Bewick's swan (Tundra swan/whistling swan) ( Cygnus columbianus ) - A swan has only one mate for the rest of its life

Phylum: Chordata

Class: Aves

Order: Anseriformes

Family: Anatidae

Genus: Cygnus

Species: C. columbianus

Binomial name - Cygnus columbianus

The tundra swan is a little Holarctic swan. (Cygnus columbianus) The two taxa within it are normally considered conspecific, however, they are sometimes separated into two species: the Palaearctic Bewick's swan (Cygnus bewickii) and the Nearctic whistling swan (Cygnus columbianus). Birds from eastern Russia (approximately east of the Taimyr Peninsula) are occasionally classified as C. c. Jankowski, although this distinction is not universally acknowledged, with most writers lumping them in with C. c. bewickii. Tundra swans are occasionally included together with the other Arctic swan species in the subgenus Olor.

William Yarrell called the Bewick's swan after the engraver Thomas Bewick, who specialized in bird and animal pictures. The name Cygnus derives from the Latin word Cygnus, which means "swan," and columbianus comes from the Columbia River, which is the type location.

Details about swans

With a length of 115–150 cm (45–59 in), a wingspan of 168–211 cm (66–83 in), and a weight of 3.4–9.6 kg (7.5–21.2 lb), C. columbianus is the smallest of the Holarctic swans. Both subspecies' adult plumage is totally white, with black feet and a mainly black bill with a thin salmon-pink streak running down the mouthline and more or less yellow in the proximal section, depending on the subspecies. The iris is a deep brown color. The head and neck plumage of birds that live in waters with high levels of iron ions (such as bog lakes) acquires a golden or rusty hue. Pens (females) are somewhat smaller than cobs (males), but otherwise seem identical.

Immatures of both subspecies are white with some dull grey feathering, particularly on the head and top neck, which are often totally light grey; their first-summer plumage is already fairly white, and they molt into adult plumage in their second winter. Their bills are black with a big dirty-pink patch covering the majority of the proximal half and frequently black nostrils, while their feet are dark grey with a pinkish tinge. The young of the downy is silvery grey on top and white on the bottom.

A adult pens and her two months years old baby (cygnets )

Cygnets, ride on the back of an adult mute swan.

The Bewick's swan is a smaller subspecies of the swan. There is a modest size difference between the eastern and western populations, with the eastern birds being somewhat bigger; however, solid measurement data is only available for the western populations. These weigh 3.4–7.8 kilograms (7.5–17.2 lb), with males averaging 6.4 kg (14 lb) and females averaging 5.7 kg (13 lb). They are 115–140 cm (45–55 in) long overall, with each wing being 46.9–54.8 cm (18.5–21.6 in) long, with males measuring 51.9 cm (20.4 in) and females at 50.4 cm (19.8 in). They are 115–140 cm (45–55 in) long overall, with each wing being 46.9–54.8 cm (18.5–21.6 in) long, with males measuring 51.9 cm (20.4 in) and females at 50.4 cm (19.8 in). The tarsus is 9.2–11.6 cm (3.6–4.6 in) long, while the bill is 8.2–10.2 cm (3.2–4.0 in) long, with an average of 9.1 cm (3.6 in). The parapatric whooper swan (C. Cygnus) looks similar to Bewick's swan, but it's smaller, shorter-necked, and has a more rounded head shape, with a varied bill pattern that always shows more black than yellow and a blunt forward edge of the yellow base patch. Whooper swans have a beak with more yellow than black, and the yellow patch's forward border is generally pointed. Every Bewick's swan has a unique bill pattern, thus scientists typically draw precise drawings of each bill and name the swans to aid in their research. Aside from being bigger, eastern birds have less yellow on their bills, possibly indicating that gene flow over Beringia was never completely stopped. Eastern Siberia has reported an apparent hybridization between a Bewick's and a vagrant whistling swan.

Whistling swans weigh 9.5–21 lb (4.3–9.5 kg) on average, with males weighing 16 lb (7.3 kg) and females weighing 14 lb (6.4 kg), and measuring 47–59 in (120–150 cm) in length. Each wing measures 19.7–22.4 in (50–57 cm) in length, with the tarsus measuring 3.7–4.5 in (9.4–11.4 cm) and the beak measuring 3.6–4.2 in (9.1–10.7 cm). The bigger size of C. c. columbianus distinguishes it from C. c. bewickii, as does the mostly black bill with just a tiny and often difficult to notice a yellow patch of varied size at the base. The mostly allopatric trumpeter swan (C. buccinator) of North America is recognized by its significantly greater size and notably long beak, which is black all over except for a stronger pink mouthline than the whistling swan.

Color variants with more or less yellow, or pink instead of yellow or black, are not uncommon, particularly in Bewick's swans, which may have yellowish feet on rare occasions. The tiny size and especially the short neck, which give it the appearance of a huge white goose, are still defining features.
Tundra swans have a high-pitched honking cry that resembles that of a black goose (Branta). When feeding in flocks on their wintering grounds, they are very vociferous; any conspecific coming or departing will evoke a round of loud agitated shouting from its compatriots. The ground cries of the whistling swan are not a whistle, and they are not significantly different from those of Bewick's swan.

They are strong and fast swimmers who jump to the air with a running start, holding the water's surface with their wings. The cygnes' rhythmic blowing generates a sound known as "whistling swan" in flight.

Distribution

The tundra swan breeds in the Arctic and subarctic tundra, where they live in small ponds, lakes, and rivers, as its name suggests. These birds, unlike mute swans (C. olor), are migratory, as are the other Arctic swans. Both subspecies spend their winters in grassland and marshland, frequently along the coast; they prefer to visit farms after harvest to eat on spilled grains, and they may stop at alpine lakes when migrating. According to National Geographic, these birds can fly in a V formation at altitudes of 8 km (5.0 mi) when migrating.

Fly in a V formation

The breeding range of C. c. bewickii stretches from the Kola Peninsula east to the Pacific Ocean in Siberia's coastal plains. Towards mid-May, they begin to arrive on the breeding grounds, and around the end of September, they depart for winter quarters. The inhabitants west of the Taimyr Peninsula move to Denmark, the Netherlands, and the British Isles for the winter, crossing the White Sea, Baltic Sea, and Elbe estuary. In the winter, they can be found in the Royal Society for the Protection of Birds' and the Wildfowl and Wetlands Trust's wildfowl nature reserves. Some birds also spend the winter on the North Sea's southern beaches. Bewick's swans that breed in eastern Russia travel via Mongolia and northern China to winter in Korea, Japan, and southern China's coastal districts, as far south as Guangdong and occasionally as far as Taiwan. A few birds from the central Siberian range winter in Iran, south of the Caspian Sea; these flocks used to travel to the Aral Sea before an ecological disaster in the late twentieth century converted most of the habitat there into an uninhabitable wasteland.

C. c. columbianus breeds in Alaska's and Canada's coastal plains, departing for winter quarters around October. By November/December, they'll be in winter quarters. Birds that breed in western Alaska spend the winter along the Pacific coast from southern Alaska to California; they frequently migrate inland – particularly to the rich feeding grounds of the Californian Central Valley – and some cross the Rocky Mountains again to spend the winter as far east as Utah and south as Texas and northern Mexico. Birds that nest near the Arctic Ocean's coast migrate to the Atlantic coast of the United States for the winter, mostly from Maryland to South Carolina, although some go as far south as Florida. By mid-March, Whistling Swans are leaving for the breeding grounds again, and they arrive in late May. The Bermudas, Cuba, the Hawaiian Islands, Puerto Rico, and England, Ireland, Japan, northeastern Siberia, and Sweden have all reported vagrants.

Biology, Ecology

They feed mostly aquatic vegetation in the summer, such as mannagrass (Glyceria), Potamogeton pondweeds, and marine eelgrass (Zostera), which they get by dipping their heads underwater or upending while swimming; they also eat some dry-land grass. At other seasons of the year, they eat leftover grains and other crops such as potatoes, which they pick up in open fields after harvest. Tundra swans primarily forage during the day. They are territorial and violent to many animals that pass by during the mating season; outside of the breeding season, they are sociable birds.

predator

Adult birds have a few natural predators. Arctic foxes (Vulpes Lagopus) may pose a hazard to mating females, as well as their eggs and young. Adults can usually hold their ground and evict foxes, although foxes can succeed on occasion. Brown bears (Ursus arctos), another surprise major nest predator for tundra swans, were presumably the leading cause of nesting failure in both the Arctic National Wildlife Refuge and the Izembek National Wildlife Refuge. Red foxes (Vulpes vulpes), golden eagles (Aquila chrysaetos), parasitic jaegers (Stercorarius parasiticus), and glaucous gulls are all possible nest predators (Larus hyperboreus).

Brown bears, golden eagles, and gray wolves (Canis lupus) have all been known to capture and kill adults. Small or avian predators generally prompt an aggressive response or the behavior of holding tight on nests, but bigger animals, which are potentially more threatening to adults, usually elicit the behavior of bringing the cygnets into deep waters and staying motionless until they pass. Each year, roughly 15% of adults die for different reasons, resulting in an average lifetime of about 10 years in the wild. The oldest tundra swan ever reported was nearly 24 years old.

Reproduction

Tundra swans mate in late spring, generally after returning to their breeding sites; they couple monogamously until one spouse dies, as is customary for swans. If one partner dies before the other, the surviving bird may not mate for several years, if not for the rest of its life. The nesting season begins in late May. The couple constructs a big mound-shaped nest out of plant material near open water and defends a vast area around it. The pen (female) sits on the nest and lays and incubates a clutch of 2–7 (typically 3–5) eggs, keeping an eye out for danger.

The cob (male) keeps a constant watch for predators approaching his mate and offspring. When any of them detects a threat, they emit a warning sound to alert their companion to the impending danger. In an attempt to scare away a predator, the cob may sometimes flap his wings to run faster and seem larger.

The Bewick's swan takes 29–30 days from laying to hatching, whereas the whistling swan takes 30–32 days. Tundra swan cygnets grow faster than those of swans breeding in warmer climates; whistling swan cygnets take about 60–75 days to fledge—twice as fast as mute swan cygnets, for example—while Bewick's swan cygnets, about which little breeding data is known, may fledge a record 40–45 days after hatching already. For the first winter migration, the fledglings stay with their parents. While on the wintering grounds, the family is occasionally joined by children from prior breeding seasons; Tundra swans do not attain sexual maturity until they are 3 or 4 years old.