| Common Cuckoo | |
|---|---|
 Male | |
 Female | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Cuculiformes |
| Family: | Cuculidae |
| Genus: | Cuculus |
| Species: | Cuculus canorus |
The Common Cuckoo (Cuculus canorus) is a very well-known Eurasian bird named after its call.
Taxonomy[]
The scientific name of the species stems from the Latin words cuculus (the cuckoo) and canorus (melodious; from canere, meaning to sing). Its family's common name is of onomatopoeic origin based on the male Common Cuckoo's distinctive calls. The English word "cuckoo" comes from the Old French cucu, and its earliest recorded usage in English is from around 1240, in the song Sumer Is Icumen In. Written in Middle English, its first two lines are: "Svmer is icumen in / Lhude sing cuccu." In modern English, this translates to "Summer has come in / Loudly sing, Cuckoo!"
4 subspecies of the Common Cuckoo are recognized.
- C. c. canorus, the nominate subspecies, was first described by Linnaeus in 1758. Its range extends from the British Isles through Scandinavia, northern Russia and Siberia to Japan in the east, and from the Pyrenees through Turkey, Kazakhstan, Mongolia to northern China and Korea. It is assumed to winter in Africa and South Asia.
- C. c. bakeri, first described by Hartert in 1912, breeds in western China in the Himalayan foothills of northern India, Nepal, Myanmar, northwestern Thailand and southern China. In winter, it is found in Assam, East Bengal and Southeast Asia.
- C. c. bangsi was first described in 1919 by Oberholserom. The breeding range covers the Iberian Peninsula, Balearic Islands and North Africa, wintering in Africa.
- C. c. subtelephonus, first described by Zarudny in 1914, breeds in Central Asia from Turkestan to southern Mongolia. It is assumed to migrate to South Asia and Africa by winter.
Description[]
Male in flight.
These sexually dimorphic birds range from 32-34 cm in length and 55-60 cm in wingspan. Males weigh around 130 g, whereas females are at around 110 g in mass. In males, the top of the body, wings, as well as the head and neck are solid gray. The chest and the abdomen is white with transverse gray stripes. Females generally have a similar coloration, but the plumage of the throat and neck sides are reddish, the top of the back and wings have a somewhat noticeable brown tint, and the wing coverts have dark spots. In some females, these features are weak or absent, making the coloration more similar to the male. There are females, or more often, juveniles of a rather rare so-called "red morph", in which the gray color of the upperparts are replaced by reddish orange with a dark transverse pattern, with black bars on the underparts being narrower. The legs of adult Common Cuckoos are yellow, short and have zygodactyl feet. The eyes are either orange or yellow. Males are on average slightly larger than females.
First autumn Common Cuckoos have variable plumage. Some have strongly-barred chestnut-brown upperparts, while others are plain grey. Rufous-brown birds have heavily barred upperparts with some feathers edged with creamy-white. All have whitish edges to the upper wing-coverts and primaries. The secondaries and greater coverts have chestnut bars or spots. In spring, birds hatched in the previous year may preserve some barred secondaries and wing-coverts. White feather fringes and nape patch are the most obvious characteristics of juvenile Common Cuckoos.
There are not much seasonal changes in plumage. However, Common Cuckoos do molt twice a year. These two molts are a partial moult in summer and a complete moult in winter. In flight, the Common Cuckoo resembles a small hawk or falcon.
Resemblance to the Eurasian Sparrowhawk[]
The adult Common Cuckoo's barred underparts resemble that of the Eurasian Sparrowhawk's, a predator of adult birds. The fact that the Common Cuckoo is similar to a sparrowhawk is very beneficial for the bird and functions fairly much as protective mimicry. By this, Common Cuckoos are capable of scaring away smaller birds so they can swoop in on their nests and quickly lay an egg. The plumage similarities also reduce the probabilities of the bird being attacked by many birds of prey.
Voice[]
The Common Cuckoo has a very well known onomatopoeic call that gave rise to its name, an iconic ku-ku. Another of its calls, the loud bubbling call is only produced by females. The song starts as a descending minor third early in the year in April, and the interval gets wider, through a major third to a fourth as the season progresses, and in June, the Cuckoo "forgets its tune" and may make other calls, including ascending intervals.
Behavior[]
The Common Cuckoo leaves its wintering place early, but moves to nesting places gradually and not fast enough, usually in the second half of April. In the vortex of the winter, Common Cuckoos begin to fly away in the summer alone, and then fly in small flocks.
The male Common Cuckoo may lower its wings when calling intensively, and in vicinity of a female, raise its long, slightly spread tail, wagging from side to side.
Feeding[]
Common Cuckoos forage on tree branches, primarily gorging on caterpillars, beetles, flies, and sometimes berries. In an hour, the Common Cuckoo can eat more than 100 caterpillars. It is one of the few birds that eat many hairy caterpillars (silkworm, pine and others), which, for most birds, are very harmful to eat. The poisonous hairs of silkworm caterpillars do to the adult cuckoo no harm. Consuming such a caterpillar, the Common Cuckoo would not be able to feed its chicks, because for them, those hairs are very dangerous. In addition, the Common Cuckoo feeds on many larvae of pollinators, beetles, and other insects, which are also very harmful. Therefore, the Common Cuckoo is an extremely useful bird.
Reproduction and Brood Parasitism[]
Common Cuckoos do not build their nests nor incubate their eggs. Instead, they're brood parasites, which means they lay their eggs on other birds' nests as their foster parents will take care of them. In fact, there are almost 300 recorded different species of birds that are the hosts of the Common Cuckoo, in which the most complete list of them was compiled by a Russian ornithologist Alexander Dmitrievich Numerov. It should be taken into account that the propensity to parasitize one species or another varies not only in areas of the range remote from each other, but often within the same small area. It happens that one of the most common adoptive parents in one region rarely takes part in breeding chicks in another; for this reason, studies in different countries and regions sometimes give conflicting results. The Common Cuckoo mainly lays its eggs on the nests of reed warblers, Dunnocks and Meadow Pipits. Depending on where it lives in Europe, it also usually takes Garden Warblers, White Wagtails, robins, wrens, redstarts, chaffinches, and Bramblings (especially in Finland) into account. In North Africa, it is known to parasitize on the nests of Sardinian and Tristram's Warblers and Moussier's Redstarts, and in Korea, often on Daurian Redstarts and Vinous-throated Parrotbills. By scurrying over the ground, the cuckoo frightens small birds that take off from their nests, revealing their location. Meanwhile, it looks into each bush, descends to the ground, and finds the nests of the birds it needs to lay its egg there. Sometimes, the Common Cuckoo sits unnoticed somewhere in a tree, watching where the birds build their nests, and then, in the absence of the owners of the nests, will supplement their clutch with its own eggs. The cuckoo's eggs almost correspond in color with eggs of the owners of a nest. The female Common Cuckoo for one season can lay from 8 to 25 eggs. However, around each 5 eggs, only one chick hatches and grows. The time from laying eggs to hatching chicks in Common Cuckoos is less than in those whose nests they are.
The embryo in the Common Cuckoo's egg develops faster, so the cuckoo hatches 1-3 days earlier than the host bird's eggs. The Common Cuckoo chick hatches after about 12 days the egg is laid and weighs 3 grams. In a newly born cuckoo, naked, without traces of embryonic fluff, the skin is colored pinkish-orange and the oral cavity is orange. Just like in newly hatched chicks of passerines, the eyelids of the cuckoo chick are tightly closed, but the ear canals remain open. A very small Common Cuckoo, as comfortably settled and with an obeying instinct, throws the eggs out of the nest even if the chicks have hatched before it hatched. Therefore, the host parents feed him alone, but they would not cope with the whole brood because the Common Cuckoo is very voracious. On the fourth day after hatching, the cuckoo chick's weight increases 5 times more than when first hatched. After 20 days, not yet able to fly, the Common Cuckoo gets out of the nest, but for another month, the foster parents take care of it, find food and feed it. Sometimes, the parents have to sit on the back of the chick to reach its beak.
Some species, in whose nests the Common Cuckoo parasitizes, are able to detect and dispose of cuckoo eggs, but never of chicks. Experiments have shown that a cuckoo chick encourages its adoptive parents to feed it by emitting a quick "chick call" (a cry for food) that sounds surprisingly similar to a whole brood of host species' chicks. The researchers suggested that the cuckoo needs to use this vocal technique to encourage proper nest owner care, compensating for the fact that the chick can present only one visual stimulus, its open begging mouth". However, the cuckoo chick needs the amount of food intended for a whole brood of chicks of the host species, and it struggles to induce adoptive parents to feed it with such intensity only with vocal stimulation. Adoptive parents feed the cuckoo chick longer than their own chicks, both before the last one leaves the nest and after it.
The Common Cuckoo cannot incubate chicks on its own because it does not lay eggs immediately, but at intervals of 1 to 3 days. During the time of laying eggs, the female manages to lay 20 and even up to 26 eggs. Since the development of the embryo ends in 11-12 days, it would be impossible to incubate each egg and feed the chick separately. Free from the hassle of building a nest and laying eggs, the Common Cuckoo flies to places where there are many forest pests.
There are also other hypotheses on why the cuckoo lays its eggs on the nests of other birds. One of the hypotheses is that competition with the nestlings of foster parents for food leads to a decrease in the weight of the cuckoo, which is the selection pressure leading to the formation of the behavior of discarding the eggs of the nest owners. An analysis of the amount of food brought to the cuckoo chick by foster parents in the presence or absence of nest owners' chicks showed that cuckoos receive insufficient food when they compete with host chicks, demonstrating an inability to effectively compete for food with the host brood. Selection pressure leading to the development of egg ejection may be due to the cuckoo's lack of precise visual cues to stimulate feeding, resulting in nest hosts either distributing food evenly among all chicks or becoming able to recognize the nest parasite. Another suggests that weight loss in the cuckoo does not serve as a selection pressure on the development of egg ejection. An analysis of the resources received by the cuckoo in the presence and in the absence of the chicks of the nest owners also showed that the weight of cuckoos that grew up together with the chicks of foster parents was much less after leaving the nest than that of cuckoos that grew up alone, but within 12 days thereafter, cuckoos reared with host chicks grew faster than cuckoos reared alone, thus masking initial developmental differences and demonstrating the flexibility of developmental strategies that makes selection for the host oviposition stereotype unnecessary.
Distribution and Habitat[]
The Common Cuckoo occurs in all climatic zones of the western Palearctic. It mainly inhabits forests, steppes, forest-steppes, parks, and mountains up to 3000 m above sea level. It occurs in Eurasia from Western Europe and North Africa to Kamchatka and Japan. The nominate subspecies C. c. canorus is widespread throughout Europe with the exception of Iceland, the far north of Scandinavia and the northeastern part of the Baltic States. The northern limit of distribution of the species runs along the northern edge of the taiga from northern Norway to Kamchatka, roughly along the northern polar circle. The southern limit of distribution to the Himalayas extends approximately along the 40th degree of latitude. They migrate to most of sub-Saharan Africa for the winter.