Trumpeter Swan

Identificazione

The trumpeter swan is the largest extant species of waterfowl, and both the heaviest and longest native bird of North America. Adults usually measure 138–165 cm (4 ft 6 in – 5 ft 5 in) long, though large males can exceed 180 cm (5 ft 11 in) in total length. The weight of adult birds is typically 7–13.6 kg (15–30 lb). Possibly due to seasonal variation based on food access and variability due to age, average weights in males have been reported to range from 10.9 to 12.7 kg (24 to 28 lb) and from 9.4 to 10.3 kg (21 to 23 lb) in females. It is one of the heaviest living birds or animals capable of flight, and, in terms of average mass, the heaviest flying bird in the world. Alongside the mute swan (Cygnus olor), Dalmatian pelican (Pelecanus crispus), kori bustard (Ardeotis kori), and Andean condor (Vultur gryphus), it is one of a handful to weigh in excess of 10 kg (22 lb) between the sexes, and one survey of wintering trumpeters found it averaged second only to the condor in mean mass. The trumpeter swan's wingspan ranges from 185 to 304.8 cm (6 ft 0.8 in to 10 ft 0 in), with the wing chord measuring 60–68 cm (24–27 in). The largest known male trumpeter attained a length of 183 cm (6 ft 0 in), a wingspan of 3.1 m (10 ft 2 in) and a weight of 17.2 kg (38 lb). It is the second heaviest wild waterfowl ever found, as one mute swan was found to weigh a massive 23 kg (51 lb), but it was unclear whether the latter swan was still capable of flight because of its bulk.<p>The adult trumpeter swan's plumage is entirely white. Like mute swan cygnets, the cygnets of the trumpeter swan have light grey plumage and pinkish legs, gaining their white plumage after about a year. As with the whooper swan, this species has upright posture and generally swims with a straight neck. The trumpeter swan has a large, wedge-shaped black bill that can, in some cases, be minimally lined with salmon-pink coloration around the mouth. The bill, measuring 10.5–12 cm (4.1–4.7 in), is up to twice the length of a Canada goose's (Branta canadensis) bill and is the largest of any waterfowl. The legs are gray-pink in color, though in some birds can appear yellowish gray to even black. The tarsus measures 10.5–12 cm (4.1–4.7 in).The mute swan, introduced to North America, is scarcely smaller. However, it can easily be distinguished by its orange bill and different physical structure (particularly the neck, which is typically held curved as opposed to straight in the trumpeter). The mute swan is often found year-around in developed areas near human habitation in North America, whereas trumpeters are usually only found in pristine wetlands with minimal human disturbance, especially while breeding. The tundra swan (C. columbianus) more closely resembles the trumpeter, but is significantly smaller. The neck of a male trumpeter may be twice as long as the neck of a tundra swan. The tundra swan can be further distinguished by its yellow lores. However, some trumpeter swans have yellow lores; many of these individuals appear to be leucistic and have paler legs than typical trumpeters. Distinguishing tundra and trumpeter swans from a distance (when size is harder to gauge) can be challenging without direct comparison but it is possible thanks to the trumpeter's obviously longer neck (the great length of which is apparent even when the swan is not standing or swimming upright) and larger, wedge-shaped bill as compared to the tundra swan.<p>Trumpeter swans have similar calls to whooper swans and Bewick's swans. They are loud and somewhat musical creatures, with their cry sounding similar to a trumpet, which gave the bird its name.

Tassonomia

The trumpeter swan was formally described in 1831 by the Scottish naturalist John Richardson in the fourth volume of American Ornithology; or, The Natural History of Birds Inhabiting the United States by Alexander Wilson and Charles Bonaparte. Richardson coined the current binomial name Cygnus buccinator. A description by Richardson was also published in Fauna Boreali-Americana, or, The Zoology of the Northern Parts of British America by William Swainson and Richardson but although the volume has 1831 printed on the title page, it was not published until 1832. The specific epithet is from Latin bucinator meaning "trumpeter"; bucina is the Latin word for a military trumpet. The trumpeter swan is monotypic: no subspecies are recognised.

Nome scientifico

Cygnus buccinator

Autorità

Richardson, 1831

Ordine

Anseriformi

Famiglia

Anatidae

Genere

Cigno

Areale e habitat

Beginning in 1968, repeated in 1975, and then conducted at 5-year intervals, a cooperative continental survey of trumpeter swans was last conducted in 2015. The survey assesses trumpeter swan abundance and productivity throughout the entire breeding ranges of the three recognized North American populations: the Pacific Coast (PCP), Rocky Mountain (RMP), and Interior (IP) populations (see Figure). From 1968 to 2010 the population has increased from 3,722 to approximately 46,225 birds, in large part due to re-introductions to its historic range.<p>Their breeding habitat is large shallow ponds, undisturbed lakes, pristine wetlands and wide slow rivers, and marshes in northwestern and central North America, with the largest numbers of breeding pairs found in Alaska. They prefer nesting sites with enough space for them to have enough surface water for them to take off, as well as accessible food, shallow, unpolluted water, and little or no human disturbance. Natural populations of these swans migrate to and from the Pacific coast and portions of the United States, flying in V-shaped flocks. Released populations are mostly non-migratory.<p>In the winter, they migrate to the southern tier of Canada, the eastern part of the northwest states in the United States, especially to the Red Rock Lakes area of Montana, the north Puget Sound region of northwest Washington state; they have even been observed as far south as Pagosa Springs, Colorado. Historically, they ranged as far south as Texas and southern California. Since 1992, trumpeter swans have been found in Arkansas each November – February on Magness Lake outside of Heber Springs. In addition, there is a specimen in the Museum of Comparative Zoology in Cambridge, Massachusetts, that was shot by F. B. Armstrong in 1909 at Matamoros, Tamaulipas, Mexico. C. buccinator is therefore considered extirpated from Mexico. In early 2017, a juvenile trumpeter swan took up residence in the French Broad River in Asheville, North Carolina, marking the first such sighting in that part of the state.<p>Non-migratory trumpeter swans have also been artificially introduced to some areas of Oregon, where they never originally occurred. Because of their natural beauty, they are suitable waterfowl to attract bird watchers and other wildlife enthusiasts. Introductions of non-indigenous species in the Western states, for example through the Oregon Trumpeter Swan Program (OTSP), have also been met with criticism, but the introduction program argues that the perceived attractiveness of natural sites has priority over the original range of any given species.<p>Occasional sightings of trumpeter swans have occurred in the United Kingdom; while some of these are believed to be vagrants, most are presumed escapes into the wild. A single instance of the species breeding in the United Kingdom is reported from 1997, where two swans out of a group that escaped from a wildfowl collection at Apethorpe Palace, Northamptonshire raised a single cygnet on the River Nene.

Areale riproduttivo

NA : Alaska, w Canada and nc USA

Areale non riproduttivo

w Canada and nw, c USA

Migrazione

Migratori completi

Comportamento

Comportamento migratorio: Migratori completi.

Conservazione

Tendenza della popolazione: in aumento.

Tendenza della popolazione

in aumento