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The Majestic Sulawesi Hawk-Eagle: A Fascinating Bird of Prey

Sulawesi Hawk-Eagle: A Majestic Bird of Prey

Birdwatchers, nature enthusiasts, and wildlife photographers all have one thing in common: a love for birds. Among the 10,000 species of birds that grace the skies, the Sulawesi Hawk-Eagle stands out from the rest, commanding attention and awe from those who encounter it in the wild.

In this article, we will delve deeper into the identification, plumage, and behavior of this magnificent bird of prey.

Identification

Field Identification

The Sulawesi Hawk-Eagle, also known as Nisaetus lanceolatus, is a large bird of prey that can reach up to 60-80 cm in length and has a wingspan of approximately 120-150 cm. They have broad, rounded wings and a short tail, which helps them maneuver swiftly in the air.

The adult Sulawesi Hawk-Eagle has a distinctive black crown, reddish-brown nape, and a bright yellow beak with a darker tip. The upperparts of the bird are mostly dark brown, and the underparts are lighter, with faint whitish bars running along the belly and legs.

The legs and feet are yellow and feathered down to the toes.

Similar Species

The Sulawesi Hawk-Eagle bears some resemblance to other eagles, such as the Black Eagle and the Crested Serpent Eagle. However, it can be easily distinguished from them by its black crown, yellow beak, and overall structure.

The juvenile Hawk-Eagle is similar in size and structure to the adult but has a different plumage, with a creamy white base color and darker brown streaks along the feathers. Younger birds can also have a faint rufous head color.

Plumages

Molts

The Sulawesi Hawk-Eagle undergoes two molts a year: a pre-basic molt, which occurs after breeding and before migration, and a pre-alternate molt, which takes place in the winter or early spring before the breeding season. During the molting period, the bird sheds its old feathers and replaces them with new ones, which can change its overall appearance.

The Sulawesi Hawk-Eagle has three distinct plumages: juvenile, sub-adult, and adult. The juvenile Sulawesi Hawk-Eagle has a creamy white base color and dark brown streaks along the feathers.

These markings help to camouflage the bird and protect it from predators. The head can have a faint rufous color, which fades as the bird matures.

The sub-adult Sulawesi Hawk-Eagle has more defined markings than the juvenile, with dark brown feathers covering the upperparts and faint white bars along the belly and flanks. The bird also starts to develop its distinctive black crown and reddish-brown nape color.

The adult Sulawesi Hawk-Eagle is the most recognizable, with a striking black crown and distinctive yellow beak. The upperparts are mostly dark brown, and the underparts are lighter, with faint whitish bars running along the belly and legs.

Behavior

The Sulawesi Hawk-Eagle is an apex predator, feeding on a variety of prey, including birds, mammals, and reptiles. They are adept hunters and use their sharp talons and strong beak to catch and kill their prey in mid-air or on the ground.

They are also known to steal food from other raptors. The Sulawesi Hawk-Eagle is solitary and territorial, with both male and female birds defending their territory with aerial displays and calls.

During breeding season, the birds mate for life and build large nests in tall trees, which they use for several years. The female lays one to two eggs, which both parents incubate for approximately 42 days.

After hatching, the chicks stay in the nest for about 70 days before fledging and leaving the nest. In conclusion, the Sulawesi Hawk-Eagle is a majestic bird of prey that commands respect and admiration.

The distinct black crown, reddish-brown nape, and bright yellow beak make it easy to identify, and its hunting prowess and territorial behavior make it a fascinating subject for observation and study. As we continue to explore the natural world, we must take care to protect these magnificent creatures and their habitats to ensure their survival for generations to come.

Systematics History

The Sulawesi Hawk-Eagle, scientifically known as Nisaetus lanceolatus, belongs to the family Accipitridae. In the past, it was classified within the genus Spizaetus and was also known as the Sulawesi Mountain-Hawk.

Nisaetus was later established as a new genus, and the bird was placed in it in 2007.

Geographic Variation

The geographic variation of the Sulawesi Hawk-Eagle is extensive, as it is found across much of Sulawesi, Indonesia. This island is divided by a deep sea strait that has resulted in the subdivision of the species into different zones.

The Central Core Zone, in particular, is where the majority of the species is found, and it covers the central part of the island.

Subspecies

There is currently no standard agreement on the number of subspecies of the Sulawesi Hawk-Eagle, though some reports suggest that there may be as many as seven designated subspecies.

One of the designated subspecies, N.

l. lanceolatus, is found throughout Sulawesi and is characterized by its white head, reddish-brown nape, and striking black cap.

It is also noted for its larger size and overall body structure in comparison to the other subspecies. Another subspecies of Sulawesi Hawk-Eagle is N.

l. celebensis, which is found in the northern part of the island.

This subspecies tends to have a browner head and is overall smaller than N. l.

lanceolatus.

Related Species

The Sulawesi Hawk-Eagle is closely related to other species of hawk-eagle, including the Philippine Hawk-Eagle, Javan Hawk-Eagle, and Wallaces Hawk-Eagle. These related species are also found in island regions of Southeast Asia and share a similar appearance, behavior, and habitat used.

Historical Changes to Distribution

The historical changes to the distribution of the Sulawesi Hawk-Eagle remain unclear. However, it is believed that the bird’s range has been diminished in tandem with the loss of forests across Sulawesi.

Natural habitat destruction has resulted in the decreased survival of many rainforest species, including the Sulawesi Hawk-Eagle. In the past, deforestation and the rapid expansion of agricultural areas have had a significant impact on the species’ range and population.

The decline of its prey animals, especially the extinction of black macaques (Macaca nigra), has presented an additional challenge to the survival of the species. Despite these challenges, conservation efforts have been implemented to help protect the Sulawesi Hawk-Eagle and its habitat.

The BirdLife International organization has recommended that a greater focus be placed on exploring more potential protected habitats for this bird and reintroducing animals that the Sulawesi Hawk-Eagle preys upon.

In summary, the Sulawesi Hawk-Eagle has a rich taxonomic history, with changes in its subspecies and the genus that it is placed within evolving over the past few decades.

This bird’s geographic variation, subtly different subspecies, and close relationships to other hawk-eagle species indicate that we still have much to learn about this fascinating bird. The historical changes in the distribution of this species are also of concern, and ongoing conservation efforts are necessary to ensure that the Sulawesi Hawk-Eagle remains a vital part of the ecosystem and is protected for generations to come.

Habitat

The Sulawesi Hawk-Eagle is an inhabitant of the dense tropical forests that occur throughout most of Sulawesi. These dense forests consist of lowland dipterocarp forests, montane forests, and even mossy mountain forests.

The dipterocarp forests are the most extensive, covering the low, inland areas of Sulawesi. The montane forests, distinguished by their cooler temperatures, occur at higher elevations of the island.

The mossy mountain forests, found mainly in the central region of the island, are characterized by the dense growth of moss and fungi. The Sulawesi Hawk-Eagle is particularly well-suited to life in these dense forests.

They often perch on the tallest tree branches to observe their surroundings, scanning the forest floor for prey. They are also known to roost in the crowns of tall trees, where they are protected from predators and can keep an eye out for threats.

The vegetation in these forests is dense and lush, providing an ideal habitat for the Sulawesi Hawk-Eagle’s prey. The large trees and myriad plant species also offer an abundant food source for the bird, with its prey consisting of a range of animals like birds, mammals, and reptiles.

However, human activities like logging, agriculture expansions and illegal trapping of the Sulawesi Hawk-Eagle have caused a significant loss of habitat, adversely affecting their survival.

Movements and Migration

The Sulawesi Hawk-Eagle is a resident bird species of Sulawesi and is known to have a limited range of movement. However, there is still much to be learned about its movements and habits.

Research is underway to better understand the territorial range of individual birds, and to determine whether migration between different parts of the island is common. Studies have shown that the Sulawesi Hawk-Eagle is a territorial bird and that both male and female birds defend their home ranges similarly.

There is also evidence to suggest that some range overlaps can occur between different birds during the breeding season. It is thought that the Sulawesi Hawk-Eagle may engage in seasonal dispersals, where the birds move into new territories to exploit seasonal food sources.

It is also postulated that the birds move between different altitudes on the island, where there is a variation in prey availability. While there is no formal evidence for migration among Sulawesi Hawk-Eagles, it is possible that the birds move across the island to exploit food resources that vary seasonally with changing rainfall patterns.

Research to track the movements of individual birds over time is still in its early stages, with limited data available. Successful conservation efforts for the Sulawesi Hawk-Eagle will require a deeper understanding of its movements and habitat use.

By identifying and protecting key areas of forest cover, we can help ensure an optimal range of habitats for this species. Programs to reduce poaching and deforestation will also have a significant positive impact on the bird, promoting overall population growth and encouraging greater movements and genetic diversity amongst the population.

In summary, the Sulawesi Hawk-Eagle relies on its habitat in the dense tropical forests that are prevalent throughout the island of Sulawesi. While it can move within a limited range, there is still much to be learned about their territory and movement patterns, as well as migratory patterns.

Conservation efforts must identify key habitat areas, reduce deforestation and poaching and promote overall population health to preserve the Sulawesi Hawk-Eagle for generations to come.

Diet and Foraging

Feeding

The Sulawesi Hawk-Eagle is a predatory bird with a diet that consists mainly of small mammals and birds. It is capable of hunting in the air or on the ground, using its sharp talons and strong beak to capture and kill its prey.

The bird is a skillful hunter, using a combination of stealth and agility to ambush or chase its prey. It often surprises its victims from above, often diving upon them in an aerial attack.

The Sulawesi Hawk-Eagle is usually seen perched on the highest branches of tall trees, scanning the area below for any potential prey movement. When a prey animal is spotted, it swiftly dives down, using the momentum of the dive to strike its target quickly and powerfully.

When hunting on the ground, it is known to stalk its prey, occasionally hiding in the shrubs or bushes and launching sudden attacks on the victim.

Diet

The Sulawesi Hawk-Eagle’s diet varies, depending on what is available in its environment. A few of its common prey items include small mammals, reptiles, and birds.

Some of the mammal species that the bird is known to prey upon include rats, squirrels, and bats. Reptiles that it feeds on include snakes and lizards.

The bird is very opportunistic, and it is known to attack and kill other bird species, including doves, pigeons, and even the majestic Hornbill bird. It is capable of taking down larger prey than its own size due to its powerful feet and beak.

Metabolism and Temperature Regulation

Due to its carnivorous nature and large body size, the Sulawesi Hawk-Eagle has a high metabolic rate. Its internal body temperature is relatively stable, and it relies on thermoregulation to maintain the proper internal environment.

Thermoregulation is the process whereby the bird’s internal body temperature is kept within a certain range, despite any changes in the external environment. The bird’s adaptive physical mechanisms have enabled it to have excellent control over its body temperature.

It has a high degree of feather insulation, which insulates it against extremes of temperature, keeping it warm in colder environments and cool in hotter areas. Sounds and Vocal

Behavior

Vocalization

The Sulawesi Hawk-Eagle is typically silent, except during the breeding season when it vocalizes to communicate with its partner or to define its territory.

Natural vocalizations for the species are pliant chirping and chattering sounds that are often repeated, allowing them to establish audible contact with other birds of their species. During the breeding season, the Sulawesi Hawk-Eagle will typically call out to its partner or let out sounds that elucidate any impending dangers or threats that need to be addressed.

The calls are generally loud and designed to carry to birds in other territory nearby. The Sulawesi Hawk-Eagle also uses visual displays to communicate.

Their vivid aerial displays showcase their soaring skills; it features high soaring and diving, and a quick spin, to flaunt their colors and to assert dominance over their range. In conclusion, the Sulawesi Hawk-Eagle is a fascinating bird species with a diverse feeding behavior and prey range.

It relies on its excellent hunting skills to locate and hunt its prey using a combination of surprise and speed. The bird is capable of adapting its metabolism to survive in a range of climatic conditions, and it employs various thermoregulation techniques to maintain its body temperature.

The species is generally silent but communicates through chirping, calling, and visual displays. Understanding their vocal behavior will continue to be an essential tool for monitoring, conserving and protecting the Sulawesi Hawk-Eagle for future generations.

Behavior

Locomotion

The Sulawesi Hawk-Eagle boasts a pair of wings that allow it to fly gracefully, at times with great speed. It is a dominant bird of prey that is well adapted to life in the dense forests of Sulawesi, using the trees and their height to watch for prey and survey its territory.

When not soaring, it perches on the tops of trees, using its sharp eyesight to scan for potential prey. It is a skilled hunter, capable of flying through the dense forest to catch its prey.

Self-Maintenance

The Sulawesi Hawk-Eagle is an avid self-maintainer of its feathers, preening at every given chance. It is an essential aspect of its behavior to ensure feathers are properly aligned and layers of dirt or other debris are removed.

The bird also exposes its feathers frequently to sunlight to dry and disinfect them. Agonistic

Behavior

The Sulawesi Hawk-Eagle can be territorial, and at times, tends to exhibit agonistic behavior towards intruders.

When challenged or provoked, it will prefer to perch atop a tree branch or even glide through the canopy to scare off the intruder. It is capable of waylaying any predator that encroaches its range, displaying aggression to drive them off.

Sexual

Behavior

During the breeding season, a pair of Sulawesi Hawk-Eagles will develop a strong attachment, performing aerial displays to showcase their affection towards their partner. These are typically high displays that feature soaring high up into the sky and then diving down, attempting complex aerial acrobatics to impress their partner.

This dance is usually repetitive to indicate a keen interest in learning more about the partner.

Breeding

Breeding in Sulawesi Hawk-Eagles is seasonal and takes place between early June and August. They usually build their nests, which can be up to one meter in diameter, on the largest branches of tall trees.

The eggs are usually laid between July and September, with a single clutch per breeding season. Most nests are built in relatively undisturbed areas of the forest.

The Sulawesi Hawk-Eagle spends much of its time incubating the eggs until they hatch, which usually occurs after around 42 days. After hatching, both parents will take turns to feed the chicks and keep a watchful eye over them.

The young eaglet receives nourishment from its parents, slowly building up strength to leave the nest.

Demography and Populations

The population size of Sulawesi Hawk-Eagles has not been entirely determined, but it is known that their habitat loss, habitat fragmentation, and low reproductive rates have led to a significant population decline in recent years. Logging activities and illegal hunting and trapping have threatened the bird’s survival, and there is an urgent need for increased conservation efforts to protect and conserve the remaining Sulawesi Hawk-Eagle populations.

As a result of these threats, the bird has been classified as Near Threatened under the International Union for Conservation of Nature (IUCN) Red List. Additionally, there is a network

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