Argentavis: the heaviest bird that ever flew

Lived about 9 to 6 million years ago late Miocene; rocks with its fossils in north-west Argentina are dated to 6.02 and 6.68 million years [1]

Weight about 70 to 72 kg the first estimates were 120 and 80 kg; still the heaviest flying bird known [3]

Wingspan about 5 to 6 m older estimates reached 8.3 m, now treated as an outlier [1]

Wing area about 8.1 m² in a flight model that assumed a span of about 7 m [3]

Glide angle close to 3°, about 67 km/h from the same model [3]

Power for level flapping at least 600 W its muscles could supply about 170 W [3]

Diet probably carrion perhaps taken from other hunters; older studies saw a predator [9]

Fossils La Pampa and the Valle de Santa María Argentina, about 1 200 km apart; type specimen in the Museo de La Plata [1]

Named 1980, by Campbell and Tonni 'silver bird', a reference to Argentina [1]

Closest living relatives condors and other New World vultures it belonged to the extinct family of teratorns [1]

About the pictures. Only parts of the skeleton are known and no feathers survive, so all four paintings scale up a condor-like build. The soaring birds hold long, broad wings out to the sides, as flight models require; the spread wingtip feathers are inferred from living condors. The close view of the head shows the long, deep beak with a hooked tip known from teratorn skulls. The standing bird has a shorter, evenly curved bill and slimmer legs, where teratorn legs were stout. The dark plumage, the feathered heads in b and c, and the small, darker head in d are guesses, as are the light and the plants.

Argentavis magnificens was a giant bird of Argentina that lived about 9 to 6 million years ago, late in the Miocene. At about 70 kg it is the heaviest flying bird known, around six times the average weight of an Andean condor. Its wing bones still carry the marks where contour feathers attached, so there is little doubt that it flew, and it undid an older idea that condors, swans and bustards mark the size limit for flying birds. It belonged to the teratorns, an extinct family related to the New World vultures and condors.

A wingspan that keeps shrinking

No feathers survive and the wing bones are incomplete, so the span has to be estimated, and the figure has fallen over time. Campbell and Tonni first suggested 6.5 to 7.5 m in 1980, scaling from the smaller teratorn Teratornis merriami. Scaling from the California condor in 1983, they arrived at 5.7 to 6.4 m in most estimates, with one reaching 8.3 m, which Gayford and colleagues treated as an outlier in 2024.

In 2010 Mayr and Rubilar-Rogers put the wing skeleton at about 1.83 m, against 2.1 m for the bony-toothed bird Pelagornis chilensis, whose span they estimated at 5.2 to 6.1 m, and concluded that Argentavis probably had the smaller span unless its main flight feathers were much longer. Ksepka’s estimates in 2014 were 5.09 to 5.57 m by one method and 5.70 to 6.07 m by another. A span of about 5 to 6 m is now the usual figure: far wider than the 3.3 m of the largest Andean condors, but short of the 6.06 to 7.38 m that Ksepka gave for the much lighter Pelagornis sandersi.

Soaring because it had to

The fullest flight study is a 2007 computer model by Chatterjee, Templin and Campbell, which assumed a span of about 7 m, a wing area of about 8.11 m² and a mass of 70 kg, and its numbers depend on those assumptions. Level flapping flight would have needed at least 600 W, about 3.5 times the 170 W its muscles could supply. So it lived by gliding, at about 67 km/h and an angle close to 3 degrees, climbing in thermals over the plains and on wind pushed up the slopes of the Andes. Thermals big enough to use near the ground are about 100 m across. A 2022 modelling study by Goto and colleagues also concluded that it was a thermal soarer.

Take-off was the hard part. A running take-off from level ground was out of reach, but a short run down a 10-degree slope into a light headwind, or a launch from a perch, should have been enough.

Scavenger, thief or hunter

Teratorns have long beaks and wide gapes, more like eagles than vultures, and in theory Argentavis could swallow an animal the size of a hare whole. That has made them look like active predators to some authors. Their feet were no help in that: blunt, moderately curved claws could not hold prey the way a hawk’s talons do. A large claw bone once credited to Argentavis itself was reassigned to a terror bird in 2012.

In a study published in 2025, Torres Etchegorry and Degrange used CT scans of the type skull to reconstruct the brain. Its shape is condor-like and its smell centres are about the size of an Andean condor’s, but ridges linked to vision look more like those of hawks and falcons. They concluded that it was a scavenger, perhaps one that stole kills, finding food more by sight than by smell. Small terror birds may have been among the animals it robbed, and large ones were probably its main threat. The largest in its time, Devincenzia, weighed up to 350 kg.

A slow life, from a few broken bones

The evidence is thin. The type specimen, named in 1980, is a badly fractured partial skeleton found about 15 km south of Hidalgo station in La Pampa Province. A coracoid and a tibiotarsus from about 1 200 km to the north-west, in rocks dated to 6.02 and 6.68 million years, are the only other bones still assigned to it. From these and from living birds, Palmqvist and Vizcaíno calculated in 2003 what life a bird this large could lead: one or two eggs of about 1 kg every two years, young independent after some 16 months, adulthood at about twelve years, and a territory of more than 500 km². These are estimates from scaling, not observations.

Where it sits in deep time

Argentavis: About 9 to 6 million years ago, in the Neogene.

Argentavis

Earth forms, 4.57 billion years agoToday

Each step to the right is ten times closer to today, so the last few million years get as much room as the first billion.

If Earth's history were one day

Squeeze all of Earth's history, about 4.6 billion years, into 24 hours, starting at midnight. Argentavis runs from 23:57:10 to 23:58:06, ending 2 minutes before midnight.

On this clock one second is about 52 862 years. All of written history fits into the last tenth of a second.

How big

Wingspan of Argentavis, at the top of modern estimates, next to the largest Andean condors and a person.

Argentavis, wingspan 6 m
Andean condor, largest wingspan 3.3 m
Person, for scale 1.7 m

Modern estimates run from about 5 to 6 m. Older ones reached 7 to 8.3 m.

Reconstructions

A huge, dark bird with very long, broad wings and spread wingtip feathers soaring low over dry golden plains under towering white clouds, an impression of Argentavis, the giant soaring bird of Argentina 7 million years ago. AI-generated painting.

A huge, dark brown bird with a thick body, a short, curved bill and slim legs standing on a dry, grassy hillside, open plains stretching away behind it, an impression of Argentavis, the giant soaring bird of Argentina 7 million years ago. AI-generated painting.

Close-up of the head of a huge dark brown bird in profile, with a dark eye and a long, deep, pale beak with a hooked tip, against a blurred blue sky and dry plains, an impression of the head of Argentavis, the giant soaring bird of South America 7 million years ago. AI-generated painting.

A huge, dark bird with very long, broad wings gliding low along a golden, grassy slope, its shadow falling on the grass below, brown hills in the distance, an impression of Argentavis soaring in the foothills of the Andes 7 million years ago. AI-generated painting.

Questions people ask

How big was Argentavis?

It weighed about 70 to 72 kg and had a wingspan of about 5 to 6 m by modern estimates. Older estimates reached 7 m and even 8.3 m, but those figures have come down as the wing bones have been studied further. Its body length and standing height are not well established.

Was Argentavis the largest bird ever?

It is the heaviest flying bird known, but not the largest bird. Pelagornis sandersi had a longer wingspan, estimated at 6.06 to 7.38 m, while weighing only 21.9 to 40.1 kg. Flightless birds such as the elephant birds were far heavier.

Could Argentavis pick up a person?

No. Teratorn toes ended in blunt, moderately curved claws that could not hold prey the way a hawk's or an eagle's talons do. Teratorns probably swallowed their food whole, and Argentavis could in theory manage an animal about the size of a hare.

How could something so heavy fly?

Mostly by gliding. A 2007 model found that it needed at least 600 W to flap in level flight but had only about 170 W available. It rode thermals and wind rising off slopes, gliding at an angle close to 3 degrees and about 67 km/h, and probably took off by running downhill or launching from a perch.

What did Argentavis eat?

Probably carrion, perhaps stolen from other animals. A brain reconstruction published in 2025 pointed to a scavenger that found food more by sight than by smell. Some earlier authors saw teratorns as active predators because of their long beaks and wide gapes.

When and where did Argentavis live?

In central and north-western Argentina, about 9 to 6 million years ago, late in the Miocene. Its fossils come from La Pampa Province and from the Valle de Santa María.