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Cassowary (Casuarius spp.) Fact Sheet: Behavior & Ecology

Activity Cycle

  • Diurnal; forage during daylight hours, walking slowly, seeking fruit and other food (Coates 1985; Westcott et al. 2005; Brodie and Pangau-Adam 2015)
    • Spend about 35% of the day foraging
  • Actively forage more frequently in the morning and late in the day; spent more time resting in the afternoon (White 1913; Westcott et al. 2005)
  • Rest at night (White 1913; Bentrupperbäumer 1997)

Movements and Territorial Behavior

Southern Cassowary

  • Presumed to be resident, with some evidence of wider-ranging movements (Folch et al. 2017a)
    • Westcott et al. (2005) report maximum movements:
      • 1,200 m (0.74 mi) in a single movement bout
      • Longer movements of up to about 12,500 m (8.4 mi) in 100 days
  • Home range overlap (Bentrupperbäumer 1997; Campbell et al. 2012)
    • Home ranges of females and males overlap
    • A female’s home range may loosely encompass the home ranges of several males
    • Territorial to members of their own sex (hold distinct territory boundaries)—females do not share territory with one another, males do not share territory with one another
  • Home range size
    • In a study of five Southern Cassowaries in Australia, Campbell et al. (2012) found that females had home ranges 3 to 6 times larger than males
    • Bentrupperbäumer (1997) also found females had, on average, 32% larger home ranges than males

Northern and Dwarf Cassowaries

  • Presumed to be resident (Folch et al. 2017b; Folch et al. 2017c)
  • Dwarf Cassowary possibly makes an altitudinal migration in some parts of its range (Wright 2005; Birdlife International 2016a)

Other notes on cassowary spatial ecology

  • Little known about the movements of individual birds (Biggs 2013)
  • Cassowaries may remain in the same area, if food is abundant there (White 1913)
  • Rehabilitated birds may show high fidelity to release sites (Biggs 2013)

Social Behavior

Social groups

  • Often solitary (Birdlife International 2016b)
  • Interactions among adults outside the breeding season rare; members of the same sex generally avoid each other (Bentrupperbäumer 1997)
    • Normally aggressive towards one another, especially between females
  • Come together to breed (Bentrupperbäumer 1997)
  • Usually seen singly or in small family groups (Coates 1985)
  • May form larger groups (up to 6 birds; White 1913) while aggregating around food resources (Davies 2002; Latch 2007); do not feed together (Marchant and Higgins 1990)

Dominance interactions

  • Females dominant to males (Crome 1976; Marchant and Higgins 1990)
    • Male retreats when a female raises her neck
  • Males compete for females during the breeding season (Davies 2002)

Communication

Vocalizations and related displays (Folch et al. 2017a, except as noted)

  • Audio samples
  • Capable of producing very low frequency sounds; near the lower threshold of human hearing (Mack and Jones 2003)
    • Among the lowest frequency vocalizations of any bird
      • Down to 23 Hz for Dwarf Cassowary and 32 Hz for Southern Cassowary
    • Given the cassowary’s solitary behavior, may help them communicate with other individuals far away
  • Calls are most often associated with breeding; not known to vocalize much outside of the breeding season
    •  “Boo-boo-boo” most often made during breeding season and before mating
      • Most frequent during June and July (Davies 2002)
      • Calls last about 2 seconds; repeated for 3 minutes or longer
      • Birds may stamp feet at the same time (Hindwood 1962)
    • During male-male competition, defeated males will give mewing calls while fleeing (Davies 2002)
  • Calls between chicks and male parent
    • Chicks make frequent, high pitched whistles if they lose sight of their male parent (Biggs 2013; Birdlife International 2016b)
    • Coughing sounds (“heugh-heugh-heugh”) sometimes made by males to locate chicks (Hindwood 1962; Davies 2002)
  • Types of alarm calls and related vocalizations (generally made when disturbed) (Birdlife International 2016b; Folch et al. 2017a)
    • Low, deep, rumbling threat calls
    • Low hisses
      • May stand upright with plumage raised to give perception of larger size [Southern Cassowary] (Coates 1985)
  • Other vocalizations reported
    • Grunts (Folch et al. 2017b; Folch et al. 2017c)
    • Low, booming display call (Coates 1985; Birdlife International 2016b; Folch et al. 2017b)
      • Lasts several seconds (Coates 1985), with bouts of preening in between (Davies 2002)
      • Often heard at night (Davies 2002)
      • Produced by males and females
      • Reported for Southern and Dwarf Cassowaries
      • While standing, head is lowered toward ground; bill points toward ground (Southern Cassowary) or back towards legs (Dwarf Cassowary); naked skin of neck is inflated; body trembles while producing the sound; may stamp feet (White 1913)
      • Suggested functions (Coates 1985; Davies 2002)
        • To defend territory
        • May be a warning call or indicate an intention to attack
        • The same or similar behavior exhibited during courtship
  • Dwarf Cassowary
    • While foraging, sometimes makes a quiet glugging noise (Pratt and Beehler 2015)
    • Alarm/threat: high-pitched piping that turns into barking and snarls; produces low growl-grunts and claps its bill; sometimes a loud “mwaaaaa!” (Rothschild 1900; Pratt and Beehler 2015; Folch et al. 2017b)
  • Also see Agonistic Behavior and Defense

Agonistic Behavior and Defense

Territoriality or competition for mates (Crome 1976; Davies 2002)

  • Make low, rumbling or loud, roaring calls (‘boom’), often in the absence of other cassowaries
  • “Stretch display”: (1) stretch neck and body vertically, (2) raise feathers on lower body, and (3) extend wings out in order to appear larger
  • During intense competition, lower head toward the ground while vocalizing
    • Bill points towards ground (Southern Cassowary) or back towards legs (Dwarf Cassowary)
    • Bird may inflate naked skin of its neck
    • Body trembles while producing a low, booming sound
    • Variation on this display: stretching head and neck out for 15 seconds; bill is open; bird gradually inflates neck; followed by a bow and jerk motion, where bill and wattles clap together, paired with barking grunts
  • If confrontation escalates, birds charge each other, jump into the air, kicking out with both feet (Marchant and Higgins 1990)
    • Defeated bird flees, making mewing vocalizations, while being chased by the victor
  • Short bouts of vigorous preening is also indicative of passive agonistic behavior (Wright 1988; Biggs 2013)
  • See Vocalizations and related displays

Female-female aggression

  • Displays in which two females vocalize, pace, preen, and charge in front of each other (Bentrupperbäumer 1997; Biggs 2013)
    • Bird holds itself horizontally as it charges
    • No physical contact, except sometimes grazing opponent with the chest
    • “Winner” passively supplants the losing opponent

Submission and escaping aggressor

  • When running away, a cassowary holds its body parallel to the ground and stretches its neck forward (Crome 1976; Coates 1985)
    • May run past an adversary, making “mewing” or grunting noises
  • If in close proximity to opponent and cannot escape, submissive bird draws its head and neck close to its body in a ‘S’-shape (Wright 1988; Biggs 2013)
    • May also lower bill, similar to how head is held during roosting
    • In captivity, may pace along fence lines in attempting to escape/avoid a perceived threat

Fight adversary

  • When attacking, cassowaries leap and strike out with the sharp claws on their feet (Coates 1985)
    • Capable of delivering lethal blows

Other Behaviors

General

  • Few systematic behavior studies have been conducted on cassowaries, aside from Bentrupperbämer (1997) (Biggs 2013)

Bathing

  • Cassowaries visit water and streams frequently to drink and bathe (Thomson 1935)

Play (Biggs 2013)

  • Chasing and kicking behavior observed among chicks, juveniles, and subadults
  • May also kick and stomp inanimate objects

Ecological Role

Promote seed dispersal and germination

  • Cassowaries are important dispersers of seeds in tropical forests (Noble 1991; Bradford and Westcott 2011)
    • Cassowaries are considered keystone species (Webber and Woodrow 2004; Mack and Wright 2005)
      • In Papua and Australia, occupy the ecological role of large-bodied, fruit-eating mammals typical of other rainforest ecosystems (Mack and Wright 2005)
      • Particularly important for dispersing seeds of large fruits (Wright 2005)
    • Cassowaries move long distances while searching for food, moving seeds far from the parent plant (Mack 1995; Westcott et al. 2005)
    • Known to disperse seeds of several hundred rainforest plant species (Crome and Moore 1990)
      • Dispersal affects seed survival, plant population genetic structures, and plant distribution and colonization ability (Westcott et al. 2005)
    • Piles or clumps of feces might contain thousands of seeds (Bradford and Westcott 2011)
      • Dispersal limited by seeds being clumped rather than scattered (Westcott et al. 2005)
  • Seed survival/germination not affected by moving through a cassowary’s digestive system (Stocker and Irvine 1983; Mack and Druliner 2003; Bradford and Westcott 2011)
    • Possible that passing through the cassowary’s gut helps with germination (Webber and Woodrow 2004)
  • Seed survival after excretion is variable; some types of seeds survive a few days; others may still be able to germinate after an full year (Bradford and Westcott 2011)
    • In Australia, predators shown to remove up to 40% of seeds found in cassowary feces
      • Ground-dwelling mammals—rodents, feral pigs, small marsupials (musky rat-kangaroos)—are key consumers of seeds
        • White-tailed rat (Uromys caudimaculatus) thought to be responsible for eating the largest proportion of seeds
      • Mixed scientific findings as to whether insects can damage soft seeds (Webber and Woodrow 2004; Bradford and Westcott 2011)
    • Abiotic influences on seed survival: gravity, effects of water, forest floor litter disturbance

Interspecies Interactions

Relationship with plants

  • Important ecological role as consumers of fruits and seeds, promote germination of native and non-native plants
  • See Ecological Role
  • See Diet

Relationship with humans

  • Usually shy/timid around humans; often retreat or bolt from sight (Coates 1985; Pratt and Beehler 2015)
  • “Elusive in dense forest” (Birdlife International 2016b)
  • Difficult to find for scientific study—live at low population densities, are secretive (Westcott 1999; Mack and Druliner 2003)
  • Often detected by presence of their colorful, conspicuous droppings of partially digested fruit or by their large, three-toed footprints (Coates 1985; Pratt and Beehler 2015; Birdlife International 2016c)
  • “Most easily seen in Australia alongside certain roads and lodges” (Birdlife International 2016b)
  • More bold in places regularly visited by humans; wary of humans everywhere else (Pratt and Beehler 2015)
  • In New Guinea, hunted and captured as chicks to be raised in villages for their meat and feathers; they are not bred (Pratt and Beehler 2015)
  • Reputation as being dangerous; attacks on humans in Australia (Kofron 1999)
    • Should be regarded cautiously; if feel threatened, cassowaries will chase or strike at humans, dogs, and small horses in self-defense, defense of young, or in pursuit of food
    • Being fed by humans seems to change the cassowary’s natural behavior; may be more bold and aggressive if people have fed them before and they are expecting food
    • “Feeding cassowaries puts individuals of an endangered species at even greater risk by attracting them to human-use areas with cars and dogs”
    • Illegal to feed cassowaries in Australia (Nature conservation (wildlife) regulation 2006)

Locomotion

  • Walk and run
    • Leave worn trails in forests along routes to food and water resources (Crome and Moore 1990; Marchant and Higgins 1990)
  • Capable of swimming to cross creeks and rivers (Southern Cassowary; Thomson 1935; Coates 1985; Pratt and Beehler 2015), and to escape from dogs (Andrew Stehly, personal communication, 2017) and hunters
    • Kick vigorously to stay afloat and keep moving
    • Enjoy water, but can't stay in deep water for extended periods

Head Ornament

Large casque of a Southern Cassowary

The cassowary's casque likely functions as a social ornament of age, sex, and status.

Some researchers have speculated that the casque also plays a role in vocalizations (more research is needed).

The casque's complex internal structure has remained a scientific mystery for decades.

Image credit: © San Diego Zoo Global. All rights reserved.

Image location: Lone Pine Koala Sanctuary, Queensland, Australia

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