Indian Nightjar (Caprimulgus asiaticus) – A Detailed Study

Taxonomy & Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Caprimulgiformes
• Family: Caprimulgidae
• Genus: Caprimulgus
• Species: Caprimulgus asiaticus

The Indian Nightjar (Caprimulgus asiaticus) belongs to the family Caprimulgidae, a group of nocturnal insectivorous birds known for their cryptic plumage and silent, gliding flight. These birds are masters of camouflage, blending seamlessly with their surroundings.

Morphology & Physical Description

• Size: 21–24 cm in length
• Wingspan: 50–55 cm
• Weight: 50–70 grams
• Plumage: Highly cryptic, featuring brown, grey, and buff streaks that mimic dry leaves and forest debris.
• Head Features: Large eyes adapted for night vision, with a small but wide mouth equipped with bristle-like feathers for capturing insects.
• Beak: Short and slightly hooked, well-suited for catching flying prey mid-air.
• Legs & Feet: Short and weak, as these birds spend most of their time on the ground.
• Tail: Medium-sized and rounded, used for maneuvering during silent flight.

Habitat & Distribution

The Indian Nightjar is widely distributed across South and Southeast Asia, occupying diverse landscapes such as:

• Dry forests and scrublands
• Grasslands and open woodlands
• Coastal mangroves and estuaries
• Agricultural fields and rural outskirts

Presence in the Sundarban

The Sundarban, with its dense mangrove forests, open scrub areas, and sandy riverbanks, provides an ideal habitat for the Indian Nightjar. It is commonly observed:

• Resting on the forest floor, where its camouflaged plumage keeps it hidden during the day.
• Foraging along riverbanks and clearings during dusk and night.
• Inhabiting drier patches within the mangrove ecosystem, where sandy soil and open canopies allow easier movement.

While not as common as in dry deciduous forests, Indian Nightjars are present in the Sundarban, particularly in areas with a mix of mangroves and open land.

Feeding Behavior & Diet

The Indian Nightjar is a strictly nocturnal insectivore, relying on:

• Moths and beetles, captured mid-flight.
• Flying ants and termites, particularly after seasonal rains.
• Grasshoppers and other nocturnal arthropods.

Foraging Strategy

• Aerial hawking: Catches insects on the wing using its wide mouth.
• Silent flight: Specialized feathers allow near-soundless movement, increasing hunting success.
• Perch hunting: Sometimes waits on a branch or ground before ambushing passing prey.

Breeding & Nesting

• Breeding Season: March to July, coinciding with warm temperatures and increased insect activity.
• Nesting Sites:
  • Lays eggs directly on the ground, without making a traditional nest.
  • Prefers gravel patches, dry leaves, or sandy soil for better camouflage.
• Eggs:
  • Usually 2 eggs per clutch.
  • Eggs have a mottled brown coloration to blend with the surroundings.
• Parental Care:
  • Both parents take turns in incubation (about 18-20 days).
  • Adults perform distraction displays to lead predators away from the nest.

Vocalization & Communication

The Indian Nightjar is more often heard than seen, producing:

• A distinctive “chuck-chuck-chuck” call, repeated rapidly at dusk.
• Low whirring sounds during flight, created by specialized wing feathers.
• Soft growls when disturbed near its nest site.

Special Adaptations

1. Cryptic Camouflage: Plumage mimics dry leaves and bark, making it nearly invisible during the day.
2. Night Vision: Large, highly sensitive eyes allow excellent low-light vision.
3. Silent Flight: Soft-edged feathers enable it to fly without making noise, enhancing its hunting efficiency.
4. Mouth Bristles: Fine, whisker-like structures around the beak help guide insects into the mouth during flight.
5. Minimal Energy Use: Spends long periods motionless, conserving energy for night-time activity.

Threats & Conservation Status

Despite its adaptability, the Indian Nightjar faces several threats:

• Habitat destruction due to deforestation and land-use changes.
• Disturbance from human activities like tourism and agriculture.
• Light pollution, which disrupts nocturnal insect populations.
• Predation by domestic cats, dogs, and larger birds of prey.

IUCN Status: Least Concern (LC)

The Indian Nightjar is widespread and not currently endangered, though local populations in fragmented forests and mangrove areas like the Sundarban require protection.

Conclusion

The Indian Nightjar (Caprimulgus asiaticus) is a mysterious and elusive nocturnal bird, well adapted to hunting in darkness. Though it is not as commonly associated with dense mangrove ecosystems, it has established a niche within Sundarban’s open scrub and sandy riverbanks. Protecting its habitat and reducing human disturbances will be key to ensuring its continued presence in this fragile ecosystem.