Trumpeter Swan
Last Update/Review: June 17, 2002
Status | Description | Habits | Reproduction | Food | Limiting Factors | Management and Outlook
Status
The trumpeter swan is the largest and rarest swan in the world. In the Alberta Policy for the Management of Threatened Wildlife, it is listed as a vulnerable species, found near the edge of its range in Alberta. Without active management and protection, this species could easily become threatened or endangered in the province.
Trumpeter swans used to breed in boreal, parkland, and prairie habitats throughout Canada and the United States from James Bay to the Rocky Mountains south to Missouri and Wyoming. In Canada, the birds nested throughout the central regions of Alberta, Saskatchewan, and Manitoba as well as along the James Bay coast of Ontario and Quebec. Although the total population size was unknown, the species was abundant.
By the early 1900s, trumpeter swans were nearly extinct. Large numbers of birds had been shot for their down, feathers, and meat. Increasing settlement had disturbed suitable nesting areas, particularly in the southern part of their range. In 1930, the only known breeding population was in the newly created Yellowstone National Park in Wyoming. Other small remnant flocks probably also existed in Alberta, Alaska, and Montana.
An international program to save trumpeter swans from extinction began in the 1930s when the birds and their remaining habitat were granted additional protection. The public was made aware of the problem and encouraged to report sightings of trumpeters or their nests and to reduce human activity near nesting areas. Trumpeter swans have responded well to the restoration program. Populations in the United States, Alaska, and the Tri-state Region of Montana, Wyoming and Idaho, have increased steadily to where these birds have been removed from the endangered species list in the U.S. Trumpeters are still considered vulnerable in Canada, with approximately 550 swans nesting in 1990. Locations of breeding flocks include the Yukon, northern B.C., southwestern Northwest Territories and the Grande Prairie/Peace River region of Alberta. A major part of the Alberta flock is concentrated on lakes and sloughs near Grande Prairie. This population has increased slowly and steadily from approximately 120 birds in 1975 to 321 birds in 1990. In addition, a few trumpeter swans breed locally near Cardston, Edson, and various lakes north of Peace River and St. Paul. In 1990, a total of 156 birds were counted in these other areas.
Description
In general, swans are easy to identify as large white birds with an unusually long neck. Often the head and neck are stained with a rusty-orange colour from feeding in bottom substrates high in iron. In flight, the neck stretches straight out in front of the bird and there is no black on the wings. The sexes are similar in size and colour.
Trumpeter
swans are difficult to distinguish from the much more common tundra
swans (which used to be called the Whistling Swan).
The only consistent difference between the two species is their voice: trumpeter swans have a deep loud horn or trumpetlike call; tundra swans have a higher pitched bark, more like a musical whistle. A longer and double-looped windpipe in trumpeter swans allows them to make the deeper, louder call.
Other
characteristics used to separate the two species of swans may vary
and an observer must look closely to make a correct identification.
Trumpeter swans normally do not have a yellow patch in front of the
eye and each eye appears to blend into the black base of the bill.
Tundra swans usually (but not always) have the yellow spot and the
eye looks separate from the bill trumpeter swans often have a red line
on the upper edge of the lower jaw. Tundra swans usually do not have
this line.
Trumpeter swans are larger and heavier than Tundra Swans but this is hard to judge in the field. Immature birds of both species are pale grey with darker colour on the head and neck. The young birds molt to white early in their second summer. Identification of young swans should be based on the characters of adult birds with them. However, any swan nesting in Alberta or seen here between late May and late August is probably a trumpeter swan. (Tundra swans usually nest only in the Arctic.)
Habits
Trumpeter swans are migratory waterfowl, and are found in Alberta during the spring, summer and fall. However, they are not long distance travellers and fly only far enough to reach suitable habitats for nesting or wintering. The birds arrive in Alberta in April and move north as the lakes and sloughs open in the spring. The swans require shallow lakes with an abundant supply of aquatic plants, insects and snails (for nest sites and food) and a low level of human disturbance. The water must be a constant level throughout the summer and have little wave action or currents. Most of the trumpeter swans in the Grande Prairie flock stop (stage) at Bear Lake or Sinclair Lake early in the spring and then move to other lakes in the area.
|
Adults
and cygnets are collared to learn more about their migration
and survivalFall migration starts at freeze-up in late October or November. The swans again gather in the staging areas, then fly south until they reach an area of shallow lakes and streams with food and open water. In the early winter, most birds from Grande Prairie stay on the Yellowstone Lake in Yellowstone National Park. As the temperature drops and the river ices up, the birds move to a 15-km section of the Henry's Fork, of the Snake River in eastern Idaho. This area has hot springs and fast-flowing water that stay open throughout the winter. Wintering swans spend most of their time eating and resting.
Trumpeter swans have very strong ties to their nesting and wintering areas. They return to the same lakes and usually the same nest year after year. The birds may live up to 35 years in captivity but usually do not live more than 12 years in the wild. Family groups stay together during migration, and thus, the adults guide the young to the wintering areas.
The following spring, the young again migrate with the adults but have left the family group by the time they reach their destination. Young birds and nonbreeding adults gather in small groups and feed in lakes not used by a breeding pair. These groups account for up to 60% of the summer population.
Trumpeter swans usually mate for life or until one of the pair is killed or dies. Bonding takes place during the summer and most birds three years or older are paired. These pairs stay together throughout the year and may defend a nesting territory even though they often do not breed until they are four or five years old.
Reproduction
Like the birds themselves, the nests of trumpeter swans are big and bulky. They may be used repeatedly and each year the adults add more material. Some pairs may have two or three alternate nesting sites. The nest is a mound of reeds, rushes, roots, and grasses lined with fresh swan's down. Often it is built on top of a beaver lodge, muskrat house, small island, or mat of floating plants. The adults may remove vegetation until the nest is surrounded by open water. This provides protection from land predators and good visibility around the nest.
The
nest is fiercely defended by both adult birds and all other swans are
driven away from the nesting lake. Thus, the usual density of breeding
swans is one pair per lake (unless it is a very large lake). This helps
guarantee enough food for the two large adults and five or six hungry
young birds (cygnets) throughout the summer.
In order to provide continual defence of the nest, the moulting period of breeding trumpeters is different for females and males. The males usually moult first, whereas the females moult after the eggs hatch. Each adult is flightless for about a month and the asynchronous moult allows for one adult to be able to fly while the other stays with the cygnets.
Each breeding pair uses only one nest, and the female lays five or six white eggs. If these eggs are destroyed, the pair will probably not renest, as the short northern summer is not long enough for late-hatched cygnets to survive to the flight stage.
In Alberta, the eggs are laid in mid-May and the female incubates them for approximately 32 days. Foraging is greatly reduced during this time and she depends on her stored body reserves for energy.
Most of the eggs hatch in mid-June and the cygnets stay in the nest with the female for approximately 24 hours until they can keep themselves warm. They have very little food reserve and must start feeding quickly. Cygnets in the Grande Prairie area start to fly in late September, just in time to avoid an early freeze-up. However, the family groups usually stay in the area for about a month and leave in late October.
Food
Swans are well adapted to using a variety of aquatic foods not used by other waterfowl. Their long neck and powerful bill allow them to reach down and pull up roots and stems that other birds cannot reach. They reach even farther by upending, like dabbling ducks, with just the tail and back portion of the body out of the water. The strong legs and large webbed feet with long, sharp claws are used to dig up roots or produce water currents that wash the mud away from the roots. The currents also bring food to the surface. This is particularly important for getting food to the cygnets.
Trumpeter swans eat a variety of aquatic plants such as arrowhead, pondweeds, sedges, cattail, duckweed, and water moss. They are not choosy and will eat roots, stems, leaves, and seeds. They also eat a few large aquatic insects and snails. Adult swans eat up to 9 kg each per day and this is the reason each pair defends such a large territory.
Initially, young cygnets eat large aquatic invertebrates (such as beetles and bugs), a good source of protein for the growing birds. Cygnets feed at the surface and often depend on the adult birds to stir up the water around them. Within two or three weeks, the cygnets start to eat aquatic plants and gather their own food.
Limiting Factors
The major limiting factor affecting Alberta's trumpeter swans appears to be the size of their wintering area. In winter they are concentrated in a very small portion of the Snake River. In addition, they share this small area with migratory trumpeter swans from the Yukon, Northwest Territories, and British Columbia, as well as nonmigratory birds that live in the area all year. The competition for food is high throughout the winter and some birds may be in relatively poor condition by spring. This lack of stored energy for migration, egg laying, and incubation may cause the death of a mate, or decrease the nesting success of the pair. Thus, a combination of factors in the wintering area seems to limit the potential for increase in the Alberta population of swans.
Any
decrease in the amount of available winter habitat could easily result
in the loss of most or all of the population. Overcrowding and concentration
in one area increases the potential for major losses from disease,
parasites, or severe weather. In fact, in February 1989, more than
100 trumpeter swans died after severe winter weather caused the Snake
River to freeze.
Human
activity and disturbance in the breeding areas may cause the death
of adult birds and/or decreased survival of eggs or cygnets. Trumpeter
swans are sensitive to repeated disturbance and may refuse to nest
or abandon an existing nest in such situations. The birds are most
sensitive from mid-April to mid-June. Unfortunately, this also is when
the eggs and cygnets are at greatest risk.
Swans will not nest on lakes intensively developed for recreation. For example, trumpeter swans have stopped nesting on Wembly Lake and Crystal Lake in the Grande Prairie area. Management programs to control the amount and/or type of recreational activity could reduce this problem. Swans can nest on lakes near areas developed for resource exploration or forestry; however, the increased access often results in greater recreational uses.
Unfortunately many birds are still shot accidentally or on purpose. Their large size and habit of flying low over marshes makes them relatively easy to kill. Some birds are mistaken for snow geese (nnow geese have black wing tips) or, in some areas of the United States, for tundra swans. Both native swan species are completely protected in Canada and killing them is illegal.
Management and Outlook
Various management programs have been used to directly or indirectly benefit trumpeter swans. An international swan management plan has been outlined and goals for the minimum breeding population in each area have been established. Annual fall surveys are used to identify areas and habitats used by swans and to estimate the population size throughout their range. Some birds marked with collars have provided information about migration, wintering areas, survival rates, and population dynamics. In many areas, dams and dikes are used to stabilize water levels and ensure that specific lakes remain suitable for swans and other waterfowl species throughout the summer.
The awareness and concern of the public is perhaps the most important factor in restoring the trumpeter swan population in Canada and the United States. In particular, the residents in and around Grande Prairie adopted the trumpeter swans in their area and support efforts to protect the nesting habitat and reduce human disturbance near nests. They also cooperate in protecting areas used by nonbreeding birds as feeding, loafing, and moulting habitat.
In order to study migration and survival, biologists in both Canada and the United States have marked trumpeter swans with colored collars. In addition, they have marked a number of swans by coloring areas of their white feathers with yellow-orange dye. Anyone who sees any of these birds is asked to provide information about the sighting to the Natural Resources Service or the Canadian Wildlife Service.
Other management programs have focused on the high risks facing wintering populations. There is suitable winter habitat in Wyoming, Utah, and southern Idaho; however, the birds continue to use their traditional wintering area. Biologists in the United States are trying to relocate wintering birds away from the Henry's Fork region of the Snake River and into other suitable areas.
Trumpeter swans can be relocated into new breeding areas or reintroduced into their previous areas with good success. At least seven flocks in the United States have been started by relocation or reintroduction efforts. In Canada, attempts are underway to reintroduce trumpeter swans in Elk Island National Park. The program began in 1983 and used trumpeter swans from the Pacific coast as guide birds to lead cygnets to wintering areas in British Columbia. Unfortunately, it was unsuccessful, the guide birds became confused and could not migrate.
A new program began in Elk Island National Park in 1987. In the late summer or fall, family groups were relocated from the Grande Prairie flock to lakes at Elk Island. Although these adult birds returned to the Grande Prairie area in the years following relocation, some transplanted cygnets have returned to Elk Island as subadults. In 1990, a cygnet from the 1987 transplant nested and hatched two cygnets in the Elk Island area. This reintroduction program is showing success, and the techniques developed can now be used to establish new breeding and wintering traditions in other areas.
Biologists are also trying to reintroduce trumpeter swans to specific sites in southern Ontario. Eggs from birds in Grande Prairie and elsewhere were placed under mute swan foster parents. The goal is to establish a population of trumpeter swans in Canada that will use a wintering area in the eastern United States. In addition, Ontario wants to replace feral mute swans (birds that have escaped captivity) with wild trumpeter swans. Mute swans are not native to North America and may compete with our native swans for breeding areas. Trumpeter swans breed well in captivity. A small breeding flock of trumpeter swans has been established at Camrose, Alberta. Young from these birds will be fostered back to the wild.
In general, trumpeter swans in North America are a conservation success story. The outlook for the swans in Alberta and the rest of Canada looks bright. The flock at Grande Prairie is increasing and appears to be re-establishing in some of its earlier range. Continued success depends on a reduction of disturbance of breeding pairs in these areas and the ability to spread breeding and wintering birds onto new range. Public awareness and support of the birds and the various management programs is high. Such support and cooperation will help secure the future for trumpeter swans. Additional information about trumpeter swans is available from:
Wildlife Management Branch
Fish and Wildlife Division
Alberta Sustainable Resource Development
9915 -108 Street
Edmonton, Alberta
T5K 2G8
