Haast's eagle (Hieraaetus moorei), also called Fuller's eagle, was an extinct species of eagle that lived on the South Island of New Zealand. It is believed to be the pouākai of Māori mythology. It was the largest eagle ever known, weighing between 10 to 18 kilograms (22 to 40 pounds). This is heavier than the next-largest living eagle, the harpy eagle (Harpia harpyja), which weighs up to 9 kilograms (20 pounds). Its very large size is thought to be an evolutionary response to its prey, the flightless moa. The biggest moa could weigh up to 200 kilograms (440 pounds). Haast's eagle became extinct around the year 1445 after the arrival of the Māori. The Māori hunted moa to extinction, introduced the Polynesian rat (Rattus exulans), and burned large areas of forest, which led to the eagle's disappearance.

Taxonomy

Haast's eagle was first studied by scientist Julius von Haast in 1871 using remains found by Frederick Richardson Fuller, a taxidermist at the Canterbury Museum, in a former marsh. Haast named the eagle Harpagornis moorei after George Henry Moore, who owned the Glenmark Estate where the bones were discovered. The genus name Harpagornis comes from the Greek word harpax, meaning "grappling hook," and ornis, meaning "bird." In a 2025 article, biologist Richard Holdaway stated he introduced the common name "Haast's eagle" in the 1990s but later suggested the name "Fuller's eagle" to honor the bird's actual discoverer.

DNA analysis later showed that this bird is most closely related to the smaller little eagle (Hieraaetus morphnoides) and the booted eagle (Hieraaetus pennatus), not the large wedge-tailed eagle (Aquila audax) as previously believed. Because of this, Harpagornis moorei was reclassified as Hieraaetus moorei.

H. moorei is estimated to have separated from these smaller eagles as recently as 1.8 million to 700,000 years ago. If this is correct, its increase in weight by 10 to 15 times would represent the fastest and largest average weight increase of any known vertebrate species. This change likely occurred because of the availability of large prey and the lack of competition from other large predators, a phenomenon called ecological release and island gigantism. A recent mitochondrial DNA study found H. moorei to be more closely related to the little eagle than the booted eagle, with a divergence from the little eagle around 2.2 million years ago. Recent taxonomists have placed it in the genus Aquila.

Description

Haast's eagle was one of the largest true raptors known to science. In size, it was larger than the Andean condor, the largest living vulture. Another large bird, called Woodward's eagle, found in North America, was nearly as long as Haast's eagle. Female Haast's eagles were bigger than males. Most estimates say female Haast's eagles weighed between 10–18 kg (22–40 lb), while males weighed about 9–12 kg (20–26 lb). Comparisons with living eagles in the Australasian region suggest male Haast's eagles weighed around 11.5 kg (25 lb) and females around 14 kg (31 lb). Some sources suggest the largest females might have weighed more than 16.5 kg (36 lb). Modern eagles, which are not known to weigh more than 9 kg (20 lb) in the wild, are about 40% smaller than Haast's eagles.

Haast's eagle had a wingspan that was shorter for its size. Female Haast's eagles likely had a wingspan of up to 2.6 m (8 ft 6 in), possibly as much as 3 m (10 ft) in rare cases. This wingspan is similar to the largest female eagles alive today, such as the wedge-tailed eagle, golden eagle, martial eagle, white-tailed eagle, and Steller's sea eagle. Some large vultures in the Old World may also have had similar average wingspans. Haast's eagle’s short wings were not a sign of flightlessness, as evidence shows it could fly. Instead, its wings were adapted for moving through dense forests, unlike the soaring flight of its ancestors. Haast's eagles likely hunted in New Zealand’s forests, similar to other forest-dwelling raptors like goshawks or harpy eagles.

Fossils of Haast's eagle wings and legs allow scientists to compare it with living eagles. The harpy eagle, Philippine eagle, and Steller's sea eagle are today’s largest and strongest eagles. The harpy and Philippine eagles also have shorter wings, an adaptation for living in forests. A lower jaw bone of Haast's eagle measured 11.4 cm (4.5 in), and its foot bones measured between 13.7–16.2 cm (5.4–6.4 in). In comparison, the largest beaks of living eagles are less than 7 cm (3 in), and the longest foot bones of living eagles are about 14 cm (5.5 in).

Haast's eagle had talons similar in length to the harpy eagle. The front-left talon measured 4.9–6.15 cm (1.96–2.42 in), and the hallux-claw (the largest claw) could have been up to 11 cm (4.5 in). The Philippine eagle is a good modern comparison because it also evolved to be large on an island with no large predators. Haast's eagle’s talons suggest it hunted, not scavenged. Its strong legs and large flight muscles allowed it to jump from the ground to take off, despite its weight. Its tail was long, over 50 cm (20 in) in females, and very broad, helping it fly despite its short wings. Female Haast's eagles were estimated to be up to 1.4 m (4 ft 7 in) long and about 90 cm (2 ft 11 in) tall.

Māori cave art from South Canterbury near Timaru shows Haast's eagle with a pale head. This, along with its vulture-like feeding habits, suggests it may have had a bald head or shorter feathers on its head compared to the rest of its body.

Behaviour and ecology

Haast's eagle mainly hunted large, flightless birds, such as the moa, which eventually caused the moa's extinction. The moa could weigh up to fifteen times more than the eagle. Its large beak could tear into the internal organs of its prey, causing death from blood loss. Because there were no other large predators or animals that steal food, a Haast's eagle could control a single large kill for several days. The moa could weigh up to 200 kg (440 lb).

A 2021 study found that, although Haast's eagle was a predator, its beak functioned more like that of the Andean condor (Vultur gryphus) than other eagles. This is also shown in historic Māori cave art, which depicts Haast's eagle with a pale head. The art suggests the eagle used feeding methods similar to vultures after killing prey, such as inserting its head into the body cavity to eat vital organs. This may have been a way to adapt to hunting animals much larger than itself.

Extinction

Before humans arrived and brought animals like rodents and cats, the only placental land mammals in New Zealand were three types of bats. Birds filled most important roles in the animal life of New Zealand. Moa were large, plant-eating animals that worked in a similar way to deer or cattle in other places. Haast's eagles were the top hunters, taking the same role as the largest predators in other ecosystems.

One study found that Haast's eagles had between 3,000 and 4,500 breeding pairs. Early Māori people arrived in New Zealand between AD 1250 and AD 1275. The Māori hunted many large flightless birds, including all species of moa. This hunting caused the moa to go extinct by about 1440 to 1445. Both eagles and Māori likely hunted the same animals. Unlike humans, who could adapt to different food sources, eagles focused on hunting medium and large flightless birds. When these birds disappeared, Haast's eagles also became extinct around the same time.

Relationship with humans

Some people think these birds are mentioned in stories from Māori mythology, where they are called pouākai, Hakawai (or Hōkioi in the North Island). According to a story shared with George Grey, an early leader of New Zealand, Hōkioi were large black-and-white birds with yellow-green colored wings and a red head crest. In Māori stories, Pouākai were said to hunt and kill humans and moa. Scientists think this might have been possible if the name refers to the eagle, because eagles are very large and strong. However, others argue that the "Hakawai" and "Hōkioi" stories might describe the Austral snipe, especially the extinct South Island type. It has also been suggested that pouākai likely does not refer to Haast's eagle, because this bird is not known to have lived in the North Island.

In popular culture

Artwork showing Haast's eagle can now be seen at OceanaGold's Heritage and Art Park in Macraes, Otago, New Zealand. The sculpture, which weighs about 750 kg (1,650 lb), stands 7.5 metres (25 ft) tall, and has a wing span of 11.5 metres (38 ft), is made from stainless steel tubes and sheets. It was designed and built by Mark Hill, a sculptor from Arrowtown, New Zealand. Haast's eagle was also featured in a 2003 BBC documentary titled Monsters We Met.

There is also a statue showing Haast's eagle in Karamea, West Coast. This statue was unveiled by the local community and the Ngāti Waewae iwi.