Concept
Haast's eagle (Hieraaetus moorei) is an extinct species of eagle that lived in the South Island of New Zealand, commonly accepted to be the pouakai of Māori legend. It was the largest eagle known to have existed, with an estimated weight of , compared to the harpy eagle. Its massive size is explained as an evolutionary response to the size of its prey, the flightless moa, the largest of which could weigh . Haast's eagle became extinct around 1400, following the arrival of the Māori, who outcompeted it for its moa prey. Haast's eagle was first described by Julius von Haast in 1871 from remains discovered by the Canterbury Museum taxidermist, Frederick Richardson Fuller, in a former marsh. Haast named the eagle Harpagornis moorei after George Henry Moore, the owner of the Glenmark Estate, where the bones of the bird were found. The genus name was from the Greek harpax, meaning "grappling hook", and ornis, meaning "bird". DNA analysis later showed that this bird is related most closely to the much smaller little eagle as well as the booted eagle and not, as previously thought, to the large wedge-tailed eagle. Harpagornis moorei was therefore reclassified as Hieraaetus moorei. H. moorei is estimated to have diverged from these smaller eagles as recently as 1.8 million to 700,000 years ago. If this estimate is correct, its increase in weight by ten to fifteen times is an exceptionally rapid weight increase. The suggested increase in the average weight of Haast's eagle over that period would therefore represent the largest, fastest evolutionary increase in average weight of any known vertebrate species. This was made possible in part by the presence of large prey and the absence of competition from other large predators. A recent mitochondrial DNA study found it to be more closely related to the little eagle than the booted eagle, with an estimated divergence from the little eagle around 2.2 million years ago. It was placed in the genus Aquila by recent taxonomists. Haast's eagle was one of the largest known true raptors.
