Sooty Gull (Ichthyaetus hemprichii) – A Detailed Analysis

Taxonomy and Classification

• Scientific Name: Ichthyaetus hemprichii
• Common Name: Sooty Gull
• Family: Laridae (Gulls, Terns, and Skimmers)
• Order: Charadriiformes
• Genus: Ichthyaetus
• Conservation Status: Least Concern (IUCN Red List)

Morphological Features

Size and Shape

• The Sooty Gull is a medium-sized gull with a body length of 45–52 cm and a wingspan ranging from 115–125 cm.
• It has a slim and elongated body compared to other gull species, with relatively long legs.

Plumage and Coloration

• Head and Neck: Dark brown to blackish, especially during breeding season.
• Upperparts: Slate-grey back and wings.
• Underparts: White with a gradual transition from the darker upper body.
• Tail: White, often with a distinct black terminal band.
• Beak: Yellowish with a black tip, slightly hooked at the end.
• Legs and Feet: Yellowish to olive-green in color.
• Eyes: Dark with a striking white eye-ring.

Juvenile vs. Adult Plumage

• Juveniles are darker brown with mottled patterns on their wings and body, gradually acquiring adult plumage over 2–3 years.

Habitat and Distribution

• The Sooty Gull primarily inhabits tropical and subtropical coastal regions, often seen along coastlines, estuaries, islands, and mangrove ecosystems.
• It is native to the Red Sea, Persian Gulf, Indian Ocean, and the coasts of East Africa, India, and Southeast Asia.
• It prefers areas with shallow waters, sandbanks, and mangrove-covered shorelines, where food availability is high.

Diet and Feeding Behavior

• Carnivorous & Opportunistic Feeder: Feeds on fish, crustaceans, mollusks, marine invertebrates, and carrion.
• Foraging Technique: Often seen scavenging along beaches, fishing harbors, and intertidal zones, sometimes following fishing boats for scraps.
• Can also steal food from other seabirds (kleptoparasitism).

Breeding and Nesting

• Breeding Season: Generally between March and June, depending on the region.
• Nesting Sites: Prefers small islands, rocky cliffs, and coastal sandbanks, occasionally using mangrove-covered areas.
• Nest Type: Simple scrapes on the ground lined with plant material and shells.
• Clutch Size: Usually 2–3 eggs, pale brown with dark speckles for camouflage.
• Parental Care: Both parents take turns incubating the eggs and feeding the chicks.

Vocalization and Behavior

• Calls: A harsh, grating call often heard in breeding colonies or while foraging.
• Social Behavior: Usually found in small to medium-sized flocks, particularly near feeding and nesting sites.
• Flight Pattern: Steady and direct, with slow wingbeats; often seen soaring near the coast.

Presence of Sooty Gull in the Sundarban

Sundarban Ecosystem and Its Suitability

The Sundarban, the world’s largest mangrove forest, located in the delta region of India and Bangladesh, is home to diverse bird species due to its rich biodiversity, extensive intertidal zones, and abundant fish populations.

Sooty Gull in the Sundarban

• The Sooty Gull is not a common resident of the Sundarban but has been occasionally recorded along the coastal fringes and estuarine waters.
• Its presence is more frequent during winter months, when migratory seabirds visit the region.
• Likely seen near the southern part of the Sundarban, particularly in mudflats, open water zones, and sandy shores where food availability is high.

Factors Affecting Its Presence

1. Food Availability: The Sundarban’s rich fish population attracts various gull species, including the Sooty Gull.
2. Climate Conditions: Favorable humid and tropical coastal climate supports occasional visits by this species.
3. Human Activities: Fishing activities in the Sundarban delta can sometimes lead to scavenging opportunities for gulls.
4. Competition: Faces competition from other seabird species, such as Brown-headed Gulls and Lesser Black-backed Gulls, which are more common in the region.

Challenges and Conservation Concerns

Although the Sooty Gull is listed as Least Concern on the IUCN Red List, some factors might impact its population in the Sundarban:

• Mangrove Degradation: Habitat loss due to deforestation and climate change.
• Overfishing: Reduced fish stocks could limit its food supply.
• Pollution: Oil spills, plastic waste, and fishing net entanglements pose potential threats.

Conclusion

The Sooty Gull (Ichthyaetus hemprichii) is a coastal seabird adapted to tropical and subtropical marine environments. While it is not a primary resident of the Sundarban, its occasional presence in the delta’s estuarine waters highlights its adaptability and opportunistic feeding behavior. Monitoring its sightings in the region could provide valuable insights into migratory bird patterns and coastal ecosystem health.