Magpie Goose (Anseranas semipalmata) Fact Sheet: Reproduction & Development

Breeding groups

• Commonly, one male with two females (Carboneras and Kirwan 2017)
  • Females often share some genetic similarity (Kear 1973)
• Variation in group size (Whitehead 1999)
  • 2-4 individuals
  • Trio common
    • One male, two females
  • Four individuals less common
    • One male, three females
    • Two males, two females
• Group members share duties in nest-building, incubation, and caring for young (Frith and Davies 1961)

Mating system

• Usually polygamous (Carboneras and Kirwan 2017)
• Probably lifelong pair bonds (Marchant and Higgins 1990; Carboneras and Kirwan 2017)
  • Partners that die may be quickly replaced (Marchant and Higgins 1990)
• Promiscuous interactions (Marchant and Higgins 1990; Whitehead 1999)
  • Female may mate with a different male
  • Male may associate with more than one nest

Breeding colonies

• Density of nests (Tulloch et al. 1988)
  • Varies from year to year
  • Influenced by rainfall
  • Up to 1,000 nests per km² (0.39 m²)

Courtship and copulation

• Courtship displays
  • First, male and female tread water together and call loudly (Johnsgard 1961)
    • “Concerting” behavior (Davies 1963)
      • Stretch neck, open and close bill rapidly, and vocalize
        • May “bow and scrape” to each other
      • Display varies, depending on how familiar two individuals are with each other
        • Postures range from alert to relaxed
        • Initially, male concerts to female
  • Then, climb up to the nest, female first (Johnsgard 1961)
    • Male quickly mounts
    • Mating out of water unusual for waterfowl (Johnsgard 1961)
      • Most ducks, geese, and swans mate in water
• Copulation occurs at nest site (Johnsgard 1965; Kear 1973)
  • Lasts about two minutes, according to Johnsgard (1961)
  • Male not known to grasp female’s neck, as in similar birds (Johnsgard 1961)
  • Observations of post-copulatory “triumph” display (Johnsgard 1961)
    • Shake wings and/or neck

General

• Sexual maturity
  • Information limited (Delaney et al. 2009)
  • Female
    • 2 years of age (Whitehead 1998a; Carboneras and Kirwan 2017)
  • Male
    • 3-4 years of age (Whitehead 1998a; Carboneras and Kirwan 2017)
• Breeding cycle
  • Annual (Johnsgard 1961; Morton et al. 1990)
• Breeding season
  • Begins at start of wet season (Frith and Davies 1961; Whitehead and Saalfeld 2000; Carboneras and Kirwan 2017, except as noted)
    • North Australia
      • Typically February-April
        • Some eggs laid in January and May (Frith 1967; Marchant and Higgins 1990)
      • Groups visit breeding sites and build “test” stages in January (see “Construction”) (Frith 1967)
    • South Australia
      • August-October
  • Nest building precedes egg laying by about two months (Frith and Davies 1961)
  • Hatching coincides with peak seed abundance (e.g., wild rice) (Whitehead et al. 1990, citing Dexter 1988)
• Influences on nesting activity
  • Amount and timing of rainfall (Bayliss 1989; Whitehead and Saalfeld 2000)
    • Strong effects
    • Magpie Geese nest when floodplain water levels are stable or decreasing
      • Helps to ensure floods do not destroy nests
  • Growth of spike-rush (Frith and Davies 1961)
• Intra-specific nest parasitism
  • Possible evidence; unconfirmed (Whitehead and Tschirner 1991b; Carboneras and Kirwan 2017)

Breeding success

• Important influences
  • Weather
    • Dry conditions reduce breeding success (Frith 1967; Carboneras and Kirwan 2017)
    • Flooding commonly causes nest losses (Whitehead and Tschirner 1990; Whitehead and Saalfeld 2000)
  • Predation (Carboneras and Kirwan 2017)
    • Many eggs lost to predators
      • See “Predators” in Mortality and Health
• Re-nesting
  • Some birds able to nest twice (Peter Bayliss, personal communication, 2018)
  • Group may begin a second clutch, if first is destroyed (Dexter and Bayliss 1991; Whitehead and Saalfeld 2000)
  • Replacement clutches have a similar number of eggs and larger eggs, compared to first clutch (Kear 1973; Whitehead and Saalfeld 2000)
    • Rare among birds
    • May be due to the joint nesting strategy of Magpie Geese

Characteristics

• Type
  • Floating mound (Frith 1967; Carboneras and Kirwan 2017)
    • Deep, unlined cup
• Placement (Frith and Davies 1961; Davies 1962b)
  • Water depth
    • About 0.2-1.0 m (10-36 in)
      • Prefer 0.6-0.8 m (25-30 in)
      • Fewer laid in water deeper than 0.8 m (30 in)
  • Surrounded by emergent plants (Eleocharis and Oryza)
    • Plant height
      • About 0.6-1.2 m (2-4 ft) above water level
    • Plant density
      • 1,000-1,600 shoots per square meter
      • Select areas of dense shoots
• Materials
  • Grasses and sedges (Whitehead and Saalfeld 2000)
    • Favor sites with spike rushes (Eleocharis sphacelata and E. dulcis), or mixture of spike rushes and wild rice (Oryza meridionalis) (Davies 1962b; Tulloch et al. 1988; Corbett et al. 1996)
    • Also Hymenachne (Corbett et al. 1996)
      • See Interspecies Interactions

Construction

• Participation
  • Male and females participate in nest building (Davies 1962b)
    • Male spends more time building
• Behavior
  • First, build “platform” or “stage” (Davies 1962b, except as noted)
    • Grasp shoots with bill and neck, and trample/flatten them using neck and feet
    • Weave shoots into a compact “platform” or “stage”
      • Can occur during any time of year
        • Used throughout the year for preening and courting
      • Except during breeding, only use once (Frith 1967)
        • Then, move to new location
    • Innate behavior (Davies 1962b)
      • Goslings build the platforms/stages they rest on (prior to fledging)
  • Second, uproot shoots and place on platform (Davies 1962b)
    • Only occurs during breeding
  • See illustrations by Davies (1962b)
• Distribution of nests
  • Arranged as a loose colony (Todd 1979)
  • Influenced by water depth, vegetation height, and shoot density (Frith and Davies 1961; Davies 1962b)

Maintenance

• Broken egg in the nest (Whitehead and Turner 1998)
  • Parent removes egg shell pieces
  • Cleans spilled yolk off other intact eggs by licking

Egg

• Shape
  • Oval (Marchant and Higgins 1990)
• Size
  • 64–84 mm (2.5–3.3 in) x 46–63 mm (1.8–2.5 in) (Frith 1967; Carboneras and Kirwan 2017)
• Weight
  • 76-138 g (2.7–4.9 oz) (Carboneras and Kirwan 2017)
  • For captive birds, Kear (1973) reports 105-149 g (3.7-5.3 oz)
  • Egg weight tends to increase with a female’s age (Kear 1973)
• Shell
  • Color
    • Pale cream to yellowish-white (Carboneras and Kirwan 2017)
  • Surface
    • Glossy (Marchant and Higgins 1990)
    • Pitted (Kear 1973)

Egg laying

• Females of a breeding group lay in the same nest (Frith and Davies 1961)
• Eggs laid at 24-36-hour intervals (Johnsgard 1961; Carboneras and Kirwan 2017)
  • Laid over 5-10 days (Whitehead 1999)
• Clutch size
  • Variable—usually 5-11 eggs (range: 1-16) (Carboneras and Kirwan 2017)
    • Laid by one or both females (in a trio)
  • Larger females typically lay larger clutches and larger eggs (Whitehead and Saalfeld 2000)
• Breeding groups in a colony do not lay at the same time (Marchant and Higgins 1990)
  • Asynchronous (i.e., first eggs may be months apart)

Incubation and hatching

• Nesting period (from first egg to departure from nest)
  • About 32 days (Whitehead 1999)
• Incubation time
  • 23-30 days (Carboneras and Kirwan 2017)
    • Might be longer in managed care
• Internal egg temperatures
  • 34°C (93°F), on average (range: 32-37°C [89-99°F]) (Dawson et al. 2000)
• Hatching of eggs within a nest
  • Not closely synchronized in the tropics (Whitehead 1999)
    • Eggs may be laid up to 10 days apart
    • Experience high temperatures that affect development

Gosling description

• Image of young gosling
• Weight at hatching
  • 56-92 g (about 2-3 oz) (Carboneras and Kirwan 2017)
• Feathers (Davies 1957; Johnsgard 1961; Carboneras and Kirwan 2017)
  • Color
    • Head and neck cinnamon-colored at hatching
      • Color fades to yellowish color after 3-5 days
    • Body has gray down
    • Underside whiter
  • At hatching, sheaths surround downy feathers (Johnsgard 1961)
    • Fall off within a day
  • Downy tail feathers replaced with juvenile tail feathers during first week of life (Johnsgard 1961)
• Bill and leg color (Johnsgard 1961)
  • Orange
    • Bill has dark gray tip
  • Transitions to yellow color by 3-5 days of age
  • Fades to gray during second week of life
• Facial skin color
  • Orange (Johnsgard 1961)
    • Similar to bill color
• Voice
  • Shrill call (Kear 1973)
    • Beg for food from parents

Events in the week after hatching

• Goslings fully hatch within a day of pipping (Whitehead 1999)
• Usually leaves nest within 24 hours of hatching (Frith and Davies 1961; Carboneras and Kirwan 2017, except as noted)
  • May remain in nest for up to four days (Whitehead 1999)
• Parents may take goslings to water the day after hatching (Johnsgard 1961)
• Family group leaves nest site within 1-4 days of the first chick hatching (Whitehead 1999)
  • Goslings follow parents through marsh
    • Family group climbs over vegetation instead of swimming (Frith 1967)
    • Parents defend brood from other waterfowl (Johnsgard 1961)
    • Build grassy “brood nest” at a different location than original nest site (Johnsgard 1961; Johnsgard 1965)
      • Uncommon behavior among waterfowl
      • Abandoned two weeks after hatching
  • Video: family group on water (advance footage to 03:50)
    • Note aggressive interactions among goslings
• Also see “Goslings” in Life Stages

Investment in care

• All members (both sexes) of a breeding group participate (Frith 1967)
  • Incubate, shade, protect, and feed young (Johnsgard 1961; Frith 1967; Whitehead 1999; Carboneras and Kirwan 2017)
• Time on nest (Johnsgard 1961; Whitehead 1999; Carboneras and Kirwan 2017)
  • Earlier in incubation period, males incubate during the day and females incubate at night
    • Females forage during the day
  • Near hatching and after hatching, females incubate more frequently

Prior to hatching

• Temperature regulation (Marchant and Higgins 1990)
  • Egged incubated by parents when conditions cool (e.g., at night)
  • Shade eggs when conditions warm (e.g., sunny)
• Turning of eggs (Johnsgard 1961)
  • Occurs as one group member relieves another of incubation duties
  • Appears to be haphazard rather than systematic (i.e., not all turned at the same time)
• Defense of eggs (Whitehead 1999)
  • Adults avoid detection by being still and sitting low on the nest, especially during the day
  • If approached at close range, commonly leave and return to the nest
    • Some do not leave the nest
  • Decoy displays
    • Exhibit a “broken wing” behavior
      • Draws attention of potential predators away from the nest
      • More commonly exhibited by females
        • Males also sometimes exhibit this behavior
  • Attack with bill, wings, and feet
    • Males much more likely to show this behavior
  • Threat postures
    • Face threat, standing on nest with wings spread to cover the eggs
      • Neck and bill extended
    • Vigorous thrusts of head and neck in water
    • Rapid, treading motion on vegetation and water surface
  • Male plays greater role in defense compared to female
  • Also see “Vocalizations” in Communication

After hatching

• After fledging, young partly dependent on parents until the following breeding season (Marchant and Higgins 1990; Carboneras and Kirwan 2017)
• Defense of young (Marchant and Higgins 1990)
  • Adults defend goslings fiercely
• Brooding
  • Young brooded at night (Johnsgard 1961; Marchant and Higgins 1990)
    • For approximately 2-3 weeks after hatching
• Feeding
  • Parents feed young bill-to-bill or drop food close to young (Johnsgard 1961; Johnsgard 1965; Todd 1979, except as noted)
    • Behavior observed in very few waterfowl
    • Adults bend down seed heads or strip seeds from plant parts that are out of reach of goslings (Frith 1967; Kear 1973)
    • Bring up submerged plant material
    • Feeding behavior most noticeable during the first week after hatching
      • Can continue for up to 5-6 weeks (Johnsgard 1961; Kear 1973)
    • Young also forage independently
• Also see “Goslings” in Life Stages

Gosling

• Imprinting
  • Imprint on parents and other young (Marchant and Higgins 1990)
  • Exhibit strong following response (Davies 1963)
    • Similar to geese
    • Imprint on parents and other goslings
    • Reduced intensity by one year of age
• Growth rates
  • Magpie Geese goslings grow faster than most waterfowl of similar body size (Whitehead et al. 1990)
    • Males grow faster than females (Carboneras and Kirwan 2017)
      • Males obtain larger adult body size
    • Wings develop quickly, particularly in females (Whitehead et al. 1990)
• Diet (Frith and Davies 1961; Frith 1967)
  • Mainly feed on seeds (e.g., wild rice)
  • Some arthropods
• Behavior
  • Beg for food from parents (Johnsgard 1961)
    • Produce whistling call
    • Tilt bill upward and open mouth
      • Stimulus for parent to feed gosling
  • Show aggression to other chicks in the nest (Davies 1963; Kear 1973, and as noted)
    • Compete for food provided by parents (Johnsgard 1961)
    • Dominance hierarchy forms
• Fledging
  • Timing
    • In the wild
      • Young able to fly at 11 weeks of age (Frith 1967)
      • Goslings remain with parents until next breeding season (Frith and Davies 1961)
    • Managed care settings
      • Hand-reared birds may fledge in 7-8 weeks (Johnsgard 1978)
  • Weight at fledging (Whitehead et al. 1990)
    • Males
      • About 2.2 kg (4.9 lb)
      • 30% heavier than female
    • Females
      • About 1.7 kg (3.7 lb)

Juvenile

• Description (Johnsgard 1961)
  • Bill color
    • Turns from gray to green
    • At about one year of age, turns yellow, and finally, pink
  • Leg color
    • Turns from gray to pale yellow/orange by end of the first year
  • Plumage
    • Downy feathers gone by 6-8 weeks of age
    • Coloration
      • Head, throat, and breast uniform gray
      • Upperparts uniform gray except for white on lower back and at base of tail
      • Underparts white
    • Patch of bare skin between eye and crown becomes larger, close to maturity
• Development (Johnsgard 1961)
  • Molting
    • At four months, juvenile plumage begins to grow
      • See Johnsgard (1961) for detailed description
    • At 7-8 months of age, primaries and secondaries (“flight feathers”) are progressively shed
      • Retain ability to fly
    • After molt at end of first year, has patches of pure white on shoulders, upper wings, and at base of tail
  • Head protuberance in males
    • First noticeable at 1-2 years old
    • Almost fully developed by 2.5 years old
    • No obvious change in females after one year old
• Vocalizations
  • First “honks” at about six months (Johnsgard 1961)
  • Males develop deeper call by eight months (Johnsgard 1961)
    • Trachea is more elongated
      • About 71 cm (28 in) long

Wild populations

• Not reported

Managed care

• No AZA estimates

Survival rates

• Egg mortality
  • Frith and Davies (1961) found that 77% of nests suffered complete or partial predation
    • 72% of eggs eaten by predators
  • Whitehead and Turner (1998) found that 36.5% of nests failed completely
• Survival of young
  • High mortality between hatching and fledging (Delaney et al. 2009)
    • Marshes may dry up before young have fledged (Frith and Davies 1961)
• After fledging
  • Unknown (Delaney et al. 2009)

Predators

• Reptiles
  • Water python (Liasis fuscus) (Frith and Davies 1961; Whitehead and Tschirner 1990; Whitehead and Turner 1998)
  • Possibly monitor lizards (Varanus) (Marchant and Higgins 1990)
• Birds
  • Torresian Crow (Corvus orru) (Whitehead and Tschirner 1990)
  • Whistling Kite (Haliastur sphenurus) (Whitehead and Tschirner 1990; Whitehead 1999)
  • White-bellied Sea-eagle (Haliaeetus leucogaster) (Whitehead 1999)
• Mammals
  • Common water rat (Hydromys chrysogaster) (Whitehead and Tschirner 1990)
  • Dingo (Canis lupus dingo) (Davies 1963; Frith 1967)
  • Red fox (Vulpes vulpes) (Nye et al. 2007)
• Humans (Delaney et al. 2009)
• Few predators at the time of European settlement (Nye et al. 2007)

Accidental death

• Egg stage (Whitehead and Turner 1998)
  • Infertility
  • Physically damaged
  • Developmental abnormality

Diseases (non-comprehensive list)

• Avian influenza viruses (Traill, Bradshaw, et al. 2009)
• Toxoplasmosis observed in managed care (Dubey et al. 2001)
• Traill et al. (2009) suggest that avian botulism, avian cholera, and aspergillosis are the diseases most likely to cause mass mortality events resulting from climate change (Traill, Bradshaw, et al. 2009)
• Also see Olsen (2009)

Magpie Goose goslings at the San Diego Zoo.

Hatchlings have a cinnamon-colored head and neck, which fades to yellowish-gray within a week.

Goslings mainly feed on seeds. Parents supplement food near the nest for up to six weeks.

Image credit: © San Diego Zoo Wildlife Alliance. All rights reserved.