Common cuckoo (Cuculus canorus): Distinctive call, parasitism, and migration

The common cuckoo (Cuculus canorus) is a migratory bird widely known for its distinctive “cu-coo” call and its unique brood parasitism behavior, where it lays eggs in the nests of other bird species. This species is found across Europe and Asia, migrating to Africa for the winter.

Common cuckoo (Cuculus canorus)
Common cuckoo (Cuculus canorus) | Photo by Gary Faulkner
Common nameCommon cuckoo
Scientific nameCuculus canorus
Alternative nameEuropean cuckoo, Eurasian cuckoo
OrderCuculiformes
FamilyCuculidae
GenusCuculus
IdentificationGrey upperparts, pale barred underparts, long tail, slender body, pointed wings, distinct “cu-coo” call
RangeBreeds across Europe and Asia, from the British Isles to Japan
MigrationLong-distance migrant; winters in sub-Saharan Africa
HabitatOpen woodlands, farmlands, moorlands, and marshes
DietInsects and larvae, especially hairy caterpillars
Conservation statusLeast concern

Discovery

The common cuckoo has been recognized since ancient times, featuring prominently in European folklore. The Greek philosopher Aristotle mentioned the cuckoo’s brood parasitism in his History of Animals, marking one of the earliest recorded observations of this unique behavior. In the 16th century, Swiss naturalist Conrad Gessner included the cuckoo in his Historiae Animalium, offering one of the first systematic descriptions of the species.

The bird’s parasitic behavior fascinated early ornithologists, with significant contributions from Francis Willughby and John Ray in The Ornithology of Francis Willughby (1678), where they detailed the cuckoo’s habits and morphology. However, it was Edward Jenner who made groundbreaking discoveries in 1788 by publishing Observations on the Natural History of the Cuckoo to the Royal Society. Jenner was the first to document how cuckoo chicks eject host eggs and nestlings – a behavior that had puzzled naturalists for centuries.

The common cuckoo belongs to the order Cuculiformes and family Cuculidae. Its reproductive strategy continues to captivate researchers, contributing to broader studies on evolution and co-evolution with host species.

Identification

The common cuckoo is about 32-34 cm (12.5-13.3 inches) in length, with a wingspan of 55-60 cm (21.7-23.6 inches), and weighs approximately 110–130 grams (3.9-4.6 oz). Adults are grey, with solid grey coloring on the head, neck, and wings, and lighter underparts marked by dark horizontal bars. The tail is long and graduated, with dark grey feathers and white spots on the underside. The bill is pointed and slightly curved, with a yellow base transitioning to a dark grey or black tip, often appearing lighter on the sides.

 juvenile common cuckoo
Juvenile common cuckoo | Photo by Imran Shah

Males and females look similar, though females may exhibit rufous morphs with reddish-brown tones replacing the gray. Juveniles are browner, featuring a white patch on the nape.

Vocalization

The male’s iconic two-note “cu-coo” call is most prominent during the breeding season (April to June) and serves to establish territory and attract females. This call, often repeated up to 80 times per minute, is one of the most recognizable bird sounds in Europe. Females emit a distinctive bubbling or purring sound, a rapid series of gurgling notes used for communication and mate attraction.

The cuckoo’s call is deeply rooted in European folklore, symbolizing the arrival of spring, though it is sometimes confused with the similar-sounding Eurasian collared dove.

Listen to the common cuckoo call:

Range and habitat

The common cuckoo breeds across Europe and Asia, from the British Isles to Japan. It inhabits a wide variety of open and semi-open landscapes, including moorlands, forest edges, farmlands, and heathlands. The species thrives in forests and woodlands (both coniferous and deciduous) as well as second-growth areas, wooded steppes, scrub, meadows, and reedbeds. It is commonly found in lowlands, moorlands, and hill country, reaching elevations up to 2,000 meters (6,500 feet).

common cuckoo map
Cuculus canorus range and distribution | Map by BirdLife DataZone

Migration

The common cuckoo is a long-distance migrant across most of its range. Northern populations arrive in Southwest Britain and other parts of Europe from April to May, with occasional sightings of small flocks during peak migration. In Asia, seasonal populations breed in regions like Assam and the Chin Hills from March to August, while some remain resident in the tropical lowlands of South Asia.

In autumn, cuckoos migrate to sub-Saharan Africa, with birds reaching Senegal as early as July and continuing south through Central and Southern Africa until December. Migration routes are influenced by rainfall patterns, which affect food availability. Some Asian populations winter in India, Sri Lanka, Southeast Asia, and the Philippines, while others may migrate to Africa.

The species is also recorded as a passage migrant in the Middle East and occasionally on islands in the Western Indian Ocean, such as the Seychelles and Aldabra. Rare vagrants have been recorded in Iceland, the Faroe Islands, Azores, and even North America. One record exists of a Cuculus canorus individual in Indonesia off West Java during winter.

Behavior

The common cuckoo is most renowned for its brood parasitism, a reproductive strategy where females lay their eggs in the nests of other bird species. Preferred hosts include warblers, pipits, wagtails, flycatchers, buntings, and chats. To reduce detection, the female cuckoo often removes one of the host’s eggs before depositing her own, sometimes laying the egg on the ground and delicately transporting it to the nest in her beak when the opportunity arises.

Reed warbler feeds a common cuckoo nestling
Reed warbler feeds a common cuckoo nestling | Photo by Lynn Martin

Cuckoo eggs are polymorphic, with color and patterns that closely mimic those of the host species, an adaptation that helps evade egg rejection. Host species frequently mob cuckoos near their nests to deter parasitism. Despite these defenses, cuckoo chicks hatch earlier than host chicks and instinctively push out the host’s eggs or nestlings to monopolize parental care. The chick’s rapid growth and incessant begging calls stimulate the foster parents to feed it intensively, often exhausting themselves in the process.

Breeding

The breeding season of the common cuckoo varies depending on its geographic range, occurring from May to June in Northwest Europe, April to May in Algeria, and extending from April to July in India and Myanmar.

A single female can lay up to 25 eggs per season, typically one in each nest. The incubation period lasts about 12 days, and the nestling period is around 17-18 days. Cuckoo chicks are known for their aggressive behavior shortly after hatching, instinctively evicting the host’s eggs and chicks to secure all parental resources for themselves.

Egg mimicry plays a critical role in breeding success, with studies identifying up to 11 distinct egg morphs adapted to different host species. For example, the Sylvia morph is common in reed warbler nests, while the Anthus morph is adapted for pipit nests. While some cuckoos specialize in specific host species (host preference hypothesis), others select nests based on habitat structure (habitat imprinting hypothesis).

Diet

The common cuckoo primarily feeds on insects, with a strong preference for hairy caterpillars that are often avoided by other birds due to their toxic hairs. Their diet also includes a variety of other invertebrates such as dragonflies, mayflies, damselflies, crickets, and cicadas. Occasionally, they consume spiders, snails, and, more rarely, fruit.

Common cuckoo caught a caterpillar
Common cuckoo caught a caterpillar | Photo by Lukasz Prajzner

In addition to invertebrates, common cuckoos have been known to prey on the eggs and nestlings of small birds. They forage in trees, shrubs, and on the ground, using their sharp eyesight to spot prey in diverse habitats.

Culture

The common cuckoo holds a significant place in European culture and folklore, often symbolizing the arrival of spring due to its distinctive, melodic call. In many cultures, hearing the first cuckoo of the season is seen as a harbinger of change or good fortune. However, the bird’s notorious parasitism has also linked it to themes of deception and unfaithfulness in myths and legends, where it is portrayed as a cunning trickster exploiting the efforts of others.

The cuckoo’s call has inspired countless traditional songs and poems, and its presence in folklore is widespread. For a deeper dive into these cultural associations, explore the Story of the Little Boy and the Wicked Stepmother, where the cuckoo plays a central symbolic role. Additionally, our piece on cuckoo meaning and symbolism delves into the bird’s broader significance across different cultures, highlighting its complex representation as both a messenger of seasons and a symbol of betrayal.

Threats and conservation

The common cuckoo is currently listed as least concern by the IUCN (International Union for Conservation of Nature), owing to its extremely large range and population size. The species does not meet the thresholds for a vulnerable status under key criteria, including range size, population size, and population trend.

Although the population trend appears to be decreasing, the decline is not sufficiently rapid to trigger a higher threat category – there has not been a decline of more than 30% over ten years or three generations.

However, in certain parts of its range, particularly in Western Europe, the common cuckoo is experiencing more pronounced declines. Factors contributing to this include habitat loss, changes in agricultural practices, and the decline of host species due to environmental pressures. Modern farming techniques reduce the availability of insect prey and suitable nesting habitats for host birds, indirectly affecting cuckoo populations.

Conservation efforts focus on preserving diverse habitats, maintaining healthy populations of host species, and monitoring population trends. While the species is not currently under severe threat globally, continued observation is essential to ensure that localized declines do not become widespread.

Similar species

The common cuckoo (Cuculus canorus) shares physical and behavioral traits with several other bird species, leading to frequent misidentifications in the field. These similarities often stem from plumage patterns, size, or parasitic behaviors. However, close observation of features like call patterns, tail shape, and habitat range can help distinguish the common cuckoo from its “look-alikes.”

Common hawk-cuckoo (Hierococcyx varius)

Common hawk-cuckoo (Hierococcyx varius)
Common hawk-cuckoo | Photo by Vijay Anand Ismavel

Also known as the brainfever bird, the hawk-cuckoo resembles the common cuckoo with its grey plumage and barred underparts. Found mainly in the Indian subcontinent, it is slightly smaller and has a rounded tail compared to the more graduated tail of the common cuckoo. Its call is a repetitive, high-pitched “brain-fever” cry, distinct from the common cuckoo’s classic “cu-coo.”

Lesser cuckoo (Cuculus poliocephalus)

Lesser cuckoo (Cuculus poliocephalus)
Lesser cuckoo | Photo by Tisha Mukherjee

The lesser cuckoo is a smaller relative of the common cuckoo, with a softer call and darker plumage. Found in parts of Asia and Africa, it lacks the strong, far-carrying “cu-coo” call of its larger cousin. Its tail is also shorter, and its flight pattern is more erratic.

Oriental cuckoo (Cuculus optatus)

Oriental cuckoo (Cuculus optatus)
Oriental cuckoo | Photo by Rick Franks

The oriental cuckoo closely resembles the common cuckoo but can be distinguished by its duller plumage and more subdued call. Its underparts have heavier barring, and it is often found in denser forests across Asia. Vocalization is a key difference, with the oriental cuckoo producing a slower, more monotone call compared to the common cuckoo’s rhythmic “cu-coo.”

Eurasian sparrowhawk (Accipiter nisus)

Eurasian sparrowhawk (Accipiter nisus)
Eurasian sparrowhawk | Photo by Paul Crabtree

The common cuckoo is often mistaken for the Eurasian sparrowhawk due to its similar size and barred underparts. However, sparrowhawks have shorter wings, a more robust body, and a hooked beak typical of raptors. The cuckoo’s slender build, pointed wings, and straight beak are key distinguishing features.

Further reading

Our work on the common cuckoo is the result of lifelong observation and field studies. Members of Planet of Birds team have been monitoring cuckoos and their behavior for over four decades, witnessing firsthand the intricate dynamics of their parasitism, migration patterns, and interactions with host species. These insights are the culmination of years spent in diverse habitats across Europe, Asia, and Africa.

For those interested in delving deeper into the captivating world of Cuculus canorus, we recommend the following resources:

Updated: February 8, 2025 — 5:35 am

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