Not to be confused with the Muscovy Duck

Muscovy Duck

The Muscovy Duck is a large duck which is native to Mexico and Central and South America. A small wild population reaches into the United States in the lower Rio Grande Valley of Texas...

 (Cairina moschata).

The Musk Duck (Biziura lobata) is a highly aquatic, stiff-tailed duck

Duck

Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...

 native to southern Australia

Australia

Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

. It is the only living member of the genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Biziura

Biziura

Biziura is a genus of stiff-tailed ducks endemic to Australasia and containing one living and one fossil species.-Species:* B. lobata Stephens, 1824 – Musk Duck – Widely distributed through south-eastern Australia, south-west Western Australia and the Murray-Darling Basin.* B...

. An extinct relative, the New Zealand Musk Duck

New Zealand Musk Duck

The New Zealand Musk Duck , also known as de Lautour’s Duck, is an extinct stiff-tailed duck native to New Zealand. It is only known from prehistoric subfossil bones...

 or de Lautour's Duck (B. delautouri), once occurred on New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, but is only known from prehistoric subfossil

Subfossil

Subfossil refers to remains whose fossilization process is not complete, either for lack of time or because the conditions in which they were buried were not optimal for fossilization....

 bones. It was about 8% longer than the living species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

, with a particularly large head.

They are moderately common through the Murray-Darling and Cooper Creek

Cooper Creek

Cooper Creek is one of the most famous and yet least visited rivers in Australia. It is sometimes known as the Barcoo River from one of its tributaries and is one of three major Queensland river systems that flow into the Lake Eyre Basin...

 basins, and in the wetter, fertile areas in the south of the continent: the south-west corner of Western Australia

Western Australia

Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...

, Victoria

Victoria (Australia)

Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....

, and Tasmania

Tasmania

Tasmania is an Australian island and state. It is south of the continent, separated by Bass Strait. The state includes the island of Tasmania—the 26th largest island in the world—and the surrounding islands. The state has a population of 507,626 , of whom almost half reside in the greater Hobart...

. Musk Ducks avoid the far north, or the arid west and north-west.

Description

Adult males are 60 to 70 cm long and have a distinctive large, leathery lobe underneath the bill; females are 47 to 55 cm long and unadorned. Their drab dark grey-brown, sightly pin-striped plumage

Feather

Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds and some non-avian theropod dinosaurs. They are considered the most complex integumentary structures found in vertebrates, and indeed a premier example of a complex evolutionary novelty. They...

 is unconspicuous and does not differ between the sexes. Musk Ducks float very low in the water, almost like a cormorant

Cormorant

The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...

, and the large webbed feet are well back on the body. The ducklings are covered in dark brown down.

In its native range, the fanned tail is distinctive, allowing to distinguish this species from the Freckled Duck

Freckled Duck

The Freckled Duck is a moderately large, broad-bodied duck native to southern Australia. The duck is protected by law...

 (Stictonetta naevosa) which has similar size, coloration and habits. The Blue-billed Duck

Blue-billed Duck

The Blue-billed Duck is a small Australian stiff-tailed duck, with both the male and female growing to a length of 40 cm . The male has a slate-blue bill which changes to bright-blue during the breeding season, hence the duck’s common name . The male has deep chestnut plumage during breeding...

 (Oxyura australis) has a similarly shaped tail but the main colour of its males in breeding plumage is a much richer chestnut brown. Females and males in nonbreeding plumage are very similar however and if one is not intimately familiar with the slight differences in behavior, they cannot be told apart from female Musk Ducks at a distance. Male Musk Ducks in the breeding season are usually unmistakable due to the large bill lobe.

Systematics

The relationships of this peculiar species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 are quite enigmatic. It is traditionally included with the stifftail subfamily Oxyurinae

Oxyurinae

Oxyurinae is a subfamily of the duck, goose and swan family of birds, Anatidae. It has been subject of considerable debate about its validity and circumscription. Most of its members have long stiff tail feathers which are erected when the bird is at rest, and relatively large swollen bills...

, but appears only distantly related to the genus Oxyura, and its peculiar apomorphies make it difficult to place. Its relationship with the equally strange pink-eared ducks (Malacorhynchus) is unresolved but seems to be quite close, and it seems to be part of an ancient Gondwana

Gondwana

In paleogeography, Gondwana , originally Gondwanaland, was the southernmost of two supercontinents that later became parts of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago . Gondwana is believed to have sutured between ca. 570 and 510 Mya,...

n radiation of Anatidae

Anatidae

Anatidae is the biological family of birds that includes ducks, geese and swans. The family has a cosmopolitan distribution, occurring on all the world's continents except Antarctica and on most of the world's islands and island groups...

. As such, it is quite closely related to the stiff-tailed ducks proper, but as it seems not as closely as generally believed, with many similarities due to convergent evolution

Convergent evolution

Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

.

Ecology and status

This species prefers deep, still lakes and wetlands with areas of both open water and reed beds. They seldom emerge from the water and are awkward on dry land. They rarely fly: take off is made with difficulty, and landing is a clumsy, low-angled affair with no attempt to lower the feet. However, at need Musk Ducks fly swiftly and for long distances, with rapid, shallow wing beats.

In the water, Musk Ducks display an effortless agility, twisting and turning on the surface with both feet and tail. In general, Musk Ducks remain in the water all day long, alternately loafing and feeding energetically, though they sometimes emerge to sit on a log or on dry land for a while. They stay on the water at night, sleeping well out from land with the head tucked into the body or under a wing.

Musk Ducks are very much at home below the surface, slipping under head-first with barely a ripple, and staying submerged for as long as a minute at a time, often resurfacing only for a few moments before diving again. They dive to escape predators or unwanted company, and to search for food, typically in fairly deep water. They can descend to at least 6 metres (about 20 feet). The primary diet items are water beetle

Water beetle

A water beetle is a beetle adapted to living in water. Water beetles rise to the water surface and take atmospheric air into their tracheal systems. There are approximately 2000 species of water beetles. The rest marine species tend to live in the intertidal zone...

s, yabbies, water snails, freshwater shellfish

Shellfish

Shellfish is a culinary and fisheries term for exoskeleton-bearing aquatic invertebrates used as food, including various species of molluscs, crustaceans, and echinoderms. Although most kinds of shellfish are harvested from saltwater environments, some kinds are found only in freshwater...

, and the like, supplemented with a variety of aquatic plants and a few fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

.

When not breeding, adults are generally solitary. Adult males hold and defend territories, excluding other males and quite often females too. Younger birds – juveniles and unmated adults – form flocks on larger bodies of water at some times of year. It is not known at what age they reach sexual maturity in the wild, but it may take several years. They are a long-lived species and are still capable of breeding when 20 years old or more.

Reproduction

The Musk Duck breeding season varies with rainfall and water levels, but is typically between July and January, with the greatest number of clutches laid in September or October. Despite a number of more general studies, remarkably little is known about Musk Duck breeding. For example: it is during breeding season that they give off the musky odour from which the species derives its common name. Also, in the season males advertise themselves loudly with a repetitive sequence of sounds: first, a ker-plonk splash made with the feet on the surface of the water; then two soft, sharp cuc cuc calls; then a loud whistle and a deep grunt. This sequence can be started at any time of day or night, with or without an associated visual display, and repeated every 4 or 5 seconds for as long as half an hour at a time. Although male Musk Ducks have a large leathery lobe below the bill and this swells during the breeding season, it is not connected to the vocal cavities and appears to be purely for visual purposes.

It is thought that mating is promiscuous, quite possibly on a lek system like that of the Kakapo

Kakapo

The Kakapo , Strigops habroptila , also called owl parrot, is a species of large, flightless nocturnal parrot endemic to New Zealand...

 (a very large, flightless parrot found only in New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

), but this remains uncertain. The male plays no part in building the nest or raising the young.

Females select a secluded location for nesting, usually in tall reeds well away from land and protected by deep water, or under the cover of overhanging shrubbery, but sometimes in a range of innovative places, such as on a stump, in a hollow log, or even under an upturned boat. The nest is a simple platform of trampled plant material with a slight cup, lined with fine plant matter and, after the eggs

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 are laid, plenty of down. She seems to be unable to carry nest material and must rely on whatever is within reach. With the nest complete, she pulls reeds down from overhead to make a canopy, hiding it from view. When leaving the nest to feed, she slips quietly into the water and submerges, not surfacing until she is well away from it.

Clutch size in unknown: as many as 10 eggs have been counted in a nest, but it seems likely that this is the result of dump nesting: 3 or 4 eggs is considered more likely. In most cases only one chick survives, sometimes two. They are able to swim and dive within a few days, after which they probably leave the nest. Young stay close to the mother for several months at least, sometimes riding on her back to begin with. They can peck at food items on the surface and dive a little while still quite small, but the mother continues to provide the bulk of their food until they are almost full-grown.

Conservation status

Musk Ducks are sometimes shot by hunters but are little prized, not being considered good eating. Wholesale clearing and draining of wetlands has impacted on their numbers, as has the widespread rise in Australian water salinity

Salinity

Salinity is the saltiness or dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates...

levels, but the species is not presently considered to be in danger.