Bird Families

Red Knot - Why does the red Knot Breed in the Arctic?

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Red knot is a A dumpy, short-legged, stocky wading bird. In winter it makes a lot of jerks that wheeled and their fading suburbs flashed as the plane rolled and rotated. Sticky, little sandpiper, Knot will be seen at the attraction from August… Under the Birds of Conservation Concern 4 in the UK, classically as Amber.

Red Knot

Nuts, in zoology, are several large, lumpy shelf birds of the genus Calidris of the subfamily Calidritini (family Scolopacidae).

The red knot (Calidris canutus) (barely knot in English-speaking Europe) is a medium-sized arrow bird that originated in Canada, Europe and the north of Russia, in the tundra and the Arctic Cordillera. This is a large member of the Kalidris Sandpipers, the second after a great knot. Six subspecies are recognized.

Their diet varies according to diet tu; Arthropods and larvae are the preferred food items in the breeding fields, while at other times different hard-shelled molluscs are eaten at different feeding sites. North American breeders sail along the coast of Europe and South America, while Eurasian populations winter in Africa, Papua New Guinea, Australia and New Zealand. This breed produces a lot of jerks when not breeding.

Classification, method and evolution

The red knot was first described by Linnaeus as his Trisha Cantus of Sistema Naturai in the landmark 1758 tenth edition. One theory is that it derives its name and species from the King name; The name refers to the story of the boil and the cort and tide along the lines of the tide. This etymology seems to have no historical historical basis. Another etymology is the name is anomatopoic, based on the bird's sudden call notes.

The red knot and the great knot were the only two species originally kept in the genus Calidris, but many more species of sandpiper were added later. A 2004 study found that the genus was polyphyletic and that the closest relatives of the two knot species were surfbirds (now Afriza virgata).

Why does the red Knot Breed in the Arctic?

The Red Knot Shorebird is a solid, long-range flying that transports annually from the Arctic to the southern hemisphere and back. For decades, the bird has been at risk as food sources such as crab eggs have dwindled in the eating fields of its migratory tract.

Delivery and transfer

C. Large size shake c. The islands in Britain's coastal wetlands, along with other winter warders. The Wash, Norfolk

During the breeding season, red knots distribute a circopolar to the high Arctic, then migrate to coasts around the world at 50 ° N to 58 ° C. The red knot is one of the longest migrations of any bird. Each year it travels more than 9,000 miles (14,000 km) from the Arctic to the southern tip of South America. The exact migration routes and wintering grounds of individual subspecies are still somewhat uncertain. Designated race c. C. Cantus migrated to Western Europe and later to West and South Africa on the Temi Peninsula and possibly to Yakutia. C c. Rosary species on the Chukchi Peninsula in eastern Siberia and winters in eastern Australia and New Zealand.

In the Gulf of Mannar and on the eastern coast of India Kadaflatt, a small and declining wintering winter (but probably described as Pierceae), is a recently divided species of winter c. C. Pierceum breeds winters in the New Siberian Islands and northwestern Australia. C c. There are rose varieties in Siberia's Wrangell Island and northwestern Alaska, and it is obviously wintering in Florida, Panama, and Venezuela. C c. The low art of Canada is known as the Rafa species, and in winter South America, & c. C. The islands breed winter species in Canada's High Arctic as well as in Greenland and Western Europe.

In West Africa, winter birds are seen to limit their daily herd to only 2-16 km 2 (0.77-6.18 sq mi) inland and prune a single site for several months. In temperate regions such as the Wadden Sea, they have been shown to change roost sites every week, and during a week their feeding can be up to 800 kilometers (310 square miles).

Description and anatomy

An adult red knot is the second largest calidris sandpiper, measuring 47-253 cm (19-25 inches) with a length of 23-25 ​​cm (9.1-1010 inches) to the right. The body shape is common to Janos, with a small head and eyes, a small neck and a slight tapping bill that is no longer on his head. It has short legs and moderately thin dark bills. Winter or basic, the plumage is evenly faded to gray, and is similar between the sexes. The alternate, or progenitor, feather is gray with a cinnamon face, neck and breast and a light colored rear belly topped.

The feminine alternate plumage is somewhat lighter and the eyes are less distinct except in the male. The canutas, islands and piers are the “dark” subspecies. Subsea rosemary has a lighter belly than rosemary or pearsome, and rufa is the lightest in overall plumage. The transition from alternative to basic plumage begins at breeding sites but is most pronounced when migrating southward. Mall-to-alternative plumage begins just before migrating north to the breeding fields, but most migrations occur during the period.

Large, white wing bars and gray pieces and ledges make it easy to detect in flight. It gives a characteristic 'low-slung' appearance when feeding a short dark green foot. When floating alone, they seldom call, but when making a sail, they make less monosyllabic knots and pronounce a disconnected noop-nup while shifting.

They breed in moist tundra from June to August. The male's display song struck me as high-pitched with beats of wings trembling on a weak poor display, and the wings pressing upward and trembling on the ground. Both sexes hatch, but after hatching, the wife leaves the parental care of the male

Adolescent birds have distinct submarine lines and brown cover during the first year. The breeding season can be distinguished by the difficulty of males (<80% accuracy compared to the molecular method) based on the greater shade of red under parts that extends to the back of the abdomen.

Weight varies with subspecies, but ranges between 100 and 200 g (3.5 and 7.1 oz). Red knots can double their weight before migrating. Like many mature birds, they also reduce the size of their digestive organs before emigration.

The amount of atrophy is not pronounced as a species like a bar-tailed angel, as there is probably more opportunity for red knots to eat during migration. The red knots are able to change the size of their digestive organs ally. Gizzard size increases in thickness when feeding solid food on winter ground and decreases in size when feeding soft food at breeding ground. These changes can be very rapid, occurring in as little as six days.

Red Knot Diet and feeding

In breeding areas, knots are most commonly eaten by spiders, arthropods, and larvae on the ground, and depending on winter and migration, they eat a variety of hard shells such as itch, gastropods and small crabs that are completely infected and nourished by a muscular stomach.

Red knot touch feeder for feeding and migrating to the mudflats in winter, it involves the use of shallow probes in the mud while packing along their shores, searching for invisible prey in the mud. They tilt to the surface when the tide is falling, and in soft mud they can probe the bill with a depth of about 1 cm (0.39 inches) and propagate the plow. Miscellaneous mollusc macomas are their favorite prey on the European coasts, swallowing them whole and breaking them into gizzards.

In Delaware Bay, they feed on large numbers of nesting crab eggs that spread as birds arrive in the middle of summer. They are able to detect mollusks buried under wet sand as a result of changes in water pressure that they think are used by the corps of Hervest in their bills. Unlike many touch feeders, their visual field is not panoramic (allowing for approximately ৩ 360০ degree field of view), such that during the short breeding season they switch to continuous mobile prey, which is tied. Used to obtain some surface foods in cold winters and in migratory feeding places, such as horseshoe eggs.

Breeding

Red knots on the breeding plumage

The red knot is regional and exclusive to the season; It is unknown if the pair are together during the season from pairs. In Russia, male and female breeders have been shown to display site fidelity for years in their breeding locales, but there is no evidence that they show regional fidelity. Men appear before wives after migration and begin to protect territories. As the men arrive, they begin to display and aggressively defend their territory from other men.

The red knot is on the ground, near the water, and usually inside. A shallow scrap covered with nest leaves, lichen and shoyla men make three to five nest scraps in their area before the wives arrive. Females lay three or more eggs, which usually lays four eggs in six days. Eggs measure 43 mm × 30 mm (1.7 in × 1.2 in) and are lightly from the ground color, from light olives to deep olive buffs, both parents lay eggs, sharing duties evenly. Off-duty parents are burned in the livestock with others of the same species. The incubation period lasts about 22 days.

In the early stages of incubation, the mammals are very easily shaken from the nest by the presence of humans near the nest and cannot return for several hours. However, at the next stage of incubation they will be faster on the egg. Clutch hatching is usually synchronized. Roofs are natural during hatching, covered in down cryptic feathers. Chicks and parents move out of the nest within a day of the baby's birth and begin to graze with their parents. The men leave while they are young, while the youths are committed, the man begins his migration to the south and the young men begin their first voyage.

Status

The red knot has a wide range, estimated at 100,000-1000,000 km 2 (39,000 km386,000 square miles), and has a huge population of about 1.1 million people. The species is not believed to reach the edge of the IUCN Red List population degradation criteria (i.e., has declined by more than 30% over ten years or three generations), and is therefore evaluated at least as a concern. However, many local disadvantages have been noted, such as the dredging of inland flats of edible cockles (Cerostoderma edulis) that led to the winter depletion of the islands in the Dutch Wadden Sea. The quality of food at migration stopover sites is an important factor in their relocation strategy.

It is one of the species in the Treaty on African-Eurasian Migration Waterbirds (AUA) committed to signatories to control listed species or their eggs, establish protected zones for the habitat of listed species, control hunting and monitor bird-related populations.

Tribes threaten

A large number of brown, white and red birds submerge their heads in shallow water behind a large crab-like carapace.

Feeding red knots on horse crab eggs in the Gulf of Delaware

In the late nineteenth century, large numbers of red knots were shot for food in North America. It is estimated that very recently, commercial bites of crab crabs in the Gulf of Delaware were threatened by birds that began in the early 1990s. Delaware Bay is an important stopover point during spring migration; Birds re-fuel the eggs hatched by these crabs (with something else like eating in the Delaware Bay). If the abundance of crabs in the bay decreases, there may be fewer eggs to eat, on which the knot can damage survival.

Watch the video: The Great Knot (March 2021).

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