Last time we talked about nests and eggs, today we will talk about adult birds and chicks.
# 1. The colony, as I said, is very dense. Because I did not shoot from a blind spot, but from the approach - some of the birds do not sit on the nest, but stand nearby
# 2. I came closer - the terns have readiness number one!
Number 3. The most nervous ones can't stand it
No. 4. And now the rest are taking off
No. 5. In a second, no air is visible
No. 6. Terns do not fly far away - they circle over the colony, scream. Almost never a person is attacked, which pleases, given their size :)
No. 7. If you stand and do not try to come closer, the terns calm down and begin to sit on the nests.
No. 8. Krachina "whatnot" :)
No. 12. The nestling of the variegated tern is very different from the nestling of the river - both in the structure and color of the down, and in the color of the legs and beak.
No. 13. The best way to protect yourself is to close your eyes.
No. 14. "Large" family - one chick has already hatched and one more will be. 2 eggs in a nest are rather rare, most have one egg.
No. 16. And this is already a teenager - down is almost replaced by feathers. He cannot fly yet, so in case of danger he tries to swim away
No. 17. Spotted terns are very "psychotic" parents, so chicks leave their nests early enough and hide in the grass. Well, or in stones, like here, on the spit of the Kuyalnitsky estuary. In case of danger, they crawl out of their shelters and accumulate on the shore.
No. 18. When frightened, some regurgitate fish, which is still poorly digested and interferes with turning their heads (in small chicks, fish can even stick out of the beak - it is gradually digested in the stomach and sinks deeper)
No. 19. If a dangerous object continues to approach, the chicks arrange a "swim"
No. 20. I'm leaving the braid. The birds calm down and sit on their nests.
No. 21. And only the "honor guard" reminds me that I am only a guest here.
Description of the bird
Outwardly, the Arctic tern resembles a gull, but it has a shorter body and longer wings. The length of the bird's body is from 35 to 40 cm. The wingspan is within 75-85 cm. The weight is 90-130 g. Visually, the polar tern seems larger due to the elongated wings. The head is black on top. The body is mostly white. Chest, outer side of the wings and back with a grayish tinge. The tail is white at the top and light gray at the bottom. The beak is dark red, the legs are short with webbed feet. The tail is forked. Females and males look the same.
In winter, the forehead of the Arctic tern turns white. In the first year of life, young birds have a brownish-variegated shade on the back, and their tail is shorter than that of adults. By the second year, young animals acquire all the characteristics of adult birds.
- Boehme R.L., Flint V.E.
A five-language dictionary of animal names. Birds. Latin, Russian, English, German, French / Edited by Acad. V.E.Sokolova. - M .: Rus. lang., "RUSSO", 1994. - P. 92. - 2030 copies. - ISBN 5-200-00643-0.
- ↑ 12
[www.iucnredlist.org/details/106003271/0 Sterna paradisaea]
- [jncc.defra.gov.uk/default.aspx?page=1917 Mousa Reserve]
- [jncc.defra.gov.uk/default.aspx?page=1895 Papa Stour Wildlife Refuge]
- [jncc.defra.gov.uk/default.aspx?page=1923 Samboro Head Wildlife Refuge]
- [jncc.defra.gov.uk/default.aspx?page=1896 Fula Nature Reserve]
- [www.membrana.ru/lenta/?9995 Membrana: Named the bird with the longest annual flight]
- [www.pnas.org/content/early/2009/12/29/0909493107.abstract PNAS: Tracking of Arctic terns Sterna paradisaea reveals longest animal migration]
Peculiarities of food of the Arctic tern
Arctic terns feed on fish, krill, molluscs and crustaceans. The bird hunts, flying at heights of about 10 m above the water and below. At the same time, she carefully looks for prey with her gaze and can hang in one place, quickly flapping her wings. Seeing the target, the tern abruptly rushes down and seizes the prey with its beak. Such a throw is known as diving flight. Interestingly, only every third such attempt usually ends successfully. But in case of an unsuccessful first throw, the tern continues to pursue its prey under water: the bird dives well to shallow depths, where it manages to grab fish.
Arctic terns, like seagulls, follow the hunting grounds of their relatives and other seabird species, and thus find schools of small fish.
During the nesting period, the bird's diet consists of aquatic insects, larvae, and small fish. In addition, terns can feast on berries on the shore.
Common tern molt, as a rule, takes place during the wintering period, less often in the fall. Plumage changes by early spring.
Adult birds can molt twice a year - after the mating season and partially before it. Molting stops during migratory flights, in August-September, and resumes during wintering.
River terns living in the eastern territories molt in the same way as those living to the west. It only happens that this process is faster in the east.
Arctic tern nesting sites are northern Canada, Alaska, the Greenland coast, Scandinavia and the tundra zone of Russia from the Kola Peninsula to Chukotka. With the onset of a cold autumn in the Arctic, birds migrate south. Arctic terns spend most of their life above the sea surface, while they gradually move south and reach the eternal ice of Antarctica. By this time, summer has begun in the southern hemisphere, thanks to which Arctic terns live in a comfortable summer climate all year round.
Where does it live?
The river tern lives in the Palaearctic, lives in North America, Europe, Russia, Africa, Turkey, Pakistan.
In Russia, these birds settle in Karelia, Yakutia, Kamchatka, Western Siberia, Crimea, Transcaucasia. The southern boundaries of the habitat lie in the area of the Yellow and Yangtze rivers, as well as in Tibet. There is a noticeable tendency to change habitats towards the north.
Birds settle in river valleys and deltas, along lakes and ponds, coasts and bays of the seas. Sometimes they are found in forest-tundra zones.
Common types of terns
In addition to the Arctic tern, the tern family includes related species that differ in habitat and appearance.
River Tern (Sterna hirundo)
Outwardly, this bird looks like a polar tern, but it is smaller. The length of its body is from 30 to 35 cm, the wingspan is 70-80 cm, the weight is from 100 to 175 g. The constitution is slender, the tail is bifurcated, the beak is red with a black end. The plumage color is white or light gray, the head is deep black on top. The forehead is usually light. The legs are red. The shout sounds like "kick" or "krie".
The species is common on the coasts of seas and reservoirs in Europe. In winter, it migrates to the south and west of Africa, to New Guinea, to the Philippines, to South America.
Pink tern (Sterna dougallii)
Inhabitant of islands and coasts of Europe, Africa, North and Central America, southeast Asia. The plumage on the back and wings is gray, the abdomen is white. On his head is a cap made of black feathers. The bird has a pink or orange beak.
Light Tern (Sterna sumatrana)
The body length of the bird is 34-37 cm, the wingspan is about 60 cm. The plumage on the back is light gray. The abdomen is white, occasionally with a pink tint. The occiput is black; a black stripe passes through the eyes. The head and neck are pure white. The beak is black with a yellow top, the paws are black. The tail is white, fork-shaped.
The plumage of young animals is grayish-brown, striped, the top of the head is decorated with gray-brown spots and a black spot in the back of the head. The beak is yellow, the legs are yellow-brown.
The species is widespread on the tropical islands of the Indian Ocean (Comoros, Maldives and Seychelles, the Chagos archipelago). Also light tern nests in the Pacific islands and in Australia.
South American Tern (Sterna hirundinacea)
The body length of the birds is about 45 cm, the wingspan is up to 90 cm, the tail is bifurcated. Weight from 170 to 200 g. The beak and legs are red. The chicks have a black beak and brown legs.
Inhabits the coastal regions of South America, Tierra del Fuego and the Falkland Islands.
Antarctic tern (Sterna vittata)
It is a small bird, with a body length from 31 to 38 cm. The beak is dark red or black, the color of plumage in adult birds is white, in chicks it is gray, black color is present only on the head.
The distribution area includes the southern Antarctic and Subantarctic seas up to Kerguelen, New Zealand, Tierra del Fuego, Falkland Islands and Tristan da Cunha.
Indian tern (Sterna aurantia)
Medium-sized species, body length from 38 to 43 cm. The back is dark gray, the abdomen is white, the tail is deeply cut, fork-shaped, the wings are long, pointed. The beak is yellow with a gray base, the legs are red. In the mating season, a black cap appears on the head, in winter it is grayish-white with black streaks. There is a black mask on the eyes.
The bird is common in Pakistan, India, in the east of Iran and Myanmar, in Thailand. Lives near freshwater bodies of water.
Lesser Tern (Sterna albifrons)
The smallest member of the family. The weight of the bird is up to 45 g, the body length is about 20 cm. The plumage on the back is light gray, on the belly is white. During the mating season, a black cap appears on the head. The forehead and stripes above the eyebrows are white. The beak is yellow with a black tip, the legs are yellow.
For nesting, it chooses sandy shores or gravel banks of large rivers.
Spotted tern (Thalasseus sandvicensis)
Body length up to 40 cm, weight 180-310 g, wingspan up to 110 cm. This bird has a long, thin black beak with a light yellow tip. The wings are light gray above, white below. The neck is white. There is a black cap on the top of the head. The scream is like a croak and sounds like "caric".
Spotted tern is an inhabitant of the European coasts of the North, Baltic, Mediterranean, Black, Caspian Seas and the Atlantic. In winter it migrates to the south of Europe and Africa.
Bengal tern (Sterna bengalensis)
Body length is from 33 to 40 cm. The beak is thin and sharp, orange-yellow in young birds and bright orange in adult birds. There is a black cap on the head, and the forehead is white. The back is painted dark gray. The paws of young birds are brown-gray, in adults they are black.
The species breeds in Libya, winters on the northwest coast of Africa.
Breeding times vary greatly depending on some factors, including habitat. Birds arrive from the southern edges closer to mid-May, the first clutches can be found already in the first half of June.
River tern in clutch, as a rule, has three eggs, much less often four, they have a green-buffy or olive tint with specks of brown or almost black color. The eggs are small in size, from 3.8-5 cm in length and 2.9-3.2 cm in width.
The brooding process of the river tern (photo can be seen above) begins from the moment the first egg is laid, and this period lasts on average about 20-22 days. It is carried out alternately. The female sits at night, while the male most often replaces her only during the day. Chicks begin to hatch in early July, and by August they are able to fly (about 25 days after hatching).
Breeding Arctic terns
Arctic tern is a monogamous bird, forming one pair for life. The male takes care of the female, performs special "dances" for her in the air and treats her to fish. If the female accepts such a gift, then the birds then fly together and make various cracking sounds.
The nest of terns is usually built on the shore of a reservoir, in the tundra, often near lakes. But most often birds prefer small islands that are surrounded by water on all sides. Several pairs settle on such islets, which together form a small but friendly colony. Conflicts between terns are extremely rare.
Terns have a simple nest. The female only rakes the grass and moss and lays eggs in such a hole. One clutch contains 2 or 3 eggs. Both parents incubate them from 22 to 27 days.
Terns are very brave birds. When they are in danger, they courageously attack birds of prey, polar foxes, and people. At the same time, they deliver tangible blows with their strong beak. And people are not advised to come close to tern nests without a headgear, so as not to get injured. This fearlessness makes terns good neighbors and protectors for waders, ducks and other birds. They often nest near terns, which scare away predators.
Newborn chicks are covered with down. On the second or third day of life, they begin to actively explore the territory near the nest. When dangerous situations arise, the chicks scatter and hide in the grass. Parents feed babies for a month. They become on the wing in the second month of life.
Terns reach sexual maturity in the 3-4th year of life. The minimum life span is 20 years. And long-lived birds live up to 35 years.
Swallows (Latin Hirundinidae) are one of the most graceful birds on the planet. This little heroic bird makes an annual flight of about 10 thousand km. And what is interesting, the swallows fly away to winter and return back on the same day. For example, the California swallow leaves its "home" on October 23rd and returns back on March 19th.
Interesting facts about the bird
- Arctic terns are the only bird species that seasonally fly from the Arctic to the Antarctic, with each bird covering a distance of up to 70 thousand kilometers per year. Such a flight in one direction lasts about a month. Scientists attached miniature geolocators to the legs of Arctic terns, and traced the routes of their annual migrations. It turned out that terns are champions in terms of migration range. For 30 years of life, the bird covers a distance equal to three flights to the moon and back.
- Today, there are about 1 million Arctic terns in the world, and the population remains stable. At the same time, the birds are dispersed over a large area that covers the entire globe. Their colonies are small and usually located at a great distance from each other.
- In past centuries, the feathers of polar terns were used to decorate ladies' hats, for this purpose birds were caught. In our time, this fishery is not in demand.
Enemies and dangers
River Tern (the photo shows her) is not devoid of enemies. These are:
- large seagulls - herring and gray in color,
- feathered family of corvids - crows, for example,
- some mammals - ermines, foxes, Ussuri raccoons, wild boars,
- steppe snakes.
A negative factor for terns is a rise in the water level due to natural processes - prolonged rains, floods. As a result of these conditions, the chicks die, the fertility of adult gulls decreases.
Chicks also die as a result of tick infestations, when the colony is disturbed by humans, and when livestock is grazed in nesting areas.
One of the most famous land animal migrations is the Great Migration, which involves millions of African animals found in Tanzania and Kenya. The most unique natural phenomenon in East Africa, covering the entire Serengeti / Masai Mara ecosystem.
Every year, millions of Wildebeests, more than 250 thousand zebras and 500 thousand gazelles move from the Serengeti to Masai Marai back, covering a distance of 1800 km. Animals migrate in search of food and follow the rains. This is a very dangerous path: predators always follow the ungulates, so about 200,000 animals die along the way, many of them die when crossing the Mara River.
Red earthen crab
The red earthen crab (Latin Gecarcoidea natalis) is one of the brightest migratory animals. This migration can be safely called the "Invasion of Red Crabs". And this incredible event takes place on Christmas Island, where every year about 120 million of these arthropods cross the island in the direction of the Indian Ocean, where they will begin their mating season.
This journey lasts more than two weeks and presents a great challenge for red crabs, as these crabs do not move much during normal times. The distance covered by crabs cannot be compared with the migration of birds or other animals, but for them this path of several kilometers is a real feat.