ARTICLES ON HAWAIIAN AND PACIFIC BIRDS, BIRDWATCHING AND WILDLIFE

The Trumpeter Swan (Cygnus buccinator)

The Trumpeter Swan was once found across North America from the Atlantic Coast to the Pacific Coast. However, when Europeans arrived, they hunted and harassed the species almost to extinction and in 1933 there were only a maximum of 77 Trumpeters breeding in Canada and 50 breeding in the United States. Today, due to an intensive international conservation effort, there are about 16,000 wild Trumpeter Swans in North America, and the species is no longer considered in danger of extinction. Continued habitat protection and enhancement, and the initiation of reintroduction programs, should ensure that numbers of this magnificent bird will continue to rise and that it will once again inhabit much of its former range. Although Tundra Swan (Cygnus columbianus) has reached Hawai'i as a vagrant on two occasions, Trumpeter Swan has not yet been recorded.

Distribution

The Trumpeter Swan formerly nested from Alaska and northern Canada to areas south of the Great Lakes and along the St. Lawrence River. Large wintering populations were known from the central Atlantic coast of the United States, the Gulf of Mexico, the Ohio and Mississippi river valleys, and parts of the west coast. Excessive hunting by European settlers, for their own use and for the swan skin trade, and probably habitat changes associated with settlement combined to eliminate the Trumpeter from all but a small part of its former range.

Today, biologists recognize three populations of Trumpeter Swans (see map): the Pacific Coast Population, the Rocky Mountain Population, and the Interior Population. Two of these populations developed primarily from remnant flocks that survived the historic decline, and the third consists of flocks that have been created by transplanting wild birds from established flocks into promising habitat and by breeding swans in captivity and releasing the young into the wild.

At present he most serious threat to the continued success of the Trumpeter Swan population is the loss of habitat. Humans are also responsible for accidental deaths, although it is rare that these have a serious effect on populations, except perhaps on a local scale. Accidental deaths can occur from lead poisoning caused by the ingestion of lead shot in areas that are heavily shot over by hunters; through collisions with human-made objects, most notably power transmission lines and other overhead wires; and occasional misidentification and illegal shooting.

The Pacific Coast Population is at present increasing and expanding its range, especially within its Alaskan breeding areas, however, recreationists, oil prospectors, miners, wood cutters, and settlers are rapidly invading productive lowland areas of Alaska, including the Trumpeters' nesting range. The development of Alaska may prove to be as bad for Trumpeter Swans as was the settlement of the plains. The Rocky Mountain Population is also increasing, although not as quickly as the Pacific Coast Population. This population is vulnerable to catastrophic losses from disease, habitat destruction, or exceptionally cold weather while the birds are concentrated on their Tri-State wintering grounds. Any long-term expansion of this population probably depends on the enhancement of existing wintering habitat and the creation of new wintering traditions.

There are also over 1,000 Trumpeter Swans held in zoos and by private aviculturists worldwide. Canada's captive breeding programs are in Manitoba, Alberta, and Ontario. Map and bill drawing: Authority of the Minister of the Environment © Minister of Supply and Services Canada, 1975, 1984, 1992.


Identification

Adults: The most useful feature to identify Trumpeter and Tundra Swans in the field is the shape and colour of the bill. Adult Trumpeter Swans have all black bills, whilst Tundra Swans have more sloping bills, usually with a small yellow patch in front of the eye. In some birds this yellow patch is missing, which can make it quite difficult to distinguish between the two species unless the voice is heard. Adult Trumpeter Swans are very large birds with white feathers and black legs and feet. As the species often feeds in areas rich in iron salts the feathers of the head and the upper part of the neck often become stained orange. At closer range a salmon-red line on the lower bill is visible. The male swan weighs an average of 12 kg. The female weighs an average 10 kg. According to Sibley however, Trumpeter Swans weigh in around 23lb and Tundra Swans around 14lb. Their Wingspan is about 3 metres. Trumpeter Swans have survived in captivity for up to 35 years, but in the wild most swans live for less than 12 years.

Juveniles: Young of the year (cygnets), can be distinguished from adults by their greyish plumage, yellowish legs and feet, and until their second summer, their smaller size. Trumpeter Swans are well adapted for the harsh environments in which they sometimes live. Their unusually dense layer of down, which can be up to 5 cm thick, seems to make them almost impervious to the cold. It is not unusual for Trumpeter Swans to tolerate extended periods with temperatures as low as -30°C.

Separating Trumpeter and Tundra Swans

The following extract is from an article by Michael A. Patten and Matthew T. Heindel, Identifying Trumpeter and Tundra Swans in the Field (available for about $3.00+ postage from ABA, 1-800-634-7736).

The name Tundra Swan includes the Whistling (North American) and Bewick's (Eurasian) swan subspecies. Characteristics are age related, and vary by populations and within populations. No characteristic, except the call, should be considered by itself diagnostic. Several characteristics should be used in combination when diagnosing the species. The following describes differences between Trumpeter and Whistling (Tundra) swans. Trumpeter(s) are signified by [T], and Whistling(s) are designated by [W].

Mature Trumpeters and Tundras:

Mature Trumpeters and Tundras may be defined as all white birds (including all white neck and head).

A. Size: Males are usually larger than females. [T] are generally larger than [W], although there is some size overlap.

B. Physical Proportions: Neck Length / Body Length Ratio. [T] is usually greater than [W]. The longer neck of [T] is usually fairly easily recognizable. Body Length / Body thickness Ratio. [T] is usually greater than [W]. This is noticeable in a profile view of the rump, where the included angle between the back and the underside is smaller on [T] than it is on [W].

C. Angle of The Body Major Axis (BMA): The BMA is a straight line through the base of the neck and through the tail. The BMA of both species usually slopes up toward the tail when the swans are swimming or sitting, but the slope is greater for [W] than it is for [T]. This and body length-to-thickness differences combine to give [W] a higher, steeper rump appearance when swimming or sitting. Use this mark when viewing a large flock of sleeping or feeding [W] to eliminate potential [T] candidates.

D. Feet size: [T] feet are larger than [W] feet, with no overlap. [T] feet are typically 6-1/2" to 7" wide. This is useful for swans in flight and when the swan is standing on one foot with the up foot extended to the rear.

E. Head Profile and Bill Shape: Head profiles vary for both species.

Some [T] have a pronounced flat, or nearly flat, head for about 2" to 2-1/2" from where the forehead feathers meet the culmen to the apex near the back of the head (call this Type 1 head). On other [T] the flat area is less pronounced, and even can appear as a rather smooth curve (call this Type 2 head). The line of this "flat" area on Type 1 and 2 heads usually continues slightly BELOW the line of the upper mandible. Most [W] have a distinctive round head, with varying radius of curvature that is almost always smooth. Some [W] heads can look like Type 2 [T] in profile, not considering size differences. However, the distinguishing difference between the species is almost always noted in the fact that for [W] the line of the forehead continues ABOVE the line of the upper mandible. Martha Jordan describes the species head differences this way: [W] is like a smaller black cone stuck on the front of a Styrofoam ball; [T] is like a larger black cone that just covers the front of the Styrofoam ball.

In the case of [T] the ball has been reshaped somewhat with, to varying degrees, a flat top and pointed apex. [T] exhibits an abrupt change of contour at the apex (associated with the flat head, Type 1) which gives the head a "pointed" look. [W] exhibits a smooth curve around the apex. The apex of [T] is near the rear of the head well behind the eye. The apex of [W] is near the center of the head just slightly behind the eye. [T] has a flat area along the nape (sometimes not flat). [W] has a curved nape.
The nape of [T] transitions abruptly at the neck (not always). [W] has a smooth transition of the nape to the neck. The distance from the bill tip to the eye of [T] is about 2 times the distance from the eye to the nape. The distance from the bill tip to the eye of [W] is about 1 times to 1-1/2 times the distance from the eye to the nape. Measurements of 4 Trumpeters revealed that the total length of the bill from tip to eye was 5-1/2" to 6", and the distance from the eye to nape was 2-1/2". The upper mandible of [T] is almost straight (can be concave), while the upper mandible of [W] is concave (can be straight). Often [T] has a "Canvasback" profile. [T] has a massive bill (not always). The bill of [W] is not massive. The lore skin of [T] meets the eye. The lore skin of [W] also meets the eye but it may be slightly narrower near the eye on some swans. The yellow patch on the lore of [W] may make it appear that the lore pinches near the eye. To give some idea how wide is the lore skin at the eye of [T], typically the eye of [T] is 3/8 inch diameter while the lore skin joining the eye is 5/16 inch wide. [T] has no yellow on the lore. [W] has a yellow spot on the lore proceeding from the eye (15 percent do not have yellow).

The forehead feathers of [T] are shaped like a V, with the sides of the V curved inward so that the angle between the sides becomes smaller near the point. The forehead feathers of two year old and older [W] form a U. This forehead feather shape is one of the most reliable features for separating [T] and [W], although it is not diagnostic by itself. For example, first year, all white [W] may have a V forehead feather pattern. The distance from the bill tip to the nostril of [T] is only a little less than the distance from the nostril to the eye. The distance from the bill tip to the nostril of [W] is about 1/2 the distance from the nostril to the eye. Measurements of 4 Trumpeters revealed that the distance from the bill tip to the nostril was 2-1/2" and the distance from the nostril to the eye was 3-1/2".

F. Vocalizations: Diagnostic. The vocalizations of both species may be heard on The Trumpeter Swan Society web site, http://www.taiga.net/swans/swanid.html . Small groups of [T] on the ground are usually silent for several hours. Occasionally all members of a small [T] group will begin to "talk" to each other. This may last from 1 to 15 minutes. Large groups talk more frequently. The pitch of [T] individuals varies.

G. Habits: Head Bobbing. [T] and [W] head bob, although [T] perhaps more frequently. [T] head bobs when nervous, prior to flight, and at other times. [W] often greet each other by extending their heads forward so that the extended, straight neck makes about a 30 to 45 degree angle with the vertical; [T] never greet with this head and neck posture.
The "Kink" in The Neck. Both [T] and [W] exhibit the kink in the lower part of the neck when the swan is inactive.
Angle of The Standing Swan. [W] usually stands horizontal (not always); [T] stands from horizontal to about 20 degrees above horizontal.

H. Color of Feet and Legs: [T] and [W] have black feet and legs. Young all white [T] have extensive yellow along the sides of the toes and up the legs. The yellow diminishes with age. Three year old [T] may show the yellow. Young all white [W] show no yellow on the feet or legs.

Immature Trumpeters and Tundras:

Separating the immature of [T] from the immature of [W] is even more difficult than separating the mature of the two species. Color differences, physiological development of bill and head, dependence of characteristics on age, and variation among individuals are primary sources of confusion. Look for juveniles associating with adults. Association with an adult must be combined with other characteristics. The following characteristics differ between juveniles and adults. Characteristics not mentioned below are the same for juveniles as for adults.

I. Body color: [T] are dark gray (battleship gray). [W] are light gray. [T] holds the gray color longer into late winter than does [W]. [W] have completed their body molt to white by early March, while [T] do not complete their body molt to white until April or later. Both species often show gray around the head and neck until well after the body molt is completed.

J. Size: Immatures of [T] and [W] are slightly smaller than adults and do not achieve full adult size until their second spring. Size difference of males and females of both species is less pronounced than in adults.

K. Head and Bill Deviations From the Adult Characteristics: Culmen shape. [W] can have a flat, or even convex, culmen. Even first year [W] can have a straight culmen. Bill size. Bill size can appear to be disproportionately large on [T] and [W] because the bill reaches adult size by the first fall, whereas the body does not reach full size until the second fall or later.
The V of The Forehead Feathers. The U of [W] forehead feathers develops slowly on some swans. First spring all white [W] may still show a V forehead feather pattern. Bill Color. Juvenile [W] gradually acquires a black bill during its first winter. By spring its bill has become mostly black. Thus, an immature swan showing extensive black at the base of the bill could be either species, especially after November. Nevertheless, juvenile swans in early fall may be separated on the basis of this character with some confidence because most immature [W] have pink meeting the face. Martha Jordan indicates that there is a qualitative difference in the distribution of black on the bill, with [T] appearing to have a bill that is "black with a pink area in the middle'" whereas [W] has a "pink bill with black at the ends". Clearly the most fail-safe use of this mark is if an immature swan shows pink meeting or nearly touching the facial feathering, then it is [W].

L. Legs and Feet Color: [T] have olive-buff legs and yellow webs on feet. [W] have flesh colored to black legs and feet.

M. Vocalization: While some [T] do not vocalize until the 2nd year, some vocalize, generally at a higher pitch than the adults.

N. Sources: 1. Article by Michael A. Patten and Matthew T. Heindel, Identifying Trumpeter and Tundra Swans in the Field, October 1994 BIRDING. 2. The Trumpeter Swan Society. 3. Martha Jordan. 4. Jim Snowden. 5. Prepared by Rod Hug.

Food and feeding

In the summer Trumpeters feed on leaves, tubers, and the roots of aquatic plants up to a depth of 1 metre, which they reach by dipping their heads and necks, or by up-ending. Cygnets feed mainly on insects and other invertebrates for the first few weeks of their life but may start feeding on plants before they are two weeks old. Whilst on their wintering grounds in coastal British Columbia, the birds mainly eat roots and tubers of emergent plants on tidal flats. The swans prefer to feed in a shallow covering of water, as the tide floods or recedes. The Trumpeter's pump their feet up and down over edible roots to create a current of water that releases the roots from the surrounding mud, and the large size of the feet helps the bird to maintain its balance when it tips up to feed. Feeding, or grubbing, on aquatic plants results in large craters where the Trumpeter's strong bill has removed both the plant roots and the soil. Feeding by large numbers of swans, either Tundras or Trumpeters, can be quite destructive to an area's vegetation.

Life history

Trumpeter Swans are found in Canada all-year round. Birds from the Rocky Mountain Population are found only in the summer in Canada, whereas those from the Pacific Coast Population winter in British Columbia, after spending the summer in Alaska. Swans belonging to the Rocky Mountain Population arrive on their breeding grounds at Grande Prairie, Alberta, southern Yukon, and the Northwest Territories in mid-April to early May. A large proportion of the ponds where they breed are still frozen when they arrive, but some of the larger bodies of water may have open areas, where the swans congregate. Young from previous seasons usually gather in small flocks, which remain together throughout the summer on lakes not occupied by breeding pairs. Breeding birds choose nest sites that are surrounded by water, anything from 10 cm to several metres in depth. Nest are often constructed on old beaver houses and dams, but they are also built on emergent vegetation, either floating or anchored to the bottom. Pairs often begin to build or repair their nest even before a site is completely free of ice. Most nests are used year after year, usually by the same pair. Rebuilding does not usually involve much more than adding plant material to an already substantial mound.

"The pen lays one egg about every two days, until she has produced an average of five or six eggs (up to nine), which she incubates for 32 days while the cob helps to defend the nest from predators and intruders. The peak of the hatching period in the Grande Prairie region is about 15 June; in the Yukon and Northwest Territories it is nearer 1 July. The cygnets emerge covered in a dense pale grey down and remain in the nest with the pen for at least 24 hours, until they are able to maintain their own body temperature. The adults moult their feathers in summer and are flightless for a month or more. The pen usually looses some of her flight feathers about the time her cygnets hatch and is flightless during their most critical period. The cob becomes flightless about the time the pen regains her flight. In this way, one flightless parent remains with the cygnets during the brood period. The cygnets grow from approximately 300 g at hatching to approximately 7 kg at fledging. Feathers first start to appear at about 28 days: the cygnets are usually fully feathered in 9 or 10 weeks, and they start to fly in the second half of September in the Grande Prairie area, and in early October in the Northwest Territories. Trumpeter Swans leave the Grande Prairie region and Yukon/Northwest Territories in late October, when freeze-up is well advanced, for their journey south to the area where the states of Idaho, Montana, and Wyoming meet (Tri-State area).

In the Tri-State area, geothermal activity, such as geysers and hotsprings, warms ponds, rivers, and streams. In addition, fast currents make it possible for small portions of rivers to stay open even under the coldest of temperatures. The Rocky Mountain Population depends on this open water and on supplemental feeding to survive the winter in the area. Trumpeters from Alaska begin arriving along the British Columbia coast about November 1. Peak numbers are generally not seen until January or early February. During the early part of the winter, when the weather is mild and wet, the swans may be widely dispersed, feeding in freshwater and estuarine wetlands and flooded farm fields along the coast. When the freshwater areas freeze, the swans congregate on the estuaries, which do not freeze because of the combined influence of tides and salt water. The two dominant activities of Trumpeters on the wintering grounds are feeding and resting. On the B.C. coast, feeding is strongly influenced by cycling of tides in the estuaries. The birds feed at times during the day and night when the preferred amount of water covers their plant food. In some parts of the winter range, such as Vancouver Island, more of each 24 hour period is spent resting than feeding, probably thanks to relatively mild temperatures and the availability of foods rich in carbohydrates, which provide ample heat energy. Spring migration for the Pacific Coast Population begins in mid- to late February, depending on the weather. By mid-March most Trumpeters have disappeared from the coast, not to appear on the Alaskan breeding grounds until mid- to late April. After the swans leave the estuaries, they cross the Coast Mountains. Once east of the mountains they fly north, stopping at various large lakes in central British Columbia and southern Yukon on the way.

Management

The first official management action that was and still is of great benefit to the Trumpeter Swan population was the inclusion of swans as protected species under the Migratory Birds Convention of 1916. That legislation signed between Great Britain (on Canada's behalf) and the United States, recognized that the future existence of swans and many other bird species would be less uncertain if strict controls were placed on hunting and other uses. Since then, many other actions have been taken to help ensure the Trumpeter's future. These have included winter feeding programs, special sanctuaries and reintroduction programs, population surveys, and federal, provincial, and state land-use guidelines. The North American Management Plan for Trumpeter Swans (1984) calls for the continuation of these actions and outlines many others that are needed to ensure the continued survival and growth of the Trumpeter Swan population. These include the following: further study of Trumpeter Swans, especially their habitat requirements, migratory routes, and diseases; the provision, at zoos and other places where wild birds are held captive, of interpretive programs that inform the public of the Trumpeters' status; and control of Mute Swan populations to ensure that native Trumpeters will not have to compete with these introduced Eurasian birds. Although the total population of Trumpeter Swans is still small compared with what it once was, such management efforts will result in a more secure future for the spectacular Trumpeter Swan." Above text: Authority of the Minister of the Environment © Minister of Supply and Services Canada, 1975, 1984, 1992.

References

BANKO, W.E. 1960. The Trumpeter Swan. North American Fauna No. 63. U.S. Fish and Wildlife Service. Washington.

COLLAR, N.J., M.J. CROSBY and A.J. STATTERSFIELD. 1994. Birds to Watch 2. The World list of Threatened Birds. Birdlife International. Cambridge , U.K.

DELACOUR, J. 1954. The Waterfowl of the World. London.

DEL HOYO, J.; ELLIOTT, A.; and SARGATAL, J. 1992 - 2002. The Handbook of the Birds of the World, Volumes 1. Ostrich to Ducks. Lynx Edicions, Barcelona.

GODFREY, W.E. 1986. The birds of Canada. Revised edition. National Museums of Canada. Ottawa.

HANSEN, S. 1984. The Trumpeter Swan: a white perfection. Northland Press. Flagstaff, Arizona.

JOHNSGARD, P.A. 1981. Waterfowl of North America. Indiana University Press. Bloomington.

MADGE, S. and BURNS, H. 1988. Wildfowl. London.

McKELVEY, R.W. 1975. Trumpeter Swan. Published by Authority of the Minister of the Environment © Minister of Supply and Services Canada, 1975, 1984, 1992. Catalogue No. CW69-4/53-1992E. ISBN: 0-662-19413-6. Online reproduction.

OGILVIE, M. and YOUNG, S. 1998. Wildfowl of the World. New Holland, London, UK.

PATTEN, M.A. and HEINDEL, M.T. 1994. Identifying Trumpeter and Tundra Swans in the Field. Birding.

PRATT, H.D. , BRUNER, P.L. and BERRETT, D.G. et al. 1987. A Fieldguide to the Birds of Hawai'i and the Tropical Pacific. Princeton.

PYLE, R. L. 1992. Checklist of the Birds of Hawaii - 1992. The 'Elepaio 52: 53-62.

SCOTT, P. 1972. The swans. Michael Joseph. London, U.K.

SHANDRUK, L. 1992. Trumpeter Swan. Revised Edition. Published by Authority of the Minister of the Environment © Minister of Supply and Services Canada, 1975, 1984, 1992. Catalogue No. CW69-4/53-1992E. ISBN: 0-662-19413-6. Online reproduction.

WILMORE, S.B. 1974. Swans of the world. David and Charles. Newton Abbot, U.K.

Christian Melgar, West Sussex, UK. 2003.

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