Geographic Range
Australian musk ducks (
Biziura lobata
) are endemic to southern Australia. This species is subdivided into two genetically
isolated populations, eastern and western, by the Nullarbor plain, an arid treeless
desert at the head of the Great Australian Bight. Populations are also found on Kangaroo
Island and in Tasmania, separated from Australia by Backstairs Passage and Bass Strait.
Historically, Australian musk ducks were thought to have been flightless but now are
known to fly long distances to colonize ephemeral wetlands after inland rain. They
also disperse locally based on band recoveries. These sightings might suggest movement
between the two populations in low numbers but it remains unclear if this occurs.
- Biogeographic Regions
- australian
Habitat
Australian musk ducks are endemic to deep-water wetlands, river systems, and coastal
waters of temperate Australia. In the spring they move to locations where permanent
water exists that has substantial cover vegetation, such as rushes and cattails. Australian
musk ducks have been observed on ephemeral wetlands on the Nullarbor plain after major
flooding and occasionally forage in marine habitats.
- Habitat Regions
- temperate
- saltwater or marine
- freshwater
- Aquatic Biomes
- lakes and ponds
- rivers and streams
- temporary pools
- coastal
- Wetlands
- marsh
- Other Habitat Features
- agricultural
- riparian
Physical Description
Australian musk ducks are large, strongly sexually dimorphic, stiff-tailed ducks with
elongated tail feathers well adapted for diving and maneuvering in water. The legs
are positioned far back on the body, making it difficult for maneuvering on land.
Males are almost entirely blackish-brown with finer pale barring and speckling. The
head is nearly black on the crown and nape and visibly more freckled buff on the cheeks
and neck. The breast is a whitish-buff barred and freckled blackish-brown. The tail
and wings are completely black while the feet are a blackish-grey. Males sport a large
black to grey pendulous lobe under their bill dangling towards the water. During display
the lobe inflates, by blood pressure, to the size of a golf ball. Males are substantially
larger than females, weighing up to 3.6 kg and measuring 92 cm from bill to tail.
Females are considerably smaller than males, weighing as little as 0.9 kg and measuring
61 cm. Females are identical in plumage and bare parts but display only a rudimentary
lobe. Juveniles look much like females except for a bit of yellow on the front half
of the lower mandible. It takes some time for juveniles to reach full size, the lobes
of males increase in size with time
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- male larger
- sexes colored or patterned differently
- male more colorful
- ornamentation
Reproduction
There is no special or mutual precopulatory behavior in Australian musk duck reproduction.
Males copulate with any females he manages to attract through his display activities.
This absence of mutual precopulatory displays supports the probability that a promiscuous
mating system exists in the species. As the spring breeding season approaches, Australian
musk ducks flock on permanent water. There, males attract females through a combination
of vocal and mechanical sounds as well as visual posturing which occurs from mid-July
through early August. Some or all of the display postures are shared between eastern
and western populations. Vocalizations differ markedly between these regions. The
role of the musky pheromone for which Australian musk ducks are named is unknown,
but it probably plays a role in mate attraction, male-male competition, or both. The
odor only occurs in adult males and almost exclusively breeding males and may originate
from the preen gland at the base of the tail. No preliminary displays are associated
with actual mating. The male suddenly mounts and copulates with one of the females
he has attracted. Following copulation, the female goes into a dense growth of rushes
and construct her nest. During displays of the male, a hierarchy forms that appears
in increasing degrees of modification and exaggeration of normal behavior. The postures
of the display become increasingly more unlike normal swimming formation and the time
intervals between displays become more constant and predictable. There are three main
types of displays produced by the male; the “paddling kick,” the “plonk-kick,” and
the “whistle kick.” The “paddling kick” includes a vigorous backward thrust of the
feet, in which a sheet of water is thrown upward and backwards six feet or more. This
is repeated at irregular intervals of several seconds. The “plonk kick” is the most
commonly observed display and is made up of variable tail cocking, lobe and throat
enlargement, and a simultaneous kick by both feet. Water is thrown out laterally,
and both legs are momentarily lifted from the water as they are pulled backwards.
As the feet enter the water their outstretched webbing strikes the surface producing
a distinctive “plonk” sound. Kicks are repeated at intervals of approximately three
seconds, with only slight variation. As females become attracted, the “plonk kick”
is replaced by the “whistle kick.” Extreme tail cocking, lobe enlargement and throat
inflation are associated with the display, which consists of a relatively weak lateral
kick of both feet as well as a simultaneous sharp whistle. Between kicks the body
is flexed upward to an extreme degree, the bill is raised and the tail is bent forward
until it touches the back. The interval between whistle kicks averages over three
seconds. If a female is not attracted, the male will resume “plonk kicks." If a female
is attracted, the whistle kicks will proceed in a long, unbroken series. “Onlooker”
males sometimes approach the group and, if they move too close to the female, the
displaying bird will rush toward them across the water, or dive and attempt to attack
them from below. The victim retreats usually but sometimes a vicious battle occurs
with biting, wing beating, scratching amid a frenzied splashing of water. Smaller
and weaker males are often injured, so there is a distinct advantage for larger and
stronger males. Another notable display, the “splash-dive” occurs when other males
are on site while the displaying male dives quickly amid a great splash of water thrown
up as the bird disappears from view. This display appears to have a hostile or threat
function.
- Mating System
- polygynous
Breeding season occurs from July or August through December or January. Clutches have
been observed as late as January. Females build their nests in the dense growth of
rushes. The nest can be built on the branch of a tree that has been partially submerged
which happens often during the flooding of lowlands and in rainy years. Flooded cutting
grass is an important nesting habitat and there will be a decline in nesting activity
in years with retreating water levels. Such areas flood seasonally, and depth may
not be sufficient for nesting in any given year. Australian musk ducks are capable
of surviving long enough to experience favorable breeding conditions repeatedly. Nest
materials in cutting grass sites consist of dry cutting grass stems and small amounts
of down, nests in trees are made of sticks and bark. Most nests possess hoods composed
of folded grass stems. The normal clutch size is 2 to 3 eggs but numbers as much as
5 to 6 have been reported. The female lays eggs and tends to the young. Females lay
unusually large, elliptical, green eggs. Nest parasitism may occur and Australian
musk ducks may be facultative nest parasites. The incidence of parasitism in these
ducks, the hatching success of host-brooded eggs, and the degree of foster-parental
care given to the young need further research. Sexual maturity in Australian musk
ducks is delayed at 2 to 3 years old.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- fertilization
- oviparous
Female Australian musk ducks tend to young entirely on their own. Chicks are precocial,
swimming and diving shortly after hatching. Occasionally they ride on the mothers
back as she swims partially submerged. The chicks will grasp the feathers of the mother’s
neck and, during times of danger she may even dive with the young clinging to her.
Usually only one or two chicks survive in one clutch. Chicks are covered with dark
brown down at hatching. The young remain with the mother for several months. She provides
them the most part of their food until they are full-grown. The male doesn’t take
part in incubation or protection.
- Parental Investment
- precocial
- female parental care
-
pre-fertilization
-
protecting
- female
-
protecting
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- female
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- female
-
provisioning
Lifespan/Longevity
Australian musk ducks have a relatively long lifespan. In captivity they have been
known to live around 23 years. Little information regarding lifespan was found for
wild populations.
Behavior
Australian musk ducks frequently appear in flocks during the breeding season, otherwise
they can be independent or appear in small groups. Most literature describes the mating
behavior of Australian musk ducks due to its unique character. There are few descriptions
of social behavior. Australian musk ducks are aggressive. In captive breeding programs
males are kept away from offspring, and they are generally kept separate from other
waterfowl species because Australian musk duck are likely to attack them. In cases
where Australian musk ducks are kept in captivity with other birds, they terrorize
almost all other waterfowl by attacking them underwater and their appearance consistently
causes a fast, general retreat to the shore by all other ducks. In general, male Australian
musk ducks are dominant to females and males may be more active than females and range
over greater distances. Australian musk ducks have demonstrated remarkable abilities
to mimic the calls of other waterfowl, as well as mechanical and human sounds. Calls
of immature, wild Australian musk ducks show only a rough resemblance to vocalizations
of adult males and suggest a combination of social imprinting, learning, or practice
is involved in vocal transmission from one generation to the next. The calls of captive
Australian musk ducks differ depending on the region from which they originated and,
when reared in isolation from wild ducks performing adult calls, captives never develop
the wild type call even after as many as 25 years. Young ducks likely listen to mature
adult calls and practice repeatedly in a social context. The duration of this vocal
development period is unknown but may be more than a year. This learning requirement
may be why male Australian musk ducks spend a considerable amount of time observing
the advertising displays of other males.
- Key Behaviors
- flies
- natatorial
- diurnal
- nocturnal
- motile
- sedentary
- solitary
- social
- dominance hierarchies
Home Range
There is no known literature regarding the home range of Australian musk ducks. Because
of band recoveries, it is well known that these ducks disperse locally and may move
between eastern and western populations. They tend to colonize newly flooded areas.
Communication and Perception
Australian musk ducks communicate through vocalizations, visual postures, and mechanical
sounds. The most notable form of communication is the male's splashing displays in
a lek. These displays can be so loud and conspicuous that they can be heard from half
a mile away. Males emit an unusual whistling call as well as a “plonk call” of which
the origin is unknown. Males also emit a musky odor, although no substantial evidence
has been found to associate a response from females. Females emit very few calls and
are relatively silent. Vocalizations of captive ducks differ between regions (eastern
and western Southern Australia) and are unlike those called by wild birds of the same
species. Regional dialects are acquired through social context by repeated observation
of adult males as well as a combination of social imprinting, learning or practice.
Australian musk ducks, which have a notably large brain, also have the ability to
mimic other waterfowl, mechanical sounds, and complex human sounds.
- Other Communication Modes
- mimicry
Food Habits
Australian musk ducks obtain their food almost exclusively by diving. The diet consists
primarily of aquatic animals and plants. They generally limit their feeding to shallower
areas where submersed and/or immersed vegetation is abundant. The diet is composed
of freshwater yabbie, freshwater shrimp, snails, freshwater mussels, and insects.
Plants eaten include both marsh and upland species and are limited almost exclusively
to seeds. Sex and age differences in food use exist: males eat mainly
mollusks
(60% adult male, 30% adult female, and 7% immature),
trichopterans
(36% adults, 18% immature), and
Marsiliaceae
(36% adult males, 23% adults females, 14% immature). Food composition varies little
through the seasons. In captivity males are known to prey on the offspring of conspecifics
and other waterfowl species.
- Primary Diet
-
carnivore
- eats non-insect arthropods
- molluscivore
- Animal Foods
- birds
- amphibians
- fish
- insects
- terrestrial non-insect arthropods
- mollusks
- aquatic crustaceans
- Plant Foods
- seeds, grains, and nuts
Predation
Australian musk ducks are too large to be eaten by fish and will dive from a site
when a hawk or an eagle appears. There was no other information found on the potential
predators of Australian musk ducks in the literature.
Ecosystem Roles
Nest parasitism may occur in Australian musk ducks as a response to local crowded
conditions. Not much is known about the frequency of parasitism in this species, including
the hatching success of host-brooded eggs and the degree of foster-parental care given
to the chicks. It is believed that they are facultative parasites and the large size
of their eggs (larger than any of the
Anatidae
) could correlate with their ability to retain-heat due to a reduced amount of parental
incubation if lain in another ducks nest. The diet of Australian musk ducks is almost
entirely of animal origin. They consume the larva and adults of aquatic insects as
well as mollusks and crustaceans including large crayfish. Occasionally they consume
small ducklings as well as fish and frogs. Australian musk ducks are extremely aggressive
and in captivity they have been known to terrorize other waterfowl by attacking them
underwater.
Economic Importance for Humans: Positive
Presently, Australian musk ducks are not important as a game species because of their
dull gray color and tendency to rarely be in flight, making them poor targets. They
rarely fly during daylight hours and many hunters believe the musky odor renders the
meat unfit for consumption. During the 1930's Australian musk ducks were used for
food in the Mandura district of Western Australia. In the 1900's colonists of Flinders
islands, in Bass Strait, collected the lobes of male Musk Ducks, dried them, and placed
them in their stored clothing. The musky odor was believed to have a pleasing scent
and served well as a perfume and fumigant.
- Positive Impacts
- food
- body parts are source of valuable material
Economic Importance for Humans: Negative
There are no known adverse effects of Biziura lobata on humans.
Conservation Status
Australian musk ducks are of no importance as a game species. They do however tend
to become entangled in fishing nets and drown. Their dependence on permanent swamps
that are in danger of being drained for agriculture purposes may cause conservation
problems for the species in the future. Although the population of
Biziura lobata
appears to be decreasing, the decline is not rapid enough to approach the thresholds
of the IUCN Red list category to justify a listing as vulnerable currently.
Additional Links
Contributors
kassondra hendricks (author), Northern Michigan University, Alec Lindsay (editor), Northern Michigan University, Tanya Dewey (editor), University of Michigan-Ann Arbor.
- Australian
-
Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- temperate
-
that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- freshwater
-
mainly lives in water that is not salty.
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- agricultural
-
living in landscapes dominated by human agriculture.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- endothermic
-
animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- sexual ornamentation
-
one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.
- polygynous
-
having more than one female as a mate at one time
- iteroparous
-
offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).
- seasonal breeding
-
breeding is confined to a particular season
- sexual
-
reproduction that includes combining the genetic contribution of two individuals, a male and a female
- fertilization
-
union of egg and spermatozoan
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- young precocial
-
young are relatively well-developed when born
- female parental care
-
parental care is carried out by females
- natatorial
-
specialized for swimming
- diurnal
-
- active during the day, 2. lasting for one day.
- nocturnal
-
active during the night
- motile
-
having the capacity to move from one place to another.
- sedentary
-
remains in the same area
- solitary
-
lives alone
- social
-
associates with others of its species; forms social groups.
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
- mimicry
-
imitates a communication signal or appearance of another kind of organism
- food
-
A substance that provides both nutrients and energy to a living thing.
- carnivore
-
an animal that mainly eats meat
- molluscivore
-
eats mollusks, members of Phylum Mollusca
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
References
Attiwill, A. 1981. Possible nest parasitism in the Australian stiff-tailed ducks (Anatidae: Oyurini). Emu , 81: 41-42.
Birdlife International 2012, 2012. "Biziura lobata" (On-line). IUCN Redlist. Accessed January 21, 2013 at http://www.iucnredlist.org/details/100600363/0 .
Gamble, K. 1966. Breeding Biology and Food Habits of the Musk Duck ( Biziura Lobata ). Master's Thesis, Univeristy of Wisconsin (WI) , 1: 1-40.
Guay, P., R. Chesser, R. Mulder, A. Afton, D. Paton, K. McCracken. 2010. East–west genetic differentiation in Musk Ducks ( Biziura lobata ) of Australia suggests late Pleistocene divergence at the Nullarbor Plain. Conservation Genetics , 11: 2105-2120.
Guay, P., R. Mulder. 2005. Isolation and characterization of microsatellite markers in musk duck ( Biziura lobata : Aves), and their application to other waterfowl species. Molecular Ecology Notes , 5: 249-252.
Johnsgard, P. 2010. Ducks, Geese, and Swans of the World- Tribe Oxyurini: Stiff-Tailed Ducks . Nebraska: University of Nebraska.
Johnsgard, P. 1966. Behavior of the Australian Musk Duck and Blue-Billed Duck. The Auk , 83: 98-110.
Johnsgard, P. 1965. The Elusive Musk Ducks. Papers in Ornithology , 30: 1-6.
Livezy, B. 2002. Phylogeny and comparative ecology of stiff-tailed ducks (Anatidae: Oyurini). Wilson Bulletin , 107: 214-234.
McCracken, K., A. Afton, D. Paton. 2000. Nest and eggs of Musk Ducks (Biziura lobata) at Murray Lagoon, Cape Gantheaume Conservation Park, Kangaroo Island, South Australia. South Australian Ornithologist , 33: 65-70.
McCracken, K., P. Fullagar, E. Slater, D. Paton, A. Afton. 2002. Advertising displays of male Musk Ducks indicate population subdivision across the Nullarbor Plain of Australia. Wildfowl , 53: 137-154.
Ogilvie, M., S. Young. 2002. Wildfowl of the World . London: New Holland Publishers (UK) Ltd.