Whiskered Tern (Chlidonias hybrida) – A Detailed Study

Taxonomy

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Charadriiformes
• Family: Laridae
• Genus: Chlidonias
• Species: Chlidonias hybrida

The Whiskered Tern (Chlidonias hybrida) belongs to the tern family and is known for its elegant flight and distinctive plumage. It is a widespread species found across Europe, Africa, and Asia, including India and the Sundarban region.

Morphology & Physical Description

• Size: Medium-sized tern, approximately 25–30 cm in length.
• Wingspan: Around 65–70 cm.
• Weight: Averages between 70–100 g.
• Plumage:
  • Breeding Season: The head, nape, and underparts are deep black, contrasting with silvery-gray upper wings and back. The white cheeks give it a ‘whiskered’ look, hence the name.
  • Non-Breeding Season: The black plumage fades, replaced by a white underbody and a grayish crown.
• Beak: Dark red to blackish, slightly curved.
• Legs: Reddish with webbed feet.
• Eyes: Dark and sharp, adapted for spotting prey over water.

Habitat & Distribution

The Whiskered Tern inhabits wetlands, freshwater lakes, marshes, rivers, estuaries, and coastal areas. It is a migratory species, moving between breeding and wintering grounds based on seasonal changes.

• Breeding Range: Europe, Central Asia, and South Asia.
• Wintering Range: Africa, the Indian subcontinent, and Southeast Asia.

In India, it is found across wetlands, riverine habitats, and mangrove forests, including the Sundarban region.

Feeding Behavior & Diet

The Whiskered Tern is an opportunistic feeder, relying on:

• Small Fish (primary diet)
• Aquatic Insects & Larvae
• Crustaceans & Mollusks
• Amphibians & Tadpoles

It hunts by hovering over water bodies and plunging to catch its prey. Unlike other terns, it frequently picks food from the surface rather than deep-diving.

Breeding & Nesting

• Breeding Season: April to July (varies with region).
• Nesting Sites: Typically in floating vegetation, reed beds, and shallow wetland areas.
• Nest Type: Simple, cup-shaped structures made from aquatic plants.
• Eggs: Clutch size of 2-4 eggs, incubated for about 18-22 days.
• Parental Care: Both parents participate in incubation and feeding hatchlings.

Special Features & Adaptations

• Migratory Behavior: Travels long distances between breeding and wintering grounds.
• Flight Pattern: Agile and graceful; can hover before diving to catch prey.
• Adaptation to Wetlands: Strong webbed feet allow it to balance on floating vegetation.
• Seasonal Plumage Change: Provides camouflage and helps in mate attraction.

Presence in the Sundarban

The Whiskered Tern is commonly observed in the Sundarban, particularly in areas with brackish water, tidal creeks, and estuarine wetlands. Its presence is significant due to the rich fish population and diverse aquatic ecosystem.

• Feeding Grounds: The terns are often seen in shallow waters of the Sundarban delta, where they prey on small fish and insects.
• Seasonal Migration: Present throughout the year but peaks in winter months (October–March), when migratory flocks arrive.
• Breeding in Sundarban: Limited evidence of nesting within the Sundarban core, but some pairs are observed during the breeding season in surrounding freshwater wetlands.

Conservation Status & Threats

• IUCN Status: Least Concern (LC) – The population is stable.
• Threats in Sundarban:
  • Habitat Degradation due to rising sea levels and erosion.
  • Pollution & Plastic Waste affecting fish availability.
  • Climate Change Impact causing changes in wetland dynamics.

Conclusion

The Whiskered Tern (Chlidonias hybrida) is a vital part of the Sundarban’s avian biodiversity, contributing to the ecological balance by controlling insect populations and serving as an indicator of wetland health. Its migratory patterns and adaptability make it an important species in India’s wetlands, emphasizing the need for wetland conservation efforts.