Bird O'clock

Discover the Unique Features and Behaviors of the Endemic Sulawesi Goshawk

The Sulawesi Goshawk, scientifically known as Accipiter griseiceps, is a bird species that can be found in the forests of Sulawesi, Indonesia. This bird belongs to the family Accipitridae, and it is known for its distinct physical features and peculiar behaviors.

Identification

When identifying the Sulawesi Goshawk, it is important to take note of its physical characteristics. This bird species is 2733 cm in length, with a wingspan of 5569 cm.

Adult Sulawesi Goshawks have a grey head, unlike the juvenile birds which have white and brown head feathers that gradually change to grey as they mature.

The upperparts of this bird are dark grey, while its underparts are white, with fine blackish barring on the breast and underwing coverts.

Its bill is grey with a yellow cere, and its legs and feet are yellow.

Field

Identification

The Sulawesi Goshawk is known for its flying behavior.

It usually flies in a way that its wings appear to be bowed. This bird flies quickly and agilely through the dense forest canopy, keeping close to branches and tree trunks.

It often makes a low-pitched kiyuuu! call that sounds like two short whistles.

Similar Species

The likeness of a Sulawesi Goshawk to other Accipiter species, particularly other small goshawks, could lead to confusion. However, the presence of a gray head and the conspicuous white underparts make it easy to distinguish Sulawesi Goshawks from other Accipiters

Plumages

The Sulawesi Goshawk goes through different molts to attain its adult plumages. The juveniles have a white head with rusty brown cheeks, streaky underparts, and brown upperparts.

The moulting sequence of the Sulawesi Goshawk is not well documented, and thus the rate of molt, timing, and sequence of feather replacement is not known.

There is a hypothesis that Sulawesi Goshawks undergo a full molt before proceeding to breed.

After breeding, the birds undergo another full moult before the non-breeding season.

Final Thoughts

Overall, the Sulawesi Goshawk is a fascinating bird species that exhibits distinct physical features and peculiar flying behavior.

References:

Ferguson-Lees, J., & Christie, D.

A. (2001).

Raptors of the World. Houghton Mifflin Harcourt.

de Vries, T., Reijnen, R., & Vines, R. (1996).

Birds of paradise : Paradisaeidae. Brill.

Simmons, R. E., Brown, L., & Kemper, J.

(2015). Birds to watch in southern Africa.

Struik Nature.

Systematics History

The Sulawesi Goshawk, or Accipiter griseiceps, was first described by the German zoologist Hermann Schlegel in 1866. It was believed to be closely related to the African Goshawk, Accipiter tachiro, and the Grey Goshawk, Accipiter novaehollandiae, of Australia.

However, molecular analyses conducted in the 21st century proposed that the Sulawesi Goshawk is closely related to the Nicobar Sparrowhawk, Accipiter butleri, and the Moluccan Goshawk, Accipiter henicogrammus, rather than the African or Grey Goshawks.

Geographic Variation

The Sulawesi Goshawk is endemic to Sulawesi, an island province of Indonesia. This bird species has a vast distribution range across the island, from the lowlands to the mountains.

Geographical variation is evident in the size and plumage of the birds across different regions on the island.

Subspecies

The Sulawesi Goshawk has three recognized subspecies based on geographic variation:

1. A.

g. griseiceps is found in the northern and north-central part of Sulawesi.

This subspecies displays less barring on the underparts and a more distinct white supercilium compared to the other subspecies. 2.

A. g.

stresemanni is endemic to the central highlands of Sulawesi. This is the largest of the subspecies and has narrower underpart barring.

3. A.

g. wallacei is found in the southern part of Sulawesi.

It is the smallest of the subspecies and has the most prominent and thick underpart barring.

Related Species

The Sulawesi Goshawk is part of the Accipiter genus, which is composed of small to medium-sized diurnal birds of prey. Other species in this genus include the Eurasian Sparrowhawk, the Sharp-shinned Hawk, and the Cooper’s Hawk.

The Sulawesi Goshawk’s close relative, the Moluccan Goshawk, is also found in Indonesia. This bird species has a dark slate-grey head with a conspicuous copper or russet breast barring, giving it a unique appearance.

Historical Changes to Distribution

There are no known historical changes to the distribution of the Sulawesi Goshawk, as it is endemic to Sulawesi, an island that has not undergone any significant geological changes in recent history.

However, the Sulawesi Goshawk, like many other birds on the island, faces threats from habitat loss and fragmentation due to deforestation and agricultural expansion.

These threats have led to a decline in its population in recent years, making this bird species vulnerable to extinction.

Additionally, this bird species is heavily hunted for use in traditional medicine and as food in some areas of Sulawesi.

The combined threats of habitat loss and hunting have led to a decline in the population of the Sulawesi Goshawk.

Conclusion

The Sulawesi Goshawk is an endemic bird species to Sulawesi, Indonesia, with distinct physical features and behaviors. Its historical systematics and geographic variation have been closely studied, with three recognized subspecies based on their plumage and size.

The bird species is part of the Accipiter genus, which includes other small to medium-sized diurnal birds of prey. While there have been no historical changes to the distribution of this bird species, it is currently facing significant threats due to habitat loss and hunting, making conservation measures necessary to ensure its survival.

Habitat

The Sulawesi Goshawk is found in a wide variety of forested habitats across Sulawesi, Indonesia. These habitats include primary and secondary lowland forests, upland forests, and montane forests.

The Sulawesi Goshawk also inhabits plantations and other areas of disturbed habitat, such as gardens and parks.

This bird species is known to be dependent on the maintenance of forest areas for its survival.

Any activity that leads to habitat loss or fragmentation is a significant threat to the Sulawesi Goshawk’s population. Ensuring the protection and conservation of forest habitats is critical for the survival of this bird species.

Movements and Migration

Little is known about the movements and migration patterns of the Sulawesi Goshawk. This bird species is generally thought to be non-migratory, although there are some reports of seasonal movements across Sulawesi in search of prey and nesting sites.

During the breeding season, male Sulawesi Goshawks are known to exhibit territorial behavior and defend their nesting sites vigorously. Females typically stay within the nesting area, while males are more mobile and often seen searching for prey.

Once the breeding season is over, the Sulawesi Goshawk becomes less territorial and may move around its habitat in search of food. While there have been no reports of long-distance migration in the Sulawesi Goshawk, this bird species has been known to disperse to other areas in search of breeding or nesting sites.

Juvenile birds often disperse from their natal area once they reach maturity, and some may travel long distances to find suitable breeding grounds. The Sulawesi Goshawk’s movements and migration patterns are still not fully understood, and more research is needed to shed light on these aspects of its behavior.

Conservation Implications

Habitat loss and fragmentation are significant threats to the Sulawesi Goshawk’s population, as this bird species is dependent on forested habitats for its survival. Deforestation for agricultural development and other human activities is a significant threat to the Sulawesi Goshawk’s habitat, leading to habitat degradation and fragmentation.

Conservation measures to protect forested habitats on Sulawesi, including the establishment of protected areas, will benefit the Sulawesi Goshawk and other forest-dependent bird species on the island. Efforts to restore degraded forests and promote sustainable land use practices are also essential for the long-term conservation of the Sulawesi Goshawk’s habitat.

The hunting and harvesting of the Sulawesi Goshawk for traditional medicine and food are additional threats to this bird species’ population. Implementation and enforcement of laws to regulate the hunting and trade of the Sulawesi Goshawk are necessary to ensure its conservation.

Conclusion

The Sulawesi Goshawk is dependent on forested habitats for its survival.

Habitat loss and fragmentation due to deforestation and other human activities are significant threats to this bird species’ population.

The Sulawesi Goshawk’s movements and migration patterns are not well understood, and more research is needed. Conservation measures to protect forest habitats, restore degraded areas, and regulate hunting and trade of this bird species are critical to its long-term survival.

Diet and Foraging

Feeding

The Sulawesi Goshawk is primarily a predator of small birds and mammals. It is known to be an agile and swift hunter, chasing prey through the dense forest canopy.

This bird species is also known to hunt for bats, lizards, and occasionally insects, albeit not frequently. When hunting, the Sulawesi Goshawk perches on a branch or flies through the forest canopy and scans for prey.

Once located, it swoops down and captures the prey in its sharp talons. The Sulawesi Goshawk is also known to cache its prey in a tree fork or hidden crevice, returning to feed on it later.

Diet

The Sulawesi Goshawk’s diet is varied, and it is known to prey on a range of small birds, including fruit-doves, white-eyes, and thrushes. The diet of the Sulawesi Goshawk is heavily influenced by the availability of prey in its habitat, which can vary across its distribution range.

The Sulawesi Goshawk has also been observed feeding on arboreal mammals, including rats and squirrels, by chasing them through the dense vegetation. In addition, this bird species is known to prey on bats, which it captures in mid-air using its sharp talons.

Metabolism and Temperature Regulation

The Sulawesi Goshawk has a high metabolic rate that enables it to maintain its energetic needs while hunting for prey. This bird species’ energy requirements are primarily met by a diet rich in protein, which allows for the rapid breakdown of food into energy.

The Sulawesi Goshawk is also well-adapted to regulate its body temperature. Its plumage helps maintain its body temperature by trapping heat close to the skin when it is cold and facilitating heat dissipation when it is hot.

In addition, its beak and legs serve as an efficient heat exchange system, enabling the bird species to regulate its body temperature to suit its environment.

Sounds and Vocal Behavior

Vocalization

The Sulawesi Goshawk has a unique vocalization that is essential to its communication and territorial behavior. This bird species is known for its low-pitched kiyuuu! call, which is a two-note whistle that sounds like “kee-yoo.” The call is usually delivered in short bursts of two to three notes and is given by both male and female birds.

The kiyuuu! call is used in several contexts, including territorial defense, pair bonding, and communication between parents and chicks. When defending their territory, male birds use the call as a warning to other Sulawesi Goshawks to stay away from their nesting sites.

Females, on the other hand, use a softer version of the call to communicate with their mates. During the breeding season, the Sulawesi Goshawk also engages in an elaborate aerial display that involves flying high in the sky while uttering its kiyuuu! call.

The display is thought to be essential in pair bonding and in defending their territorial boundaries.

Conclusion

The Sulawesi Goshawk is a predator of small birds and mammals that hunts primarily through the dense forest canopy. This bird species’ high metabolic rate is well-suited to its hunting behavior, allowing it to maintain its energetic needs.

Its vocalization, including its low-pitched kiyuuu! call, is used in several contexts, including territorial defense, pair bonding, and communication between parents and chicks. The Sulawesi Goshawk is also well-adapted to regulate its body temperature, enabling it to survive in a range of different environments across its distribution range.

Behavior

Locomotion

The Sulawesi Goshawk is known for its agile and swift movement through the dense forest canopy. This bird species is also known to be an excellent flier, characteristically flying with bowed wings, darting in and out of cover and flying through gaps between trees to chase its prey.

The Sulawesi Goshawk’s powerful and sharp talons enable it to capture prey, while its broad wings provide excellent maneuverability, allowing it to navigate the dense forest canopy with ease.

Self Maintenance

Like other bird species, the Sulawesi Goshawk spends a significant portion of its day engaged in self-maintenance behaviors such as preening and grooming. These behaviors are essential in keeping the feathers and skin healthy and in preventing parasites or other infections.

Agonistic Behavior

The Sulawesi Goshawk displays agonistic behaviors during the breeding season and when defending territorial boundaries. This bird species’ territorial behavior is characterized by high-pitched, piercing calls, hopping, and flapping of wings.

During territorial disputes, Sulawesi Goshawks can become very aggressive and engage in what appears to be acrobatic displays in the air. These displays can include diving and chasing each other through the forest canopy and are thought to be essential in protecting their breeding territories.

Sexual Behavior

Sulawesi Goshawks are typically monogamous, with both male and female birds pairing for the breeding season. Pair bonding often involves courtship displays, such as synchronized flights and the exchange of food between the pair.

Breeding

Sulawesi Goshawks breed between September and February and are known to produce a single brood per year. During the breeding season, the male bird performs courtship displays to attract a mate and establishes a breeding territory.

Once a mate is secured, the pair builds a nest together using sticks and other forest debris. The Sulawesi Goshawk’s nests, which are usually located in the branches of trees, are between 7 and 15 meters above the ground.

The female typically lays two or three eggs, which hatch after about 24-27 days of incubation. The young chicks are fed by both parents, and they fledge after about 33-37 days.

Demography and Populations

The population size of the Sulawesi Goshawk is not well known, with estimates ranging from 5000 to 50,000 individuals. The bird species is considered vulnerable to extinction, primarily due to habitat loss, hunting, and other human activities.

Conservation measures, such as those aimed at protecting forest habitats, are necessary to ensure the long-term survival of the Sulawesi Goshawk. This bird species’ population must be monitored closely to understand how it is affected by changes in its habitat and other threats.

Additionally, targeted conservation efforts like habitat restoration and sustainable land use practices can help to ensure that this bird species has a future in the wild. Education and awareness programs aimed at promoting the conservation of the Sulawesi Goshawk are also essential to ensure the survival of this unique bird species.

Conclusion

The Sulawesi Goshawk’s behavior is characterized by its sharp, talon-like movements, swift flying, and territorial behavior during the breeding season. Pair bonding involves courtship displays and the exchange of food between birds.

During the breeding season, the Sulawesi Goshawk builds a nest using sticks and other forest debris, with both parents feeding young chicks. This bird species remains vulnerable to extinction due primarily to habitat loss, hunting, and other human activities.

Efforts to conserve its habitat, promote sustainable land use practices, and educate the public on the importance of the Sulawesi Goshawk’s conservation are essential to ensure its survival. In summary, the Sulawesi Goshawk, or Accipiter griseiceps, is an endemic bird species to Sulawesi, Indonesia, that is known for its distinct physical features, behaviors, and vocalizations.

The bird species is dependent on forested habitats for its survival and is threatened by habitat loss, hunting, and other human activities. Efforts to conserve its habitat, promote sustainable land use practices, and regulate hunting and trade of this bird species are critical to its long-term survival.

Understanding the Sulawesi Goshawk’s behavioral patterns and the ecological factors that affect its population is necessary to ensure the conservation of this unique bird species.

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