Cuckoos

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Cuckoos
Cuckoo (Cuculus canorus)

Cuckoo ( Cuculus canorus )

Systematics
Sub-stem : Vertebrates (vertebrata)
Superclass : Jaw mouths (Gnathostomata)
Row : Land vertebrates (Tetrapoda)
Class : Birds (aves)
Order : Cuckoo birds
Family : Cuckoos
Scientific name of the  order
Cuculiformes
Wagler , 1830
Scientific name of the  family
Cuculidae
Vigors , 1825
Indian Koel , females - one of the few fruit-eaters within the cuckoo family

The cuckoos (Cuculidae) are the only family in the order of the cuckoo birds (Cuculiformes). It contains about 140 species , of which more than 50 obligate brood parasites are that do not make use of their young birds themselves. They specialize in individual host bird species and sometimes show very strong adaptations to these species.

Two types of cuckoo are represented in Europe with the cuckoo and the jay cuckoo . Most of the species in this family live in Africa, Asia, and Australia. Most of them are tree dwellers.

features

Cuckoos are mostly medium-sized birds. The smallest species reach a length of 14 cm, the largest of 70 cm thanks to their extra-long tails. The tail feathers are tiered, but the tails are never pointed. The wings are often quite short. The cuckoo's foot is zygodactyl , that is, the first and fourth toes point backwards, the second and third toes point forward. The beak is usually short and slender.

Most types of cuckoo are simply gray, brown or olive in color. The colors usually form a rough pattern of stripes and spots. Some species also show a shiny metallic black such as anise . Bright, bright colors are rarely pronounced, but can be found, for example, in the real gold cuckoos . Many cuckoos do not show any sexual dimorphism , with others the sexes often differ greatly in size and weight. The cuckoo's call consists of repeated rows of melodious sounds.

Distribution and way of life

With the exception of Antarctica , the northern tundra regions , the deserts of North Africa and the Middle East and many oceanic islands, cuckoos live on all continents worldwide. The main area of ​​distribution is Asia, Africa and South America. In Western Europe only the cuckoo and the jay cuckoo occur, in European Russia and occasionally in Finland the hoof cuckoo is also represented as a breeding bird. In North America, there are only eight species native to the yellow-billed cuckoo , black- billed cuckoo , mangrove cuckoo , road cuckoo , racing cuckoo as well as the deep-beaked ani and the smooth- beaked ani .

The preferred habitat of cuckoos are forests and bush landscapes. Most of the cuckoos are tree dwellers. A few species, such as those from the subfamily of the ground cuckoo , to which the racing cuckoo belongs, are ground dwellers. The cuckoos also prefer to stay on the ground.

Most cuckoos eat insects and their larvae. Very hairy caterpillars, which are avoided by most bird species, are eaten by numerous species of cuckoo. Many of the cuckoos remove hair and intestinal contents from the caterpillars by beating their prey against branches. In addition, cuckoos also eat other invertebrates and small vertebrates and are occasionally also nest robbers. A few species prefer to eat fruit.

Brood parasitic cuckoos

Striped cuckoo, one of the brood parasites among the cuckoos
Gold cuckoo
Young bronze cuckoo ( Chrysococcyx lucidus ) with caterpillar
Gould cuckoo

Classification of individual species as brood parasites

The oldest references to brood parasitism of a type of cuckoo can be found in the Indian Vedas around 2000 BC. Chr .: These writings comment on the behavior of the Indian koel ( Eudynamys scolopaceus ), who is referred to as a bird that is raised by others. Further details are not given. It was not until around 375 AD that another document from this cultural area recorded that this species was used in crows. These are classified as the most common host birds even today. Greek natural philosophers already in the 4th century BC. Commented on the brood parasitism of the cuckoo, which is widespread in Eurasia. The next mention of a brood parasitic species was made by Jahangir , a ruler of the Mughal Empire (1605–1627), who recorded that Clamator jacobinus used Timalia as host birds. It was not until 1802 brood parasitism was first described for a species that did not belong to the family of cuckoos: Félix de Azara , one of the most important Spanish South America researchers, held this year found that the Glanzkuhstärling that the Kuhstärlingen heard in Paraguay and Argentina a Is a brood parasite.

In 1806, the French ornithologist François Levaillant noted that other species of cuckoo, namely Cuculus clamosus , Cuculus gularis and the golden cuckoo , are brood parasites. In 1853, Alfred Brehm cited the first evidence for the jay cuckoo that it was a brood parasite, and in 1879 this was also reported for the grizzled cuckoo .

The classification of other species as brood parasites continued in the 20th century. The striped cuckoo was classified as a brood parasite in 1909 and the peacock cuckoo in 1914. This was established for the genus Pachycoccyx in 1936; the British ornithologist Reginald Ernest Moreau pointed out in 1939 that there was sufficient evidence to classify the genus Cercococcyx as a parasite. For most species of this genus, however, it is still unclear what the typical host birds are. In contrast, the host birds of the pheasant cuckoo are known , but have not yet observed whether it removes other nestlings and eggs from the nest after hatching.

Behavioral characteristics of obligate brood parasites

Bird species that never raise juveniles themselves, but always lay their eggs in foreign clutches, are referred to as obligate parasitic species.

The detailed investigation of behavioral characteristics in brood parasitic cuckoo species began in the 20th century. Edgar Chance examined the behavior of individual female cuckoos in a carefully carried out field study between 1918 and 1925. He was able to prove that cuckoos prefer to look for the nests of a host bird species, that they observe the nests of their host bird beforehand and that the egg-laying takes place within a few seconds directly in the host bird's nest. Since one repeatedly observed female cuckoos with an egg in their beak, it was previously thought possible that the cuckoo lays the egg sitting on the ground, then takes it in its beak and lays it in the host bird's nest. In 1921 he was even able to film the entire process of oviposition. The results of Chance's research are confirmed by a number of similar field studies. In sum, it is the following adaptations that allow brood parasitism:

  • Synchronization of egg maturation with the host bird
  • Accelerated oviposition, as host parents are sensitive to disturbances and give up nests
  • Adjustment of egg size and egg mimicry
  • Removing eggs and fledglings from the host bird
  • Higher assertiveness of the cuckoo nestlings compared to the nestlings of the host bird species

For the brood parasitic species within the subfamily of the old world cuckoos, they usually choose those that are smaller than themselves as host birds. Mostly, they are small-sized insectivorous species such as timalia or shrike . In most species, the female only lays one egg per host nest and the newly hatched juvenile removes the eggs or the other young birds from the nest and is then raised by the host birds alone. Exceptions are Eudynamys scolopaceus and the grimacing cuckoo. Both are breeding parasites of crows of equal size. NB Davies therefore speculates whether the newly hatched nestlings of these two species might also try to remove the other nestlings and the eggs that have not yet hatched, but then finally give up because they are too big for it. However, the parasitic species of the genus Clamator also do not show this behavior and, according to current knowledge, do not try to either. The jay cuckoo, which belongs to the clamator species, parasitizes even species that are significantly larger than it with magpie , carrion crows and tortoiseshells . Although nestlings of these parasites grow up together with the nestlings of their host birds, they are often more assertive when it comes to begging for food. Nestlings of the host birds often starve to death or are crushed by the alien nestlings. According to some studies, an average of only 0.6 magpies fledglings in a nest parasitized by jay cuckoos, while an average of 3.5 magpies fly out in a non-parasitized nest.

Some of the brood parasitic cuckoos lay eggs that are similar in color to the eggs of the host birds. This is particularly pronounced in the cuckoo found in Central Europe . Females specialize in individual host bird species and the cuckoo eggs resemble the clutch very well in terms of color and pattern. How it is possible for the female cuckoo to match the laid eggs to the clutch was clarified in the case of the bluish eggs: the females have both the preference on their W sex chromosomes (as with other birds, females have ZW chromosomes, males ZZ chromosomes) for a certain host bird species (e.g. the common redstart with a bluish clutch) as well as for the coloring (bluish) and pattern (uniform) of the egg. However, this strong adaptation does not apply to all brood parasitic cuckoos, in many species the cuckoo's egg differs greatly in size and color from that of the host birds.

Community nesting cuckoos as a pre-form of brood parasitism

Guirakuckuck

Since all Old World cuckoos (Cuculinae) and only three of the New World cuckoos are obligate brood parasites , NB Davies argues that this species of reproduction evolved twice in this family. Since there are other unusual forms of rearing young birds within the cuckoo, he further argues that this family is particularly predestined for the development of brood parasitism.

A preform of brood parasitism can be found in the species of the genus of the maggot cuckoo . In addition to the aniseed, they also include the South American guirakuckuck . All species of this subfamily raise their young in a community nest. There is fierce competition between the parent birds. During the breeding season, guira-chucks form small flocks that can range from two to 18 individuals, but the rule is six to eight individuals. The females of the troop lay their eggs in a community nest, the number of eggs is higher, the more females belong to a troop. On average, around half of the eggs in these joint clutches are lost. This loss of eggs is brought about by the guira cuckoos in a targeted manner: adult guira cuckoos take individual eggs in their beak and throw them directly out of the nest or take an egg in their beak, move a few meters away from the nest and drop it there. This behavior can be observed especially at the beginning of the egg-laying, but can also occur when the eggs are already incubated. There is evidence that this behavior occurs mainly in females who have not yet begun to lay eggs. Basically, a female's eggs vary so much in size, shape, color and pattern from one another that she is not able to identify her own eggs within a clutch. Nestlings are occasionally removed from the nest by members of the squad or even killed there. This usually happens in the first few days after the nestlings have hatched. This infanticide leads to the fact that the nest is occasionally abandoned by the troop. According to individual studies, the percentage of nests in which there is a full or partial infanticide is 69 percent.

Guirakuckucke place occasionally as so-called facultative brood parasites and eggs in the nests of birds like the smooth-billed ani , Caracara , chimango caracara , band plantcutter and bronze lapwing .

Systematics of the cuckoo birds

Common Blue Cuckoo ( Clamator glandarius )
Grimace devil ( Scythrops novaehollandiae )
Guirakuckuck ( Guira guira )
Jacobin cuckoo from the genus of the crested cuckoo in flight

There are 28 genera and 136 species in 6 subfamilies

literature

Single receipts

  1. ↑ Davies: Cuckoos, Cowbirds and Other Cheats . P. 12.
  2. ↑ a b Davies: Cuckoos, Cowbirds and Other Cheats. P. 14.
  3. ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 3.
  4. ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 19.
  5. ↑ a b c Davies: Cuckoos, Cowbirds and Other Cheats. P. 15.
  6. ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 17.
  7. ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 31 and p. 32.
  8. ↑ Secrets of Nature: The Cuckoo's Secret (1922) . Wild film history. Retrieved July 16, 2016.
  9. ↑ a b c Davies: Cuckoos, Cowbirds and Other Cheats. P. 16.
  10. ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 104.
  11. ↑ Frode Fossøy, Michael D. Sorenson, Wei Liang, Torbjørn Ekrem, Arne Moksnes, Anders P. Møller, Jarkko Rutila, Eivin Røskaft, Fugo Takasu, Canchao Yang, Bård G. Stokke: Ancient origin and maternal inheritance of blue cuckoo eggs . In: Nature Communications , Volume 7, Article Number 10272, January 12, 2016, doi : 10.1038 / ncomms10272 .
  12. ↑ Davies: Cuckoos, Cowbirds and Other Cheats. P. 246.
  13. ↑ a b c d Erhitzøe, Mann, Brammer, Fuller: Cuckoos of the World . P. 102.
  14. ^ RB Payn (1997): Family Cuculidae , in Josep, del Hoyo; Andrew, Elliott; Jordi, Sargatal: Handbook of the Birds of the World . Volume 4, Sandgrouse to Cuckoos , Barcelona: Lynx Edicions, pp. 246-269, ISBN 978-84-87334-22-1

Web links

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