Cuckoos are birds known for brood parasitism, a behavior where they lay eggs in other bird species' nests for incubation and rearing. This habit is present in all Cuculinae and some Phaenicophaeinae species. Adaptations that enhance the survival of young cuckoos include egg mimicry, where the cuckoo egg resembles the host's, reducing the chances of rejection, and nest-mate ejection, where the young cuckoo pushes the host’s eggs and nestlings out of the nest. Some Cuculus species resemble bird-eating hawks, potentially scaring potential hosts, allowing the cuckoo to approach the nest without disturbance. Cuckoos are distributed worldwide, mainly in tropical and temperate regions. They are primarily insectivorous, consuming crawling insects, with some larger species eating lizards, snakes, and small vertebrates.

Where do cuckoos live in the world?

Cuckoos of the family Cuculidae inhabit temperate and tropical regions virtually worldwide. While some genera are limited to certain areas, others are cosmopolitan. For example, Cuculus cuckoos are found in Europe, Asia, Africa, and Australia, while Centropus coucals live in Africa, Asia, Australia, and adjacent islands. As a group, cuckoos are forest birds, often found in dense thickets, though some, like those of the genus Cuculus , inhabit open woodland. The guira of South America and members of Clamator and Chrysococcyx are found in open savanna, but only where trees are present. Roadrunners live in open scrub and cactus deserts. Most temperate-zone cuckoos migrate toward or across the Equator for the winter, like most insectivorous birds in those climates.

Cuckoos are largely insectivorous, with a diet mainly consisting of crawling insects. They often eat Orthoptera, such as grasshoppers, locusts, and mantids. The greater roadrunner is known to leap to catch flying grasshoppers. Larger cuckoos, like lizard cuckoos, roadrunners, and coucals, consume lizards, snakes, other small vertebrates, and sometimes even birds. The Madagascar couas are reported to eat some fruit. Some cuckoos are brood parasites , laying their eggs in the nests of other bird species. The host parents then incubate the eggs and raise the young cuckoos.

How do cuckoos build their nests or lay their eggs?

Cuckoos exhibit two main types of nesting behavior: parasitic and nonparasitic. About 50 cuckoo species are brood parasites, including the subfamily Cuculinae. Brood parasitism is when a bird lays its eggs in the nests of other species. The host parents then incubate the eggs and rear the young cuckoos. However, about three-fifths of cuckoos mate, nest, and rear their young like most birds. These nonparasitic cuckoos form stable pair bonds and defend territories where they build nests and rear their young. Their nests are loose platforms of twigs placed in low vegetation. Some cuckoos, like the coucals, build sizable domed nests of grass and twigs on or near the ground with side entrances.

What is brood parasitism and how are cuckoos known for it?

Brood parasitism is when a bird species lays its eggs in the nest of another bird species. The cuckoo is well-known for this behavior. Around 50 cuckoo species lay their eggs in the nests of other species, who then raise the young cuckoos. Female cuckoos watch host nests and lay their eggs after the host has started laying but before incubation begins. The cuckoo may remove one or more of the host’s eggs. Cuckoo eggs often match the color and pattern of the host eggs. This egg mimicry is important to the parasite's success; hosts reject mismatched eggs more often. After hatching, young cuckoos sometimes evict the other nestlings to avoid competition.

How do baby cuckoos survive and grow in other birds' nests?

Cuckoo chicks enhance their survival through various adaptations. Cuckoo eggs often mimic the host's eggs, reducing the chances of rejection. The adult cuckoo may remove host eggs, minimizing competition and preventing the host from recognizing a foreign egg. Newly hatched cuckoos exhibit nest-mate ejection behavior, where they push the host's eggs and nestlings out of the nest to secure more food from the foster parents. Some cuckoo species resemble bird-eating hawks, frightening potential hosts and allowing the cuckoo to approach the nest without disturbance. This ensures the young cuckoo receives undivided attention and care from its foster parents, facilitating rapid growth.

Cuckoo

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A common cuckoo, Cuculus canorus, holds a large caterpillar in its beak against a blurred green background.

Body plans of representative Cuculiformes.

Quick Facts

Related Topics:: Coucal; Ani; Roadrunner; Ground cuckoo; Guira

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Cuckoo

bird

Also known as: Cuculidae, cuckoo bird

Written and fact-checked by

Britannica Editors

Last updated

Nov. 12, 2026 •History

Top Questions

What is a cuckoo?
Cuckoos are birds known for brood parasitism, a behavior where they lay eggs in other bird species' nests for incubation and rearing. This habit is present in all Cuculinae and some Phaenicophaeinae species.

Adaptations that enhance the survival of young cuckoos include egg mimicry, where the cuckoo egg resembles the host's, reducing the chances of rejection, and nest-mate ejection, where the young cuckoo pushes the host’s eggs and nestlings out of the nest. Some Cuculus species resemble bird-eating hawks, potentially scaring potential hosts, allowing the cuckoo to approach the nest without disturbance.

Cuckoos are distributed worldwide, mainly in tropical and temperate regions. They are primarily insectivorous, consuming crawling insects, with some larger species eating lizards, snakes, and small vertebrates.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
Where do cuckoos live in the world?
Cuckoos of the family Cuculidae inhabit temperate and tropical regions virtually worldwide. While some genera are limited to certain areas, others are cosmopolitan. For example, Cuculus cuckoos are found in Europe, Asia, Africa, and Australia, while Centropus coucals live in Africa, Asia, Australia, and adjacent islands.

As a group, cuckoos are forest birds, often found in dense thickets, though some, like those of the genus Cuculus, inhabit open woodland. The guira of South America and members of Clamator and Chrysococcyx are found in open savanna, but only where trees are present. Roadrunners live in open scrub and cactus deserts.

Most temperate-zone cuckoos migrate toward or across the Equator for the winter, like most insectivorous birds in those climates.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What do cuckoos eat?
Cuckoos are largely insectivorous, with a diet mainly consisting of crawling insects. They often eat Orthoptera, such as grasshoppers, locusts, and mantids. The greater roadrunner is known to leap to catch flying grasshoppers. Larger cuckoos, like lizard cuckoos, roadrunners, and coucals, consume lizards, snakes, other small vertebrates, and sometimes even birds. The Madagascar couas are reported to eat some fruit.

Some cuckoos are brood parasites, laying their eggs in the nests of other bird species. The host parents then incubate the eggs and raise the young cuckoos.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do cuckoos build their nests or lay their eggs?
Cuckoos exhibit two main types of nesting behavior: parasitic and nonparasitic. About 50 cuckoo species are brood parasites, including the subfamily Cuculinae. Brood parasitism is when a bird lays its eggs in the nests of other species. The host parents then incubate the eggs and rear the young cuckoos.

However, about three-fifths of cuckoos mate, nest, and rear their young like most birds. These nonparasitic cuckoos form stable pair bonds and defend territories where they build nests and rear their young. Their nests are loose platforms of twigs placed in low vegetation. Some cuckoos, like the coucals, build sizable domed nests of grass and twigs on or near the ground with side entrances.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
What is brood parasitism and how are cuckoos known for it?
Brood parasitism is when a bird species lays its eggs in the nest of another bird species. The cuckoo is well-known for this behavior. Around 50 cuckoo species lay their eggs in the nests of other species, who then raise the young cuckoos.

Female cuckoos watch host nests and lay their eggs after the host has started laying but before incubation begins. The cuckoo may remove one or more of the host’s eggs. Cuckoo eggs often match the color and pattern of the host eggs. This egg mimicry is important to the parasite's success; hosts reject mismatched eggs more often. After hatching, young cuckoos sometimes evict the other nestlings to avoid competition.
4 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
How do baby cuckoos survive and grow in other birds' nests?
Cuckoo chicks enhance their survival through various adaptations. Cuckoo eggs often mimic the host's eggs, reducing the chances of rejection. The adult cuckoo may remove host eggs, minimizing competition and preventing the host from recognizing a foreign egg.

Newly hatched cuckoos exhibit nest-mate ejection behavior, where they push the host's eggs and nestlings out of the nest to secure more food from the foster parents. Some cuckoo species resemble bird-eating hawks, frightening potential hosts and allowing the cuckoo to approach the nest without disturbance. This ensures the young cuckoo receives undivided attention and care from its foster parents, facilitating rapid growth.
3 Britannica Sources
Created from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.

Cuckoo, (family Cuculidae), any of numerous birds of the family Cuculidae (order Cuculiformes). The name usually designates some 60 arboreal members of the subfamilies Cuculinae and Phaenicophaeinae. In western Europe “cuckoo,” without modifiers, refers to the most common local form, elsewhere called the common, or European, cuckoo (Cuculus canorus). Many cuckoos have specialized names, such as ani, coua, coucal, guira, and roadrunner. Members of the subfamily Neomorphinae are called ground cuckoos.

The family Cuculidae is worldwide, found in temperate and tropical regions but is most diverse in the Old World tropics. Cuculids tend to be shy inhabitants of thick vegetation, more often heard than seen. Many species are named for the sounds they make—e.g., brain-fever bird (a hawk cuckoo, Cuculus varius), koel (Eudynamys scolopacea), and cuckoo itself, the latter two names being imitations of the bird’s song.

Physical description

Cuculids range in length from about 16 cm (6.5 inches) in the glossy cuckoos (Chrysococcyx and Chalcites) to about 90 cm (36 inches) in the larger ground cuckoos. Most are colored in drab grays and browns, but a few have striking patches of rufous (reddish) or white, and the glossy cuckoos are largely or partially shining emerald green. Some of the tropical cuckoos have strongly iridescent bluish plumage on their backs and wings. With the exception of a few strongly migratory species, most cuckoos are short-winged. All have long (sometimes extremely long), graduated tails, usually with the individual feathers tipped with white. The legs vary from medium to rather long (in the terrestrial forms) and the feet are zygodactyl; i.e., the outer toe is reversed, pointing backward. The bill is rather stout and somewhat downcurved.

Young chimpanzee dressed in a shirt and sweater vest, scratching his head thinking. (primates)

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Brood parasitism

The attribute for which the cuckoos are best known is the habit of brood parasitism, found in all of the Cuculinae and three species of Phaenicophaeinae. It consists of laying the eggs singly in the nests of certain other bird species to be incubated by the foster parents, who rear the young cuckoo. Among the 47 species of cuculines, various adaptations enhance the survival of the young cuckoo: egg mimicry, in which the cuckoo egg resembles that of the host, thus minimizing rejection by the host; removal of one or more host eggs by the adult cuckoo, reducing both the competition from host nestlings and the danger of recognition by the host that an egg has been added to the nest; and nest-mate ejection, in which the young cuckoo heaves from the nest the host’s eggs and nestlings. Some species of Cuculus resemble certain bird-eating hawks (Accipiter) in appearance and mannerisms, apparently frightening the potential host and allowing the cuckoo to approach the nest unmolested.

Non-parasitic cuckoos

Not a parasiteYellow-billed cuckoo (*Coccyzus americanus*).

The nonparasitic phaenicophaeine cuckoos are represented in North America by the widespread yellow-billed and black-billed cuckoos (Coccyzus americanus and C. erythropthalmus) and the mangrove cuckoo (C. minor), which is restricted in the United States to coastal southern Florida (also found in the West Indies and Mexico to northern South America); they are represented in Central and South America by about 12 other species, some placed in the genera Piaya (squirrel cuckoos) and Saurothera (lizard cuckoos). The 13 Old World phaenicophaeine species are divided among nine genera.

The phaenicophaeine cuckoos build flimsy stick nests in low vegetation. Both parents share in incubation and feeding the young.

The Editors of Encyclopaedia BritannicaThis article was most recently revised and updated by Melissa Petruzzello.

Cuckoo

Physical description

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Brood parasitism

Non-parasitic cuckoos