Curlew Sandpiper (Calidris ferruginea) – A Detailed Study

The Curlew Sandpiper (Calidris ferruginea) is a fascinating migratory shorebird that is commonly observed in coastal and wetland regions. As a species that undertakes long-distance migrations, it holds ecological significance in several important habitats, including the Sundarban region. Below is a comprehensive analysis of its taxonomy, morphology, habitat, distribution, behavior, conservation status, and its presence in the Sundarban ecosystem.

1. Taxonomy & Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Aves
• Order: Charadriiformes
• Family: Scolopacidae
• Genus: Calidris
• Species: Calidris ferruginea

The Curlew Sandpiper belongs to the Scolopacidae family, which includes various sandpipers, snipes, and other waders. It is closely related to other Calidris species, especially the Dunlin (Calidris alpina), but can be distinguished by its unique morphology and plumage.

2. Morphology & Physical Characteristics

The Curlew Sandpiper is a medium-sized wader, well-adapted for feeding in shallow coastal waters and mudflats.

Key Features:

• Size: Around 18–23 cm in length
• Wingspan: Approximately 38–41 cm
• Weight: Ranges between 44–117 grams
• Bill: Long, slender, and distinctly curved downward
• Legs: Long and black, suited for wading in mudflats
• Plumage:
  • Breeding Plumage: Rusty-red (ferruginous) coloration on the head, neck, and underparts
  • Non-Breeding Plumage: Pale greyish upperparts with white underparts
• Eyes: Dark and round

During the breeding season, the bird displays a rich reddish-brown coloration, making it quite distinct. However, in non-breeding seasons, it adopts a more subdued greyish-white coloration, similar to many other shorebirds.

3. Habitat & Distribution

Global Distribution

The Curlew Sandpiper is a long-distance migratory bird, primarily breeding in the Arctic tundra of Siberia and wintering in Africa, South Asia, Southeast Asia, and Australia.

Preferred Habitats

• Coastal mudflats
• Estuaries
• Salt pans
• Lagoons
• Wetlands and shallow freshwater marshes

It is highly dependent on intertidal mudflats for foraging during migration and wintering periods.

4. Feeding Behavior & Diet

The Curlew Sandpiper is primarily a probing feeder, using its long, curved bill to extract food from soft mud.

Diet Includes:

• Small crustaceans
• Mollusks
• Marine worms
• Insect larvae
• Small aquatic invertebrates

It forages in shallow waters, often moving in small groups, and exhibits probing and picking behavior to extract prey from mud and sand.

5. Migration Pattern

The Curlew Sandpiper is a highly migratory bird, covering vast distances between its breeding and wintering grounds.

• Breeding Season: Arctic tundra (Siberia) – May to July
• Migration Southward: Begins in August-September
• Wintering Grounds: Coastal Africa, India, Southeast Asia, and Australia – October to March
• Return Migration: April-May

This bird follows the East Atlantic and Central Asian flyways, making it a regular visitor to India’s coastal regions, including Sundarban.

6. Presence in the Sundarban Ecosystem

The Sundarban, the world’s largest mangrove forest, serves as a critical wintering ground for many migratory shorebirds, including the Curlew Sandpiper.

Why Sundarban is Important for the Curlew Sandpiper?

• Intertidal Mudflats: The bird relies on the nutrient-rich mudflats and estuaries for feeding.
• Abundant Food: The presence of small invertebrates and marine worms in the Sundarban supports its dietary needs.
• Resting & Roosting Areas: Sandbanks and shallow wetlands provide safe resting spots.
• Mangrove Protection: The dense mangrove cover offers some level of protection from extreme weather and predators.

Sightings in Sundarban

• Found in mudflats, estuarine zones, and coastal wetlands during the winter months (October to March).
• Frequently observed in Sundarban Tiger Reserve, Sajnekhali Wildlife Sanctuary, and adjacent coastal zones.
• Usually spotted in small flocks, occasionally mixed with other waders like Lesser Sand Plovers, Dunlins, and Redshanks.

Despite its presence, detailed scientific studies on its exact population in the Sundarban remain limited.

7. Conservation Status & Threats

IUCN Status: Near Threatened (NT)

Threats Facing the Curlew Sandpiper:

1. Habitat Destruction – Coastal reclamation and wetland degradation due to urbanization.
2. Climate Change – Rising sea levels and changes in coastal ecosystems affecting its feeding grounds.
3. Pollution – Oil spills, plastic pollution, and heavy metal contamination in estuaries and wetlands.
4. Disturbance from Human Activity – Increased tourism, fishing, and boating activities in wetlands.

Conservation Efforts in Sundarban

• Protected Areas: Sundarban Biosphere Reserve ensures some level of protection for migratory shorebirds.
• Eco-tourism Regulations: Restrictions on human activity in core areas help reduce disturbances.
• Mangrove Conservation Programs: Maintain critical intertidal habitats used by birds like the Curlew Sandpiper.
• Wetland Protection Initiatives: Promote conservation of estuaries and mudflats crucial for migratory birds.

8. Conclusion

The Curlew Sandpiper (Calidris ferruginea) is a remarkable migratory shorebird that relies on the Sundarban’s mudflats and coastal wetlands as a wintering ground. As a Near Threatened species, its survival depends on habitat conservation efforts and sustainable management of coastal ecosystems. Given its presence in the Sundarban, further research and monitoring are essential to ensure the long-term conservation of this species and its delicate habitat.

The conservation of migratory shorebirds like the Curlew Sandpiper is a crucial step in maintaining the ecological balance of wetland ecosystems, including the Sundarban – a UNESCO World Heritage Site.