CUCULIFORM

Cuckoo (Cuculus) (order Cuculiformes), any member of the cosmopolitan group containing two very distinct families, the cuckoos (Cuculidae; see photograph) and the turacos, or plantain-eaters (Musophagidae). Discussion of their relationship has led authorities increasingly to give the turacos ordinal rank. The Cuculidae family is much the larger group, containing about 127 species, found in the tropical and temperate zones of all the continents except Antarctica and on many oceanic islands; the Musophagidae contains 20 species, found only in Africa. The cuckoos are an ancient group with uncertain phylogenetic affiliations and no living near relatives, even the turacos being quite distinct and with no intermediate, or connecting, species. The cuckoos are of unusual biological, especially ethological, interest because many species are brood parasites; i.e., they lay their eggs in the nests of other species, which then rear the young cuckoos. Other cuckoos make their own nests, in which they incubate their eggs and rear their young as do most birds; and still others (Crotophaga and Guira) build communal nests. Some cuckoos are among the few birds that feed extensively on hairy caterpillars. any member of an order of birds (Cuculiformes) containing two distinct families, the cuckoos (Cuculidae) and the turacos (Musophagidae). The approximately 127 species of cuckoos occur throughout the world, except for Antarctica and some oceanic islands; the 20 musophagid species are found only in tropical Africa. The cuckoos include the typical arboreal cuckoos of the Eastern and Western hemispheres, the terrestrial roadrunners (Geococcyx) of the southwestern United States and Mexico, and the terrestrial coucals (Centropus) of Africa and Australasia. The smallest cuculids are the glossy, or emerald, cuckoos (Chrysococcyx), which measure only 15 cm (6 inches) in length; the ground cuckoos (Carpococcyx) and some coucals (Centropus) may reach lengths of 0.9 m (3 feet). These slender-bodied birds have fairly long wings and medium to very long tails. The bill is characteristically slender and downcurved, although in ground cuckoos and coucals it is quite stout. In the anis (Crotophaga) the bill is heavy and laterally compressed. Except for the roadrunners, cuckoos have relatively short legs. All cuculiform birds have the distinctive trait of zygodactylous feet (the outer toe is directed backward). Many species are coloured in grays and browns, but some species appear in bright, iridescent greens, purples, and yellows. The musophagids are all fairly large birds. Turacos have relatively short, rounded wings, and their very long tails widen toward the tip. Musophagids typically have long legs and strong, short, downcurved bills, frequently brightly hued. The plumage of the forest forms is generally brightly coloured in iridescent greens and purples. Scrubland musophagids such as the go-away birds (Crinifer) are generally gray. Two unique pigments are found in the wing feathers of Musophaga and Tuaracoturacin, a crimson pigment containing copper, and turacoverdin, a green pigment. Almost all turacos have large feathered crests on the head. Most of the cuculiforms are forest birds, but some members of the group inhabit other environments. The cuckoos of the genus Cuculus inhabit open woodlands, while South American guiras (Guira guira) and some members of the Old World genera Clamator and Chrysococcyx occur in savannas where some trees are present. Only the roadrunners can be found where there is no treelike vegetation. The temperate-zone cuckoos are migratory, and some species travel up to 3,200 km (2,000 miles) in each direction. Cuckoos are almost totally insectivorous; a few species are among the few birds that will readily eat the hairy caterpillars. The larger cuckoos also take lizards, snakes, and even small birds. The only cuckoos known to eat any fruit are the couas (Coua) of Madagascar. Turacos, in contrast, subsist almost entirely on fruits and berries, although they may take some insect life as well. Except for the communal nesters Crotophaga (anis) and Guira, the cuckoos are shy, solitary birds, while most turacos go about in noisy flocks and create an incredible cacophony when they observe a predator. The typical turaco call is a series of laughing or barking notes. The cuckoos are also highly vocal. Their repertoire includes various contact calls, alarm notes, and territorial songs. These calls run the gamut of sound, from melodious to extremely discordant. The familiar call of the common cuckoo (Cuculus canorus) is produced only by the male. The reproductive behaviour of the cuckoos is interesting, as about 50 species are parasitic breeders; they lay their eggs in the nests of other species and let the foster parents do the work of raising the young cuckoos. Brood parasitism is found in all members of the subfamily Cuculinae and in three species of the Neomorphinae. The rest of the cuckoos and all the turacos nest and care for the young in a regular manner. The turacos build twig nests high up in trees. Incubation lasts 1618 days and the young hatch thickly covered with down. They are fed regurgitated fruit pulp and fledge at about six weeks. A female cuckoo of a parasitic species must find suitable host nests within her territory. She will usually lay one egg in each of many different nests, waiting until after the host female has started laying but before incubation has begun. As birds will often then build new nests or remove strange objects found in their nest, egg mimicry has evolved in some cuckoos. For example, cuckoos that prey on a particular host species have a selective advantage if they lay eggs that resemble those of the host. The characteristic shell pattern is a female trait, unaffected by the male. Shortly after hatching, while still blind and naked, young cuckoos of parasitic species will evict other objectssuch as eggs and smaller hatchlingsfrom the host nest. The young bird does this by pushing its way under the object and shoving it up and over the edge of the nest. This clears away any competition that might arise for the food brought by the foster parents. Surprisingly this adaptive behaviour does not appear in all parasitic cuckoos; it is lacking, for instance, in the crested cuckoos (Clamator). Additional reading Edgar P. Chance, The Cuckoo's Secret (1922), is an important and highly readable book about the common cuckoo. See also Ian Wyllie, The Cuckoo (1981). D.E. Davis, Social Nesting Habits of the Smooth-Billed Ani, Auk, 57:179218 (1940), presents the results of extensive fieldwork on anis. Herbert Friedmann, The Parasitic Cuckoos of Africa (1948), Evolutionary Trends in the Avian Genus Clamator (1964), and The Evolutionary History of the Avian Genus Chrysococcyx (1968), are technical papers on Old World tropical cuckoos. Reginald E. Moreau, A Contribution to the Biology of the Musophagiformes, the So-Called Plantain-Eaters, Ibis, 2: 639671 (1938), is one of the few detailed studies of musophagids. Herbert Friedmann The Editors of the Encyclopdia Britannica