The Haast Eagle is the large eagle known to have ever existed !

Scientists hypothesize it evolved to such a massive size in order to adapt to its favorite prey : the flightless moa.

Studies of the Haast Eagle's evolution indicate it morphed into this form extremely fast, suggesting the environment was very welcoming to this type of physical adaptation.

Despite its size, its wings are shorter than one might expect. Scientists explain this by changes in mode of flight, favoring maneuvering in dense forest environment rather than high-altitude soaring.