Birds come in all different shapes and sizes, from tiny hummingbirds to massive ostriches. But what was the largest bird to ever live on planet Earth? Throughout history, there have been some truly gigantic birds that would dwarf even the largest birds alive today.
The Elephant Bird
One of the top contenders for the largest bird ever is the elephant bird, or Aepyornis, that lived in Madagascar until around 1,000 years ago. Elephant birds belonged to an ancient family of large, flightless birds called ratites that today includes ostriches, emus, rheas, and kiwis.
There were several elephant bird species, the largest of which was Aepyornis maximus. Based on bone fragments and eggshell remains, researchers estimate that A. maximus could grow over 10 feet tall and weigh around 880 pounds or more, making it the world’s largest bird that is known from verifiable evidence.
To put that in perspective, the ostrich, today’s largest living bird, reaches maximum heights over 9 feet tall and weighs around 350 pounds. The now-extinct A. maximus was more than a foot taller and over twice as heavy as an ostrich! Other elephant bird species were smaller, but still much bigger than ostriches.
Elephant birds, like ostriches, were flightless and had small wings relative to their body size. They had long, powerful legs for running. Their most striking feature was the enormously thick legs and feet needed to support their massive weight.
Elephant birds laid the largest eggs of any known animal that ever existed. The biggest elephant bird eggs were over 1 foot long, with a capacity of around two gallons – 20 times larger than an ostrich egg! They were first discovered by explorers in the 19th and early 20th centuries and initially confused for giant replicas.
Fragments of elephant bird eggshells are still found today across Madagascar. Unfortunately, all elephant bird species became extinct by the 17th century or earlier, most likely due to human hunting and habitat loss.
Giant Moa of New Zealand
The moa were a group of flightless birds that lived in New Zealand up until around 500 years ago. At least eleven species have been identified, ranging from turkey-sized to the Giant Moa (Dinornis) that grew over 12 feet tall and weighed around 500 pounds.
Giant Moa were the tallest birds ever known with their necks outstretched upwards – they could reach heights of around 12.5 feet. That’s like the height of a female giraffe! They had long necks perfect for browsing leaves from tall trees.
Researchers have calculated that Giant Moa females were more than 200 pounds heavier on average than the largest moa males. This extreme size difference between sexes is greater than in any other bird species alive today.
Moa birds were likely hunted to extinction by the Maori people who settled New Zealand around 1280 AD. Loss of habitat was also a factor in their disappearance shortly after human arrival.
Other Extinct Giant Birds
In addition to elephant birds and moa, there were many other now-extinct flightless birds that rivaled or exceeded the size of today’s ostriches:
- The Dromornithids, or “demon ducks,” were a group of massive, flightless birds that lived in Australia until around 40,000 years ago. Genyornis newtoni was the largest, standing over 10 feet tall and weighing over 500 pounds.
- Gastornis was a genus of giant flightless birds that inhabited ancient forests across North America, Europe, and Asia beginning over 50 million years ago. The largest species, Gastornis gigantea of North America, grew up to 8 feet tall.
- Terror Birds were carnivorous flightless birds that dominated South America for millions of years until around 2.5 million years ago. The largest was Kelenken, which grew over 10 feet tall, had a massive skull, and likely preyed on medium-sized mammals.
All of these birds were likely driven to extinction by a combination of climate change and competition with mammals. The arrival of humans in the past 100,000 years also impacted giant bird species still around at that time through hunting and habitat destruction.
Largest Flying Birds
The largest birds capable of flight were not as big as the giant flightless birds above, but still impressive in size compared to all living flying birds.
The extinct Argentavis magnificens from South America is considered the largest flying bird ever discovered. With an estimated 23 foot wingspan and weighing over 150 pounds, it was heavier than many adult humans!
Pelagornis sandersi was another huge prehistoric flying bird with an estimated wingspan of around 20-24 feet, considered the largest flying bird known from North America.
Today’s largest living flying birds are much smaller in comparison. The Andean condor has the widest wingspan of any current bird, ranging up to around 11 feet tip to tip. The heaviest living flying bird is the Dalmatian pelican, which can reach up to around 30 pounds.
Heaviest Birds Ever
When considering sheer bulk or weight, the heaviest birds to ever live were likely some enormous flightless species that are now extinct. However, estimates of body mass for extinct animals can be uncertain and debated by researchers.
Most scientists agree that the “Dreadnoughtus” dinosaur was probably the single heaviest bird ever at over 30 tons, though others argue it was actually slightly lighter. Some estimates also place the heaviest moa in the same 20-30 ton range as the largest dinosaurs.
Among more uncontroversial candidates, Giant Moa, elephant birds, gastornithids, dromornithids and giant terror birds all likely reached body weights somewhere between 500-1500 pounds at maximum size.
By comparison, the heaviest living birds today are ostriches and emus, which rarely exceed 350 pounds even in captivity with abundant food provided.
Why were extinct birds so large?
Paleontologists continue to study and debate why so many birds evolved to huge sizes that are never seen among avian species today.
Some key theories include:
- Absence of human hunters – Many giant birds went extinct shortly after humans reached their habitats, suggesting human activity played a role.
- Plentiful food sources – Abundant plants and small prey may have allowed giant herbivorous and carnivorous birds to thrive.
- Lower predation – Lack of efficient mammalian predators may have enabled flightlessness and large bodies.
- Warmer climate – Many giant birds lived during globally warmer periods in Earth’s past.
The tendency to become larger over evolutionary time, called Cope’s Rule, may have simply allowed birds with access to plentiful resources and few predators to grow massive. This happened independently many times across avian lineages.
Could giant birds re-evolve?
While we will likely never see birds the size of Dromornithids or elephant birds again, it is possible that birds could re-evolve to giant sizes if given enough time.
Ostriches and other ratites still carry many of the primitive characteristics that enabled their extinct cousins to grow so massive. If placed in predator-free environments and given abundant food sources, natural selection could once again gradually favor increased body size.
This process would still likely require millions of years to generate birds larger than the biggest moa or elephant birds. But given the right evolutionary pressures, substantially larger birds could make a comeback sometime in the far future.
Artificial selection could also generate larger bird breeds for food production over just decades or centuries, as already done with turkeys and chickens. However, there are limits to how enormous domesticated fowl could become and remain biologically functional.
Largest Birds Alive Today
While no living birds rival the long-extinct giant species, several rank among the largest avian species on Earth today. Here are some of the record holders:
| Bird | Height | Weight |
|---|---|---|
| Ostrich | 9+ feet | 350 lbs |
| Emu | 5.5 feet | 110 lbs |
| Dalmatian Pelican | 5 feet | 30 lbs |
| Andean Condor | 4 feet | 25 lbs |
The ostrich far outweighs all other living birds and can sprint at speeds over 40 miles per hour. Emus rank second in height and weight. Dalmatian pelicans are the heaviest of the flying birds, while Andean condors have the widest wingspan.
Conclusion
The likely contestants for largest bird ever all lived thousands or millions of years ago and included giant species such as elephant birds, moa, and gastornithids. Several exceeded 10 feet tall and over 500 pounds – dwarfing even the largest ostriches alive today.
Humans and a warming climate likely contributed to the extinction of most truly massive birds. While birds today are much smaller, it’s possible giant birds could evolve again someday if ecological conditions are right.
