The fulvous whistling duck or fulvous tree duck (Dendrocygna bicolor) is a species of whistling duck that breeds across the world's tropical regions in much of Mexico and South America, the West Indies, the southern United States, sub-Saharan Africa and the Indian subcontinent. It has plumage that is mainly reddish brown, long legs and a long grey bill, and shows a distinctive white band across its black tail in flight. Like other members of its ancient lineage, it has a whistling call which is given in flight or on the ground. Its preferred habitat consists of wetlands with plentiful vegetation, including shallow lakes and paddy fields.

The nest, built from plant material and unlined, is placed among dense vegetation or in a tree hole. The typical clutch is around ten whitish eggs. The breeding adults, which pair for life, take turns to incubate, and the eggs hatch in 24–29 days. The downy grey ducklings leave the nest within a day or so of hatching, but the parents continue to protect them until they fledge around nine weeks later.

The fulvous whistling duck feeds in wetlands by day or night on seeds and other parts of plants. It is sometimes regarded as a pest of rice cultivation, and is also shot for food in parts of its range. Despite hunting, poisoning by pesticides and natural predation by mammals, birds, and reptiles, the large numbers and huge range of this duck mean that it is classified as least concern by the International Union for Conservation of Nature.

Taxonomy

The whistling ducks, Dendrocygna, are a distinctive group of eight bird species within the duck, goose and swan family, Anatidae, which are characterised by a hump-backed, long-necked appearance and the whistled flight calls that give them their English name. They were an early split from the main duck lineage, and were predominant in the Late Miocene before the subsequent extensive radiation of more modern forms in the Pliocene and later. The fulvous whistling duck forms a superspecies with the wandering whistling duck. It has no recognised subspecies, although the birds in northern Mexico and the southern US have in the past been assigned to D. b. helva, described as having paler and brighter underparts and a lighter crown than D. b. bicolor.

The duck was first described by Johann Friedrich Gmelin in 1789 and given the name Anas fulva but the name was "preoccupied", or already used, by Friedrich Christian Meuschen in 1787 for another species. This led to the next available name proposed by French ornithologist Louis Pierre Vieillot in 1816 from a Paraguayan specimen as Anas bicolor. The whistling ducks were moved to their current genus, Dendrocygna, by British ornithologist William Swainson in recognition of their differences from other ducks. The genus name is derived from the Ancient Greek , "tree", and Latin , "swan", and is Latin for "two-coloured". "Fulvous" means reddish-yellow, and is derived from the Latin equivalent fulvus. Old and regional names include large whistling teal,

It is a long-legged duck, mainly different shades of brown; head, neck and breast are particularly rich buff (fulvous) with a darker back. The mantle is more darker shade of brown with buff-tipped feathers, the flight feathers and tail are dark brown, and a dark brown to black stripe runs through the center of the crown down the back of the neck to the base of the mantle. It has whitish stripes on its flanks, a long grey bill and grey legs. In flight, the wings are brown above and black below, with no white markings, and a white crescent on the rump contrasts with the black tail. All plumages are fairly similar, but the female is slightly smaller and duller-plumaged than the male. The juvenile has paler underparts, and appears generally duller, especially on the flanks.

These are noisy birds with a clear whistling kee-wee-ooo call given on the ground or in flight, frequently heard at night.

Adult birds in Asia can be confused with the similar lesser whistling duck, which is smaller, has a blackish crown and lacks an obvious dark stripe down the back of the neck. Juvenile fulvous whistling ducks are very like young lesser whistling ducks, but the crown colour is still a distinction. Juvenile comb ducks are bulkier than whistling ducks and have a dark cap to the head. In South America and Africa, juvenile white-faced whistling ducks are separable from fulvous by their dark crowns, barred flanks and chestnut breasts.

Several arthropod parasites have been recorded on this duck, including chewing mites of the families Philopteridae and Menoponidae, feather mites and skin mites. Internal helminth parasites include roundworms, tapeworms and flukes. In a survey in Florida, all 30 ducks tested carried at least two helminth species; none had blood parasites. Only one duck had no mites or lice.

Breeding

thumb| Dendrocygna bicolor - [[MHNT]]

Breeding coincides with the availability of water. In South America and South Africa, the main nesting period is December–February, in Nigeria it is July–December, and in North America mid-May–August. Fulvous whistling ducks show lifelong monogamy; the courtship display is limited to some mutual head-dipping before mating and a short dance after copulation in which the birds raise their bodies side by side while treading water.

Both sexes incubate, changing over once a day, with the male often taking the greater share of this duty. The eggs hatch in about 24–29 days, and weigh within a day of hatching. Like all ducklings, they are precocial and leave the nest after a day or so, but the parents protect them until they fledge around nine weeks later. in most parts of southern Africa, the two species breed at different times, bicolor during the dry season (April to September) and viduata during the rains (October to March). Hybridization in captivity is more frequent but limited to other species in the genus Dendrocygna.

Feeding

thumb|Long legs enable the duck to stand erect and walk without waddling.|upright

The fulvous whistling duck feeds in wetlands by day or night, often in mixed flocks with relatives such as white-faced or black-bellied whistling ducks. Its food is generally plant material, including seeds, bulbs, grasses and stems, but females may include animal items such as aquatic worms, molluscs and insects as they prepare for egg-laying, which may then comprise up to 4% of their diet. Ducklings may also eat a few insects. Foraging is by picking plant items while walking or swimming, by upending, or occasionally by diving to a depth of up to . Favoured plants include water snowflake, aquatic ragweeds, bourgou millet, shama grass, Cape blue water lily, waxy-leaf nightshade, beakrush, flatsedge and polygonums. Rice is normally a small part of the diet, and a survey in Cuban rice fields found that the plants taken were mainly weeds growing with the crop. However, in a study in Louisiana, 25% of the diet of incubating females consisted of cereal.

The fulvous whistling duck has expanded its range in the West Indies, and into the southern US. A series of invasions from South America and reaching the eastern US commenced around 1948, fueled by rice cultivation, and breeding was recorded in Cuba in 1964, In Africa, it bred on the Cape Peninsula between 1940 and the 1960s. A survey of eighteen species which had colonised the area in recent decades found that most were wetland species that had used irrigated farmland as "stepping stones" across the arid country separating the peninsula from the breeding main range. However, the status of the two whistling duck species featured in the research is dubious since they are popular ornamental species, so their origin is unclear.

Outside North America it is subject to hunting for food or because of its liking for rice, and persecution means that it is now rare in Madagascar. Pesticides used on rice fields may also have an adverse impact,

Notes

References

Cited texts

  • Fulvous Whistling-duck videos at the Internet Bird Collection
  • Tribe Dendrocygnini (Whistling or Tree Ducks) from Johnsgard, Paul A. Ducks, Geese, and Swans of the World
  • Species text in The Atlas of Southern African Birds
  • Calls at Xeno-canto