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Cygnus buccinatortrumpeter swan

By Kaitlyn Robins

Geographic Range

Trumpeter swans are found throughout the Nearctic Region, mainly in Alaska, Canada, and the northern United States. A large percentage is found in Alaska, specifically in Prince William Sound and the Copper River Delta. Some trumpeter swans have even taken up residence in Yellowstone Park, Wyoming. (Grant and Henson, 1994; Henson and Cooper, 1993; Mills, 1991; Schmidt, et al., 2009; Squires and Anderson, 1997; Squires, 1995)

Habitat

Trumpeter swans live on land but always in close proximity to water. They are found in wetlands with open water and areas with many rivers or streams. Waters can be salt water, fresh water, or brackish water. Their climate ranges from temperate to polar. Reasons for their choice of environment have to do with their diet and nesting habits. Cygnus buccinator feeds off many plants native to those areas. They are also known for laying their eggs near or on the water. They seek out the same habitat type for wintering grounds. (Grant and Henson, 1994; Henson and Cooper, 1993; Mills, 1991; Proffitt, 2009; Schmidt, et al., 2009; Squires and Anderson, 1997; Squires, 1995)

Physical Description

As the largest North American swans, these birds can weigh up to 13.5 kg and measure approximately 1.6 m in length. Wingspan can often exceed 2 m. When they are young "cygnets", the bill features some degree of pink but is always black at the base. The feet and tarsi (portion of the foot that makes up the ankle region) may be a grey-yellow. The body is light to dark grey, and will gradually whiten with age. At age two, most but not all of their feathers have turned white, except for a few on the upper portion of the body.

At adulthood their feet, bill, and tarsals are black. They have pink to red mouths which can be seen as a small pink or red line (a 'grin') on the bill. Their feathers are completely white. There is also a small percentage of trumpeter swans that have a grey-white tint for feather color instead of pure white.

They appear very similar to tundra swans (Cygnus columbianus), with the most reliable differences found near the beak. Viewed face-forward or top-down, trumpeter swans have an angular, v-shaped forehead at the base of the beak. Tundra swans have a curved or straight forehead. Most tundra swans have a yellow-white 'teardrop' on their black beak, however this is not always a reliable field mark. (Slater, 2006)

  • Sexual Dimorphism
  • sexes alike
  • Range mass
    9.5 to 13.5 kg
    20.93 to 29.74 lb
  • Range length
    1.4 to 1.6 m
    4.59 to 5.25 ft
  • Range wingspan
    2.0 to 2.4 m
    6.56 to 7.87 ft

Reproduction

Trumpeter swans are monogamous and mate for life. During mating season, trumpeter swans reunite with their former mates or begin a process of courtship to secure a mate. Courtship displays consist of pairs simultaneously spreading or raising wings, wing quivering, head bobbing and trumpeting. (Slater, 2006)

Adults begin mating at 4 to 7 years of age. Mating usually occurs from March to May. Nest-building can take 2 to 5 weeks to complete, and both parents are involved in construction. The nests range from 1.2 to 3.6 m in diameter and are usually surrounded by water. The materials used in nests building include various aquatic vegetation, grasses, and sedges.

After copulation and fertilization, the females lay 4 to 6 eggs. Incubation lasts for 32 to 37 days, done mainly by the female. The young, precocial cygnets spend their first 24 hours in the nest, then begin to swim. They fledge after 91 to 119 days and are independent after one year. (Slater, 2006)

  • Breeding interval
    Trumpeter swans breed once yearly.
  • Breeding season
    Trumpeter swans breed from March to May.
  • Range eggs per season
    4 to 6
  • Range time to hatching
    32 to 37 days
  • Range fledging age
    91 to 119 days
  • Average time to independence
    1 years
  • Range age at sexual or reproductive maturity (female)
    4 to 7 years
  • Range age at sexual or reproductive maturity (male)
    4 to 7 years

Both parents contribute to nest building which lasts 2 to 5 weeks. The female will perform the majority of incubation. Unlike many birds, trumpeter swans do not have a specialized brood patch and instead will incubate the eggs using their feet. Upon hatching, the young are precocial but still require significant parental care. Both parents care for the cygnets throughout their first year. (Slater, 2006)

  • Parental Investment
  • precocial
  • male parental care
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • post-independence association with parents
  • extended period of juvenile learning

Lifespan/Longevity

Young trumpeter swans often have survival estimates from 40% to 100%, adult swan survival increases to 80% to 100%. The oldest captive trumpeter swan on record was 33 years old. In the wild, the oldest known individual was 24. (Krementz, et al., 1997; Slater, 2006)

  • Range lifespan
    Status: wild
    24 (high) years
  • Range lifespan
    Status: captivity
    33 (high) years

Behavior

Trumpeter swans live in small flocks, often with members of their own family. Their daily routine varies from season to season. In winter they rest more and eat less, while in spring they consume large amounts of food and are very active during the day. Flock size also varies seasonally. In spring, flock size can be almost half than found in the fall because the young have left and the breeding season is about to begin.

Trumpeters are known to be very territorial during the mating season. They can become incredibly violent to competitors, other swans, or any animals that could pose as a threat that invades their space.

Trumpeters are migratory birds. When the weather gets colder (mid-October to late November) they begin a slow migration southward, with the first stop usually at Yellowstone National Park, and other parts of Wyoming and also North Dakota. They remain there until the water freezes over and then they move onto places such as Utah and Arizona where the winter climate is much warmer. Many trumpeter swans spend the winter on the western coast of Canada, Alaska, and Washington. (Earnst, 1994; Slater, 2006)

Home Range

Trumpeter swans are very territorial and rarely leave their nests unguarded. Their nests are built on or near aquatic vegetation, and the adults do not need to wander far from the nest for food. Thus, the home range during the breeding season, though not calculated, is not expected to be substantial. (Slater, 2006)

Communication and Perception

Trumpeter swans produce a variety of sounds, but they are known for their low bugle call. In addition to the bugle call, they also use motions such as head bobbing to alert others of disturbances or in preparation for flight. Trumpeter swans are very social creatures except for in times of mating, when they become quite territorial. Pheromones are also used in mating rituals. The female emits pheromones when she is ready to mate. Breeding pairs perform visual, synchronous displays which likely reinforce the pair-bond. Trumpeter swans call to warn the flock of impending danger. Trumpeter swans perceive their environment through visual, auditory, tactile, and chemical stimuli. (Slater, 2006)

Food Habits

As cygnets, trumpeter swans' diets are mostly comprised of aquatic invertebrates. At five weeks of age, most cygnets have converted to a nearly herbivorous diet. This diet consists mostly of tubers, roots, stems, leaves and occasionally insects. In Alaska during mating season, the wetland plants commonly known as horsetail (genus Equisetum) and Lyngbye's sedge (Carex lyngbyei) are consumed in great quantities. However, because of the wide distribution of the species there are some variations of their diet such as duck potato (Sagittaria latifolia), water weeds (genus Elodea), pondweeds (genus Potamogeton) and sago pondweed (Potamogeton pectinatus) tubers.

Trumpeter swans attain their food by foraging underwater with tails bobbing in the air. They also yank plants out of the damp ground, with most of the plant intact. (Slater, 2006)

  • Animal Foods
  • aquatic or marine worms
  • Plant Foods
  • leaves
  • roots and tubers

Predation

Although adults aggressively defend their nests, ground nests are easy targets for land predators. Many predators, such as bears, wolves and coyotes, wolverines, raccoons, and common ravens are known to snatch eggs. Post-hatchlings and adults are prey to fast predators such as coyotes, bobcats, red foxes, and golden eagles. The main predator of adult trumpeter swans is mankind. Humans have hunted more of these swans than anything else.

Trumpeter swans are aggressive towards predators, and at 12 kg with a 2 m wingspan, they can potentially inflict serious damage. Trumpeter swans do exhibit warning behaviors before they attack, including head bobbing and hissing. (Kraft, 1946; Schmidt, et al., 2009; Slater, 2006)

Ecosystem Roles

Trumpeter swans' main role in the ecosystem is linked to their diet. Trumpeter swans eat many insects when they are young. As they grow they switch to roots and aquatic plants, digging around to get them which in many cases allows water to fill the remaining holes supplying a very valuable nutrient to the plants. Cygnus buccinator can also be a host to a small number of parasites including tapeworms (Anoplocephala perfoliata), caecal paramphistomids (Zygocotyle lunata), trematode flukes (Echinostoma revolutum), another type of trematode (Orchipedum tracheicola), filarial worms (a nematode found in the heart) of the species Sarconema eurycerca, and other forms of tapeworms (Hymenolepis). (Cowan, 1946; Slater, 2006)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

Trumpeter swans used to be a commercial hunting target for feathers and skins, but over-hunting led to their marked decline. Today, only illegal hunting occurs. (Slater, 2006)

  • Positive Impacts
  • body parts are source of valuable material

Economic Importance for Humans: Negative

Trumpeter swans are very territorial animals, especially during mating season, and humans that enter their territory may be attacked. (Slater, 2006)

Conservation Status

Historically, birds were heavily harvested for decorative feathers and skins. Many birds continue to be hunted illegally. If birds are illegally shot and do not die immediately, an embedded bullet may cause lead poisoning and eventual death. Today, habitat destruction is likely the greatest threat to trumpeter swans. Efforts are being made to protect trumpeter swans and their wetland habitat, with many states involved in reintroduction programs. As migratory birds, they are protected under the United States Migratory Bird Act.

Trumpeter swans are also affected by recent population increases of invasive mute swans. Mute swans are markedly more aggressive and will often chase trumpeters away from their shared wetland habitats. Some states are involved in mute swan control programs with the goal of reducing populations to allow for native swans to return. (Slater, 2006)

Contributors

Kaitlyn Robins (author), Radford University, Karen Powers (editor), Radford University, Rachelle Sterling (editor), Special Projects.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

chemical

uses smells or other chemicals to communicate

coastal

the nearshore aquatic habitats near a coast, or shoreline.

diurnal
  1. active during the day, 2. lasting for one day.
duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polar

the regions of the earth that surround the north and south poles, from the north pole to 60 degrees north and from the south pole to 60 degrees south.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tundra

A terrestrial biome with low, shrubby or mat-like vegetation found at extremely high latitudes or elevations, near the limit of plant growth. Soils usually subject to permafrost. Plant diversity is typically low and the growing season is short.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Baskin, Y. 1993. Trumpeter swans relearn migration. Bioscience, 43/2: 76-79.

Bergman, C. 1985. The Triumphant Trumpeter. National Geographic, 168/4: 544-558.

Cowan, I. 1946. Death of a Trumpeter Swan from Multiple Parasitism. The Auk, 63/2: 248-249.

Earnst, S. 1994. Tundra Swan Habitat Preferences during Migration in North Dakota. The Journal of Wildlife Management, 58/3: 546-551.

Grant, T., P. Henson. 1994. Feeding ecology of trumpeter swans breeding in south central Alaska. Journal of Wildlife Management, 58/4: 774.

Hanson, P., J. Cooper. 1994. Nocturnal Behavior of Breeding Trumpeter Swans. The Auk, 111/4: 1013-1018.

Henson, P., J. Cooper. 1993. Trumpeter Swan incubation in areas of differing food quality. Journal of Wildlife Management, 57/4: 709-716.

Johnsgard, P. 1978. The Triumphant Trumpeter. Natural History, 87/9: 72.

Kraft, F. 1946. The Flying Behemoth is Coming Back. Saturday Evening Post, 219/6: 6.

Krementz, D., R. Barker, J. Nichols. 1997. Sources of Variation in Waterfowl Survival Rates. The Auk, 114/2: 93-102.

LaMontagne, J., L. Jackson, R. Barclay. 2003. Characteristics of ponds used by trumpeter swans. Canadian Journal of Zoology, 81/11: 1791-1798.

Lynch, W. 2007. Perfection in White. Canadian Wildlife (Canadian Wildlife Federation), 13/4: 18-23.

Mills, J. 1991. The Swan That Would Not Fly. National Wildlife, 29/6: 4.

Proffitt, K. 2009. Trumpeter Swan Abundance and Growth Rates in Yellowstone National Park. Journal of Wildlife Management, 73/5: 728-736.

Schmidt, J., M. Lindberg, D. Johnson, J. Schmutz. 2009. Environmental and human influences of trumpeter swan habitat occupancy in Alaska. Condor, 111/2: 266/275.

Slater, G. 2006. "Trumpeter Swan (Cygnus buccinator): a technical conservation assessment" (On-line pdf). US Forest Service. Accessed February 16, 2010 at http://www.fs.fed.us/r2/projects/scp/assessments/trumpeterswan.pdf.

Squires, J. 1995. Trumpeter swan (Cygnus buccinator) food habits in the greater Yellowstone ecosystem. American Midland Naturalist, 133/2: 274.

Squires, J., S. Anderson. 1997. Changes in trumpeter swan (Cygnus buccinator) activities. American Midland Naturalist, 138/1: 208.

Truslow, F. 1960. Return of the Trumpeter. National Geographic, 118/1: 134.

Wilkinson, T. 1991. Call of the Trumpeter. National Parks, 66/7-8: 26.

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