Great Thick-knee

The adult Great Thick-knee is easily recognizable by its large size, reaching up to 55 centimeters in length. It has a predominantly gray-brown plumage that provides excellent camouflage against its natural habitat of sandy or rocky riverbanks. The bird's most distinguishing features are its thick, upturned bill and large, yellow eyes, which give it a somewhat stern appearance. Its wings are long and pointed, aiding in its strong, rapid flight. Juveniles resemble adults but have slightly duller plumage and less pronounced eye color. There is little sexual dimorphism in this species, making males and females quite similar in appearance. However, during courtship, subtle differences such as the intensity of eye color might be more noticeable. The Great Thick-knee can sometimes be confused with other thick-knee species, but its size and the distinctive shape of its bill make it relatively easy to identify. In flight, its broad wings and steady wingbeats create a characteristic silhouette, often seen when the bird is disturbed or moving between feeding areas. When perched, it stands upright with a slight forward lean, often adopting a motionless stance that allows it to blend seamlessly into its surroundings.

The Great Thick-knee's diet consists mainly of insects, small crustaceans, and other invertebrates, which it gleans from the ground. It also occasionally preys on small vertebrates such as frogs and lizards. Its feeding technique involves a methodical walk along riverbanks or shallow waters, using its keen eyesight to spot prey. The bird often uses its thick bill to probe into the sand or mud, extracting hidden morsels. Seasonal changes can influence its diet, with a greater emphasis on aquatic prey during the rainy season when water levels rise. The Great Thick-knee typically feeds during the cooler parts of the day, such as early morning and late afternoon, avoiding the midday heat.

The Great Thick-knee exhibits solitary or paired behavior, especially during the breeding season when individuals establish territories. Males engage in courtship displays that include vocalizations and posturing to attract mates. Outside the breeding season, these birds may form small, loose flocks, especially around abundant food sources. Their response to predators is often to rely on their camouflage, remaining motionless to avoid detection. When threatened, they can take to the air with a swift, direct flight. Daily activities include foraging during cooler parts of the day and resting in shaded areas during the heat. The Great Thick-knee's nocturnal tendencies make it most active during twilight hours.

Great Thick-knees nest on the ground, typically choosing open, flat areas with sparse vegetation for their nesting sites. The nest itself is a simple scrape in the sand or gravel, sometimes lined with small stones or debris. The clutch size usually consists of two eggs, which are cryptically colored to blend with their surroundings. Both parents participate in incubation, which lasts about 28 days. After hatching, the young are precocial and are able to leave the nest within a few days, although they remain dependent on their parents for food and protection. Fledging occurs around four weeks after hatching. The species typically raises one brood per year, though favorable conditions might allow for a second attempt.

The Great Thick-knee's primary call is a loud, wailing whistle that carries over long distances, often heard during the twilight hours. This call, a series of rising and falling notes, serves to establish territory and communicate with mates. Its call notes can be described as haunting and melancholic, reminiscent of distant cries across a river. Alarm calls are sharper and more abrupt, used to alert others of potential danger. During the dawn chorus, the Great Thick-knee's voice stands out against the backdrop of other bird calls, providing an auditory marker of its presence in its habitat.

• 1The Great Thick-knee's eye size is one of the largest among wading birds, aiding its nocturnal foraging.
• 2Despite their size, Great Thick-knees are remarkably adept at camouflage, often mistaken for rocks.
• 3These birds can live up to 15 years in the wild, showcasing their adaptability and survival skills.
• 4Their unique bill shape allows them to efficiently catch and handle a variety of prey, including hard-shelled crustaceans.
• 5Great Thick-knees have a wingspan of up to 90 cm, making them powerful fliers capable of swift escape from predators.
• 6They are known to practice 'anting,' using ants to help cleanse their feathers of parasites.
• 7The species' name 'thick-knee' derives from the prominent joints in their legs, which aid in their powerful locomotion.

The IUCN currently lists the Great Thick-knee as Near Threatened, with populations declining due to habitat loss and degradation. Primary threats include riverbank development, pollution, and disturbances from human activities. Conservation efforts focus on habitat protection and restoration, particularly in key breeding areas. Historical data indicate a more widespread distribution, with modern pressures contributing to its contraction. Continued monitoring and conservation initiatives are crucial to reverse the decline and safeguard the future of the Great Thick-knee.