Little Tern (Sternula albifrons) – A Comprehensive Study

Taxonomy & Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Charadriiformes
• Family: Laridae
• Genus: Sternula
• Species: Sternula albifrons

The Little Tern (Sternula albifrons) is a small seabird belonging to the Laridae family. It is known for its graceful flight, rapid wingbeats, and distinctive black-capped head. The species is widely distributed across coastal regions, estuaries, and inland water bodies.

Morphology & Physical Description

• Size: 21–25 cm in length
• Wingspan: 41–47 cm
• Weight: 40–60 grams
• Plumage:
  • Upperparts: Pale grey
  • Underparts: White
• Head Features:
  • Black cap extending from the beak to the nape
  • White forehead (a distinguishing feature)
• Beak: Slender, yellow with a black tip
• Legs & Feet: Short and yellow-orange in color
• Tail: Deeply forked, aiding in quick and agile flight

Habitat & Distribution

The Little Tern inhabits coastal and inland wetlands, showing a preference for:

• Sandy beaches, riverbanks, and estuaries
• Mangrove-lined shores and tidal mudflats
• Lagoons, salt pans, and shallow coastal waters

Presence in the Sundarban

The Sundarban, the largest tidal mangrove ecosystem in the world, serves as an important seasonal habitat for the Little Tern. The species is observed in:

• Estuarine river channels and mangrove-fringed shorelines
• Intertidal sandbanks and mudflats
• Shallow waters of creeks and deltaic regions

In the Sundarban Biosphere Reserve, the Little Tern is seen primarily during the winter months, when it migrates southwards in search of food and favorable climatic conditions.

Feeding Behavior & Diet

The Little Tern is an opportunistic feeder, relying primarily on:

• Small fish (such as anchovies and gobies)
• Crustaceans and marine invertebrates
• Aquatic insects and larvae

Foraging Strategy

• Hovering and plunge-diving to catch prey near the water’s surface
• Prefers shallow coastal and estuarine waters for hunting
• Uses quick, agile flight patterns to locate prey efficiently

Breeding & Nesting

• Breeding Season: Varies by region, but generally from April to July
• Nest Sites:
  • Prefers open sandy beaches, gravel bars, and islets
  • Avoids densely vegetated areas
• Nesting Type: Scrape nests (shallow depressions in the sand or soil)
• Eggs: Typically 2-3 eggs per clutch, speckled to blend with surroundings
• Parental Care:
  • Both parents share incubation duties (~20-22 days)
  • Chicks are semi-precocial, meaning they can move soon after hatching but remain dependent on parents

Vocalization & Communication

The Little Tern is a highly vocal bird, producing:

• Sharp “kik-kik” calls, often heard during flight
• Loud alarm calls when disturbed, especially near nesting areas
• Soft chattering sounds used for communication between mates and chicks

Special Adaptations

1. Lightweight and Agile Flight: Helps in rapid directional changes while hunting.
2. Cryptic Nesting Strategy: Camouflaged eggs reduce predation risk.
3. Adaptation to Coastal and Freshwater Habitats: Can thrive in brackish estuaries and freshwater lakes.
4. Sharp Eyesight: Enables precise targeting of fish in fast-moving tidal waters.

Threats & Conservation Status

Threats to the Species

• Coastal Habitat Loss: Due to urbanization, tourism, and land reclamation
• Human Disturbance: Unregulated beach activities, sand mining, and fishing
• Predation: Eggs and chicks are vulnerable to foxes, crows, and larger seabirds
• Climate Change Impacts: Rising sea levels and increased storm surges threaten nesting sites

IUCN Status: Least Concern (LC)

Despite localized threats, the Little Tern maintains a stable population due to its wide distribution and ability to adapt to different coastal environments. However, conservation efforts in the Sundarban are necessary to protect its feeding and wintering grounds.

Importance in the Sundarban Ecosystem

The Little Tern plays a vital role in maintaining the balance of coastal and estuarine food webs. As a fish-eating bird, it helps regulate small fish populations, contributing to the health of the Sundarban’s aquatic ecosystem.

Conclusion

The Little Tern (Sternula albifrons) is a graceful and highly adaptable seabird, found across coastal, estuarine, and freshwater habitats. In the Sundarban, it serves as an important seasonal visitor, relying on the region’s rich aquatic biodiversity. Conserving mangrove forests, estuarine waters, and sandbank habitats is essential to ensuring the survival of this delicate yet resilient species.