Haast's Eagle (Harpagornis moorei) was a species of eagle that once lived on the South Island of New Zealand.
The species was the largest eagle known to have existed. Its prey consisted mainly of Moa, gigantic flightless birds that were unable to defend themselves from the striking force and speed of these eagles, which at times reached 80 km/h (50 mph). The Eagle's massive size may have been an evolutionary response to the size of its prey, as both would have been much smaller when they first came to the island, and would have grown larger over time due to lack of competition (see island gigantism). Haast's Eagle became extinct around the year 1400, when its major food source, the Moa, were hunted to extinction by Maori and much of its dense-fore st habitat was cleared.