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The Majestic Ayres’s Hawk-Eagle: Exploring Identification Habits and Conservation

The Ayres’s Hawk-Eagle (Hieraaetus ayresii) is a majestic bird of prey found in South America. This species is one of the lesser-known hawk-eagles, known for its striking appearance and impressive hunting skills.

In this article, we will explore the identification features of the Ayres’s Hawk-Eagle, its plumages, and molts. Identification:

Field Identification:

Ayres’s Hawk-Eagle has a distinctive appearance, with dark brown feathers and a white, crest-shaped patch on its forehead.

It has a pale bill with a black tip, which contrasts with its yellow cere. Its legs are yellow, and its talons are black.

Its wingspan ranges from 110-130 cm (43-51 in), and it weighs around 1.5-2.4 kg (3.3-5.3 lb). Similar Species:

The Ayres’s Hawk-Eagle can be mistaken for other species, such as the Black Hawk-Eagle (Spizaetus tyrannus) and the Ornate Hawk-Eagle (Spizaetus ornatus).

However, there are specific features that help identify this bird from its counterparts. The Black Hawk-Eagle lacks the Ayres’s Hawk-Eagle’s white forehead crest and has a yellow cere, while the Ornate Hawk-Eagle has a distinct black-and-white pattern on its wings, which is different from the Ayres’s Hawk-Eagle’s brown wings.


The Ayres’s Hawk-Eagle has six distinct plumages throughout its life, which are classified into juvenile, sub-adult, and adult. Juvenile birds have a white belly and underwing coverts, while their upper parts are dark brown.

Their feathers’ tips are white, giving them a mottled appearance. Sub-adult birds have dark brown upper parts and are beginning to molt some feathers, indicating that they are transitioning to adulthood.

Adult birds have a uniform dark brown color with a white forehead crest, as mentioned earlier. Molts:

Ayres’s Hawk-Eagle goes through different molts throughout its life.

It has a basic molt, which occurs annually and affects all body feathers. This molt begins during the breeding season when female birds incubate their eggs.

It also has a prebasic molt, which occurs after the breeding season and affects only body feathers. The prebasic molt also involves feather replacement on the head and body of these amazing birds.


The Ayres’s Hawk-Eagle is a remarkable bird of prey, known for its striking appearance and impressive hunting skills. As we explored in this article, it has distinct features that help identify it from other species, and it undergoes several molts throughout its life, affecting its plumages.

The Ayres hawk-eagle is one of the many natural wonders that observe in the wild, and a bird, for birdwatchers, not to miss. Systematics History:

The Ayres’s Hawk-Eagle (Hieraaetus ayresii) was first described by the American ornithologist John Cassin in 1865.

At that time, it was classified under the genus Spizaetus with the scientific name of Spizaetus coronatus ayresii. Later, in 2006, molecular testing revealed that the species fit better within the genus Hieraaetus.

Therefore, its current scientific name is Hieraaetus ayresii. Geographic Variation:

The Ayres’s Hawk-Eagle is distributed in South America, where it inhabits various habitats such as forests, savannas, and open areas.

This species shows geographic variation in its feather coloration across its range. Generally, birds from the northern parts of its distribution have a darker brown plumage than those from the southern regions.


There are three recognized subspecies of the Ayres’s Hawk-Eagle, each with distinct distribution ranges and physical characteristics:

– Hieraaetus ayresii ayresii: This subspecies is the nominate form and is found in Brazil, Paraguay, and Argentina. Its plumage is uniformly dark brown, with a white crest on its forehead.

– Hieraaetus ayresii pallidus: This subspecies is found in northeastern Colombia and northwestern Venezuela. It has lighter plumage, with pale feathers on its chest and under-wing coverts.

– Hieraaetus ayresii solitarius: This subspecies is found in Uruguay and central Argentina. It is the palest of the three subspecies, with a light-brown plumage, and a white vent.

Related Species:

The Ayres’s Hawk-Eagle is closely related to other hawk-eagles of the Hieraaetus genus, including the African Hawk-Eagle (Hieraaetus fasciatus) and the Indian Hawk-Eagle (Hieraaetus pennatus). These species share similar physical characteristics, such as their dark-brown plumage and yellow eyes.

Historical Changes to Distribution:

Like many other bird species, the Ayres’s Hawk-Eagle has experienced changes in its distribution range. In the late 19th century, this species was considered rare in Argentina due to hunting and habitat loss.

However, in the early 20th century, its population in Argentina increased, possibly due to the decrease in deforestation and hunting. Further declines in the Ayres’s Hawk-Eagle population have occurred as a result of habitat loss and fragmentation.

Forests and other natural habitats have been cleared for agriculture, logging, and urbanization, drastically reducing the species’ available breeding and hunting grounds. In addition, the use of pesticides and other agricultural chemicals has led to the contamination of the eagles’ prey and habitat, further impacting their numbers.

In recent decades, conservation efforts have been put in place to protect the Ayres’s Hawk-Eagle and its habitat. These measures have included the establishment of protected areas, habitat restoration programs, and education and awareness campaigns.

While the effectiveness of these measures varies, there have been some positive indications of their success. In Argentina, for example, the species’ population has increased thanks to these conservation efforts.


The Ayres’s Hawk-Eagle is an impressive bird of prey with a complex history of systematics and distribution. Its geographic variation, subspecies, and related species highlight the rich diversity of birds found in South America.

However, like many other species, it faces threats to its survival, mainly due to habitat loss and human activity. Conservation efforts must continue to be implemented to ensure that the species remains a natural wonder of South America.


The Ayres’s Hawk-Eagle is generally found in South America, inhabiting various habitats such as tropical rainforests, deciduous forests, savannas, and open areas. It can also be found in areas of human habitation such as agricultural fields and suburban areas, as long as there are sufficient tree cover and prey.

This species requires tall trees for nesting and a diverse prey base. Their nests are usually built high in trees and are made up of sticks and twigs.

Ayres’s Hawk-Eagles prefer to hunt by stealth, patiently waiting in a tree or flying low over the forest, scanning the ground for prey. They hunt a variety of prey, including birds, mammals, and reptiles.

Movements and Migration:

The Ayres’s Hawk-Eagle is generally a non-migratory species, but some individuals may move short distances from their breeding territories during non-breeding seasons. In areas of South America with distinct wet and dry seasons, these birds will generally move to follow the distribution of their prey, although they may remain in the same general area of their breeding territory.

Outside of these short movements, Ayres’s Hawk-Eagles generally remain within a localized area that provides sufficient prey and nesting sites. This has led to the formation of a highly territorial lifestyle, where pairs of birds will defend their territory from others of their species.

Despite being non-migratory, there is still some variation in Ayres’s Hawk-Eagle’s movements across their range. For example, in Peru, during the breeding season, these birds are found in the eastern lowland forests but are more commonly noticed in the western subtropical and temperate forests during non-breeding periods.

Conservation Status:

The Ayres’s Hawk-Eagle falls under the IUCN Red List as a species of “Least Concern.” Although populations in some regions have suffered declines due to hunting and habitat destruction, the overall population trend is not believed to be decreasing in any meaningful way. However, some conservation concerns persist, given that this species remains vulnerable to habitat loss and degradation.

The Ayres’s Hawk-Eagle requires large areas of forest to thrive, but deforestation across South American countries associated with agricultural expansion, cattle grazing, mining, logging, and urbanization has led to habitat destruction and fragmentation.


The Ayres’s Hawk-Eagle is a non-migratory species that requires forested habitats with a diverse prey base.

It has a highly territorial lifestyle, and its movements are generally localized to the distribution of prey. Despite being classified as a species of least concern, conservation efforts must continue to ensure the protection of their habitat and prey base.

In areas where deforestation and habitat fragmentation continue to be a concern, conservation efforts must focus on habitat restoration, protected areas, and education programs to increase awareness about the species’ ecological importance. Diet and Foraging:


Ayres’s Hawk-Eagle is a carnivorous bird of prey that preys on a variety of prey, including small mammals, birds, and reptiles.

It generally hunts by perching in high trees and scanning the ground for prey, or by flying low over the forest, using its incredible eyesight, auditory senses, and agility in flight to capture prey. The technique of Ayres’s Hawk-Eagle for hunting is to swoop down from a high place and grab prey with its strong talons.

This is an effective hunting strategy that permits the eagle to pick up large prey like coati and monkeys. Diet:

The diet of the Ayres’s Hawk-Eagle varies depending on their location and prey availability.

Some of the birds this species feeds on include Macaws, parakeets, and toucans. It also preys on rodents such as squirrels, agoutis, and rabbits.

Reptiles such as lizards and snakes are also occasional prey items, with boas and iguanas being particularly vulnerable to predation. Metabolism and Temperature Regulation:

The Ayres’s Hawk-Eagle is a bird of prey that experiences endothermy and hyperthermia to maintain body temperature.

It has a high metabolic rate, enabling it to maintain constant body temperature and provide the energy required to be active and fly. Like all birds, the Ayres’s Hawk-Eagle is warm-blooded, and therefore the metabolism of birds is significantly higher than other animals.

Birds release metabolic heat from their muscles as they move. It also permits the Ayres’s Hawk-Eagle to keep active and hunt throughout the day without becoming tired.

Sounds and Vocal Behavior:


The Ayres’s Hawk-Eagle is not known for being particularly vocal but has a few distinct calls. These calls are used primarily for communication between individuals, with different calls playing specific roles in pair bonding and territorial defense.

One of the primary vocalizations of the Ayres’s Hawk-Eagle is a loud, high-pitched whistle that is described as an “O-wip.” This call is used by individuals in a pair to locate and communicate with each other when they are out of sight. Another call is a deep, booming rumble that is used by Ayres’s Hawk-Eagles during territorial displays and pair bonding.

This call is used to intimidate rivals and attract females during the breeding season. This booming rumble is heard mostly during courtship or nest building.


The Ayres’s Hawk-Eagle preys on a variety of birds, mammals, and reptiles, using swooping and diving techniques to catch its prey. It has a high metabolic rate, enabling it to maintain a constant body temperature and hunt throughout the day.

Though the species is not noted for its vocalizations, it produces a few consistent and essential calls for communication and territorial display. Protecting the habitat and prey base of the Ayres’s Hawk-Eagle must continue to be a core focus of conservation efforts to ensure the survival of this iconic species.



Ayres’s Hawk-Eagle is a highly active bird of prey with incredible flying ability and agility. They are capable of flying in dense forested areas, making quick and sharp turns to navigate obstacles and catch prey.

They flap their wings continuously while in flight, with slow and deep beats that provide lift and momentum. When perched in trees, they stay alert, with head movement that allows them to scan the area around them.

The birds also have strong legs, allowing them to grab prey in mid-air or on the ground. They are very acrobatic when seizing prey, diving and twisting to avoid obstacles.

Self Maintenance:

The Ayres’s Hawk-Eagle has a strict daily routine, with an extended period spent preening feathers and maintaining its body hygiene. Preening is a crucial part of animal maintenance that provides various advantages, such as feather flexibility, water repellence, and parasite control.

Agonistic Behavior:

Ayres’s Hawk-Eagle species of birds show aggression in territorial defense. However, they are also social, and unrelated pairs are often seen flying and calling to each other.

During breeding season, males display aggressive or territorial behaviors towards other males. Sexual Behavior:

The Ayres’s Hawk-Eagle is monogamous, meaning that males and females pair up and breed for life.

The pair bonds are generally established during courtship displays, closer to breeding season. Courtship displays include various vocal and behavioral displays, such as the booming displays mentioned above.

Pairs usually defend specific territories for breeding, which they patrol and actively defend from intruders. Breeding:

The breeding season of the Ayres’s Hawk-Eagle varies depending on the region, but it generally takes place between March and October.

The birds build large nests in high trees, with both individuals working together to build nests from sticks and twigs. They will add to the nest continually throughout the breeding season, hoping to use it again next year.

The female Ayres’s Hawk-Eagle usually lays a single egg, which both male and female work together to incubate. The incubation period typically lasts between 40 and 45 days, and both parents share in the rearing of the chick.

After hatching, it takes around five months for the chick to become independent and capable of hunting for itself. Demography and Populations:

The Ayres’s Hawk-Eagle is not considered globally threatened, with a stable population trend across its range.

However, like many bird species, it does face threats from habitat loss and degradation caused by human activities such as deforestation and agriculture. The largest populations of Ayres’s Hawk-Eagle are found in Brazil and Argentina, where various conservation initiatives are in place to help protect the species.

These include habitat restoration, creation of protected areas, and education and awareness programs focusing on the species’ importance. Conclusion:

The Ayres’s Hawk-Eagle is a highly active and agile bird of prey capable of complex locomotion that enables it to dive and twist to catch prey.

They are monogamous and have strict courtship rituals that build a strong bond between breeding pairs. The species uses booming displays and territorial calls to establish and defend territories.

Although not classified globally threatened, the Ayres’s Hawk-Eagle faces numerous threats from habitat loss and degradation, highlighting the need for continued conservation efforts. The Ayres’s Hawk-Eagle is a remarkable bird of prey found in South America with a unique history, complex behavior, and a vital ecological role.

This article has explored the identification, plumages, molts, habitat, migration, diet, behavior, breeding, and population demographics of this species. Although it is not currently classified as globally threatened, the Ayres’s Hawk-Eagle faces numerous threats, particularly due to habitat loss and degradation.

Conservation efforts, including habitat restoration, protected areas, and education and awareness programs, must continue to ensure the survival of this majestic species. Protecting the Ayres’s Hawk-Eagle preserves the rich biodiversity of South America and helps maintain a balanced ecosystem.

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