Trumpeter swan
The trumpeter swan, or simply the trumpeter, is a species of swan found in North America. The heaviest living bird native to North America, it is also the largest extant species of waterfowl, with a wingspan of 185 to 304.8 cm. It is the American counterpart and a close relative of the whooper swan of Eurasia and has even been considered the same species by some authorities. By 1933, fewer than 70 wild individuals were known to exist; extinction seemed imminent until aerial surveys discovered a Pacific population of several thousand trumpeter swans around Alaska's Copper River. Careful reintroductions by wildlife agencies and the Trumpeter Swan Society gradually restored the North American wild population to over 46,000 birds by 2010.
Taxonomy
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. Although the volume has 1831 printed on the title page, it was in fact not published until 1832. The etymology of the species name, buccinator, comes from the word bucina, a specific type of military trumpet. The trumpeter swan is monotypic, meaning that no subspecies are recognised.Description
The trumpeter swan is the largest extant species of waterfowl, and both the heaviest and longest native bird of North America. Adults usually measure long, though large males can exceed in total length. The weight of adult birds is typically. Possibly due to seasonal variation based on food access and variability due to age, average weights in males have been reported to range from and from in females.It is one of the heaviest living animals capable of flight, and, in terms of average mass, the heaviest flying bird in the world. Alongside the mute swan, wild turkey, great bustard, Kori bustard, Dalmatian pelican, and Andean condor, it is one of a handful to weigh in excess of 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, with the wing chord measuring. The largest known male trumpeter attained a length of, a wingspan of and a weight of. It is the second heaviest wild waterfowl ever found, as one mute swan was found to weigh a massive, but it was unclear whether the latter swan was still capable of flight because of its bulk.
Adult plumage is entirely white. Like mute swan cygnets, trumpeter swan cygnets have light grey plumage and pinkish legs, gaining their white plumage after about a year. As with the whooper swan, this species has an upright posture and generally swims with a straight neck. The trumpeter swan has a large, wedge-shaped black bill that can be minimally lined with salmon-pink coloration around the mouth. The bill measures, up to twice the length of a Canada goose bill; the trumpeter swan bill is the largest of any waterfowl species in the world. The legs are gray-pink in color, though in some birds can appear yellowish gray to even black. The tarsus measures.
The mute swan, introduced to North America, is scarcely smaller. However, it can easily be distinguished by its orange bill and different physical structure. The mute swan is often found year-round 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 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 can be challenging without direct comparison, but it is possible thanks to the trumpeter's obviously longer neck and larger, wedge-shaped bill as compared to the tundra swan.
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.
Range and habitat
Cooperative continental surveys of trumpeter swans have been performed regularly, beginning in 1968, repeated in 1975, and then conducted at 5-year intervals. The most recent survey of trumpeter swans occurred 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, Rocky Mountain, and Interior populations. From 1968 to 2010 the population has increased from 3,722 to approximately 46,225 birds, in large part due to re-introductions to the species' historic range.The breeding habitat of trumpeter swans includes large and shallow ponds, undisturbed lakes, pristine wetlands, wide and slow rivers, and marshes in northwestern and central North America. The largest numbers of breeding pairs are found in Alaska. Trumpeter swans prefer nesting sites with enough surface water for them to have space to take off, as well as accessible and reliable food sources, shallow, unpolluted water, and little to no human disturbance. Natural populations migrate in V-shaped flocks to and from the Pacific coast and portions of the United States. Released populations are mostly non-migratory.
In the winter, trumpeter swans migrate to the southern tier of Canada, the eastern part of the northwest United States, and the northern area of the Puget Sound region of Washington state; migratory populations have even been observed as far south as Pagosa Springs, Colorado. Historically, the range of trumpeter swans extended as far south as Texas and southern California. Since 1992, trumpeter swans have also been found in Arkansas each November–February on Magness Lake, outside of Heber Springs. In addition, the collection of the Museum of Comparative Zoology in Cambridge, Massachusetts, includes a specimen that was shot by F. B. Armstrong in 1909 at Matamoros, Tamaulipas, Mexico. C. buccinator is currently 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.
Non-migratory trumpeter swans have also been artificially introduced to some areas of Oregon. Largely due to 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, 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.
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.
Diet
These birds feed while swimming, sometimes up-ending or dabbling in reaching submerged food. The diet is almost entirely aquatic plants and occasionally insects. They will eat both the leaves and stems of submerged and emergent vegetation. They will also dig into muddy substrates underwater to extract roots and tubers. In winter, they may also eat grasses and grains in fields. They will often feed at night as well as by day. Feeding activity, and the birds' weights, often peak in the spring as they prepare for the breeding season. The young initially include insects, small fish, fish eggs and small crustaceans in their diet, providing additional protein, and change to a vegetation-based diet over the first few months.Predators and mortality
Predators of trumpeter swan eggs include common ravens, common raccoons, wolverines, American black bears, grizzly bears, coyotes, gray wolves, pumas, and North American river otters. Nest location can provide partial protection from most mammalian nest predators, especially if placed on islands or floating vegetation in deep waters. Most of the same predators will prey on young cygnets, as well as common snapping turtles, California gulls, great horned owls, red foxes and American mink. Larger cygnets and, rarely, nesting adults may be ambushed by golden eagles, bobcats, and probably coyotes, wolves and pumas.When their eggs and young are threatened, the parents can be quite aggressive, initially displaying with head bobbing and hissing. If this is not sufficient, the adults will physically combat the predator, battering with their powerful wings. Adults have managed to beat predators equal to their own weight such as coyotes in confrontations. Predation of adults, when they are not nesting, is extremely rare; golden and bald eagles, and coyotes can pose a threat, but substantiated cases are very few. Photos of an exceptional attack by a bald eagle on an adult trumpeter swan in flight were taken in 2008, although the swan survived the predation attempt. In another case, a coyote succeeded in killing an injured adult trumpeter swan.
In captivity, members of this species have survived to 33 years old and, in the wild, have lived to at least 24 years. Young trumpeter swans may have as little as 40% chance of survival due variously to disturbance and destruction by humans, predation, nest flooding, and starvation. In some areas, though, the breeding success rate is considerably greater and, occasionally, all cygnets may reach maturity. Mortality in adults is quite low, with the survival rate usually being 80–100% annually, unless they are hunted by humans.