Canvasback

Canvasback

Summary:

Profile Canvasback     Literature page Canvasback
[order] Anseriformes

[order] Anseriformes | [family] Anatidae | [latin] Aythya valisineria | [UK] Canvasback | [FR] Fuligule à dos blanc | [DE] Riesentafelente | [ES] Porrón Coacoxtle | [IT] Moriglione dorso di tela | [NL] Grote Tafeleend

Grote Tafeleend determination

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The Canvasback Aythya valisineria is a wild duck that is found only in North America. The adult male, or drake, is a large white-bellied, grey-backed duck with a black chest, sloping forehead, and ruddy chestnut head and neck. The adult female is about the same size and has the same sloping forehead and long bill. Less colourful, she is more able to blend into her surroundings when on the nest or rearing her young. She is white-bellied with a pale brown back and reddish brown head, neck, and chest. Male and female Canvasbacks resemble Redheads and Ring-necked Ducks of the corresponding sex, but can be distinguished from them by their longer black bills and less abrupt foreheads.

In early autumn, the young of both sexes resemble adult females, although their breast plumage is more mottled and their back plumage is darker. During November, the young males begin to resemble the adult males, and by February the adult plumage of both sexes has almost completely grown in.

The genus Aythya to which the Canvasback belongs includes 12 species, five of which occur in North America. These are the Canvasback, Redhead, Greater Scaup, Lesser Scaup, and Ring-necked Duck. Generally, all Aythya species have rounded bodies with large feet, legs set back on the body, and a broad bill. They are all diving ducks.

During the nonbreeding period, Canvasbacks spend their time on open water in huge “rafts,” or floating flocks, which may extend for several kilometres in larger lakes and bays.

On their winter feeding grounds, they often form small compact flocks and fly about for pleasure, especially in the early morning and the late afternoon. Their wings create a loud whirring noise.

Wild ducks feed either by dabbling on the surface of the water, or by diving below the surface. Although Canvasbacks dabble at times, they are diving ducks because they usually dive for their food and because, like other divers, they have a special lobe on their hind toe that they use like a paddle in the water.

In Nederland zeldzame dwaalgast met twee bevestigde waarnemingen.

Canvasbacks usually feed by diving in water 2 to 9 m deep, but occasionally they dabble in shallow areas with surface-feeding ducks, especially American Wigeon. Their diet includes about 80 percent aquatic plants, primarily pond weeds, wild celery, duck potato, wild rice, banana water lily, and milfoils, or a species of flowering water plants. Canvasbacks also consume animal material, including insects, molluscs, or soft-bodied creatures with shells, such as snails, and various fish. Feeding generally occurs during the day, although Canvasbacks sometimes feed at night.


This species has a large range, with an estimated global Extent of Occurrence of 5,100,000 km². It has a large global population estimated to be 620,000 individuals (Wetlands International 2002). Global population trends have not been quantified, but the species is not believed to approach the thresholds for the population decline criterion of the IUCN Red List (i.e. declining more than 30% in ten years or three generations). For these reasons, the species is evaluated as Least Concern. [conservation status from birdlife.org]


By mid-February, courtship activities have begun. Commonly, several males court one or two females. A bright plumage helps a drake to attract a mate. A courting male throws his head back until the crown almost touches the tail feathers, then brings his head forward and utters a moaning, almost dove-like, ik-ik-cooo cry. The female answers with a low quacking cuk-cuk. At other times the amorous drake performs the kinked-neck display, in which the neck is stretched and bent forward momentarily.

Canvasbacks do not mate for life. Pairs form in late winter or during migration in early spring, and the female leads her mate to a nest site, usually near where she was reared. This species nests late, usually about the end of May.

Canvasbacks commonly build their nests near open water in the shallows of large sloughs, or marshy areas, among cattails, bulrushes, and reeds. The nest is a large, bulky structure made of reeds and sedges and lined with drab brown down plucked from the female’s body. As incubation, or warming of the eggs until they hatch, proceeds, the layer of down thickens into an insulating blanket. The female uses this to cover the eggs when she leaves the nest.

As soon as the females have laid their seven to nine eggs, the males desert their mates and gather in large flocks on lakes and larger sloughs to moult, or shed old feathers. For two weeks, the males are unable to fly to escape predators due to loss of their flight feathers. Their plumage changes colour to look like that of the females, which is more effective camouflage, while they wait for new flight feathers to grow in.

The burden of incubating the eggs and rearing the brood falls on the females alone, and hens younger than five years old are frequently unsuccessful. The drab green or grayish olive eggs must be incubated for 24 to 28 days. A day or two after the eggs have hatched, the ducklings must be led safely to open water to find their own food, usually drifting plant material. The young do not develop feathers until about the fifth week, and are unable to fly until about 11 weeks.

In late summer, the females and young join the males. Family units split up during the early fall, and the young may or may not migrate with their parents.

Hunters seek the Canvasback because it is so delicious. Before it became illegal to sell wild game, hundreds of Canvasbacks were taken daily using weapons, such as punt guns, and methods, such as night shooting, that have since been outlawed. Today, hunters use large flocks of 50 to 100 decoys to attract these curious trusting birds. This technique is especially effective early in the hunting season.

In the last 40 years, Canvasback populations have fluctuated from about 500 000 in the mid-1950s to about 200 000 in the early 1990s. In an attempt to ensure that populations remain healthy, the Canadian and American governments regulate hunting carefully. The Canadian Wildlife Service and the United States Fish and Wildlife Service, in conjunction with provincial and state wildlife agencies, conduct surveys to determine total numbers of ducks and the annual hunting kill.

Restrictive hunting regulations are not enough to ensure healthy populations. Loss of habitat and periodic droughts on the breeding grounds cause declines in populations of this and other species. Loss of habitat results from farmers and developers draining wetlands and the use of vast expanses of former breeding range to grow crops. In addition, wintering range has been reduced in quality. For example, Chesapeake Bay, Maryland, no longer supports the wide range of plants that wintering Canvasbacks once fed upon.

Concern for the Canvasback and other wild ducks and geese that nest in prairie wetlands has prompted the various federal, provincial, and state wildlife agencies to cooperate in programs called “habitat joint ventures” under the North American Waterfowl Management Plan, or NAWMP. Programs to enhance wetlands used by ducks and geese have been initiated in Canada, the United States, and Mexico.

Specification

  1. Measurements
  2. spanwidth min.: 79 cm
  3. spanwidth max.: 89 cm
  4. size min.: 48 cm
  5. size max.: 56 cm
  6. Breeding
  7. incubation min.: 24 days
  8. incubation max.: 29 days
  9. fledging min.: 56 days
  10. fledging max.: 77 days
  11. broods 1
  12. eggs min.: 7
  13. eggs max.: 12
  14. Conservation Status
  15. Grote Tafeleend status Least Concern
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