*Centropus sinensis*, commonly known as the Asian koel, is a large, distinctive bird found across South and Southeast Asia. Measuring about 38 to 42 cm (15 to 17 inches) in length, the Asian koel exhibits sexual dimorphism in its plumage. Males are easily recognized by their glossy black feathers, with a striking greenish sheen on their wings and tail. They possess a prominent red eye and a distinctive, long, curved tail. Females, in contrast, have a more subdued appearance, featuring a brownish or rufous coloration with white spots and streaks, which helps them blend into their surroundings.

Asian koels inhabit a variety of environments, including forests, gardens, and urban areas, where they are often heard more than seen. Their diet consists primarily of fruits, especially ripe figs, as well as insects and small invertebrates. The koel is well-known for its loud, distinctive call, often described as a repetitive "koo-koo" sound, which is especially prominent during the breeding season.

These birds are brood parasites, laying their eggs in the nests of other bird species, primarily crow nests. The female koel seeks out suitable hosts, and the chicks typically outcompete the host\'s young for food. The Asian koel’s unique behaviors and melodious calls make it a fascinating presence in its natural habitat.