(A) An artist's impression of H. moorei attacking the extinct New Zealand moa. Evidence of eagle strikes are preserved on skeletons of moa weighing up to 200 kg. (Artwork: John Megahan.)
( Comparison of the huge claws of H. moorei with those of its close relative Hieraaetus morphnoides, the “little” eagle. The massive claws of H. moorei could pierce and crush bone up to 6 mm thick under 50 mm of skin and flesh.




Ancient DNA Tells Story of Giant Eagle Evolution -- For reasons not entirely clear, when animals make their way to isolated islands, they tend to evolve relatively quickly toward an outsized or pint-sized version of their mainland counterpart. One avian giant was found in New Zealand: Haast's eagle (Harpagornis moorei), with a wingspan up to 3 meters. Though Haast's Eagle could fly, its body mass (10–14 kilograms) pushed the limits for self-propelled flight. As extreme evolutionary examples, large island birds can offer insights into the forces and events shaping evolutionary change. Bunce et al. (2005) compared ancient mitochondrial DNA extracted from Haast's Eagle bones and found that the extinct raptor underwent a rapid evolutionary transformation that belies its kinship to some of the world's smallest eagle species. Their analysis places Haast's Eagle in the same evolutionary lineage as a group of small eagles in the genus Hieraaetus. Surprisingly, the genetic distance separating the giant eagle and its smaller cousins from their last common ancestor is relatively small.
Using molecular dating techniques, Bunce et al. (2005) proposed a divergence date of 0.7–1.8 million years ago. The increase in body size—by at least an order of magnitude in less than 2 million years—is remarkable, Bunce et al. (2005) argue, because it occurred in a species still capable of flight. The absence of mammalian competitors may have precipitated the rapid morphological shift. Haast's eagle, the authors wrote, “represents an extreme example of how freedom from competition on island ecosystems can rapidly influence morphological adaptation and speciation.”