Birds
Elephant Bird
Aepyornis maximus · also called elephant bird, vorombe
The elephant bird of Madagascar was the largest bird that ever lived — a flightless giant up to three metres tall and, on the heaviest estimates, approaching a tonne. It laid an egg the size of a rugby ball, the biggest of any animal in history. And its closest living relative turns out to be the kiwi, a bird you could hold in one hand.
Overview
Elephant birds lived only on Madagascar, in forest and woodland. The biggest species stood around 3 m tall and is estimated to have weighed roughly 500–700 kg, with some analyses suggesting up to 860 kg — the heaviest bird known. It was a herbivore and a probable disperser of big tree seeds.
The largest egg ever
An elephant bird egg could be about 34 cm long, a metre around, and hold 10 litres — the volume of around 150 hen’s eggs — the largest single egg known from any animal, dinosaurs included.
Related to the kiwi
DNA from museum bones showed the elephant birds’ nearest living relatives are the kiwis of New Zealand, tiny nocturnal forest birds, not the ostrich. This means the big flightless birds lost flight independently in different places rather than drifting apart on one landmass. Brain and eye-socket studies hint that some elephant birds were themselves nocturnal and nearly blind, like the kiwi.
Extinction
People lived alongside elephant birds on Madagascar for centuries. The birds disappeared around 1,000 to 1,200 years ago, from hunting, egg collecting, forest clearance, and introduced animals acting together on a large, slow-breeding, ground-nesting bird.
Elephant Bird: common questions
Was the elephant bird bigger than the moa?
It depends which measurement you use. The tallest moa, the South Island giant moa, could stretch its neck to well over 3 metres, taller than any elephant bird. But the elephant bird was far more heavily built, and the largest species is estimated to have outweighed the biggest moa by a wide margin, with weight estimates ranging from around 500 kg to over 800 kg against roughly 250 kg for a large moa. So the moa was taller and the elephant bird was heavier, and it is the elephant bird that is generally called the largest bird that has ever lived, because size in that sense usually means mass.
How big was an elephant bird egg?
The largest were roughly 34 centimetres long and a metre in circumference, with a shell a few millimetres thick and an internal volume of about 10 litres. That is the equivalent of around 150 hen's eggs or 7 ostrich eggs, and it is the largest egg known from any animal, living or extinct, including the dinosaurs. Because an egg begins as a single cell, an elephant bird egg is also often cited as the largest single cell in the history of life. Whole eggs, thousands of years old, are still occasionally dug out of the sand dunes of southern Madagascar, and a nearly complete one has sold at auction.
Why is the tiny kiwi the elephant bird's closest relative?
It was a genuine surprise. For a long time the large flightless birds, the ratites, were assumed to be a single ancient group that split up as the southern continents drifted apart, so the giant elephant bird was expected to be close to the African ostrich. But DNA recovered from elephant bird bones placed it right next to the kiwi, a small, nocturnal, forest bird from New Zealand thousands of kilometres away. The explanation is that the ancestors of these birds could fly, dispersed across the world by air, and then lost flight separately in different places, so shared ancestry does not track shared size or shared continent.
What killed off the elephant birds?
Humans, though not by a single dramatic event. People had been on Madagascar for well over a thousand years before the last elephant birds died, so it was a slow decline rather than a rapid slaughter. The likely causes acted together — adults and chicks were hunted, the huge eggs were collected for food and their shells used as containers, forest and woodland were cleared and burned for farming and grazing, and introduced animals such as pigs and dogs raided nests. A large, slow-breeding, ground-nesting bird had little resilience against that combination, and by around the twelfth century it was gone.