White-throated Kingfisher in Sundarbans: Diet & Adaptability

The White-throated Kingfisher

 Kingdom: Animalia, Phylum: Chordata, Class: Aves (Birds), Order: Coraciiformes (This order includes kingfishers, bee-eaters, rollers, and todies). Family: Alcedinidae (Kingfishers), Genus: Halcyon, Species: Halcyon smyrnensis

-Abu Taher Prince, Guide & Owner, Travelers Link BD & The Sundarban Tour

The White-throated Kingfisher (scientific name: Halcyon smyrnensis), also known as the White-breasted Kingfisher, is a common and striking bird found in the Sundarbans and across a wide range of Asia. Here’s a detailed look:

 Local Name

In Bengali, which is widely spoken in the Sundarbans region of Bangladesh, the White-throated Kingfisher is commonly known as “Sada-buk Machhranga” (সাদা-বুক মাছরাঙা), which directly translates to “white-breasted kingfisher.” It’s also sometimes simply called “Machranga” due to its widespread familiarity.

Presence and Distribution in the Sundarbans:

The White-throated Kingfisher is a common resident in the Sundarbans mangroves and surrounding areas. It’s adaptable and can be found in various habitats, including open country with trees, wires, agricultural areas, swamps, marshes, and near ponds and lakes. While many kingfishers are strictly aquatic, the White-throated Kingfisher is less reliant on specific water bodies and can be found well away from water, even in dry deciduous forests. An average density of 4.58 individuals per square kilometer has been noted in the Sundarbans mangroves, indicating their significant presence.

Physical Characteristics:

The White-throated Kingfisher is a relatively large kingfisher, typically measuring 27-28 cm (10.6-11.0 in) in length.

• Plumage: Adults have a bright blue back, wings, and tail. Their head, shoulders, flanks, and lower belly are a rich chestnut color, strikingly contrasted by a white throat and breast.
• Bill and legs: Its most prominent features include a large, thick, and bright red bill and similarly bright red legs.
• Flight: Its flight is rapid and direct, with short, rounded wings that whir. In flight, large white patches are visible on the blue and black wings, which are key identification features.
• Sexual Dimorphism: Sexes are similar in appearance, making it difficult to distinguish males from females in the field.
• Juveniles: Juvenile birds are generally duller in color than adults, with duskier bills and less intense brown plumage.

Calls and Vocalizations:

The White-throated Kingfisher is a very vocal bird, especially during the breeding season. Its calls are often described as:

• A loud, defiant rattling laugh or a chuckling “chake-ake-ake-ake-ake.”
• A sharp repetition of high-pitched “KRICH-KRICH” tones (2-4 kHz) at a rate of 2-4 notes per second.
• A very loud descending trill (2-3 kHz), composed of separate notes (10-11 per second), which trail off in pitch and volume.

During courtship, males use their distinctive calls and display their white wing patches. Females, in invitation, make a rapid and prolonged “kit-kit-kit…” call.

Diet and Foraging:

Despite its name, the White-throated Kingfisher’s diet is incredibly varied and extends far beyond just fish, especially in areas like the Sundarbans, where a diverse range of prey is available. It is a carnivorous generalist and a sit-and-wait predator. It perches conspicuously on wires, branches, or other exposed vantage points within its territory, scanning for prey.

Its diet primarily includes:

• Large crustaceans (like crabs, including fiddler crabs)
• Insects (locusts, crickets, beetles, mantises, ants, termites, dragonflies, grasshoppers)
• Earthworms
• Small reptiles (lizards like Mabuya and Calotes, snakes)
• Amphibians (frogs)
• Small rodents (mice)
• Occasionally, small birds (such as Oriental White-eyes, sparrow fledglings, or munias).

While water dives are common, ground dives are often more successful. They will also engage in aerial feeding and ground feeding. When a larger prey is caught, they may bash it against their perch to immobilize it before swallowing.

Breeding and Life Cycle:

White-throated Kingfishers are monogamous and exhibit biparental care.

• Breeding Season: Breeding generally begins at the onset of the Monsoons (January to August, with local variations). In some areas, courtship can start as early as March.
• Courtship Display: Males perch on prominent high posts and call loudly. They may flick their tail and stiffly flick open their wings for a second or two, exposing the white wing mirrors. They also raise their bill high to display their white throat and front.
• Nest Building: The nest is typically a tunnel in an earth bank, though nests in haystacks or even old buildings have been recorded. Both birds participate in digging the nest, often by flying into a suitable mud wall until an indentation is made, then continuing to dig with their bills. The tunnel can be around 50 cm to 3 feet long.
• Eggs: A single clutch usually consists of 4-7 round, white eggs.
• Incubation: Both parents incubate the eggs, which hatch in 20-22 days.
• Chicks: The altricial chicks fledge (become ready to fly) in about 19 days. Both parents feed and care for the young, especially when they are small and unable to fly.

Behavior and Sociality:

• Territorial: White-throated Kingfishers are highly territorial birds, fiercely defending their feeding and breeding territories from intruders. They are often seen perched alone on high vantage points, maintaining a watchful eye on their surroundings.
• Solitary or Pairs: They typically live solitarily or in pairs during the breeding season. They are not known to live in groups or engage in group activities outside of mating and raising young.
• Hunting Strategy: They employ a “sit-and-wait” hunting strategy, often remaining still on a perch for extended periods (sometimes 20-25 minutes) before making a quick dive to capture prey.
• Movement: While generally resident, some populations may make short-distance movements, especially during the monsoon season when they might be attracted to lights at night, suggesting partial migratory behavior.

 Ecological Role and Conservation Status:

• Ecological Role: As a generalist predator, the White-throated Kingfisher plays a vital role in its ecosystem by helping to keep populations of various small creatures (insects, crustaceans, small reptiles, and rodents) in check. They are considered agriculturally beneficial due to their consumption of insect pests.
• Conservation Status: The White-throated Kingfisher is classified as “Least Concern” (LC) by the IUCN Red List. This indicates that its populations are currently stable and widespread, with no immediate threats. Its range is even considered to be expanding in some areas.
• Threats: While the species as a whole is not threatened, local populations might face pressure from habitat degradation or loss, especially in specific regions. Historically, they were hunted for their bright feathers for adornment.

 Other Information in Sundarbans:

• Habitat Adaptability: Its ability to thrive in both aquatic and relatively dry environments makes it a common sight even within the diverse and complex mangrove ecosystem of the Sundarbans.
• Predators: Healthy adult White-throated Kingfishers have few natural predators due to their powerful bill and rapid flight. Rare cases of predation by birds like Black Kites or Jungle Crows are often associated with sick or injured individuals.
• State Bird: The White-throated Kingfisher is the state bird of West Bengal, India, which shares a border and ecological zone with the Bangladeshi Sundarbans. This highlights its cultural significance and widespread recognition in the region