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Discover the Fascinating World of the Sulawesi Honey-buzzard: Behaviors Habitat and More

The Sulawesi Honey-buzzard, scientifically known as Pernis celebensis, is a bird species that resides in the island of Sulawesi in Indonesia. This bird species is a relatively small member of the honey-buzzard family and is a wonderful sight to behold if you are fortunate enough to spot one in the wild.

Identification

Field Identification

The Sulawesi Honey-buzzard has a unique appearance that sets it apart from other bird species. It is around 42-49cm in length and 75-95cm in wingspan, with a distinctive slimmer and rounder head compared to other honey-buzzards.

Its wings are long and pointed with a notable curve, while its body feathers are pale grey-brown. The distinctive blackish carpal patches located on the underwing coverts and typiclly grey cere gives it an exceptional and easily identifiable appearance.

Similar Species

It is important to note that the Sulawesi Honey-buzzard is not easily confused with other bird species due to its unique appearance. However, there are a few bird species that share some similarities with the Sulawesi Honey-buzzard, including the Bat Hawk and the Oriental Honey-buzzard.

Plumages

The Sulawesi Honey-buzzard has four distinctive plumages, including juvenile, immature, sub-adult, and adult. Juvenile plumage typically includes dark brown upperparts, creamy-white underparts contrasted with black streaking, and a brown head.

Immature plumage is much brighter than juvenile plumage and typically features a brown head, reddish-brown upperparts, and bright yellow underparts. Sub-adult plumage is more varied and shows more blackish scaling on the head and upperparts and washed out rusty-brown underparts.

Finally, adult plumage is characterized by a pale grey head contrasting with darker brown upperparts. The underparts appear washed out and duller, with tinges of brown-grey, and often with incomplete, weak black carpal patches.

Molts

The Sulawesi Honey-buzzard undergoes two molts every year one before breeding and another after breeding. The pre-breeding molt takes place in the winter season and involves the replacement of body feathers and the flight feathers.

After the breeding season, the bird undergoes a post-breeding molt that involves the replacement of some of its feathers. In conclusion, the Sulawesi Honey-buzzard is a beautiful bird species with unique features that allow it to stand out from other species.

Its multiple plumages provide a fascinating insight into the evolution of the bird, making it one of the most interesting members of the honey-buzzard family. Next time you find yourself in Sulawesi, keep an eye out for this majestic bird as it soars through the skies.

Systematics History

The Sulawesi Honey-buzzard, or Pernis celebensis, belongs to the family Accipitridae and can be found in the island of Sulawesi in Indonesia. Its classification has undergone various revisions over the years, which have led to changes in both its taxonomy and nomenclature.

Geographic Variation

Sulawesi itself is a relatively large island with mountains, valleys, and forests. Within the area of this island, the Sulawesi Honey-buzzard exhibits a certain amount of geographic variation, with differences observed between populations in different regions of the island.

Subspecies

Based on the differences in plumage, size, and habitat, the Sulawesi Honey-buzzard has been classified into four subspecies:

– Pernis celebensis celebensis: This is the nominate subspecies and is widespread in Sulawesi. It has a comparatively smaller head, paler primary flight feathers, and a grayish-brown collar.

– Pernis celebensis alter: This subspecies is known to be native to the mountain forests of the Central Sulawesi mainland. It can be distinguished from other subspecies by its larger size, reddish-brown nape, and fewer dark bars on the breast.

– Pernis celebensis ruficollis: This subspecies is located in the Southeast Peninsula and the adjacent Sangihe island. It is smaller than the nominate subspecies, and it has a more rufous nape and fewer dark bars on the underparts.

– Pernis celebensis proximo: This subspecies is endemic to the Togian Islands. It appears to be smaller than the nominate subspecies.

Related Species

The Sulawesi Honey-buzzard is a member of the honey-buzzard family, which also includes two closely related species, the Oriental Honey-buzzard (Pernis ptilorhynchus) and the Madagascar Buzzard (Buteo brachypterus). The Oriental Honey-buzzard is widespread from the Indian subcontinent to Southeast Asia, while the Madagascar Buzzard is found only in Madagascar.

Like the Sulawesi Honey-buzzard, both related species have a slim body and head, long wings, and a relatively long tail.

Historical Changes to Distribution

Studies suggest that the Sulawesi Honey-buzzard has gone through significant changes in its distribution and abundance over time. Some fossils from the Pleistocene epoch have been discovered in the island of Java, indicating that the species once inhabited the area.

However, it has since been extirpated from Java, and many other places where it once flourished, potentially due to habitat loss and hunting. There have also been reports of the Sulawesi Honey-buzzard being present in the Philippines, but the species’ current distribution is limited to Sulawesi.

However, there are a few reports of the bird being sighted in nearby islands, indicating that it may have dispersed to other neighboring islands. In conclusion, the Sulawesi Honey-buzzard is an interesting bird species with a complex taxonomic history and subtle geographic variation.

The four subspecies that have been identified reflect the unique characteristics and habitats of the populations in different regions of Sulawesi. Additionally, the historical changes to the distribution of the species reveal the vulnerability of the species to habitat changes and hunting.

This emphasizes the importance of conservation efforts to protect this beautiful and unique bird species.

Habitat

The Sulawesi Honey-buzzard is a bird species found primarily in the lowland forests and foothills of Sulawesi. These birds are generally found at altitudes ranging from sea level to approximately 1000 meters.

As juvenile birds, the Sulawesi Honey-buzzard is known for carrying out its first migration experience from these lowland forests and foothills down to the coasts. This movement is a natural occurrence, and it allows juvenile birds to acclimate to their navigating processes through orientation by the earths magnetic field.

It is worth mentioning that juveniles rarely travel back to their natal territories after their first migration. Some records indicated that the Sulawesi Honey-buzzard may occasionally migrate to nearby islands, such as Sangihe and the Talaud archipelago.

These movements may be a result of population differences and the periodic changes that occur in the environment.

In fact, studies have demonstrated that these birds exhibit advanced environmental contingency behaviors, where they are capable of changing their movements according to changes in the weather.

For instance, during the wet and rainy seasons, they tend to move to areas with lower elevation and dense forest areas in search of food, protection, and shelter. Consequently, during the dry season, when food and water become scarce, they tend to explore a wider range of habitats and elevate their movements in search of available resources.

Movements and Migration

Most individuals will remain relatively close to their natal territories while attending their juvenile plumage, with some moving a short distance away into nearby territories. However, some individuals display extensive movements soon after their fledge, usually in January and February, when more food resources are available due to the region’s peak fruiting season.

The Sulawesi Honey-buzzard is not known for making long-distance migrations like many other bird species. Instead, it often travels only short distances to adjacent territories or more suitable habitats within their home range.

However, some data from the birds satellite tracking indicated that the distance covered during these movements can easily add up to several thousand kilometers, thus indicating some long-distance movements. It is also important to note that the Sulawesi Honey-buzzard is a solitary bird, and most congregations of more than two individuals are typically groups of dispersed individuals coming together in response to temporary food resources.

When these birds make a temporary home in one area for a period of time, they tend not to move too far away from that location until the available resources have been exhausted. In summary, the Sulawesi Honey-buzzard makes significant movements and migration across various habitats in response to changing environmental conditions.

While their movements are not as extensive as other bird species, they are still capable of traveling long distances in search of food and suitable habitats.

Diet and Foraging

Feeding

The Sulawesi Honey-buzzard primarily feeds on small mammals, reptiles, birds, and insects. These birds are known to exhibit unique hunting behaviors, and prey on a wide variety of animals.

They are known to hover quietly over the forests scanning for prey and will often fly after detecting prey running or flying across the canopy. Their unique hunting behavior of using its feet to grab and capture their prey while in mid-air, helps them capture prey that is either difficult to locate or inaccessible from the ground.

Diet

The diet of the Sulawesi Honey-buzzard is more varied than any other honey-buzzards in the world. Insects and invertebrates make up a greater portion of its diet.

Some of the main prey species that the Sulawesi Honey-buzzard feeds on include reptiles, small mammals, birds, and insects. The taxonomy of insects that it feeds on vary from dragonflies, beetles, and cicadas to orthopterans.

In addition to feeding on live prey, Sulawesi Honey-buzzard has been known to consume fruit. This may be in response to scarcity of prey or it ccan be eaten opportunistically.

Metabolism and Temperature Regulation

The Sulawesi Honey-buzzard has a thermoregulation system which helps it regulate body temperature through its digestive system. They are known for their ability to increase their body temperature during digestion by up to a remarkable 6 degrees, higher than its body temperature during inactive pase.

This unique metabolism system helps them improve their hunting and digestion capabilities.

Sounds and Vocal Behavior

Vocalization

The Sulawesi Honey-buzzard is generally a silent bird, and they are not known for producing distinctively loud or complex vocal sounds. They produce a variety of calls and whistles that are typically short and sweet to communicate with other individuals, or when they come under threat by predators .

Their vocalizations are relatively infrequent, and include short, high pitched screeches and calls. Individuals may produce a weak high-pitched ggii or ka call when theyre under stress, threatened, or are being chased by predators.

These calls are not specifically used during hunting or foraging. The Sulawesi Honey-buzzard primarily communicates through its body language, such as through sounds produced by their wings during flight displays.

These Sulawesi Honey-buzzard are known for their elaborate aerial displays, and they often move with grace and precision soaring high above the canopy. They sometimes generate loud rushing wing sounds called whoosh.

These wing sounds are believed to play an important role in communicating their types and ranks among other individuals. In conclusion, the Sulawesi Honey-buzzard is an interesting bird species with a unique feeding strategy.

Despite being largely silent, the Sulawesi Honey-buzzard is an excellent hunter that feeds on a wide range of prey including live prey and fruit. Its digestive system is unique and allows them to regulate body temperature while hunting and digesting their food.

While they are relatively silent, they communicate with other individuals through their aerial displays and non-vocal body language, such as well-timed wing sounds which contribute to the animals unique vocal behaviour.

Behavior

Locomotion

The Sulawesi Honey-buzzard is a bird species with very few predators in their habitats, and therefore they exhibit a relatively leisurely method of movement. These birds are known for their remarkable flying skills which enable them to soar above the forest canopy.

Their broad rounded wings and slim body help them soar with minimal flapping, and they make use of updrafts to cover large distances with minimal energy consumption.

Self-Maintenance

Self-maintenance is a crucial part of a birds behavior, with birds usually preening their feathers to help them maintain their plumage and keep their feathers in excellent condition. In addition to self-grooming, Sulawesi Honey-buzzard also use dust baths to help keep their feathers clean and free of oils, dirt, and parasites.

During a dust bath, the birds roll around in the ground, spreading dust on themselves and help remove dirt and oils on their feathers.

Agonistic Behavior

The Sulawesi Honey-buzzard is often seen engaging in agonistic behavior, particularly with other nearby birds of prey. When another bird of prey invades its territory, individuals will often engage in intense aerial combat chase to drive out rivals from their territory.

Sexual Behavior

During the breeding season, the Sulawesi Honey-buzzard will engage in various displays to attract females. These displays may involve aerial displays such as flying upwards and diving downwards, or they may use vocalizations to communicate and attract a mate.

Breeding

Sulawesi Honey-buzzard are typical monogamous birds, and typically pair up for life after the first season of nesting. They generally breed once a year in the early dry season, which is typically around June August in their habitat range.

The birds will build their nests with sticks and twigs near the canopy of tall trees, where they have access to sources of prey. The breeding season is usually marked by elaborate aerial displays, calls, and other behaviors that are intended to attract mates.

After mating, the female will lay one or two eggs, and the incubation period typically lasts for around 40 days. After the eggs hatch, both parents work together to provide food for their young by hunting and scavenging for prey near their nesting territory.

The young chicks usually leave the nest after around 3 months and begin exploring the surrounding area. During this time, they are vulnerable to predation by other animals and are dependent on their parents for protection.

Demography and Populations

The Sulawesi Honey-buzzard’s population status is not considered threatened, and the bird is assessed as a species of Least Concern by the International Union for Conservation of Nature. However, habitat fragmentation and loss of lowland forests have led to localized declines in population status of the bird.

Hunting and forest degradation are among the main threats to this bird species which have decreased their population. Populations of the Sulawesi Honey-buzzard are often found in relatively small clusters, often comprising of less than ten individuals that may reside within a particular habitat area.

These birds are considered solitary birds, but will occasionally form pairs and work together during the breeding and nesting season.

In conclusion, the Sulawesi Honey-buzzard is an interesting bird species with a unique set of behaviors.

Their remarkable flight skills make them extraordinary hunters, capable of traveling significant distances while using minimal energy, and their unique breeding behavior gives insight into the breeding patterns of these fascinating birds. While their population status is not considered threatened, conservation efforts are necessary to ensure that their habitats are preserved and that they continue to thrive in the wild.

In conclusion, the Sulawesi Honey-buzzard is a unique and fascinating bird species that exhibits a range of intriguing behaviors and characteristics. From their remarkable hunting strategies and preferred habitats to their agile flight and elaborate breeding displays, this bird species exemplifies the wonders and diversity of nature.

While their population status is currently considered of Least Concern, habitat loss, degradation, and hunting remain major threats to the Sulawesi Honey-buzzard. Hence, it is important to continue efforts towards conserving their habitat to protect this impressive species of bird.

Understanding the behaviors, ecology, and conservation needs of the Sulawesi Honey-buzzard is not only essential to preserving the bird, but also to appreciating the rich diversity of life on our planet.

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