Tundra swans are widespread; they are native to parts of North America, Europe, Asia, Africa, and the Caribbean. In North America, tundra swans are migratory birds consisting of two populations: the western population and the eastern population. During the summer breeding season, the western population inhabits the southwestern coast of Alaska, from Point Hope to the Aleutian Islands, and above the Arctic circle of Canada. During the wintering season, they inhabit the Arctic slope of Alaska to the California Central Valley. They can also be found inland in areas such as Utah, Texas, New Mexico, Montana, Colorado, and Idaho. During the summer breeding season, the eastern population inhabits the Pacific Ocean and migrates southward through Canada, and into the Great Lakes region of North America. During the wintering season, they inhabit Maryland, Virginia, North Carolina, South Carolina, Georgia, and Florida. Tundra swans were introduced to Algeria, Antigua, Barbuda, Belarus, Bermuda, Guam, Jordan, Kyrgyzstan, Northern Mariana Islands, Oman, Portugal, Spain, United Arab Emirates, and the Virgin Islands. They are native to Austria, Belgium, Bulgaria, China, Canada, Croatia, Cuba, Denmark, Estonia, Finland, France, Germany, Greece, Greenland, Hungary, Iceland, India, Italy, Israel, Japan, Libya, Mexico, Mongolia, Nepal, North Korea, Norway, Pakistan, Poland, Puerto Rico, Russia, Serbia, South Korea, Sweden, Switzerland, Ukraine, and the United States. (Baughman (editor), 2003; Limpert, et al., 1991a; Limpert, et al., 1991b; Spindler and Hall, 1991; Young, 2008)
Tundra swans inhabit freshwater lakes, pools, grasslands, and marshes. During migration, they are found in rivers and lakes along their migratory pathway. The swans are most commonly seen at an elevation below 60 m. While in flight, they have been observed as high as 8,229.6 m above ground. Tundra swans are most commonly seen in wetlands close to agricultural fields during the winter months. They favor aquatic habitats that have sago pondweed, which is one of their primary food sources. Wetlands with large channels are also chosen because of the availability of aquatic vegetation. (Baughman (editor), 2003; Earnst and Rothe, 2004; Earnst, 1994; Petrie, et al., 2002; Stewart and Bernier, 1989; Wilk, 1988; Young, 2008)
Tundra swans are 1.2 to 1.5 m in length, from beak to tail, with a wingspan of 1.65 to 2.16 m, and a weight of 3.6 to 9.1 kg when fully grown. They have a long neck, which is held high and stretched out. Their head is round with brown eyes. They have a short tail with short black legs. Most of their body, including their neck, is white. Among mature tundra swans, their black beak extends up their forehead. In some swans, a yellow spot, resembling a teardrop, can be found below their eye. Males and females are sexually monomorphic. Tundra swans can easily be mistaken for trumpeter swans or whooper swans. However, tundra swans can be distinguished by their straight neck, which differs from the neck kink among trumpeter swans or the “s” shape among whooper swans. Immature tundra swans are greyish but turn fully white during the winter months. Young swans have pinkish- grey legs, which turn a dull black as they get older. Their beak is also pinkish-grey and turns pure black with age. (Baughman (editor), 2003; Kortright, 1942; National Geographic Society, 1983; Sterry and Small, 2009)
Tundra swans are monogamous and are not known to change mates within their lifetime. Pairs breed yearly, in late May through late June, with both parents helping to raise the young. One brood is raised annually. If the brood fails, they do not have a second brood. The swans court by facing each other, then quivering, spreading their wings, and calling out loudly. While calling, they also bow their heads up and down to express interest. Reproductive success determines dominance in the social structure. It is determined by the number of young from the previous year that are paired with a mate upon their arrival at their wintering site. The greater the number of cygnets that are paired, the more successful the family unit is perceived. Additionally, because swans choose mates of a similar age and similar size, the oldest and largest pairs tend to be more dominant. To help establish dominance, males fight to protect their mates. When threatened by conspecifics or predators, pairs in close proximity have a better chance of intimidating invading swans. Single females are more open to swan attacks, and can fall socially if the male is constantly absent. (Black, 1996)
Tundra swans breed from late May through late June. Nests composed of moss, dead leaves, and grasses are built in late May. The outside diameter of the nest is between 122 to 183 cm, the inside diameter averages 46 cm, and the nest height averages 61 cm. The number of offspring per breeding season is dependent on climate and can range from 3 to 7 eggs, with warmer ambient temperatures producing more eggs. The average per brood is 5 eggs. Their creamy white eggs are about 107 mm X 66 mm, with a smooth, circular shape. Eggs are laid one at a time, every 1.5 to 2 days. The incubation period ranges from 31 to 33 days. Hatchlings are born fully feathered and weigh about 180 g. Their eyes are opened, and they are able to leave their nests immediately. However, the cygnets cannot fly until they are between 60 to 75 days old. Before age 2, the cygnets are followers, and follow closely behind their mother. Young swans remain with their parents until they are 2 years old. Tundra swans are capable of reproducing by age 3, but may not begin breeding until age 4 or 5. (Baicich and Harrison, 1978; Rees, 2006; Sandilands, 2005)
A pair establishes and defends a territory in which they raise their young and feed. This territory is about 1.29 square km, which includes land and a large body of water. After laying her eggs, the female tends to the clutch the majority of the time by sitting on her eggs. When the female is absent, the male sits on the eggs. Tundra swans have a precise mechanism of changeover. The parent swan that is leaving the eggs stands and pokes downwards at the eggs a few times, and then walks off. Then, the parent that is returning to the nest quickly sits on the eggs. The male is always more reluctant to come off of the eggs. During a changeover, the male does most of the addition of the nest material around the sides and the base of the nest. During the moment the change happens, the male adds nest material around the sides and the base of the nest. The female rearranges the nest material. This changeover of labor is usually quiet. The other parent usually stays nearby to watch for predators. The incubation period is 31 to 33 days. After the eggs hatch, the parental roles are less distinct. Both sexes take care of the cygnets and assist them with getting food and chasing off predators. However, cygnets follow their mother, keep closer to her, and interact with her more than the father. Both parents tend to stay close to each other and their offspring during the pre-fledging period. Young swans can start flying around 60 to 75 days after hatching. Cygnets do not leave their parents until 2 years of age. Sometimes siblings rejoin their family, with or without a mate. (Black, 1996; Earnst, 2002; Sandilands, 2005; Wilk, 1988)
In the wild, the longest known lifespan for a tundra swan was 24.1 years, and their expected lifespan is between 15 to 20 years. In captivity, their expected lifespan is 20 to 25 years. Their annual mortality rate is 25 to 50% before they are three years of age. During and after their third year, their annual mortality rate is 10 to 15%, with lead poisoning and avian cholera (caused by Pasteurella multocida bacteria) being the leading causes of death. Other causes of death include hunting, "trauma," drowning, kidney dysfunction, parasites, starvation, and suffocation. Diseases that may cause mortality include aspergillosis (caused by the fungus Aspergillus), botulism (caused by Clostridium botulinum bacteria), and necrotic enteritis (caused by Clostridium perfringens bacteria). (Bartonek, et al., 1991; Max Planck Institute for Demographic Research, 2002; Nichols, et al., 1992)
Tundra swans are social and interact with other swans within their population. Social dominance is the key to survival in swan populations. The most stable swan unit is the family, which includes both parents, their 3 to 7 cygnets from that year, and occasionally young from previous years. The most dominant family is not necessarily the largest unit; instead, it is determined collectively by each member’s ability to gain resources. Units with more dominant ranks have greater access to food, resting areas, resources, and safe areas. Aggressive encounters are associated with dominance in a hierarchy. To establish dominance, males fight to protect their families. Unmated birds are not as likely to have aggressive encounters because of their lower social rank. For a family, once dominance is established, their social rank is maintained throughout the winter. For a young, single swan, once dominance is established, their social rank increases with years in the flock because they presumably feed more efficiently and fight more aggressively. Within a family, swans use pre-flight signaling to make sure family members take off together. Males tend to lead the movement in the autumn, and females lead the movement in the spring. These signals include head bobbing, or neck bending and stretching repeatedly prior to flight, opening of the wings, and other visual displays. (Badzinski, 2003; Black, 1996; Rees, 2006; Sandilands, 2005)
Pairs of tundra swans set up a land territory of about 1.29 square km, which includes a large body of water. (Sandilands, 2005)
Tundra swans have a high-pitched, high-frequency, loud, yelp-like call, which sounds like, “woo-oh” or a “kow-hooo”. This call is used for communication with other flock members. Tundra swans have heightened vision and hearing. These senses are helpful in avoiding predation, being aware of other flock members, and scanning for food. (Badzinski, 2003; Badzinski, 2005; Rees, 2006; Wood, et al., 2002)
Tundra swans are herbivorous. They consume plants, which include grasses, sedges, and smartweed. Specific grasses include mannagrass and seagrass. They focus on the flowers, stems, roots, and tubers. They also feed on some invertebrates such as shellfish. The swans feed by dipping their heads underwater, and stretching out their long necks to obtain food up to 1 m under the surface. Using their beaks, tundra swans dig up plants by their roots, or tear plants out of the ground using their webbed feet as paddles. (Baughman (editor), 2003; Rees and Bowler, 1991; Sandilands, 2005; Sterry and Small, 2009; Young, 2008)
Tundra swans spend their breeding time in flocks to avoid predators. The more swans in a flock, the less likely they are to be attacked. Likewise, when flock sizes increase, there are more swans to spot predators and signal that danger is nearby. When swans go head first underwater to obtain food, they are less likely to spot predators. Therefore, swans have adapted the large flock size to help recognize predators while feeding. During the nesting period, males sit close to the nest and watch for predators. After the nest period, males are more likely to display vocal characteristics and chase off predators while the mother takes care of the cygnets. Adult, non-nesting swans have few predators. However, during the nesting period, the young and mother have many predators including common ravens, long-tailed jaegers, brown bears, and Arctic foxes. After the nesting period, red foxes, wolves, and raccoons prey on young swans. (Baughman (editor), 2003; Monda, et al., 1994; Sterry and Small, 2009; Young, 2008)
Tundra swans host several parasites including heartworms (Sarconema eurycerca), guinea worms (Avioserpens taiwana), gizzard worms (Amidostomum acutum), and avian malaria (Plasmodium relictum). Tundra swans have a mutualistic relationship with sago pondweed. The swans use the pondweed as a food source during migration, and then disperse the pondweed, causing its population to expand. (Klaassen and Nolet, 2007; Thomas, et al., 2008; Wobeser, 1997)
Tundra swan feathers can be used by humans for coats, pillows, blankets, mattresses, and winter clothing. Their excrement can be used as a fertilizer to help with crop and grass growth. Tundra swans are also hunted by humans for their meat. (Bartonek, et al., 1991; Wobeser, 1997)
Tundra swans are very territorial and will violently peck when they feel threatened, but they usually do not bite. They are crop pests and pull up planted crops by their root. They can also carry avian influenza, which can be spread to humans and cause illness with symptoms such as fever, coughing, diarrhea, muscle aches, sore throat, difficulty breathing, headaches, and malaise. (Wilson, 1988)
The development of oil is threatening tundra swan breeding sites. Their staging and nesting sites have been disrupted by human activity, lead poisoning from shotgun ammunition, invasive species, and chemical waste. On wintering sites, these swans are negatively impacted by hunting, and competition from mute swans. Local agencies and the Atlantic Flyway Council have plans to help remove the mute swans. The United States allows hunting of tundra swans in eight states. The Atlantic Flyway Council is collecting data to help establish limits for hunting in all of these states. Tundra swans are managed by the U.S. Fish and Wildlife Service and Canadian Wildlife Service as two distinct populations, in which two separate management plans have been developed. The population goals are met through permitted hunting. If the three-year wintering average dips below 60,000 for the eastern population and 40,000 for the western population, then hunting is suspended until those numbers rebound. (National Audubon Society, 2013; Serie and Bartonek, 1991)
Jessica Robinson (author), Radford University, Karen Powers (editor), Radford University, Leila Siciliano Martina (editor), Animal Diversity Web Staff.
the body of water between Europe, Asia, and North America which occurs mostly north of the Arctic circle.
the body of water between Africa, Europe, the southern ocean (above 60 degrees south latitude), and the western hemisphere. It is the second largest ocean in the world after the Pacific Ocean.
living in sub-Saharan Africa (south of 30 degrees north) and Madagascar.
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.
body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
uses sound to communicate
living in landscapes dominated by human agriculture.
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.
a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.
an animal that mainly eats meat
an animal which directly causes disease in humans. For example, diseases caused by infection of filarial nematodes (elephantiasis and river blindness).
uses smells or other chemicals to communicate
the nearshore aquatic habitats near a coast, or shoreline.
used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
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.
parental care is carried out by females
an animal that mainly eats leaves.
A substance that provides both nutrients and energy to a living thing.
mainly lives in water that is not salty.
An animal that eats mainly plants or parts of plants.
(as keyword in perception channel section) This animal has a special ability to detect heat from other organisms in its environment.
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
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).
parental care is carried out by males
marshes are wetland areas often dominated by grasses and reeds.
makes seasonal movements between breeding and wintering grounds
imitates a communication signal or appearance of another kind of organism
Having one mate at a time.
having the capacity to move from one place to another.
the area in which the animal is naturally found, the region in which it is endemic.
islands that are not part of continental shelf areas, they are not, and have never been, connected to a continental land mass, most typically these are volcanic islands.
found in the oriental region of the world. In other words, India and southeast Asia.
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death
breeding is confined to a particular season
reproduction that includes combining the genetic contribution of two individuals, a male and a female
associates with others of its species; forms social groups.
uses touch to communicate
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
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.
uses sight to communicate
young are relatively well-developed when born
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