Cuckoo
Cuckoos are birds in the Cuculidae family, the sole taxon in the order Cuculiformes. The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis. The coucals and anis are sometimes separated as distinct families, the Centropodidae and Crotophagidae, respectively. The cuckoo order Cuculiformes is one of three that make up the Otidimorphae, the other two being the turacos and the bustards. The family Cuculidae contains 150 species, which are divided into 33 genera.
The cuckoos are generally medium-sized, slender birds. Most species live in trees, though a sizeable minority are ground-dwelling. The family has a cosmopolitan distribution; the majority of species are tropical. Some species are migratory. The cuckoos feed on insects, insect larvae, and a variety of other animals, as well as fruit. Some species are brood parasites, laying their eggs in the nests of other species and giving rise to the terms "cuckoo's egg" and "cuckold" as metaphors. However, most species raise their own young.
Cuckoos have played a role in human culture for thousands of years, appearing in Greek mythology as sacred to the goddess Hera. In Europe, the cuckoo is associated with spring, and with cuckoldry, for example in Shakespeare's Love's Labour's Lost. In India, cuckoos are sacred to Kamadeva, the god of desire and longing, whereas in Japan, the cuckoo symbolises unrequited love.
Description
Cuckoos are medium-sized birds that range in size from the little bronze cuckoo, at and, to moderately large birds, ranging from in length, such as the giant coua of Madagascar, the coral-billed ground-cuckoo of Indochina, and various large Indo-Pacific coucals such as the goliath coucal of Halmahera, Timor coucal, buff-headed coucal, ivory-billed coucal, violaceous coucal, and larger forms of the pheasant coucal.The channel-billed cuckoo, at and is the largest parasitic cuckoo. Generally, little sexual dimorphism in size occurs, but where it exists, it can be either the male or the female that is larger. One of the most important distinguishing features of the family is the feet, which are zygodactyl, meaning that the two inner toes point forward and the two outer backward. The two basic body forms are arboreal species, such as the common cuckoo, which are slender and have short tarsi, and terrestrial species, such as the roadrunners, which are more heavy set and have long tarsi.
Almost all species have long tails that are used for steering in terrestrial species and as a rudder during flight in the arboreal species. The wing shape also varies with lifestyle, with the more migratory species such as the black-billed cuckoo possessing long, narrow wings capable of strong, direct flight, and the more terrestrial and sedentary cuckoos such as the coucals and malkohas having shorter rounded wings and a more laboured, gliding flight.
The subfamily Cuculinae comprises the brood-parasitic cuckoos of the Old World. They tend to conform to the classic shape, with usually long tails, short legs, long, narrow wings, and an arboreal lifestyle. The largest species, the channel-billed cuckoo, also has the most outsized bill in the family, resembling that of a hornbill. The subfamily Phaenicophaeinae comprises the nonparasitic cuckoos of the Old World, and include the couas, malkohas, and ground cuckoos. They are more terrestrial cuckoos, with strong and often long legs and short, rounded wings. The subfamily typically has brighter plumage and brightly coloured bare skin around the eye.
The coucals are another terrestrial Old World subfamily of long-tailed, long-legged, and short-winged cuckoos. They are large, heavyset birds with the largest, the greater black coucal, being around the same size as the channel-billed cuckoo. Genera of the subfamily Coccyzinae are arboreal and long-tailed, as well, with a number of large insular forms. The New World ground cuckoos are similar to the Asian ground-cuckoos in being long legged and terrestrial, and includes the long-billed roadrunner, which can reach speeds of when chasing prey. The final subfamily includes the atypical anis, which are the small, clumsy anis and the larger guira cuckoo. The anis have massive bills and smooth, glossy feathers.
File:Chrysococcyx maculatus - Khao Yai.jpg|thumb|Some species, such as the Asian emerald cuckoo exhibit iridescent plumage.
The feathers of the cuckoos are generally soft, and often become waterlogged in heavy rain. Cuckoos often sun themselves after rain, and the anis hold their wings open in the manner of a vulture or cormorant while drying. Considerable variation in the plumage is exhibited by the family. Some species, particularly the brood parasites, have cryptic plumage, whereas others have bright and elaborate plumage. This is particularly true of the Chrysococcyx or glossy cuckoos, which have iridescent plumage. Some cuckoos have a resemblance to hawks in the genus Accipiter with barring on the underside; this apparently alarms potential hosts, allowing the female to access a host nest.
The young of some brood parasites are coloured to resemble the young of the host. For example, the Asian koels breeding in India have black offspring to resemble their crow hosts. In the Australian koels, the chicks are brown like their honeyeater hosts. Sexual dimorphism in plumage is uncommon in the cuckoos, being most common in the parasitic Old World species. Cuckoos have 10 and 9–13. All species have 10, apart from the anis, which have eight.
Distribution and habitat
The cuckoos have a cosmopolitan distribution, ranging across all the world's continents except Antarctica. They are absent from the southwest of South America, the far north and northwest of North America, and the driest areas of the Middle East and North Africa, although they occur there as passage migrants. In the oceanic islands of the Atlantic and Indian Oceans they generally only occur as vagrants, but one species breeds on a number of Pacific islands and another is a winter migrant across much of the Pacific.The Cuculinae are the most widespread subfamily of cuckoos, and are distributed across Europe, Asia, Africa, Australia, and Oceania. Amongst the Phaenicophaeinae, the malkohas and Asian ground cuckoos are restricted to southern Asia, the couas are endemic to Madagascar, and the yellowbill is widespread across Africa. The coucals are distributed from Africa through tropical Asia south into Australia and the Solomon Islands. The remaining three subfamilies have a New World distribution, all are found in both North and South America. The Coccyzinae reach the furthest north of the three subfamilies, breeding in Canada, whereas the anis reach as far north as Florida and the typical ground cuckoos are in the Southwest United States.
For the cuckoos, suitable habitat provides a source of food, principally insects and especially caterpillars, and a place to breed. For brood parasites the need is for suitable habitat for the host species. Cuckoos occur in a wide variety of habitats. The majority of species occur in forests and woodland, principally in the evergreen rainforests of the tropics, where they are typically but not exclusively arboreal. Some species inhabit or are even restricted to mangrove forests. These include the little bronze cuckoo of Australia, some malkohas, coucals, and the aptly named mangrove cuckoo of the New World.
In addition to forests, some species of cuckoos occupy more open environments. This can include even arid areas such as deserts in the case of the greater roadrunner or the pallid cuckoo. Temperate migratory species, such as the common cuckoo, inhabit a wide range of habitats to make maximum use of the potential brood hosts, from reed beds to treeless moors, where they parasitise meadow pipits.
Migration
Most species of cuckoo are sedentary, but some undertake regular seasonal migrations, and others undertake partial migrations over part of their range.Species breeding at higher latitudes migrate to warmer climates during the winter due to food availability. The long-tailed koel, which breeds in New Zealand, flies to its wintering grounds in Polynesia, Micronesia, and Melanesia, a feat described as "perhaps the most remarkable overwater migration of any land bird." The yellow-billed cuckoo and black-billed cuckoo breed in North America and fly across the Caribbean Sea, a nonstop flight of. Other long migration flights include the lesser cuckoo, which flies from Africa to India, and the common cuckoo of Europe, which flies nonstop over the Mediterranean Sea and Sahara Desert on the voyage between Europe and central Africa.
Within Africa, 10 species make regular intracontinental migrations that are described as polarised. That is, they spend the nonbreeding season in the tropical centre of Africa and move north and south to breed in the more arid and open savannah and deserts. This is the same as the situation in the Neotropics, where no species have this migration pattern, or tropical Asia, where a single species does. About 83% of the Australian species are partial migrants within Australia or travel to New Guinea and Indonesia after the breeding season.
In some species, the migration is diurnal, as in the channel-billed cuckoo, or nocturnal, as in the yellow-billed cuckoo.