Cygnus olor

Mute Swan foreign name Mute Swan, no subspecies, is a large swimming bird.

Mute swans moved to the south from the end of September to the middle of October for winter, and in the spring, they moved to the north in mid-late February, in small groups and family groups, mostly along lakes, rivers and other waters, and continued to stop along the way. In some places, especially in places where mute swans were introduced in the past, such as North America, South Africa, Australia and New Zealand, mute swans have become resident birds and no longer migrate. The distances of migration in the UK are also very short, generally no more than 50 km, and they are carried out along water. But mute swans, which breed in Siberia, Mongolia and northern China, migrate thousands of miles each spring and fall between their breeding grounds and their wintering grounds.

Mute swans have keen sense of sight and hearing. As its name suggests, mute swans are usually silent. When happy, it makes a hoarse and low 'hiss' sound, hence the name of the mute swan. Adult birds sometimes sneeze, hiss, or make a barking or whistling sound similar to that of a puppy dog, although the sound is not loud due to the straight windpipe. Similarly, the sound of the wings during flight is also described as a musical flutter or hum. They also use visual displays as a form of communication, such as posture. For example, males often arch secondary wing feathers on their backs in a male position.

Mute swan mainly in the water life, sex alert, strong vision, neck straight can see miles. When swimming, the two wings are raised, the neck is bent back, and the head is bowed forward, which is extremely elegant. Swimming speed is very fast, can stroke with one foot, can also row with two feet at the same time, and from time to time open and flap two wings, docile and timid, action is extremely cautious and careful, often in the open lake water surface swimming and foraging, at night also more perched in the quiet and less disturbed lake island or floating on the surface of the water and dry reed pile, there is no danger before landing. When taking off, the wings beat the water surface, running on the water surface for about 50 meters before slowly leaving the water to fly. When flying, the neck is straight forward, the feet are extended behind, and the wings flap slowly and strongly. Often in pairs or family groups, but sometimes in large groups, especially during winter and molting.

The swan feeds mainly on the leaves, roots, stems, buds and fruits of aquatic plants, as well as algae and small aquatic animals. Feed during the day, rest at night. When foraging, it mainly tears plants with its mouth, sometimes it can also head down and tail up like some ducks, and extend its head to the bottom to dig the roots of aquatic plants for food, and occasionally to the water side ground to forage for grass.

Mute swans were sexually mature at 3 years of age, a few 2 years (mostly female), and some began to reproduce as late as 4 years of age. The formation of new pairs is mostly in the autumn and winter before the first breeding, and the pairs are relatively fixed. Once formed, they remain unchanged for life, rarely disintegrate in the middle, and most of them appear in unsuccessful breeding and non-breeding pairs. Courtship begins with the male and female engaging in frequent headdip movements with each other, swimming together, the male wrapping his neck around the female's neck and then climbing onto her back to mate. The female is completely submerged, with only her head and neck above the water. After mating, the male and female birds swim together while making a distinctive raspy sound, followed by grooming and a water bath.

Mute swans breed from March to May. Nest in secluded, inaccessible pools and lakes on the shores of reeds or grass. The female nests alone or together. The nest is made of dried reeds and other plants. The structure is very large and round, with an outer diameter of 128.5-194.5 mm and an average of 164.0 cm. Inner diameter 48.5-56.6 cm, average 51.0 cm; Depth 12.7-18.6 cm, average 15.0 cm; Height 24.5-31.0 cm, average 27.0 cm. There are main nest and auxiliary nest, the main nest for the female to lay eggs; The auxiliary nest is used by male birds at night, usually 40-60 meters away from the main nest, and is also made of reeds, rushes and leaves. The shape is very simple, like a straw mat, with an outer diameter of 125.0-140.0 cm and a height of 14.0-18.0 cm. In order to facilitate access, two 0.7-1.5 meter wide "channels" are usually opened between the main nest and the beach edge, which are formed by biting or stepping on the reed from the root, and the broken reed can be used as nesting materials. Usually one goes in and the other goes out.

Mute swan field is very strong, the nest area is large, each pair of swans usually occupy a large reed beach and wide lake. The size of the area occupied by each pair varies with the conditions of the nesting environment. In the wide lake area suitable for nesting, the area is large; In riparian areas restricted by nesting conditions and areas with high population density, the domain area is small. Sometimes there are even several nests together, only a few meters apart. Old nests are usually not used, only a few prefer to use the previous year's old nests, especially successful nests, but still need to be repaired and replenished before they can be used.

Mute swans lay eggs as soon as the nest is built, laying 4-9 eggs per brood, usually 5-6 eggs, and 1 egg every other day. Fresh eggs are milky white and gradually turn to dirt white or blue-green after hatching, measuring 117.5 (113.5-21) mm x 74.9 (72.5-77) mm and weighing 362 (348-371) g. Brooding is mainly carried by female birds, male birds near the nest guard, in case of danger to swim to the center of the lake or take off quickly, when passing over the main nest, vigorously flap two wings to warn female birds, female birds immediately cover the nest, and then leave the nest along the passage.

When the temperature is the highest at noon every day, the female bird also leaves the nest to forage for food, but the time is not long, and the eggs are covered with nest material before leaving the nest or incubated by the male bird. The female love nest is very strong, especially in the late incubation period, when someone approaches the nest, the female bird not only does not leave, but advances a few steps, arches its neck, and issues a threatening sound of "ho-ho-", the incubation period is 35-36 days. When the first brood is not successful, compensatory brooding is usually performed, but the brood size is significantly reduced, usually only 1-2 eggs. Young birds are early sex and can swim soon after hatching, but growth is extremely slow, usually 120-150 days to fly. During the growth of the chicks, the adult birds also began to moult, live in the water with the chicks, and take great care of the chicks, letting them climb on their backs from time to time, returning to the nest for the night in the early night, and as the chicks gradually grew up, they did not return to the nest for the night, but slept on objects floating in the water or on the reed pile.

The global population of mute swans is estimated to be between 598,000 and 615,000 pairs. The European mute swan population is estimated to be 83,400-116,000 pairs, equivalent to 167,000-231,000 mature individuals (BirdLife International 2015). Overall species population trends are increasing, although in some places population trends are unknown. It is estimated that the number is increasing in Europe (BirdLife International, EBCC 2015).

In August 2022, the Qinghai Provincial Forestry and Grass Bureau announced at the provincial bird protection and management press conference that mute swan, a national second-class key protected wild animal, is a rare and rare bird species recorded in Qinghai but without video records.

Listed in the International Union for Conservation of Nature Red List of Threatened Species (IUCN) for 2016 ver 3.1 - Not Threatened (LC).

Listed in China's "National Key Protected Wildlife List" (February 5, 2021) Level 2.

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