For thousands of years, giants lived throughout the forests of New Zealand. These were the moa (Polynesian for ‘fowl’), flightless ostrich-like birds that, in some cases, reached heights of 3.6 m and weighed about 250 kg. They grew so large because they were strict vegetarians and most of them, so far as we can tell from preserved stomach contents, had a very fibrous diet. Such food requires a large stomach to adequately digest it and subsequently a large body to carry it.
There are two theories as to how the giant, flightless moa arrived on the remote islands of New Zealand. One is that the smaller ancestors of the moa had wings and they flew over to New Zealand shortly after its isolation around 80 million years ago. In the absence of reptilian or mammalian predators, and with an abundance of food, they lost their ability to fly and grew larger. However, many experts believe that the moa come from an extremely ancient lineage of birds that could well have been present on New Zealand when it first broke away from Antarctica. The fact that the moa did not possess wings, not even vestigial ones (a unique feature among birds), gives support to this theory.
Despite the size of the moa, it had a natural predator – and it was a giant bird too. The Haast’s eagle, the largest eagle that has ever existed, which weighed up to 15 kg (about as close as can be to the theoretical limit at which a bird can fly), subsisted extensively on the moa. Moa hip bones have been found with terrible wounds in them, which exactly match the enormous grasp of the Haast’s eagle’s talons.
These days, of course, the moa have been extinct for centuries. Around 1200 AD, the people we know call the Maori arrived in New Zealand from islands in the Pacific Ocean and quickly established colonies. They hunted the moa not only for their meat, but also for their bones to make ornaments and spear-points. Within a hundred years or so, almost all of the nine species of moa had become extinct, along with six species of flightless rail, the Haast’s eagle, and many others – up to 40% of all bird species in New Zealand.
The upload moa, one of the smallest species, was probably the last to be wiped out, for it lived it remote, inhospitable mountains. It finally became extinct around the year 1500. This is also by far the best known moa because several of their mummified bodies have been discovered in dry, cold caves in the Otago region.
The moa only became known to science in the nineteenth century when the bones of these giant birds were uncovered in New Zealand. In 1939, one such bone was given to Richard Owen, a famed biologist, palaeontologist and anatomist in London, although he quickly dismissed it as being a bone from a large land mammal such as a cow. Only after he was persuaded to take a second, more detailed, look at the bone did he realise that it must have come from a bird – and a truly enormous one at that.
Four years later, enough moa bones had been collected to enable Owen to reconstruct an entire skeleton of the animal, and it was exhibited in London. A competition soon ensued as to who could find the tallest skeleton, although some unscrupulous Victorian collectors had no objections to making their own skeletal findings just that little bit bigger by adding in the neck bones from another specimen.