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Cuckoos and other nesting parasites

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Common cuckoo (Cuculus canorus) is well known to Europeans and to residents of almost the entire former USSR (with the exception of the tundra regions). More precisely, most people are well aware of her voice - “cuckoo”, from which the name of the bird came from, and not only in Russian, but also in many other languages: cuckoo - in English, kuckkuck - in German, coucou - in -French, kukulka - in Polish, kukacka - in Czech, kaki - in Finnish. And the Latin name given to this bird by Carl Linnaeus is not original.

Common cuckoo

"Ku-ku" - a mating cry with which the male calls the female to his site. Especially often it can be heard on the morning and evening dawn. Sometimes a male can prokukovat without interruption up to 360 times!
The voice of a cuckoo can be heard in the forest and steppe, in gardens and parks, in the mountains, in thickets along the banks of rivers and even on the outskirts of settlements. The male prefers to current, sitting on a tree, but if there are no trees nearby (for example, in the steppe), he can also settle down on a pillar, bush, stone, hillock.
The female, flying up to the current male, utters a short “Kli-Kli” trill, and in moments of intense excitement a dull cry sounds like laughter. Very rarely, cuckoos can make other sounds: a quiet chatter, meowing, barking, clattering.
Few can say that they saw the cuckoo itself. This bird is cautious, usually doesn’t let a person get close, keeps it secretly, in the forest - in the middle and upper wood tiers. In addition, cuckoos are not so numerous. The voice of the current male is carried over a long distance, so it seems that there are a lot of cuckoos in the district. In fact, even in the Chernobyl zone, where there are very few people, less than one cuckoo per square kilometer is now observed.
In addition to the voice of a cuckoo, they are famous for not raising their chicks, but throwing their eggs in the nests of other birds. This phenomenon is called nest parasitism. An ordinary cuckoo can parasitize about 150 species of birds, but in each locality it usually specializes in some 2-3 species, preferring small insectivores (which more often than grain-eating birds feed their chicks). In addition, cuckoos usually choose nests located openly: near the ground or on branches, and much less often they throw eggs at nests arranged in hollows or crevices.
Most often the victims of cuckoos are wagtails, zaryanki, blackbird warblers, redstart. Minor hosts - curlers, minting, ice skates, gray flycatcher, black-headed warbler, shrike, finch. Even less often, cuckoo eggs are found in nests of froths, bluethroats, song thrush, and hawk glory. And the nightingale is considered to be a very random “educator” of cuckoos, a forest lark is a reserve for cuckoo parasitism. However, well-fed cuckoo chicks were also found in sparrow nests, and eggs were found in lentils, oatmeal, siskin, tapeworm, and linnet nests. But, as already mentioned, these granivorous birds are less likely to fly to chicks with food, and cuckoos in such nests often die of hunger.

Gray flytrap on the fly feeds the cuckoo

It is interesting that in Japan over the past 50 years ordinary cuckoos began to parasitize successfully in a form unusual for them before - blue magpie (Cyanopica cyana). And this magpie, in turn, began to develop protective behavior - an aggressive attitude towards the cuckoo, which was not previously observed.
In ordinary cuckoo owners, this behavior has developed long ago. If the birds notice the cuckoo, they raise the alarm and attack it. Perhaps her appearance also contributes to this - the relatively long tail and the alternation of light and dark transverse stripes on her chest give the cuckoo a resemblance to a hawk. Small birds try to drive away a dangerous neighbor, jump on him, peck, but the female cuckoo very patiently tolerates these attacks, only trying to shake off the attackers from time to time or moving slightly to the side. It does not fly away far and generally tries to move less. Gradually, the birds stop paying attention to the cuckoo and return to the nests, at the same time giving out their location. And later, usually between noon and dusk, the female cuckoo, seizing the moment, quickly flies up to someone else's nest, choosing where there are already one or more eggs of the host, and lays its egg there. One of the eggs already in the nest is taken by the cuckoo in its beak, so that later, aside, to peck it and eat it. All this usually takes no more than 10 s.
The male cuckoo, apparently, does not help the female to throw eggs - his very presence near the "crime scene" was observed only in very rare cases.

The cuckoo breeding season is extended and lasts from late April - early May to mid-July. During this time, the female usually lays from 6–8 to 20–25 eggs with an interval of 1-3 days.
Cuckoo's eggs are small (weighing 3–3.5 g), similar in size and color to the eggs of the most common hosts of the parasite. In total, about 30 types of egg color are known in common cuckoos. For example, bluish, like a redstart, with dark spots, like a blackbird warbler, with a brownish tint, like a garden warbler. Moreover, within the same area, different females often lay eggs of some particular type, i.e. we can say that cuckoos have ecological races oriented towards specific host species. But how such races are formed is not yet known exactly.
Sometimes the cuckoo victims can recognize the egg that has been thrown. Then they either throw it away, or cover it with a new litter on top, or generally drop the nest and begin to build a new one. But usually a cuckoo egg goes unnoticed.

Cuckoo eggs develop faster than the eggs of host birds, typically 12 days instead of 3 weeks. 8-10 hours after the birth of the cuckoo, a intolerance reflex begins to form in everything that he comes into contact with in the nest, and he tries to throw all objects out of the nest. If he cannot throw an egg or a chick, he tries to crush it with his body or pierces the egg shell with his claws. Helping himself with his wings, he lifts the burden on his back, backs to the edge of the nest, tensing, rises on his feet and throws the egg or chick down. One cuckoo egg can be thrown out in 20 seconds, and when full, it acts almost without rest and in 1-2 hours can throw all eggs out of the nest.
Intolerance to the touch of foreign objects to the body, especially to the back, is manifested in the cuckoo in the first 2–4 days of life, but sometimes drags on for 8 days.
Occasionally, a cuckoo's chick is born later than the hosts' chicks and, accordingly, is smaller than them. Nevertheless, it was observed that a cuckoo weighing 6 g threw 12 grams of crayfish from the nest of its nest, and a cuckoo weighing 8 g threw a 24 g thrush chick! If he does not get rid of other chicks, then he subsequently runs the risk of dying due to lack of food - after all, he needs no less food than the whole brood of a small insectivorous bird. And only very rarely have there been cases when a cuckoo's chick has successfully grown together with a brood of eggplants or redstart.
Sometimes it happens that several female cuckoos lay eggs in one nest, and then 2 or 3 cuckoos fight in the nest until everyone dies or one stronger one remains.

Quickly completing the period of internal egg development, the descendant of the cuckoo, and after hatching, is growing at an "accelerated pace." For 20 days of chick life, he increases his weight by 30 times! Left alone, the little cuckoo emits a chuckle from time to time, calling this sound to foster parents with food, and when they arrive it makes a trill, similar to a ringing of a bell, opens its mouth wide and does not close it, swallows food laid there until the breadwinners disappear from field of view. A wide-open mouth is a key irritant for parent birds; when they see it, they zealously feed the chick, despite the fact that it is very different from themselves and quickly begins to exceed their size. If the adoptive parents, having brought the next portion of food, do not fly away for a new one, the cuckoo begins to drive them, scare them away: swings, sways, spreads its wings, throws its head back.
In 17–18 days after hatching, the cuckoo's chick already leaves the nest with a cage, i.e. not yet able to fly, but only a flashing bird. But the young cuckoo begins to eat and fly well on its own only after 5 weeks of life. Sometimes adoptive parents feed her another 4-6 weeks after departure from the nest.

Does cuckoo parasitism affect the number of host birds? Apparently slightly. In general, in nature, about 40% of small songbird nests die for various reasons, for example, it is ruined by predators, so many of them have to do up to 2–4 clutches during the breeding season. The role of cuckoos in these processes is relatively small. In the forest zone of Russia, Ukraine, Belarus, the Baltic states, the total infection of nests with cuckoo eggs does not exceed 10–20%, only in some areas where there are many cuckoos, this value reaches 30–40%. Higher values ​​are also known, for example, in Western Europe, there were cases when up to 50–55% of reed and blackbird warblers nests were infected with cuckoo eggs, and in the Oksky Reserve they were found in 90% of the nests of the white wagtail. But these are exceptional cases.

Another well-known feature of cuckoos, which is sometimes used to “rehabilitate in public opinion”, is the ability to eat hairy caterpillars, among which there are many serious forest pests. It should be noted that cuckoos, being predominantly insectivorous birds, are, in principle, not very picky about food and eat those types of insects that are currently the most. With the mass reproduction of forest pests, including those whose caterpillars are covered with poisonous hairs, they really eat them in large quantities, bringing them significant benefits. Once in the Crimea, 300 caterpillars were found in the stomach of an adult male cuckoo! But the glory of cuckoos as "monopoly", the only ones, hairy caterpillar exterminators is exaggerated. At least 12 more species of birds eat them in our forests - just cuckoos usually swallow the whole caterpillars, so that they are then easier to find in the bird’s stomach. Other birds, before eating a hairy caterpillar, carefully grind it with their beaks and pull out hairs, so it is difficult to determine later what exactly was eaten.

There is not so much information about the extra-nesting life of cuckoos, in particular those obtained as a result of banding. Soon after the transition to independent life, young birds begin to migrate to wintering places. Since the breeding season is extended, this occurs at different times, in the southern regions - also in September. Adult cuckoos begin to migrate south soon after the completion of egg laying, from mid-July. Cuckoos of European populations winter in southern Africa, Asian ones in Southeast Asia and New Guinea. Cuckoos fly at night - at an altitude of more than a kilometer, and during the day - but already lower. The bulk of cuckoos arrives at their wintering sites in December, and in March the birds begin the return flight. So in fact, both in wintering places and in breeding places they spend 3 months each, and the remaining six months at cuckoos go on flights. In breeding places, individual sections of females, depending on the number of bird nests, occupy from 20 to 30 hectares, in males - less. There are observations that individual males returned to one site and 3, and 5 years in a row.
The total number of common cuckoos in 37 European countries is approximately estimated at 1.5 million individuals.

In addition to the common cuckoo in the cuckoo family (Cuculidae) include about 130 other bird species distributed around the world except Antarctica and the Arctic. But only 50 of them are prone to nest parasitism, and even then to varying degrees.
The most specialized parasites are those whose chicks throw eggs from their nests and host chicks - 12 species of the genus of real cuckoos (Cuculus) In addition to the usual, this includes found in Russia east of the Urals deaf cuckoo (Cuculus saturatus) - in appearance and biology, it looks like an ordinary one, but its cry is not “cuckoo,” but “doo-doo.” In the Far East, there are other species whose biology is very poorly studied - for example, small (Cuculus poliocephalus) and indian (Cuculus micropterus) cuckoos.
Of the American family, only 3 species of striped cuckoos from the genus Tapera are specialized parasites of passerines. Their chicks have a sharp hook on their beak, and when the host's chick stretches its neck to meet its parents who arrived with food, the striped cuckoo chick kills him with this hook, piercing his throat.

Crested cuckoo (Clamator glandarius), common in North Africa, Central Asia and the Iberian Peninsula, it looks somewhat reminiscent of magpie and lays eggs in nests of corvids, most often forty. But her chicks peacefully grow in a brood to scrub and do not throw them out of the nest, like a chick of an ordinary cuckoo. Interestingly, an increase in the number of magpies led to the expansion of the area of ​​the crested cuckoo - it appeared in the south of France, in Bulgaria.
African bronze cuckoos of the genus Chrysococcyx they throw eggs into other people's nests, but they feed on the departed chicks themselves.
American genus Cranberries Coccyzus can toss eggs into other people's nests occasionally when the female has too many eggs, and then their chicks successfully grow along with the chicks of the nest owner. Multi-billed cuckoos can also simply occupy other people's nests, laying their eggs there and incubating them, or they can twist their nests on their own.

And living in America Ani Larvae (Crotophaga ani) build collective nests where several females lay their eggs and then incubate them together, periodically replacing each other. True, the dominant female can throw part of the eggs laid before her into a common nest.
Finally, in the cuckoo family there are also species of a completely “decent” disposition - the male and the female build a nest together, incubate the clutch and feed their own chicks. Such, for example, is the American earthen cuckoo (Geococcyx mixicanus).
It is interesting that ordinary cuckoos, when kept in open-air cages in the spring, actively begin to collect and wear wool, feathers, threads, grass blades in their beaks - material for building a nest. But they never get to the point of construction, gradually the nesting activity fades, and they cease to pay attention to suitable material.

Ani larva

Nest parasitism is a trait that distinguishes not only cuckoos. Among birds, it is observed in about 80 species belonging to 5 families. About another 20 species are optional parasites, they can either toss their eggs to other species, and build nests and hatch the clutch on their own.

Highly specialized parasites, differing, for example, by the special sensitivity of the skin in chicks, include 27 species. This is the already mentioned cuckoo birth Cuculus and Tapera, and honey indicators (genus Indicator in the family of medical indicators). Medo-pointers are small gray birds from Africa that lay eggs in a hollow with woodpeckers and beards. In the first 4 days of their lives, honey-pointing chicks, like striped cuckoo chicks, have a hook on their beak, with which they pierce the eggs and chicks of the host, which is simply difficult for them to throw out of the hollow.

In America, as parasites more than cuckoos, cow-birds are visible - representatives of several genera from the family of cadavers. They got their name because they can often be seen among a herd of grazing cows, where they look for scared insects.
Like cuckoos, cow-birds have different stages of development of nest parasitism. For instance, winged jaundice (Molothurus badius) is able to build a nest itself, but more often it takes strangers. A noisy jaundice (Molothurus rubraxillaris) parasitizes on the borealis, tossing its eggs into its clutch. Some cow-birds can toss their eggs into the nests of more than 200 species of birds!
Usually chicks of cow parasitic birds grow in a common brood with the host chicks, but are more active and oppress them. According to some observations, the development of one parasite chick of an oxen bird costs the life of 1–2 nestling hosts. But the overall survival rate of cowhide is not higher than that of host species.

In Africa they live widow birds (genus Vidua) from the weaver family. These are also nesting parasites; they toss their eggs into the nests of related weaver birds, in particular the astrid. Each widow species parasitizes on a strictly defined host species, and their chicks are very similar in color, behavior and voice to the chicks of their adoptive parents, with whom they peacefully grow up in the same brood. At this time, young males of widows learn to sing from their adoptive parents, and young females capture the corresponding sounds. In the future, the male and female widow birds parasitizing on the same species of astrilles find a friend precisely from a song that mimics a song of a host species.

In episodic nesting parasitism, 32 species of anseriformes were also observed. In their case, this usually occurs when there is a lack of suitable nesting places, such as a hollow, or when there is a large crowding of birds in a limited area. The eggs are thrown into other people's nests, chicks emerge from them, who immediately lead an independent life in a common flock with the chicks of the nest owners. This happens in the white goose, dives, crested black. Some ducks lay their eggs in one common nest. For example, in a Gogol’s hollow duck, when there are not enough places for nests, two females can lay eggs in one hollow. And in the nest of the red-headed dive even 87 eggs laid by 13 females were once observed. Among ducks, there is only one species, South American black-headed duck (Heteronetta atricapilla), which is characterized by real nesting parasitism. This duck never builds nests, but always throws eggs into the nests of other ducks. But her chicks do not cause foster parents any concern, and immediately after hatching, they begin to lead an independent life.

Cases of tossing eggs into other people's nests are occasionally observed in some gulls and waders.

However, nest parasitism is not unique to birds - besides them, a similar phenomenon is also observed in some fish. Lives in central america leopard cichlazoma (Cichlasoma dovii) from the family of cichlids, which spawns next to other cichlomas, taking care of the offspring, and throws their eggs in their clutch. Foster parents guard the eggs, and then the fry, both their own and those of others. And in the lake of Tanganyika in Central Africa there are synodontis catfish (Synodontis), which toss their caviar to cichlids and trophies (Tropheus) incubating caviar in the mouth. In this case, the larvae of catfish parasites develop faster than the larvae of the cichlid hosts and, when switching to independent feeding, first of all, right there, in the mouth of the trophy, eat its eggs. Synodontis cuckoos are sometimes kept in aquariums. One of their most famous species is spotted synodontis (Synodontis multipunctatis) - even breeds in the Moscow Zoo. At the same time, they observed how the catfish fry quickly grew and destroyed their adoptive mothers, the female trophies, for 40 days, getting stuck in their throats with the help of sharp spikes on the fins.

Finally, nest parasitism is also observed in insects. The most famous cuckoo bumblebees from the genus Psithyrus - there are many species, and each looks very similar to the corresponding type of ordinary bumblebee. The female cuckoo bumblebee enters the host of the bumblebee host, kills the founder of the colony and begins to lay her eggs. And the working bumblebees - the owners of the nest - feed the larvae of the bumblebee-parasite, as they would feed their brethren - the larvae of their own uterus. Austrian wasp Vespula austriaca also does not build its nests, but is a parasite in the nest of a red wasp Vespula rufa, the working individuals of which feed the parasite wasp larvae. The Austrian wasp does not form its own working individuals as unnecessary, and all the larvae turn into full-fledged males or females.

Social parasitism is common among ants. Females of the parasite species penetrate the nest of the host species and lay their testicles there, from which work individuals emerge, which gradually populate the nest, replacing its owners. So, red forest ant (Formica rufa) can base nests in a nest brown forest ant (Formica fusca) Female hairy yellow ant (Lasius umbratus) settles in the nest black garden ant (Lasius niger) and kills the female owner. Occurring in the south of France ant epimirm (Epimirma vandeli) parasitizes on the ant Leptothorax recedens, killing the female founder of the nest. The epimirma has no workers, only males and females emerge from its testicles, and the former leptothorax nest exists after infection for only two years, while old working individuals live.

But in general, nest parasitism in different groups of vertebrate and invertebrate animals is not widespread. With the strong reproduction of specialized nesting parasites that destroy the offspring of the host species, the number of the latter can decrease, and as a result the well-being of the parasite itself is also undermined. Therefore, nest parasitism can be considered a dead end in the evolution of the reproduction strategy, which does not give the mind any particular advantages.

Literature

Life of animals. T. 3, 5. - M .: Education, 1969, 1970.
Ilyichev V.D., Kartashev I.I., Shilov I.A. General ornithology. - M., 1982.
Malchevsky A.S. Cuckoo and her carers. –L .: LSU, 1987.
Nikolai Yu. Birds. - M., 1974.
Welty K., Storer J., Pennwick K. Birds of the world. - M.: Mir, 1983.
Fauna of the World. Birds / Ed. Ilyicheva V.D. - M .: Agropromizdat, 1991.

The problem of nest parasitism as a complex of general and specific ecological and morphological adaptations of bird nest parasites and their evolution. Actual data on the distribution and breeding species of nesting parasites in the world bird fauna.

HeadingBiology and Natural Sciences
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TongueRussian
Date Added29.04.2014
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    Introduction
  • 1. General concept
  • 2. The evolution of nest parasitism
  • 3. Species diversity
  • 3.1 Cuckoos and other nesting parasites
  • Conclusion
  • Literature

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