as mining and deforestation.

These human activities led to a significant reduction in the bird’s population and distribution. However, conservation efforts since the 1980s have led to the protection of the black-chested buzzard-eagle and its habitats.

As more knowledge is gained about the bird, conservationists have developed various methods of monitoring their populations and ensuring the protection of their habitats. These measures have been successful in stabilizing the population of the species, although it continues to be vulnerable to habitat loss and other anthropogenic factors.


The black-chested buzzard-eagle is a remarkable raptor, with a rich history that narrates how the bird’s distribution and populations were impacted by habitat destruction and persecution. Despite these challenges, concerted efforts over the past few decades have succeeded in stabilizing the populations and restoring the species range.

The subspecies tend to be challenging to identify, but with ongoing genetic research, more detailed insight into their ecological niche and genetic population structure will come to light in the future. Understanding the systematics history of the black-chested buzzard-eagle, the geographic variation, subspecies, and historical changes to distribution, aides in conservation efforts and highlights the importance of protecting bird life.


The black-chested buzzard-eagle is a bird of prey and is native to South America. This species is distributed over the Andes, from Argentina to Venezuela, inhabiting a variety of habitats including open, arid lands, high-altitude grasslands, and subtropical forests.

These eagles are typically spotted in rocky outcrops, near cliffs, and steep hills and mountains. Black-chested buzzard-eagles are opportunistic predators, and their diet includes small and medium-sized birds, reptiles, mammals, and insects.

In their habitat, they are known to feed on rodents such as rabbits and other small mammals, birds such as doves and pigeons, and reptiles such as snakes and lizards.

Movements and Migration

The black-chested buzzard-eagle is considered a resident bird, meaning it does not migrate. These eagles are known for their territorial behavior, and they remain within their range throughout the year.

Despite being non-migratory, some populations of black-chested buzzard-eagles undertake seasonal altitudinal movements. These movements are not necessarily a response to changing weather patterns or breeding, but instead, the birds move in response to food availability during differing seasons.

During summers when rodents multiply, lower-altitude populations may move upwards to find food, while during the winter when food becomes scarce at higher altitudes, they move downwards toward valleys and rivers. This seasonal movement tends to occur within a small range, with the birds moving between altitudes of up to 800m.

Black-chested buzzard-eagles are able to fly for long distances, covering up to 40 kilometers a day. They use their exceptional flight skills to search for prey, mate, or explore new areas.


Black-chested buzzard-eagles form monogamous breeding pairs for several years or even life.

Breeding typically occurs once a year around the breeding season. The breeding season varies depending on the geographical location; for instance, in Chile, the breeding season occurs between August and October, while in Argentina, it occurs between January and March.

The pair constructs a nest that is usually well hidden and placed near cliffs or trees. The nest can measure up to two meters in diameter and is built from sticks, grass, and any available materials.

The female lays between one and three eggs, which are incubated for around 45-50 days. The male provides food for the female and chicks, and the young are ready to fly after 80 days and become independent after one year.

Conservation and Threats

The black-chested buzzard-eagle is classified as near threatened by the International Union for Conservation of Nature (IUCN), and its populations continue to face a high degree of anthropogenic threats, which significantly reduce their numbers and range. Human activities such as mining, deforestation, and agriculture are the primary threats facing black-chested buzzard-eagles.

Habitat destruction, fragmentation, and loss are particularly serious challenges, especially in the Andean region, where human activity is high. These activities have resulted in habitat loss and fragmentation, leading to a significant reduction in the eagle’s populations.

Additionally, illegal wildlife trade, involving the collection of birds for sale and trade, is a primary threat in some areas. This activity has led to the decline of several bird species, including the black-chested buzzard-eagle.


The black-chested buzzard-eagle is a unique bird of prey and is native to South America. Its distribution ranges from Argentina to Venezuela, inhabiting a variety of habitats such as open, arid lands, high-altitude grasslands, and subtropical forests.

Altitudinal movements occur within their habitat, and despite being non-migratory, black-chested buzzard-eagles are known for flying long distances in search of prey, partner birds, and to explore new regions. The eagles are also monogamous and form breeding pairs for life.

Their eggs are incubated for 45-50 days, and the chicks become independent after a year. However, their populations face several human-related threats such as habitat destruction, fragmentation, and loss; these activities have led to a significant reduction in the eagle’s populations.

With conservation efforts in place and increased awareness of the threats to their existence, we can protect these birds and ensure their survival.

Diet and Foraging


The black-chested buzzard-eagle is a diurnal bird of prey that is highly active during the day. These eagles hunt from elevated positions, such as cliffs, trees or high perches, to scan the surrounding habitat for potential prey.

They use their incredible eyesight to locate their prey, after which they swoop down at high speeds to grab their catch, using their powerful talons to capture and kill their prey on impact. Black-chested buzzard-eagles are opportunistic predators, and their diet consists of a variety of small to medium-sized prey, such as rodents, birds, reptiles, and insects.

They are known for their reliance on rodents, which can make up to almost 80% of their diet in some habitats.


Rodents that black-chested buzzard-eagles feed on include rabbits, rodents, and small mammals such as bats. They may also feed on birds such as doves, pigeons, and other small to medium-sized birds.

Other food sources that they consume include reptiles like snakes, lizards, and large insects. The black-chested buzzard-eagle is sometimes referred to as the “Andean vulture” because in areas where rodents are scarce, the eagles will feed on carrion and waste.

Their ability to locate prey through their vision helps these eagles to successfully hunt, even in dense forest habitats or areas with limited visibility. Their eyesight is notably sharp, surpassing that of humans by a vast majority.

Metabolism and Temperature Regulation

Black-chested buzzard eagles are active hunters and require a high level of energy to sustain their demanding lifestyle. Their basal metabolic rate is relatively high, meaning that they have a higher requirement for food than most birds of their size.

Their metabolic rate works in tandem with their temperature regulation, as black-chested buzzard-eagles are endothermic, meaning they regulate their body temperature internally. This regulation is facilitated by their feathers, which help to retain heat and prevent heat loss.

Eagles are known to huddle together during cold weather, as the birds can share body heat and keep each other warm.

Sounds and Vocal Behavior


Black-chested buzzard-eagles aren’t known for their vocal behavior, as they typically do not emit calls unless they are engaged in courtship or territorial disputes. Their primary vocalization is a high-pitched, whistling call that sounds like “kree-er.” These calls are sometimes used in pair bonding, and the eagles may engage in a duet of whistles to communicate with each other.

Territorial disputes may elicit a different call, which is lower-pitched and more guttural. During territorial displays, black-chested buzzard-eagles will also engage in flight displays, soaring and diving to demonstrate their dominance over an area.


The black-chested buzzard-eagle is a magnificent bird of prey with a unique foraging and feeding strategy. It is an opportunistic predator and feeds on a diverse range of prey, but its primary food source is rodents.

They are active hunters and have a high metabolic rate, the latter of which is related to their internal regulation of body temperature. The eagles are known for their whistling vocalizations used during courtship and territorial displays.

Through understanding their feeding strategies, vocal behavior, and capacity for temperature regulation, conservationists are better able to protect these magnificent birds from the various threats that affect their population.



Black-chested buzzard-eagles are strong fliers, capable of long periods of soaring flight with minimal flapping of their wings. They can remain in the air for hours, during which they travel long distances in search of food, mates, or new territories.

They use their talons to grasp, kill, and carry prey long distances, employing a horizontal mode of flight during these movements. On the ground, black-chested buzzard-eagles are capable of hopping, walking, and running.

They are also known to use thermals to gain altitude during flight and to cover greater distances in search of prey.

Self Maintenance

Black-chested buzzard-eagles are meticulous in the maintenance of their feathers and bodies. They spend considerable time grooming themselves, ensuring that their feathers are straight, clean, and free of debris.

Agonistic Behavior

Black-chested buzzard-eagles have territorial behavior and will defend their range aggressively from other eagles. They will engage in aerial displays that include soaring together and diving towards each other, vocal displays, and sometimes physical contact.

These displays aim to demonstrate dominance while signalling possession of a territory.

Sexual Behavior

Black-chested buzzard-eagles mate for life, forming pair bonds that can last several breeding cycles. They typically start breeding at the age of three years and continue to breed for the remainder of their lives.

During breeding, the male will provide food for the female and help care for their young. The pair will share incubation duties, and the chicks will be reared to independence after about a year.


Males court females by presenting them with food and performing courtship displays such as aerial flights and vocalizations. Once a pair bond is formed, the eagles will start building a nest together.

Nest building can last between a few weeks to a few months, depending on the location and materials available. Black-chested buzzard-eagle nests are typically located in elevated positions, such as cliffs, trees, or other steep surfaces.

The nests are constructed from sticks, grass, and other materials available. After they have selected a suitable site, the pair will begin collecting materials, often with the male bringing sticks and the female arranging them to form the nest structure.

After the nest is constructed, the female lays between one to three eggs, which are incubated for around 45-50 days. The male will provide food for the female while she incubates the eggs, and after hatching, he will help feed the chicks.

The young eagles will fledge after around 80 days, and become independent after their first year.

Demography and Populations

The black-chested buzzard-eagle is considered a near-threatened species by the International Union for Conservation of Nature (IUCN), primarily due to habitat loss and fragmentation. The eagles are particularly vulnerable to human activities such as mining, deforestation, and agriculture.

Habitat degradation has led to significant population declines in some areas, threatening this species’ survival. However, conservation efforts, such as habitat management, captive breeding, and legal protection, have been implemented to protect this magnificent bird.

Through scientific research, monitoring, and management efforts, conservationists can work towards the resettlement of black-chested buzzard-eagle populations in areas where they have been extirpated or are endangered. Conservation efforts such

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