D
Species Profile

Dromornis stirtoni

Dromornis stirtoni

Australia's Miocene mega-bird
Nobu Tamura, CC BY-SA 3.0

Dromornis stirtoni Distribution

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Endemic Species
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Found in 1 country

🇦🇺 Australia

Size Comparison

Human 5'8"
Dromornis stirtoni 9 ft 6 in

Dromornis stirtoni is 1.7x the height of an average human.

Dromornis Stirtoni

At a Glance

Wild Species
Also Known As Stirton's mihirung, Stirton's thunderbird, giant mihirung, thunderbird
Diet Herbivore
Activity Diurnal
Weight 650 lbs
Status Not Evaluated
Did You Know?

It's generally regarded as the largest described dromornithid; published mass estimates commonly fall around ~400-500 kg (based on limb-bone scaling in the primary descriptive literature).

Scientific Classification

Dromornis stirtoni was a gigantic, flightless bird (a dromornithid) from Australia, known from the Miocene epoch. Dromornithids are an extinct lineage of very large birds generally considered part of the waterfowl-related clade (Galloanserae) and commonly placed within/near Anseriformes.

Kingdom
Animalia
Phylum
Chordata
Class
Aves
Order
Anseriformes
Family
Dromornithidae
Genus
Dromornis
Species
stirtoni

Distinguishing Features

  • Giant, heavy-bodied, flightless bird with robust legs
  • Large skull and powerful beak typical of dromornithids
  • Miocene age; among the largest known birds of its time in Australia
  • Often grouped with other ‘mihirungs’ (dromornithids) rather than true ratites

Physical Measurements

Height
9 ft 6 in (8 ft 10 in – 9 ft 10 in)
Length
9 ft 2 in (8 ft 2 in – 9 ft 10 in)
Weight
1,168 lbs (882 lbs – 1,433 lbs)

Appearance

Primary Colors
Brown Gray Black
Secondary Colors
Cream Tan Red
Skin Type Feathered body (dense contour feathers); keratinous beak (rhamphotheca) inferred; legs/feet likely covered in thick, bird-typical scaly skin; localized bare facial skin possible but unconfirmed.
Distinctive Features
  • Extinct Australian giant flightless dromornithid, commonly placed within or near Anseriformes (Galloanserae affinity), not a ratite lineage.
  • Dromornis stirtoni was very large, among the biggest known birds. Adults are thought to be about 3 meters tall and several hundred kilograms (often ~500 kg), but exact weight depends on the scaling model.
  • Massive, deep skull and oversized beak; dromornithids are characterized by a tall, laterally compressed cranium with a powerful rhamphotheca, consistent with strong bite forces (exact bite force not directly measurable from fossils).
  • Robust hindlimbs (thick tibiotarsi/tarsometatarsi) adapted for supporting extreme body mass and terrestrial locomotion; wings strongly reduced indicating obligate flightlessness.
  • Large neck and thoracic girth implied by cervical/thoracic elements and overall body plan; center of mass carried over powerful pelvic limbs.
  • Dromornis stirtoni dates to the Miocene, especially the late Miocene, with fossils at sites like Alcoota; fossil evidence shows open woodland or savanna with seasonal dry periods in inland Australia.

Did You Know?

It's generally regarded as the largest described dromornithid; published mass estimates commonly fall around ~400-500 kg (based on limb-bone scaling in the primary descriptive literature).

Fossils are best known from Australia's Late Miocene Alcoota Local Fauna (Northern Territory), dated to ~8 million years ago (Tortonian).

Despite its ostrich-like look, Dromornis stirtoni is usually placed in/near Anseriformes (waterfowl line), within Galloanserae-making it a very distant cousin of ducks and geese.

Its huge skull and deep beak suggest extremely powerful jaw musculature; most recent interpretations favor herbivory/browsing rather than active predation.

Dromornithids as a whole span a long Australian history (Eocene to Pleistocene), showing multiple waves of giant, flightless forms-D. stirtoni sits near the extreme end of size.

The species name honors vertebrate paleontologist Ruben Arthur Stirton; the genus name Dromornis literally means "running bird."

Unique Adaptations

  • Extreme body size with flightlessness: A massive torso and reduced wings indicate a fully terrestrial lifestyle with flight abandoned long before the Miocene.
  • Reinforced skull + large beak: The disproportionately large head and beak, with extensive attachment areas for jaw/neck muscles, point to high bite forces and specialized feeding on resistant plant material (most supported interpretation).
  • Stout, weight-bearing hindlimbs: Limb proportions and robust joints are consistent with supporting very high mass on land-an adaptation seen repeatedly in giant, flightless birds.
  • Waterfowl-lineage anatomy in a giant runner: Placement near Anseriformes implies that "duck-line" birds evolved an unexpectedly diverse range of body plans, including gigantic terrestrial browsers (dromornithids) as well as swimming/flying waterfowl.

Interesting Behaviors

  • Browsing/foraging (inferred): Beak and skull mechanics are consistent with processing tough vegetation, fruits, or browse; exact diet remains debated but is most often reconstructed as primarily herbivorous.
  • Ground locomotion (inferred): As a heavy, flightless bird with robust hindlimbs, it likely walked efficiently and could have delivered powerful defensive kicks-analogous in function (not ancestry) to ratites.
  • Nesting/parental care (unknown): No confirmed nests/eggs are attributable to D. stirtoni; by analogy with large ground birds, it likely nested on the ground, but this is not directly evidenced.
  • Sociality (unknown): No trackways or bonebeds definitively demonstrate flocking; behavior is therefore largely inferred from ecology and comparative biology rather than directly documented.

Cultural Significance

Dromornis stirtoni is often shown in Australian museums and science media as one of the largest dromornithids (giant, flightless birds) and an icon of Australia's Miocene land life. Dromornis means running bird; stirtoni honors Ruben A. Stirton.

Myths & Legends

No traditional myths are tied to Dromornis stirtoni because it died out millions of years before humans reached Australia. Now Australian paleontologists and museums use an Indigenous Australian word meaning 'giant bird.'

"Thunder bird" is a nickname used for dromornithids in talks. The Thunderbird is a powerful being in Indigenous North American stories; its use for Australian dromornithids is a modern metaphor, not a local story.

A modern internet legend shows giant dromornithids as scary water birds, popularized by Bullockornis the 'demon duck of doom'. Dromornis stirtoni is shown as the biggest, but scientists think it ate plants.

Conservation Status

NE Not Evaluated

Has not yet been evaluated against the criteria.

Population Unknown

Behavior & Ecology

Social Flock Group: 2
Activity Diurnal
Diet Herbivore Woody browse (leaves and shoots of shrubs/trees); inferred primary food based on craniomandibular morphology of Dromornis stirtoni and broader dromornithid functional interpretations (e.g., Murray & Vickers-Rich, 2004).

Temperament

Behavior cannot be directly measured for this extinct species; inferred as generally cautious/avoidant rather than aggressively predatory based on reconstructed ecology (large-bodied, flightless, terrestrial) and comparative behavior of large extant ground birds.
Likely seasonally more territorial or intolerant of conspecifics at close range during breeding, if pair-bonding and nest defense occurred (inference only; no direct D. stirtoni breeding evidence).
HUBS (Dromornithidae-wide) inference: temperament likely ranged from relatively tolerant at shared resources to highly intolerant at nests; degree of tolerance probably varied with habitat productivity and local density (not directly testable from current fossil record).

Communication

Low-frequency booming/honking-style calls are plausible given large body size and anseriform affinities, but no syrinx/soft-tissue evidence exists for D. stirtoni; any call type remains inferential.
Hissing/exhalation sounds during threat display are plausible (common in large birds), but not evidenced for the species.
Visual displays (upright posture, head/neck positioning, lateral presentation) are plausible for spacing, mate attraction, and threat signaling; specific display repertoires are unknown.
Substrate signals such as foot-stomping are plausible as short-range threat/attention signals in a large, heavy terrestrial bird, but are not documented.
Contact/spacing likely relied on a combination of vision and low-frequency vocal output in open habitats; exact modalities remain untestable for this species.

Habitat

Woodland Forest Grassland Savanna River/Stream Lake Wetland Swamp Marsh +3
Biomes:
Tropical Dry Forest Savanna Temperate Forest Temperate Grassland Freshwater Wetland
Terrain:
Plains Riverine Valley
Elevation: Up to 3280 ft 10 in

Ecological Role

Megaherbivorous browser (large-bodied terrestrial bird) influencing vegetation structure in Miocene Australia.

Vegetation shaping via intensive browsing (altering shrub/tree recruitment and canopy structure) Potential seed dispersal for fleshy-fruited plants (if fruits were consumed) Nutrient redistribution through dung deposition across foraging ranges

Diet Details

Other Foods:
Woody browse Sclerophyll vegetation Soft stems and shoots Fruit Seeds

Human Interaction

Domestication Status

Wild

Dromornis stirtoni is an extinct Australian mihirung from the Late Miocene (~8–7 million years ago). It was not domesticated because it lived long before humans. People only find, dig up, care for, and display its fossils. Other dromornithids vary: Miocene species are known from fossils, while Pleistocene Genyornis newtoni overlapped humans and may have been hunted or had eggs taken.

As a Pet

Not Suitable as Pet

Legality: Not applicable as a live pet (species extinct). Possession/sale of fossils (including Dromornis material) is typically regulated by Australian state/territory heritage and fossil-protection laws; scientifically significant specimens are commonly held in museum collections and collecting/export may require permits.

Care Level: Expert Only

Purchase Cost:
Lifetime Cost:

Economic Value

Uses:
Scientific research Museum/education Geoheritage and tourism Fossil preparation/collections work
Products:
  • peer-reviewed paleontological research outputs (descriptions, phylogeny, biomechanics)
  • museum exhibits and replicas/casts
  • educational media and outreach content
  • fieldwork and fossil-preparation services associated with Miocene Australian localities (indirect economic activity)

Relationships

Predators 2

Baru darrowi Baru darrowi
Marsupial lion
Marsupial lion Wakaleo schouteni

Related Species 6

Murray's dromornis Dromornis murrayi Shared Genus
Dromornis australis Dromornis australis Shared Genus
Bullockornis planei Bullockornis planei Shared Family
Ilbandornis woodburnei Ilbandornis woodburnei Shared Family
Genyornis newtoni Genyornis newtoni Shared Family
Barawertornis tedfordi Barawertornis tedfordi Shared Family

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

Ostrich
Ostrich Struthio camelus No ecological relationship explanation provided.
Emu
Emu Dromaius novaehollandiae Large Australian flightless bird that occupies open and woodland habitats and has a predominantly plant-based diet. Ecologically comparable as a terrestrial, non-flying avian megafauna component (though far smaller than D. stirtoni).
Southern cassowary Casuarius casuarius Large-bodied, forest-associated flightless bird with strong legs and a largely frugivorous/browsing diet. Comparable niche elements: a large ground bird that feeds on tough plant matter and fruit and disperses seeds.
Giant moa Dinornis robustus Extinct, very large flightless browser. Occupied the role of a dominant terrestrial herbivore with reduced need for flight and likely vulnerability concentrated in juveniles and eggs.
Elephant bird
Elephant bird Aepyornis maximus Extinct insular avian megaherbivore. Similar in being a very large, flightless bird inferred to consume coarse vegetation and fruits, with primary predation risk likely focused on eggs and young.

“This massive flightless bird weighed as much as a full-grown horse.”

Dromornis stirtoni Facts

  1. Dromornis stirtoni lived in Australia around 2.6 million to 11,700 years ago.
  2. It weighed as much as a horse and didn’t fly, but it likely spread its wings when it ran to help it stay balanced, like a big goose.

Dromornis stirtoni Scientific name

The scientific name of this bird is Dromornis stirtoni. It comes from the Greek words “dromos,” meaning “racecourse,” and “ornis,” meaning “bird.” It’s kind of fun to think of its name as “Racing Bird.”

Description & Size

It’s possible Dromornis stirtoni was the biggest bird in history. It weighed as much as a horse: about 1,100 pounds. So if it were alive today, and somehow able to be tamed, it could easily bear the weight of one or two adult humans. It was about 10 feet long and 7 feet tall–about as tall as many NBA basketball players. Even though it couldn’t fly, it had large wings that might have helped it keep its balance when it was running, much like a goose does if you’ve ever been chased by one in the park! The wings might have also puffed it up to look bigger to frighten off enemies or rival birds in courting rituals to get the best mates. Most birds have lightweight bones, but this one had a massively heavy skeleton. This probably made it move slowly and run only in short sprints when the motivation hit it really hard.

Dromornis Stirtoni

Dromornis stirtoni was also often referred to as Stirton’s thunderbird.

©Nobu Tamura, CC BY-SA 3.0 – Original / License

Dromornis stirtoni Evolution and History

Dromornis stirtoni lived in Australia during the Pleistocene epoch, which lasted from around 2.6 million to 11,700 years ago. It went extinct around 50,000 years ago, along with similar species of big flightless birds in Australia, such as Genyornis newtoni. Humans lived in Australia by this time, so hunting or egg-gathering by people as well as destroying their habitats for settlements may have been one cause of its extinction.

Diet – What Did the Dromornis stirtoni Eat?

This bird had a powerful beak, with teeth, so some scientists think it could have been a meat-eater. But, like a supersized chicken, it it had eyes on the sides of its head and didn’t have sharp claws like hunting birds did. So it probably was an omnivore that ate mainly plants and whatever small animals and big insects it could catch.

Habitat

Dromornis stirtoni lived in Australia, which had a greater variety of humid habitats then than it does today. This big bird could thrive in forests, grasslands, and wetlands.

Threats And Predators

It’s food source was fruits, berries, grains, little animals and big insects. Big carnivores could have hunted it down for those drumsticks, but they would have to be strong and agile enough to avoid its stomping feet and sledgehammer-like beaked. Like other species of the time, it was endangered by climate change, natural disasters, and evolutionary changes that left them uncompetitive with other creatures, including humans.

Discoveries and Fossils

Fossils of Dromornis stirtoni were discovered in Australia in the Northern Territory, Queensland, and New South Wales, so that tells us it was a widely-distributed species. If you’re in Australia and want to see the remains for yourself, here are some museums that have them on display:

  1. Australian Museum, Sydney
  2. National Museum of Australia, Canberra
  3. Queensland Museum, Brisbane
  4. South Australian Museum, Adelaide

Extinction – When Did It Die Out?

Dromornis stirtoni went extinct around 50,000 years ago, along with many other species of large, flightless birds in Australia. Climate change, natural disasters, and humans multiplying, killing them, and taking their habitat may have all been part of their extinction story.

Similar Animals to the Dromornis stirtoni

  1. Genyornis newtoni
  2. Dromornis planei
  3. Bullockornis planei
View all 450 animals that start with D

Sources

  1. Wikipedia.org / Accessed December 27, 2022
  2. Australian Museum / Accessed December 27, 2022
  3. Prehistoric Wildlife / Accessed December 27, 2022
  4. Prehistoric Fauna / Accessed December 27, 2022
Drew Wood

About the Author

Drew Wood

Drew is a college professor and freelance writer who graduated from the University of Virginia. His travels have taken him to 25 countries and 44 states, where he has enjoyed learning about wildlife in a wide range of environments. In addition to his love of animals, he enjoys scary movies, landscaping, strategy games, and philosophical discussions over a cup of coffee. He is also an emotional support human to a neurotic Spanish Water Dog and a hyperactive Chihuahua mix.

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