Cassowary (Casuarius spp.) Fact Sheet: Reproduction & Development

• Sexes use separate territories for most of the year; come together for a few weeks to breed (Folch et al. 2017a); large territory of a female may encompass much smaller territories of several males (Bentrupperbäumer 1997; Campbell et al. 2012)
• Often use vocal signals to make contact (Bentrupperbäumer 1997)
• Male or female may initiate courtship (Bentrupperbäumer 1997)
• If male initiates, female chases male away at first, but then allows male to approach; feed together (Crome 1976; Marchant and Higgins 1990; Biggs 2013)
• Male then displays to female, circling around her and emitting a low, rumbling “boo-boo-boo” call (feathers not raised)
• Male’s throat swells
• May scratch/preen female’s neck or rump
• If female initiates pair formation, chases male, but then becomes less aggressive until the pair feed together (Davies 2002)
• Male mounts while female squats or sits on the ground (Davies 2002)
• Encounters reported to occur during daytime hours, peaking during early afternoon (Bentrupperbäumer 1997)
• Courtship sessions last about 25 min, on average (Bentrupperbäumer 1997)
• Biggs (2013) state 2-15 min
• Bentrupperbäumer (1997) reports copulation as being short (about 1-2 min)

Breeding

• Breeding season
  • Southern and Northern Cassowary
    • Not well known; reported with great variability
    • May breed during any time of year when conditions are favorable, but mainly breed June-November (Crome 1976; Moore 2007; Folch et al. 2017a)
      • Corresponds with time of high fruit production and the end of the dry season in New Guinea (White 1913; Noble 1991)
  • Dwarf Cassowary
    • Breeds in both dry and wet seasons (Folch et al. 2017b)
  • In managed care, may have a differenent breeding season (Nicole LaGreco, personal communication 2017)
    • In managed care in the U.S. and Europe, approximately March-Aug/September
• Mating system
  • Not easily defined; needs further research
    • Not reported for Dwarf Cassowary
  • Appears to include simultaneous polygyny (male breeds with multiple females at the same time) combined with sequential polyandry (female breeds with one male, then another) (Crome 1976; Bentrupperbäumer 1997; Folch et al. 2017a), as well as only sequential polyandry in some places (Biggs 2013)
    • Female remains with male during egg laying, but once incubation begins, seeks other mates (Marchant and Higgins 1990)
      • Females may take up to three mates
• Territory
  • Pairs nest apart from other cassowaries, in a large territory (Davies 2002; Folch et al. 2017a)

Nests

• Built on the forest floor (Coates 1985)
• Shallow depression lined with twigs, sticks, leaves, grass, fern fronds, and debris (Pratt and Beehler 2015)
• Pair choses a semi-concealed site (e.g., between tree roots, against log, near dense vegetation) (Folch et al. 2017a)
• Difficult to find nests for scientific study (White 1913; Bentrupperbäumer 1997)

Eggs (Coates 1985; Pratt and Beehler 2015; Folch et al. 2017a)

• Elliptical shape
• Background color is light green to dark teal
  • May lose color from exposure to weather/environment (White 1913)
• Surface often speckled or mottled, either fairly smooth or with raised granules
• Southern Cassowary
  • Clutch size: 3-8 eggs
  • Green or dark green in color
  • Egg dimensions: 135 x 95 mm (5.3 x 3.7 in)
    • Possible that eggs may be slightly larger, as summarized by Table 12.1 in Biggs (2013)
  • Egg weight: Hindwood (1962) reports an average of 584 g (20.6 oz) (n=5 eggs), but the average may be closer to 450 g (15.9 oz) (Nicole LaGreco, personal communication 2017)
• Northern Cassowary
  • Clutch size: presumably 3-5 eggs (not well known)
  • Gray-green to pale green in color
  • Egg dimensions: 139-160 x 93-105 mm (5.5-6.3 x 3.7-4.1 in); weight not reported
• Dwarf Cassowary
  • Clutch size: 2-5 eggs reported (Coates 1985; Pratt and Beehler 2015), but in some populations, typical clutch may be 2-3 eggs (Andrew Mack, personal communication, 2017)
  • Greenish
  • Egg dimensions: 135 x 95 mm (5.3 x 3.7 in), on average; weight not reported

Hatching, incubation, and brooding

• Eggs thought to be laid 3-7 days apart (Biggs 2013)
• About 1-24 hours between pipping and full hatching (observed in managed care) (Romer 1997)
• Egg incubation and chick raising done entirely by male (Folch et al. 2017a)
  • Anomalous cases of a female parent co-caring for chicks or assuming parenting duties after the male partner died (Biggs 2013)
• Male begins incubating the eggs continuously after all eggs of a clutch have been laid (Bentrupperbäumer 1997)
  • Male inspects and turns the eggs
• Incubation period: about 50 days (range: 47-54 for Southern Cassowary, 49-52 for Dwarf Cassowary) (Crome 1976; Coates 1985; Folch et al. 2017a; Folch et al. 2017b; Folch et al. 2017c; Nicole LaGreco, personal communication 2017)
  • May vary with ambient temperature (Davies 2002)

Food provisioning to chicks (Bentrupperbäumer 1997, except as noted)

• Chicks do not eat whole fruits, but rather pieces of fruit provided by the male
• Male will clack his bill next to a food source to stimulate feeding in the chicks (Biggs 2013)
• Male separates pulp from the seed by macerating the fruit in his bill; feeds mashed food to chicks
• Male parents also observed to capture insects for chicks; may be an important part of chicks’ nutrition (Bentrupperbäumer 1997; Biggs 2013)

Protecting young

• Males drive away females; females reported to kill small chicks (Davies 2002)

Chicks

• Physical description (Folch et al. 2017a)
• Reddish-brown head and upper neck
• Upperparts of body creamy white, with broad dark brown stripes running from the chick’s lower neck towards its tail; stripes more narrow on thighs
• Presumably disruptive coloration (to break up the outline/figure of the chick) (Pratt and Beehler 2015)
• Light colored abdomen, without bands
• Legs yellow-to-gray
• Changes in appearance
• Stripes fade between 3 and 6 months of age, transitioning to uniform, brown juvenile plumage (Crome 1976)
• Naked skin on the head and neck begins to change color between 6-9 months of age (Crome 1976)
• Behavior
• Soon leave nest (Folch et al. 2017a)
• Begin following male within 2-3 days of hatching (Bentrupperbäumer 1997)
• Follow and stay in close contact with the male, who cares for the chicks 24 hours a day (Bentrupperbäumer 1997)
• Return to area surrounding the nest site, though not back to the exact nest site (Biggs 2013)

Transition to adulthood

• Subadults wander farther from their male parent, foraging independently, outside his visual range (Biggs 2013)
• Independent at approximately 9 (up to 12) months (Bentrupperbäumer 1997; Moore 2007)
• Young may continue to associate with each other (White 1913; Crome 1976), then become solitary
• Obtain adult body size within a year (Pratt and Beehler 2015)
• Casque may not attain full size until bird is 4 or 5 years old (Rothschild 1900)
• Adult plumage attained at approximately 4 years old (Moore 2007)
• Said to mature around 3 years old (Latch 2007), but successful breed at 4 or 5 years old (Moore 2007)

Wild populations

• Not reported (Biggs 2013)

Managed care

• Median life expectancy
  • About 22 years for Southern Cassowary (AZA 2023)
• Cassowaries in managed care are long-lived; life span in the wild expected to be shorter (Biggs 2013)

Mortality

• Mortality rates
  • In Australia, subadult mortality thought to be high, as young birds leave natal territories and struggle to find territory space within less and less/fragmented forest habitat areas (Latch 2007)
• Causes of death
  • Hatching failure and abandonment (chicks) (Bentrupperbäumer 1997)
  • Hunting (Kofron and Chapman 2006; Pangau-Adam and Noske 2010)
  • Struck by motor vehicles (Dwyer et al. 2016)
  • Attacked by feral pigs and dogs (feral dogs and dogs used by hunters) (Kofron and Chapman 2006; Nicole LaGreco, personal communication 2017)
    • Chicks and subadults often attacked (Latch 2007; Nicole LaGreco, personal communication 2017)
  • Malnutrition and starvation (due to deforestation or after cyclone events) (Birdlife International 2016b)
  • Drowning (Kofron and Chapman 2006)
    • Occurs rarely; exposed to floodwaters or chased into deep water by dogs
• See Threats to Survival

Diseases and parasites (Nature conservation (wildlife) regulation 2006)

• Internal parasites, particularly ascarids
• Aspergillosis, Aspergillus fumigatus
• Avian tuberculosis
• Mycobacterium avium
• See p. 88-99 of Biggs (2013) for information on diseases, injuries, and other health concerns for cassowaries in managed care
• Also see Threats to Survival

Cassowaries lay green eggs, which are incubated by the male parent.

The male also provides all care for the chicks.

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

Image location: Lone Pine Koala Sanctuary, Queensland, Australia

The broad bands that cassowary chicks have on their sides likely help to break up their body outline. This makes it harder for predators to recognize them as potential prey.

These bands fade within six months, the chicks' coloration becoming more uniformly brown.

Image credit: © Arjan Haverkamp via Wikimedia Commons, Creative Commons License 2.0.