Great Thick-knee

The Great Thick-knee (Esacus recurvirostris) is a fascinating and elusive species belonging to the family Burhinidae. Often referred to as the Great Stone-curlew, this large wader is primarily found in the riverine systems of South and Southeast Asia. Known for its nocturnal habits and cryptic coloration, it is a prized sighting for many birdwatchers.

The Great Thick-knee is a robust bird, measuring between 50-57 cm in length. Its plumage is predominantly grey, providing excellent camouflage against river shingle and stony banks. It features striking white markings on its wings, which are most visible during flight. The bird is easily identified by its heavy, up-curved yellow bill and prominent yellow eyes, which are adapted for low-light activity.

This species is highly specialized for life near water. Its preferred habitat includes:

• Broad, rocky riverbeds with shingle banks.
• Sandy islands in large rivers.
• Estuaries and coastal areas with rocky coastlines.
• Shallow, exposed water edges where it can easily forage.

As a carnivorous wader, the Great Thick-knee feeds on a variety of small organisms found along the water's edge. Its diet typically consists of:

• Crustaceans and small crabs.
• Aquatic insects and larvae.
• Small fish caught in shallow pools.
• Mollusks and worms hidden in the riverbed substrate.

The Great Thick-knee is a ground-nesting bird. It does not build a complex nest but instead creates a simple scrape in the sand or among pebbles on riverbanks. The female typically lays one or two eggs, which are mottled to blend perfectly with the surrounding stones, offering protection from predators.

Primarily crepuscular and nocturnal, the Great Thick-knee is most active during dawn, dusk, and throughout the night. During the day, it remains relatively sedentary, relying on its grey plumage to stay hidden from potential threats. When disturbed, it often freezes or runs quickly across the shingle before taking flight with broad, heavy wingbeats.

The Great Thick-knee is currently classified as Near Threatened by the IUCN. Its population is declining due to habitat loss, specifically the disturbance of riverbeds by human activity, sand mining, and the construction of dams which alter natural water flow and nesting grounds.

1. The name 'Thick-knee' refers to the enlarged tibio-tarsal joints characteristic of this family of birds.
2. They are known for their loud, ringing calls, often heard at night near riverbanks.
3. The up-curved bill is a specialized tool for prying mollusks and crabs from between rocks.
4. They exhibit high site fidelity, often returning to the same stretch of river for breeding year after year.

To spot a Great Thick-knee, head to wide, open river systems during the early morning or late afternoon. Use high-quality binoculars or a spotting scope to scan the shingle banks, as their coloration makes them nearly invisible until they move. Avoid approaching nesting sites, as these birds are sensitive to human presence.

The Great Thick-knee is a remarkable example of adaptation to specialized riverine environments. As a species facing habitat pressure, its presence is a strong indicator of a healthy, undisturbed river ecosystem. Observing this silent guardian of the riverbanks is a rewarding experience for any dedicated ornithologist or nature enthusiast.