[8] Haast named the eagle Harpagornis moorei after George Henry Moore, the owner of the Glenmark Estate, where the bones of the bird were found.

Several of the largest extant Old World vultures, if not in mean mass or other linear measurements, probably exceed Haast's eagle in average wingspan as well.

[27][30] Haast's eagle's relatively short wingspan has sometimes led it to being incorrectly portrayed as having evolved toward flightlessness, even though evidence strongly suggests that it flew.

[31] Instead, its short and broad wings represents an evolutionary departure from the mode of its ancestors' soaring flight in favour of navigating through a crowded woodland environment.

[36] The strong legs and massive flight muscles of these eagles would have enabled the birds to take off with a jumping start from the ground, despite their great weight.

[42][43] It also suggests that it deployed feeding tactics more similar to those of vultures after making a kill, plunging its head into the body cavity to devour the vital organs of its prey.

[44] Until recent human colonisation that introduced rodents and cats, the only placental land mammals found on the islands of New Zealand were three species of bat.

Moa were grazers, functionally similar to large ungulates, such as deer or cattle in other habitats, and Haast's eagles were the hunters who filled the same niche as top-niche mammalian predators.

[19] Unlike the adaptable humans, eagles were dependent on the native medium and large-sized flightless birds, being specialized in hunting them.

[19] Some believe that these birds are described in many legends of the Māori mythology, under the names pouākai, Hakawai (or Hōkioi in the North Island).

[52][53] According to an account given to Sir George Grey—an early governor of New Zealand—Hōkioi were huge black-and-white birds with yellow-green tinged wings and a red crest.

In Māori mythology, Pouākai would prey and kill humans along with moa,[54][55][56] which scientists believe could have been possible if the name relates to the eagle, given the massive size and strength of the bird.

[58] Artwork depicting Haast's eagle now may be viewed at OceanaGold's Heritage and Art Park at Macraes, Otago, New Zealand.

[59] The sculpture, weighing approximately 750 kg (1,650 lb), standing 7.5 metres (25 ft) tall, and depicted with a wingspan of 11.5 metres (38 ft) is constructed from stainless steel tube and sheet and was designed and constructed by Mark Hill, a sculptor from Arrowtown, New Zealand.