Common cuckoo
| Common cuckoo Temporal range: | |
|---|---|
.jpg) | |
| in Thursley Common, Surrey, England | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Cuculiformes |
| Family: | Cuculidae |
| Genus: | Cuculus |
| Species: | C. canorus |
| Binomial name | |
| Cuculus canorus | |
 | |
| Range of Cuculus canorus Breeding Passage Non-breeding Possibly extant (breeding) | |
The cuckoo, common cuckoo, European cuckoo or Eurasian cuckoo (Cuculus canorus) is a member of the cuckoo order of birds, Cuculiformes, which includes the roadrunners, the anis and the coucals.
This species is a widespread summer migrant to Europe and Asia, and winters in Africa. It is a brood parasite, which means it lays eggs in the nests of other bird species, particularly of dunnocks, meadow pipits, and reed warblers. Although its eggs are larger than those of its hosts, the eggs in each type of host nest resemble the host's eggs. The adult too is a mimic, in its case of the sparrowhawk; since that species is a predator, the mimicry gives the female time to lay her eggs without being attacked.
Taxonomy
[edit]The species' binomial name is derived from the Latin cuculus (the cuckoo) and canorus (melodious; from canere, meaning "to sing").[2][3] The cuckoo family gets its common name and genus name by onomatopoeia for the call of the male common cuckoo.[4] 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. The song is written in Middle English, and the first two lines are "Svmer is icumen in / Lhude sing cuccu." In modern English, this translates to "Summer has come in / Loudly sing, Cuckoo!".[5]
There are four subspecies worldwide:[6]
- C. c. canorus, the nominate subspecies, was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. It occurs from Ireland through Scandinavia, northern Russia and Siberia to Japan in the east, and from the Pyrenees through Turkey, Kazakhstan, Mongolia, northern China and Korea. It winters in Africa and South Asia.
- C. c. bakeri, first described by Hartert in 1912, breeds in western China to the Himalayan foothills in northern India, Nepal, Myanmar, northwestern Thailand and southern China. During the winter it is found in Assam, East Bengal and southeastern Asia.
- C. c. bangsi was first described by Oberholser in 1919 and breeds in Iberia, the Balearic Islands and North Africa, spending the winter in Africa.
- C. c. subtelephonus, first described by Zarudny in 1914, breeds in Central Asia from Turkestan to southern Mongolia. It migrates to southern Asia and Africa for the winter.
Lifespan and demography
[edit]Although the common cuckoo's global population appears to be declining, it is classified of being of least concern by the International Union for Conservation of Nature. It is estimated that the species numbers between 25 million and 100 million individuals worldwide, with around 12.6 million to 25.8 million of those birds breeding in Europe.[1] The longest recorded lifespan of a common cuckoo in the United Kingdom is 6 years, 11 months and 2 days.[2]
Description
[edit]
The common cuckoo is 32–34 centimetres (13–13 in) long from bill to tail, with a tail of 13–15 centimetres (5.1–5.9 in) and a wingspan of 55–60 centimetres (22–24 in).[4] The legs are short.[7] It has a greyish, slender body and long tail, similar to a sparrowhawk in flight, where the wingbeats are regular. During the breeding season, common cuckoos often settle on an open perch with drooped wings and raised tail.[7] There is a rufous colour morph, which occurs occasionally in adult females but more often in juveniles.[4] It has been hypothesized to have evolved as a deterrence to male harassment or host species mobbing.[8]
All adult males are slate-grey; the grey throat extends well down the bird's breast with a sharp demarcation to the barred underparts.[9] The iris, orbital ring, the base of the bill and feet are yellow.[7] Grey adult females have a pinkish-buff or buff background to the barring and neck sides, and sometimes small rufous spots on the median and greater coverts and the outer webs of the secondary feathers.[9]
Rufous morph adult females have reddish-brown upperparts with dark grey or black bars. The black upperpart bars are narrower than the rufous bars, as opposed to rufous juvenile birds, where the black bars are broader.[9]
Common cuckoos in their first autumn 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 retain some barred secondaries and wing-coverts.[9] The most obvious identification features of juvenile common cuckoos are the white nape patch and white feather fringes.[7]
Common cuckoos moult twice a year: a partial moult in summer and a complete moult in winter.[9] Males weigh around 130 grams (4.6 oz) and females 110 grams (3.9 oz).[2] The common cuckoo looks very similar to the Oriental cuckoo, which is slightly shorter-winged on average.[9] This resemblance extends even to the rufous morphs, which are also present in Oriental cuckoos. The presence of rufous morphs may well be ancestral to both Oriental cuckoos and common cuckoos.[8]
Mimicry in adults
[edit]
The barred underparts of the common cuckoo resemble those of the Eurasian sparrowhawk, a predator of adult birds. A study comparing the responses of Eurasian reed warblers, a host of cuckoo chicks, to manipulated taxidermy model cuckoos and sparrowhawks found that reed warblers were more aggressive to cuckoos with obscured underparts, suggesting that the resemblance to sparrowhawks is likely to help the cuckoo access the nests of potential hosts.[10] Other small birds, great tits and blue tits, showed alarm and avoided attending feeders on seeing either (mounted) sparrowhawks or cuckoos; this implies that the cuckoo's hawklike appearance functions as protective mimicry, whether to reduce attacks by hawks or to make brood parasitism easier.[11]
Hosts attack cuckoos more when they see neighbors mobbing cuckoos.[12] The existence of the two plumage morphs in females may be due to frequency-dependent selection if this learning applies only to the morph that hosts see neighbors mob. In an experiment with dummy cuckoos of each morph and a sparrowhawk, reed warblers were more likely to attack both cuckoo morphs than the sparrowhawk, and even more likely to mob a certain cuckoo morph when they saw neighbors mobbing that morph, decreasing the reproductive success of that morph and selecting for the less common morph.[12]
Voice and courting
[edit]The male's song, goo-ko, is usually given from an open perch. During the breeding season the male typically gives this vocalisation with intervals of 1–1.5 seconds, in groups of 10–20 with a rest of a few seconds between groups. The female has a loud bubbling call.[4] 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 such as ascending intervals. The wings are drooped when the bird is calling intensely, and when in the vicinity of a potential female, the male often wags its tail from side to side or the body may pivot from side to side.[13]
Distribution and habitat
[edit]Essentially a bird of open land, the common cuckoo is a widespread summer migrant to Europe and Asia, and winters in Africa. Birds arrive in Europe in April and leave in September.[7] The common cuckoo has also occurred as a vagrant in countries including Barbados, the United States, Greenland, the Faroe Islands, Iceland, Indonesia, Palau, Seychelles, Taiwan and China.[1] Between 1995 and 2015, the distribution of cuckoos within the UK has shifted towards the north, with a decline by 69% in England but an increase by 33% in Scotland.[14]
Behaviour
[edit]Food and feeding
[edit]The common cuckoo's diet consists of insects, with hairy caterpillars, which are distasteful to many birds, being a specialty of preference.[15][16] It also occasionally eats eggs and chicks.[17]
Breeding
[edit]
The common cuckoo is an obligate brood parasite; it lays its eggs in the nests of other birds. Hatched cuckoo chicks push host eggs out of the nest.[18] A female may visit up to 50 nests during a breeding season. Common cuckoos first breed at the age of two years.[2]
Egg mimicry
[edit]More than 100 host species have been recorded: meadow pipit, dunnock and Eurasian reed warbler are the most common hosts in northern Europe; garden warbler, meadow pipit,