Cuckoos are medium-sized, slender birds that are part of the Cuculidae family and are known for their distinct calls. This diverse family includes various species such as the common cuckoo, roadrunners, koels, and anis, with some members possibly constituting their own separate families. These birds have a global presence, though they are predominantly found in tropical regions and exhibit a mixture of sedentary and migratory behaviors. Cuckoos have varied diets that can include insects, larvae, fruit, and other small animals.
A prominent feature among cuckoos is brood parasitism, practiced by some species, where they lay their eggs in the nests of other birds, leaving the host species to raise their offspring. The practice has influenced their cultural significance throughout human history, appearing in myths and symbolizing diverse concepts from springtime to unrequited love across different cultures. Physically, cuckoos range from very small to relatively large, with some species demonstrating zygodactyl feet (two toes pointing forward and two backward) and long tails that aid in flight. They exhibit varying levels of sexual dimorphism and have adapted different wing shapes and styles to suit their arboreal or terrestrial lifestyles.
Cuckoos are mostly solitary and their breeding strategies vary from communal nesting to solitary brood parasitism. Their secretive nature is often contrasted by the conspicuous nature of their calls, which is essential for communication within the species. Despite the general disadvantage of parasitism to host species, there are complex ecological interactions that sometimes lead to mutual benefits. The evolutionary history and fossil record of cuckoos are not well understood, but they have been grouped with turacos and bustards into a higher clade named Otidimorphae. With over 150 species divided into roughly 33 genera, cuckoos continue to captivate ornithologists and bird enthusiasts worldwide.