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Common cuckoo

life science Maturity 5-7 Next article →

The common cuckoo, scientifically known as *Cuculus canorus*, is a widespread migratory bird. It belongs to the order Cuculiformes, which also includes birds like roadrunners and anis.

Cuculus canorus vogelartinfo
Cuculus canorus vogelartinfo

This species is famous for being an obligate brood parasite. This means the cuckoo does not build its own nest or raise its own young. Instead, it relies on other bird species to do the work.

Reed warbler cuckoo
Reed warbler cuckoo

The cuckoo typically targets hosts such as the dunnock, meadow pipit, or reed warbler. This survival strategy is a complex biological process that involves specialized behaviors and physical adaptations.

The process of brood parasitism begins when a female cuckoo finds a suitable host nest. A single female may visit as many as 50 different nests during one breeding season. Once she finds a nest, she lays her egg among the host's eggs. Interestingly, the cuckoo eggs are often larger than those of the host birds. However, the eggs have evolved to look very similar to the host's eggs in color and pattern. This allows the cuckoo egg to blend in and avoid being noticed.

Cuckoo Eggs Mimicking Reed Warbler Eggs
Cuckoo Eggs Mimicking Reed Warbler Eggs

Once the cuckoo chick hatches, it may push the host's own eggs or chicks out of the nest. This ensures the cuckoo chick receives all the food brought by the host parents.

To make this parasitism successful, female cuckoos are divided into groups called gentes. Each gente is a group of females that prefers a specific host species. These females lay eggs that mimic the specific color and pattern of that host's eggs. Scientists believe these traits might be passed down through the female's DNA. There is a theory that this mimicry is carried on the W chromosome, which only females have. Another theory suggests the genes are located on autosomes, which are regular chromosomes.

Cuculus canorus canorus MHNT.ZOO.2010.11.149.48
Cuculus canorus canorus MHNT.ZOO.2010.11.149.48

This genetic specialization ensures that the eggs look convincing to the host birds.

Adult cuckoos also use a form of protective mimicry to stay safe while laying eggs. The common cuckoo has a slender, greyish body and a long tail.

European Cuckoo Mimics Sparrowhawk
European Cuckoo Mimics Sparrowhawk

In flight, its wingbeats and appearance look very much like a Eurasian sparrowhawk. Because the sparrowhawk is a predator, other small birds often feel alarmed when they see it. This hawk-like appearance can give the female cuckoo time to approach a nest without being attacked. It may also cause host birds to avoid the area, making it easier for the cuckoo to complete her task.

There are four distinct subspecies of the common cuckoo found across the globe. The nominate subspecies, *C. c. canorus*, was first described by Carl Linnaeus in 1758. It lives from Ireland through northern Russia and Siberia all the way to Japan.

Eurasian Cuckoo Rongli East Sikkim India 10.04.2016
Eurasian Cuckoo Rongli East Sikkim India 10.04.2016

The second subspecies, *C. c. bakeri*, breeds in western China and the Himalayan foothills. A third type, *C. c. bangsi*, lives in Iberia and North Africa. Finally, *C. c. subtelephonus* breeds in Central Asia, from Turkestan to southern Mongolia. These different groups allow the species to inhabit a massive range across Europe and Asia.

The population of common cuckoos is quite large, though it appears to be declining globally. It is currently classified as a species of "least concern" by the IUCN. Experts estimate there are between 25 million and 100 million individuals worldwide. In Europe alone, there are between 12.6 million and 25.8 million breeding birds. In the United Kingdom, the longest recorded lifespan for a cuckoo was nearly seven years.

Cuculus canorus canorus MHNT.ZOO.2010.11.149.48
Cuculus canorus canorus MHNT.ZOO.2010.11.149.48

Their distribution is also shifting, with populations increasing in Scotland while declining in England.

The relationship between the cuckoo and its hosts is a constant evolutionary race. As cuckoos evolve better egg mimicry, the host species must evolve better ways to spot the imposters. For example, cuckoos targeting common redstarts have evolved very accurate eggs. This is likely because redstarts have been parasitized for a long time and have learned to notice differences. In contrast, dunnocks have not yet evolved strong defenses against cuckoos. Because dunnocks cannot easily tell the difference, cuckoos do not need to mimic their blue eggs as closely. This connection shows how one species' behavior can force another species to change over many generations.

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🖼️ Images & Media (10)
File:Cuculus canorus vogelartinfo.jpg
Cuculus canorus vogelartinfo.jpg
File:Eurasian Cuckoo Rongli East Sikkim India 10.04.2016.jpg
Eurasian Cuckoo Rongli East Sikkim India...
File:European Cuckoo Mimics Sparrowhawk.jpg
European Cuckoo Mimics Sparrowhawk.jpg
Cuculus canorus.ogg
File:Reed warbler cuckoo.jpg
Reed warbler cuckoo.jpg
File:Cuckoo Eggs Mimicking Reed Warbler Eggs.JPG
Cuckoo Eggs Mimicking Reed Warbler Eggs.JPG
File:Cuculus canorus canorus MHNT.ZOO.2010.11.149.48.jpg
Cuculus canorus canorus...
File:Cuculus canorus bangsi MHNT.ZOO.2010.11.149.13.jpg
Cuculus canorus bangsi MHNT.ZOO.2010.11.149.13.jpg
File:Cuculus canorus chick1.JPG
Cuculus canorus chick1.JPG
File:Suomenniemi.vaakuna.svg
Suomenniemi.vaakuna.svg
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