Large Hawk-Cuckoo (Hierococcyx sparverioides) – A Comprehensive Study

Taxonomy & Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Cuculiformes
• Family: Cuculidae
• Genus: Hierococcyx
• Species: Hierococcyx sparverioides

The Large Hawk-Cuckoo (Hierococcyx sparverioides) is a fascinating member of the Cuculidae family, known for its striking resemblance to hawks and its intriguing brood parasitic behavior. It is often referred to as the “Brain-fever bird” due to its persistent and loud calls during the breeding season.

Morphology & Physical Description

• Size: 34–42 cm in length
• Wingspan: Approximately 50–60 cm
• Weight: 100–200 grams
• Plumage:
  • Upperparts are dark grey to brownish-grey, resembling a small raptor.
  • Underparts are pale with fine dark barring, particularly on the breast.
  • Tail is long, barred, and slightly rounded.
• Head Features:
  • Yellow orbital skin surrounding large, alert eyes.
  • Sharp, slightly curved beak designed for insectivorous feeding.
• Feet & Claws:
  • Zygodactyl feet (two toes pointing forward, two backward) for gripping branches.

Mimicry of Hawks

The Large Hawk-Cuckoo is a Batesian mimic, meaning it imitates the appearance of a predator (sparrowhawks and other raptors) to avoid threats from smaller birds. This helps it move through forests and exploit host nests with minimal interference.

Habitat & Distribution

The Large Hawk-Cuckoo is found in a variety of habitats across South and Southeast Asia, including:

• Dense forests and evergreen woodlands
• Mangrove ecosystems
• Deciduous and mixed forests in hilly terrain
• Plantations and secondary forests

Presence in the Sundarban

In the Sundarban, the Large Hawk-Cuckoo is an occasional visitor, preferring the dense mangrove forests and mixed riverine woodlands. It is primarily seen:

• During the breeding season (March–July) when it vocalizes intensely.
• In the upper canopy, where it searches for caterpillars and insects.
• In isolated forest patches, where it finds suitable host birds for egg-laying.

Though not a dominant resident, its presence in the Sundarban Biosphere Reserve indicates the ecological connectivity between mainland forests and mangrove ecosystems.

Feeding Behavior & Diet

The Large Hawk-Cuckoo is an insectivorous bird, with a diet primarily consisting of:

• Large caterpillars (especially hairy ones avoided by other birds)
• Beetles, grasshoppers, and locusts
• Spiders and small lizards (occasionally)

Foraging Strategy

• Moves stealthily through tree canopies, picking prey from leaves and branches.
• Uses its hooked beak to grab insects efficiently.
• Occasionally drops to the ground to catch large invertebrates.

Brood Parasitism & Reproduction

Unlike most birds, the Large Hawk-Cuckoo does not build its own nest. Instead, it engages in brood parasitism, laying its eggs in the nests of other birds.

Parasitic Strategy

• Host Species: Commonly targets babblers (Turdoides spp.) and other small passerines.
• Egg Mimicry: The cuckoo’s eggs closely resemble the host’s eggs, reducing the chance of rejection.
• Chick Behavior: The hatchling cuckoo may push host eggs out of the nest to eliminate competition.
• Faster Growth: Cuckoo chicks grow rapidly, monopolizing parental care.

Vocalization & Communication

• Famous for its loud, repetitive “brain-fever” call, especially at dawn and dusk.
• Males call persistently during breeding season to attract females.
• Calls resemble a crescendoing “pee-pee-pee-pee” that rises in intensity.

Special Adaptations

1. Mimicry of Raptors: Helps avoid predation and allows it to access host nests undisturbed.
2. Zygodactyl Feet: Aid in perching securely while foraging or resting.
3. Brood Parasitism: Allows increased reproductive success without the burden of raising chicks.
4. Efficient Camouflage: Plumage blends well with forested environments.

Threats & Conservation Status

• Deforestation & habitat loss in lowland forests and mangroves.
• Decline of host species, impacting reproductive success.
• Climate change effects, altering insect populations and nesting availability.
• Human disturbances in protected forests affecting breeding behavior.

IUCN Status: Least Concern (LC)

Though not currently threatened, localized habitat destruction poses a risk to its long-term populations. Conservation of forested and mangrove habitats, including those in the Sundarban, is essential for maintaining its presence.

Conclusion

The Large Hawk-Cuckoo (Hierococcyx sparverioides) is a remarkable forest-dwelling cuckoo, displaying both hawk-like mimicry and brood parasitism. While it is not a permanent resident of the Sundarban, its seasonal presence in the mangrove forests highlights the region’s rich biodiversity. Continued mangrove conservation and the protection of host bird species will be crucial in ensuring its survival in the wild.