Autumn Migration Patterns of Raptors in Southeast Asia: An Overview of Key Flyways and Species

 

Mega Flocking of Raptor Migratory Image Source Ladayly.post

*Heri Tarmizi

Understanding their migratory patterns and the challenges they face is crucial for developing effective conservation strategies.

Raptor migration is a fascinating natural phenomenon that showcases the endurance, navigational skills, and survival strategies of these predatory birds. Southeast Asia, with its diverse landscapes and strategic geographical position, serves as a crucial migratory corridor for various raptor species. This essay explores the autumn migratory patterns of raptors in Thailand, Malaysia, Pulau Rupat in Sumatra, the Philippines, and the Sangihe flyway. It focuses on the Oriental honey buzzard (Pernis ptilorhynchus), Japanese sparrowhawk (Accipiter gularis), Chinese sparrowhawk (Accipiter soloensis), black baza (Aviceda leuphotes), osprey (Pandion haliaetus), and various harriers.

1. Southeast Asian Flyways

Southeast Asia hosts several key flyways that facilitate raptor migration. The region's complex geography, characterized by peninsulas, islands, and mountain ranges, creates diverse migratory routes. The main flyways in the area include:

• Thai-Malay Peninsula Flyway: This route stretches from Thailand through Malaysia, serving as a major passage for raptors moving southward.
• Sumatra Flyway: Specifically, Pulau Rupat, an island off the coast of Sumatra, acts as a critical waypoint for migrating raptors.
• Philippine Flyway: The Philippines, particularly the Sangihe Islands, provides a vital link between mainland Asia and the Indonesian archipelago.

2. Oriental Honey Buzzard (Pernis ptilorhynchus)

The Oriental honey buzzard is one of the most prominent raptors migrating through Southeast Asia. These birds undertake extensive migrations from their breeding grounds in East Asia to wintering sites in Southeast Asia and beyond.

Migration Route

Oriental honey buzzards primarily migrate along the Thai-Malay Peninsula Flyway. They are often observed crossing the Isthmus of Kra in Thailand before continuing south through Malaysia. Pulau Rupat in Sumatra serves as a crucial stopover point where these birds rest and refuel before proceeding further south (Yamaguchi et al., 2008).

Behavior and Ecology

During migration, Oriental honey buzzards exploit thermals and updrafts to conserve energy. They are known for their distinctive flight pattern, characterized by slow, deliberate wingbeats interspersed with long glides (Bildstein, 2006). These raptors feed on honeybee larvae and other insects, which they locate using their keen sense of smell.

3. Japanese Sparrowhawk (Accipiter gularis) and Chinese Sparrowhawk (Accipiter soloensis)

Both the Japanese sparrowhawk and Chinese sparrowhawk are small, agile raptors that migrate through Southeast Asia. These species exhibit similar migratory behaviors and often travel in mixed flocks.

Migration Route

The Japanese sparrowhawk and Chinese sparrowhawk utilize the Thai-Malay Peninsula Flyway and the Sumatra Flyway. They are commonly observed in large numbers at migration watch sites in Thailand and Malaysia. These birds also use the Philippines as a critical stopover point during their migration (Shiu et al., 2006).

Behavior and Ecology

These sparrowhawks are highly adaptable and can exploit various habitats during migration. They typically hunt small birds and insects, using their agility and speed to capture prey. During migration, they rely on visual cues and landscape features to navigate, often following mountain ridges and coastlines (Yamaguchi et al., 2012).

4. Black Baza (Aviceda leuphotes)

The black baza is a striking raptor with a unique migratory pattern. Unlike many other raptors, black bazas often migrate in flocks, displaying social behavior during their journeys.

Migration Route

Black bazas migrate through the Thai-Malay Peninsula Flyway and are frequently observed in Malaysia and southern Thailand. Pulau Rupat in Sumatra is another significant stopover site for these birds. The Sangihe flyway in the Philippines also serves as a migration route for black bazas (Wells, 1999).

Behavior and Ecology

Black bazas are known for their acrobatic flight and distinctive plumage. They primarily feed on insects and small vertebrates, which they catch in mid-air. During migration, these birds utilize thermals and updrafts, often seen soaring in large, loose flocks (Wells, 1999).

5. Osprey (Pandion haliaetus)

The osprey, also known as the fish hawk, is a cosmopolitan raptor with a widespread distribution. In Southeast Asia, ospreys follow distinct migratory routes to reach their wintering grounds.

Migration Route

Ospreys migrating through Southeast Asia primarily use coastal flyways. They are often observed along the coasts of Thailand, Malaysia, and the Philippines. Pulau Rupat in Sumatra is a notable stopover point where ospreys can find abundant fishing opportunities (Poole, 1989).

Behavior and Ecology

Ospreys are specialized fish-eaters, with reversible outer toes and spiny foot pads that enable them to grasp slippery fish. During migration, they rely on large bodies of water to hunt and refuel. Ospreys typically migrate alone or in small groups, using their keen eyesight to locate prey from the air (Poole, 1989).

6. Harriers

Harriers, including species such as the Eastern marsh harrier (Circus spilonotus) and pied harrier (Circus melanoleucos), exhibit distinctive migratory behaviors. These ground-nesting raptors often migrate overland, following different routes than other raptors.

Migration Route

Harriers in Southeast Asia utilize the Thai-Malay Peninsula Flyway, with significant numbers passing through Thailand and Malaysia. They also migrate through the Philippines, using the Sangihe flyway as a critical link between breeding and wintering grounds (Shiu et al., 2006).

Behavior and Ecology

Harriers are known for their low, buoyant flight, often seen gliding close to the ground while hunting. They primarily feed on small mammals, birds, and insects. During migration, harriers rely on open habitats such as grasslands and wetlands, where they can easily find prey and roost (Thiollay, 1994).

Conservation Implications

Raptor migration in Southeast Asia faces several conservation challenges. Habitat loss, hunting, and climate change are significant threats that can disrupt migratory patterns and reduce raptor populations. Conservation efforts should focus on protecting critical stopover sites and migratory corridors, as well as promoting sustainable land-use practices (Bildstein et al., 2007).

International collaboration is essential for effective raptor conservation. Initiatives such as the East Asian-Australasian Flyway Partnership (EAAFP) aim to coordinate conservation actions across countries within the flyway, ensuring the protection of key habitats and promoting research on raptor migration (Choi et al., 2020).

Conclusion

The autumn migration of raptors in Southeast Asia showcases the incredible endurance and navigational abilities of these birds. Species such as the Oriental honey buzzard, Japanese sparrowhawk, Chinese sparrowhawk, black baza, osprey, and harriers utilize key flyways in Thailand, Malaysia, Pulau Rupat in Sumatra, the Philippines, and the Sangihe Islands. Understanding their migratory patterns and the challenges they face is crucial for developing effective conservation strategies. Through continued research and international cooperation, we can ensure the protection of these remarkable raptors and the habitats they depend on.

References

• Bildstein, K. L. (2006). Migrating Raptors of the World: Their Ecology and Conservation. Cornell University Press.
• Bildstein, K. L., Smith, J. P., Ruelas Inzunza, E., & Veit, R. R. (2007). State of North America's Birds of Prey. American Ornithologists' Union.
• Choi, C. Y., Ganbold, O., Goroshko, O., & Yu, Y. T. (2020). The East Asian-Australasian Flyway: Challenges and Opportunities for Global Conservation. Journal of Asian Ornithology, 3(1), 1-12.
• Poole, A. F. (1989). Ospreys: A Natural and Unnatural History. Cambridge University Press.
• Shiu, H. J., Tokita, K., Morishita, E., & Higuchi, H. (2006). Route and Site Fidelity of Two Migratory Sparrowhawks Accipiter gularis in Japan. Ornithological Science, 5(1), 51-56.
• Thiollay, J. M. (1994). Family Accipitridae (Hawks and Eagles). In Handbook of the Birds of the World, Vol. 2: New World Vultures to Guineafowl (pp. 52-205). Lynx Edicions.
• Wells, D. R. (1999). The Birds of the Thai-Malay Peninsula, Volume One: Non-Passerines. Academic Press.
• Yamaguchi, N. M., Tokita, K. I., & Higuchi, H. (2008). The Importance of Stopover Sites in Migration: An Example from the Oriental Honey-buzzard Pernis ptilorhynchus. Ornithological Science, 7(2), 117-126.
• Yamaguchi, N. M., Shoji, A., & Higuchi, H. (2012). How Do Raptors Select Migration Routes? A Case Study Using the Grey-faced Buzzard. Journal of Avian Biology, 43(1), 1-8.