Bird Families

American dwarf or snake bird

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From Wikipedia, the free encyclopedia

The serpentine, or the Snakebird (Latin Anhinga) is a bird, the only genus of the snake-necked family. To date, four species of this bird are known, one of which is endangered. It got its name from its long, slender neck, which when swimming looks like a snake when the rest of the body is hidden under water.

Dwarfs are large birds with different dimorphic (that is, different in males and females) plumage. Males have black and dark brown plumage, a straight comb at the back of the head, and a beak larger than that of females. In females, the plumage is much less bright, especially on the neck and dewlap. Both males and females have gray dashed lines on the plumage of the upper part of the wings. The beak is long, straight, pointed at the end, has slightly serrated edges. The paws of the snake-necks are completely webbed, short and located far in the back of the body. The plumage gets wet, like cormorants, and therefore, after immersion, the snakes spread their wings wide to allow them to dry out. When flying or landing, they emit clicking or chirping sounds. When breeding offspring, adult birds sometimes emit croaking or hissing sounds. Snake necks are morphologically and ecologically close to cormorants, but differ from them in a number of anatomical features.

Spread

Snake-necks are common in the equatorial, tropical and subtropical belts of the Earth. They live in fresh or brackish water bodies: lakes, rivers, swamps, estuaries, lagoons and bays. They gather in flocks of up to 100 birds, but during breeding they strictly adhere to their individual plot. Most are sedentary, and only populations at the ends of the range are migratory. The Indian snake (Anhinga melanogaster) is endangered. The main reasons for the decline in the population are called the destruction of natural habitats and other human economic activities.

Food

Snake-necks mainly feed on fish. Its long, sharp beak is used to pierce fish like a harpoon. A special joint between the eighth and ninth vertebrae allows them to jerk their neck out sharply, which helps when hunting for fish. In addition, snakes feed on amphibians (frogs, newts), reptiles (snakes, turtles) and invertebrates (insects, shrimps and molluscs). With the help of their paws, they are able to move silently under water and watch for the victim from an ambush. After the victim is captured, they quickly emerge, throw the prey up and swallow it on the fly.

Reproduction

Snake-necks are monogamous, that is, they live in pairs during the mating season. During this time, their small throat sac changes its color from pink or yellow to black, and the skin on the head becomes turquoise (previously yellowish or yellow-gray).

Crossbreeding can be both seasonal and year-round, depending on the habitat. Twig nests are built on trees or in reeds, often near water. Clutch consists of 2-6 eggs (usually four), pale green in color. The incubation period is 25-30 days. Chicks emerge asynchronously, featherless and helpless. Both the male and the female take care of the offspring. Sexual maturity occurs after two years. These birds live for about 9 years. Extinct species from Mauritius (A. nana) and Australia (A. parva) are known only from the found remains of bones. Snakes have been known since the early Miocene. Previously, a large biological diversity of prehistoric species of these birds was observed in America.

In "The Lives of Animals" by Brem, and in many other books, you can read that snake-necks are inimitable swimmers, inferior in speed of movement under water only to penguins and not at all lagging behind cormorants. Based on our observations in Frankfurt, we did not notice this. Rather, we can say that they are moving forward without much haste ”(Bernhard Grzimek).

When ankhinga, she is a snake-neck, swims, sticking out of the water only a long neck with a small head, bending it to the right and left, it looks like a water snake. The bird plunges into the water quietly and noiselessly, dives without a throw or splash. The fish does not scare away. It swims up imperceptibly and, unbending its long neck with a spring, pierces the fish with its beak, like a dagger. It grabs it with a finely serrated beak and floats up. Throws the fish up and again catches in the open beak, the fish upside down enters the bird's throat.

Then he dries feathers for a long time somewhere on a branch or on the back of a hippopotamus, spreading its wings like a cormorant: then the ankhings look like "the eagles depicted on the coats of arms." Then it soars in the sky, lightly and elegantly, spiraling into altitude and gliding downward.

A nest of branches is built by a female on a tree half-flooded with water, or on boughs bent by the river, less often on the ground in reeds. But the male chooses the place for the nest. He beckons the bride with the "play of wings", like the cormorant. The male brings twigs and branches with foliage, the female builds a nest from them. Eggs, 3-5, incubate for a month and feed the chicks together. Chicks, not yet feathered, when alarmed, like young goatsins, crawl out of the nest and hide in the foliage. Then they return to the nest.

Two types of snake-necks: American Ankinge (fresh waters of the extreme south of the United States, Central and South America, up to Northern Argentina) and Anching of the Old World, or Indian (Sub-Saharan Africa, India, Indochina, Indonesia and Australia).

Indian Ankhings also live in a small area near the borders of Turkey and Syria, separated from the nearest settlements of their relatives by wide expanses of steppes and mountains.

β€œShe moved in waves, low above the water itself. Stretching out on a wide front, she slowly crawled forward. It took a lot of time before I managed to understand what was the matter. It turns out that for fishing, thousands, maybe even tens of thousands of snakes gather in a flock of a hundred or several hundred meters long, moving forward above the water and under it as follows: the front ones dive, the rear ones fly forward, and those that emerge from behind again drive through the air. dived "(Oscar Heinroth).

On the Peruvian coast lie tiny islets, on which, as local people remember, not a single drop of rain has fallen yet, and therefore nothing grows on them. However, every meter of their dry coast is worth more than any of the most fertile land.

Even the Incas appreciated these islands: the law protected them and punished with death everyone who came here when the birds breed. Guano - that's what they were guarding! And its producers: cormorants, pelicans, gannets.

Approximately 35 million of these birds now nest here. (On Don Martin Island alone, with an area of ​​16 hectares, there are more than a million cormorants!)

After the Spaniards destroyed the culture of the Incas, guano was forgotten for a long time. But in 1840, the German chemist Liebig found that nature does not know the best fertilizer: in guano, for example, there is 33 times more nitrogen than in ordinary manure. And the "gold rush" of guano began! For several years, 12 million tons were mined off the coast of Peru! And only 32 million tons. The thickness of the original deposits reached 30 meters! With the money raised from the export of guano, the Peruvians were able to build a railway through the highest mountains in the world, fisheries and other profitable enterprises were financed. And suddenly, it seemed, the inexhaustible pantry of natural fertilizers was depleted.

Since 1909, the islands have been taken under protection, armed guards do not allow people to enter them without the special permission of the Guano Management Company. Ships passing by are prohibited from honking, so as not to disturb the birds, and aircraft are not allowed to fly below 500 meters. The banks are separated by meter-long fences to prevent the wind and waves from washing away the guano. They collect it in April - August, once every two years and only when the birds have hatched chicks.

Production in the fifties has already reached 250 thousand tons. Export of guano is limited: almost everything goes to the needs of agriculture in Peru. (Cotton fertilized with guano yields up to 320 quintals per hectare, and without it in Louisiana - only 55, in Egypt - 70.)

It is estimated that the local cormorants and gannets eat 5.5 million tons of fish per year, mainly anchovies, and produce only 200,000 tons of guano (dry weight), much of which is lost at sea. To reduce these losses, anchored platforms are being built in the sea. The experience of South Africa and the USA has shown that while resting on them, birds leave a lot of valuable droppings.

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