Cuckoo (Cuculus canorus)


These summer visitors arrive in the UK from wintering in Africa around April, and are well known ‘brood parasites’, where they lay their eggs in other birds’ nests. Their call is famous worldwide, but the cuckoo is represented aptly by the adage of ‘seen and not heard’ as though its call is recognisable, few would be able to identify this plain-looking bird.

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Alert Status:

Red - 77% decline ↓

Estimated number of UK breeding

pairs: 18,000 (updated 2016)

Listen to Cuckoo song:


Cuckoos are quite large individuals, around the size of a woodpigeon and can often be mistaken for kestrels or sparrowhawks. Their underside is mainly white, with grey barring, whereas their backs and head are a medium grey-blue with dark long wings. Their bills are curved with yellow towards the base, and they have small yellow eyes. When in flight, the cuckoo has quite a large, wedge-shaped tail and barred wings from underneath. Juveniles are red brown with barring across the back and tail, with a white patch on the nape.

Average Length: 32-36cm

Average Lifespan: 4-6 years

Average Wingspan: 55-65 cm

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Cuckoo diet

They eat invertebrates and can often be seen in bushes and trees foraging.

Hairy caterpillars are a particular favourite of cuckoos.

Cuckoo breeding and nesting information

After arriving in the UK from Africa, these summer visitors start breeding around May, and are well-known brood parasites. They lay 1-25 broods annually, with 1 egg laid per nest of the host individual. On average, cuckoos tend to lay around 9 eggs in 9 different nests. Females wait until host species have left their nest, normally due to the cuckoo scaring the host away. They then lay an egg in amongst the hosts young and often hosts believe the egg to be theirs and raise it as their own. Chicks will then hatch after around 11-13 days and begin to push the host chicks out of the nest, to ensure that they monopolise the food from the parents.  Cuckoo chicks fledge after around 17-21 days but continue to be fed by the host for several more weeks. Dunnocks, reed warblers and meadow pipits account for over 75% of hosts raising cuckoo chicks, however a wide range of other species also have been found to raise cuckoos, such as robins and sedge warblers.

Threats to cuckoos

Climate change, deforestation causing habitat loss, and decline of insect prey has the potential to have caused a decrease in the population of European cuckoos. Changing climates will shift the laying dates of the host species of the cuckoo, which may have a knock-on impact on their ability to parasitise the nests. We also know that there is a constant evolutionary arms race between hosts and cuckoos, with hosts developing new ways to identify their own eggs and reject the cuckoos.

How you can help

Plant some caterpillar friendly plants in your garden to attract the cuckoo’s favourite food.

Feed their host species by keeping your feeders full.

Don’t use pesticides in your garden to increase insect availability.

Fascinating Fact

In Ancient Greek mythology, the cuckoo is a symbol of marriage. Zeus transformed himself into a cuckoo as his courtship with his soon to be wife, Hera, was not going so well. Hera pitied the poor bird, that was so dishevelled, and cared for it, until Zeus transformed back into himself, and the two married.
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BirdLife International (2022) Species factsheet: Cuculus canorus. Downloaded from on 20/06/2022.  

Douglas, D.J.T., Newson, S.E., Leech, D.I., Noble, D.G., Robinson, R.A. (2010) How important are climate-induced changes in host availability for population processes in an obligate brood parasite, the European cuckoo? Oikos. 119(11): 1834-1840.  

Glue, D., Morgan, R. (1972) Cuckoo Hosts in British Habitats. Bird Study. 19:4, 187-192.

Jostein Øien, I., Moksnes, A., Røskaft, E. (1995) Evolution of variation in egg color and marking pattern in European passerines: adaptations in a coevolutionary arms race with the cuckoo, Cuculus canorus. Behavioural Ecology. 6(2):166-174.

Robinson, R.A. (2005) BirdFacts: profiles of birds occurring in Britain & Ireland. BTO, Thetford (, accessed on 28 March 2022)

Stanbury, A.J., Eaton, M.A., Aebischer, N.J., Balmer, D., Brown, A.F., Douse, A., Lindley, P., McCulloch, N., Noble, D.G., Win, I. (2021) The status of our bird populations: the fifth Birds of Conservation Concern in the United Kingdom, Channel Islands and Isle of Man and second IUCN Red List assessment of extinction risk for Great Britain. British Birds. 114 

Werness, H.B. (2006) The Continuum Encyclopaedia of Animal Symbolism in Art. Continuum Publishing.

Woodward, I., Aebischer, N., Burnell,D., Eaton, M., Frost, T., Hall, C., Stroud, D. & Noble, D. (2020) Population estimates of birds in Great Britain and the United Kingdom. British Birds. 113: 69–104.

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