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< >  Thalassornis leuconotus - White-backed duck (Click photographs/illustrations: full picture & further details)
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INFORMATION AVAILABLE

GENERAL & REFERENCES

EXTERNAL APPEARANCES

REPRODUCTION

BEHAVIOUR

NATURAL DIET

RANGE & HABITAT

CONSERVATION

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General and References

Alternative Names (Synonyms)

Weissrückenente(German)
Weißrücken-Pfeifgans (German)
Erismature à dos blanc (French)
Canard à dos blanc (French)
Pato lomo blanco (Spanish)
Pato Dorsiblanco (Spanish)
Thalassornis leuconotus leuconotus African white-backed duck
Thalassornis leuconotus insularis Madagascan white-backed duck

Names for newly-hatched

Duckling, downy.

Names for non-breeding males or other colour-phases

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References

Species Author

Debra Bourne

Major References

B1, B3, B6, B8, B19, B25, B26.

Aviculture references:
(General stifftail information: J23.13.w8, B29, B30, B40, B94)
B8, B29
D8.

Other References

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TAXA Group (where information has been collated for an entire group on a modular basis)

Parent Group

Specific Needs Group referenced in Management Techniques

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Aviculture Information

Notes

White-backed ducks are now thought to be most closely related to the whitling-ducks Dendrocygna spp. However in habits they are more like the stiff-tailed ducks. Therefore the general information for the maintenance of stiff-tailed ducks is given here.

General information:

  • Stiff-tails are generally hardy. They are extremely aquatic and do best on large ponds of variable depth, with clean, deep water and plenty of natural food available in the form of marginal aquatic plants, while a muddy pond bottom will provide food items such as tubifex worms. Duckweed and small-sized seeds such as millet and canary seed mixtures are preferred to conventional waterfowl feeds, although wheat and pellets will be taken if natural food is scarce, for example in hard winter weather. Ample marginal vegetation (e.g. rushes, sedge, juncus reed) should be available for general cover and for nesting, with nesting rafts also provided.
  • Most species are sociable and do best in groups rather than as a single pair; males will fight, but usually for only a short period, some degree of pursuit and rape of ducks is also likely. They can be very aggressive in nest site defence, therefore in mixed collections they should be kept on a water area sufficiently large for other ducks to escape.
  • Stiff-tail ducklings should preferably be reared with access to water from e.g. two days old, with sufficient depth for diving provided even at an early age, although enforced drying off periods between short swims may be advisable initially. Duckweed is a useful starter food for these species, although attached daphnia and water snails may carry parasites.

(J23.13.w8, B29, B30, B40, B94).

Species-specific information:

  • White-backed ducks are not commonly kept although they are bred regularly in some collections.
  • They are rather quiet birds, almost exclusively aquatic, and thrive on large, heavily-vegetated water areas.
  • They may nest in a ground-level box and prefer to nest on rafts, laying eggs in May to June.

(B8, B29, D1)

Aviornis UK Ringing Scheme suggested average closed ring size: K 10.0mm (D8).

Management Techniques

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External Appearance (Morphology)

Measurement & Weight

Length 15-16 inches, 38-40cm (B1, B3)
Adult weight General 625-790g (B1); 1.4-1.7lb (B8)
Male 650-790g (B3)
Female 625-765g (B3)
Newly-hatched weight --
Growth rate --

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Head

Adult Bill Male Black, speckled with yellow along sides, hooked.
Variations (If present) --
Eyes (Iris) Male Dark brown.
Variations(If present) --
Juvenile Bill Black, speckled with yellow along sides, hooked.
Eyes (Iris) Dark brown.

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Legs

Adult Male Greenish-grey.
Variations (If present) --
Juvenile Greenish-grey.

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Plumage

Adult Male Head and neck buff speckled with brown, heavies speckling on crown, with foreneck and sides of neck plain buff. White patch near bill.

Breast, underparts and upperparts buff with black barring, broader barring on flanks than breast and dusky on abdomen. Scapulars brown with buff barring.

Rump and uppertail coverts black with white tipping.

Lower back white. N.B. not visible when wings folded.

Wing: coverts dark brown with buff and white markings. Flight feathers paler brown.

Variations (If present) Thalassornis leuconotus insularis smaller, with more vivid markings.
Juvenile Darker, less patterned, sided of face and neck spotted.

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Newly-hatched Characteristics

General: Upperparts black with rufous patches. Underparts whitish grey shading to black on lower abdomen and flanks.
Bill: Very dark green-grey
Feet: Dark grey.

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Reproduction

Reproductive Season

Time of year Varies with location, may be any time of the year, usually when water levels are high and stable
No. of Clutches --

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Nest placement and structure

Nest in reedbeds or on small islands of vegetation, constructed from weeds, rarely with down or feather lining. Usually well concealed from above. Sometimes use old nests of coots or grebes.

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Egg clutches

No. of Eggs Average 6 (B8)
Range 4-10 (B1, B8)
Egg Description Warm brown. Size: 66 x 50 mm.

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Incubation

29-36 days (B1); 28 days (B8)

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Hatching

Synchronous.

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Fledging

About 16 weeks (B1); 60-90 days, possibly up to 120 days (B8).

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Sexual Maturity

Males --
Females --

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Behaviour

Feeding Behaviour

Adults Feeds by diving in shallow water.
Newly-hatched Dive to feed from muddy bottoms of ponds.

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Parental Behaviour

Nest-building Both sexes construct the nest. Sometimes nest in small groups with several nests close together.
Incubation Both sexes incubate, with the male performing most of the incubation and also actively defending his mate and nest.
Newly-hatched Brooded on the nest. Both parents care for the ducklings.
Juveniles

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Social Behaviour

Intra-specific Found in pairs and small groups, sometimes in larger groups. Sometimes nest in small groups with several nests close together. Males can be aggressive to one another.
Inter-specific --

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Sexual Behaviour

Pair bonds strong and may be permanent.

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Predation in Wild

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Activity Patterns

Almost exclusively aquatic. Inactive during the day, doze near emergent vegetation. "Remaining submerged for up to half a minute, the ducks can swim as far as 60 yards under water." (B8)
Circadian Crepuscular.

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Natural Diet

Adults

Adults basically vegetarian: seeds and leaves of water plants, particularly water lilies.

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Newly-hatched

Insect larvae, particularly gnats, and seeds of Polygonum.

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Range and Habitat

Distribution and Movement (Migration etc.)

Normal

Thalassornis leuconotus leuconotus: Africa, from Ethiopia south to South Africa. West Africa, from Senegal to Chad.

Thalassornis leuconotus insularis: Madagascar.

Local movements depending on water availability but basically sedentary.

Occasional and Accidental

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Introduced

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Habitat

Freshwater lakes, pools, marshes and swamps - where there are shallow waters and abundant floating vegetation. From sea level to nearly 10,000 feet.

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Conservation

Intraspecific variation

Madagascan white-backed duck Thalassornis leuconotus insularis classified as Endangered. Threatened by hunting, loss of habitat and introduced species (B44.9.w1).

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Conservation Status

Wild Population -
(Importance)

Not globally threatened, but appears scarce. West African population of Thalassornis leuconotus leuconotus is declining. However the eastern and southern African population is probably stable (B1, B8).

Madagascan white-backed duck Thalassornis leuconotus insularis considered Endangered (B44.9.w1).

CITES listing --
Red-data book listing --
Threats Gill nets (B8)

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Captive Populations

Not numerous, but are present and bred in some European and American collections. None of the Madagascan subspecies in captivity (B8, B44.9.w1).

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Trade

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