Jerdon’s Nightjar (Caprimulgus atripennis) – A Comprehensive Study

Taxonomy & Classification

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

The Jerdon’s Nightjar (Caprimulgus atripennis) is a nocturnal bird belonging to the family Caprimulgidae, which includes nightjars and nighthawks. This species is known for its cryptic plumage, silent flight, and remarkable camouflage, making it difficult to spot during the day. It was named after the British naturalist Thomas C. Jerdon, who contributed significantly to the study of Indian avifauna.

Morphology & Physical Description

• Size: Approximately 25–27 cm in length
• Wingspan: Around 55 cm
• Weight: About 60–80 grams
• Plumage: Mottled brown, grey, and buff tones, providing perfect camouflage against dry leaves and forest floors
• Head Features:
  • Large eyes adapted for excellent night vision
  • Small yet strong beak with bristle-like feathers around the mouth, aiding in insect capture
• Tail: Moderately long, with white or buff patches visible in flight
• Legs & Feet: Short and weak, as the species is primarily aerial and ground-dwelling rather than perching

Habitat & Distribution

The Jerdon’s Nightjar is primarily found in:

• Deciduous forests, dry scrublands, and grasslands
• Mangrove forests and coastal areas, including parts of the Sundarban
• Undisturbed forest floors, where its plumage provides effective camouflage

It is distributed across:

• India (especially in peninsular regions)
• Sri Lanka and parts of Southeast Asia

Presence in the Sundarban

The Sundarban, with its vast expanse of mangrove forests, sandy banks, and dense undergrowth, provides an excellent habitat for the Jerdon’s Nightjar. Though not very commonly observed due to its nocturnal and cryptic nature, this species has been recorded in:

• Dry patches within mangrove forests
• Open forest edges and sandy clearings
• Riverbanks and secluded islands of the Sundarban Biosphere Reserve

While it is not an endemic species to the Sundarban, its occasional presence here suggests that the ecosystem offers suitable conditions for roosting and foraging.

Behavior & Adaptations

Nocturnal Lifestyle

• Highly active at night, spending the day resting on forest floors or tree branches
• Uses low, silent flight patterns to avoid detection

Feeding Behavior & Diet

The Jerdon’s Nightjar is an insectivorous species, preying primarily on:

• Moths, beetles, grasshoppers, and flying insects
• Occasionally consumes small spiders and other arthropods

Foraging Strategy:

• Catches prey mid-air in flight using its wide mouth and specialized bristle feathers
• Sits on open ground or low branches and waits for insects to pass by
• Frequently seen foraging near artificial lights, as insects are attracted to them

Breeding & Nesting

• Breeding Season: February to July (varies slightly by region)
• Nest Sites: No actual nest – eggs are laid directly on the ground among dry leaves or pebbles, ensuring camouflage
• Eggs: Typically one to two eggs, pale with brown markings for concealment
• Incubation: Both parents share responsibilities for incubation (around 19-21 days) and chick-rearing
• Chick Defense: If disturbed, the adult bird may pretend to be injured (broken-wing display) to distract predators away from the nest

Vocalization & Communication

• Repeated “chuk-chuk-chuk” or “purring” calls during dusk and night
• Calls are mainly used for territorial defense and mate attraction
• Often heard rather than seen, making it one of the more mysterious birds in its habitat

Special Adaptations

1. Exceptional Camouflage: Plumage blends seamlessly with dry leaves, making it almost invisible during the day.
2. Large Eyes with Tapetum Lucidum: Enhances night vision, allowing efficient nocturnal hunting.
3. Silent Flight: Specialized wing structure minimizes sound, aiding in stealthy insect capture.
4. Bristle-Lined Beak: Helps funnel insects into the mouth during flight.
5. Minimal Energy Expenditure: Uses a sit-and-wait hunting strategy, reducing unnecessary movement and energy loss.

Threats & Conservation Status

Major Threats:

• Habitat destruction due to deforestation, agricultural expansion, and urbanization
• Disturbance from human activities, including tourism and illegal poaching in protected areas
• Light pollution, affecting their natural hunting patterns
• Predation by larger birds, snakes, and mammals

IUCN Status: Least Concern (LC)

The Jerdon’s Nightjar is classified as Least Concern by the IUCN, meaning its population is stable. However, conservation efforts in regions like the Sundarban are essential to ensure the species’ continued survival in such delicate ecosystems.

Conclusion

The Jerdon’s Nightjar (Caprimulgus atripennis) is a remarkable nocturnal bird, perfectly adapted for nighttime hunting and ground-based camouflage. Though rarely seen due to its secretive behavior, it plays an essential role in controlling insect populations in regions like the Sundarban. Its presence in this unique mangrove ecosystem highlights the richness of the Sundarban’s avian biodiversity, making its conservation an important priority.