Mick Hartley

New Zealand offered surely one of the most remarkable studies in evolution [said in the voice of David Attenborough]. When the first Maoris arrived some 800-odd years ago, there were only birds. Lots and lots of birds, evolved for every ecological niche. Huge big flightless birds – moas – as the equivalent of the big mammalian herbivores found everywhere else, and enormous birds of prey to feed on them. Because it was too isolated for any other life to get there – until man, and all the other animals that came in his wake. 

With a wingspan of up to three metres and weighing 18kg, the female was twice as big as the largest living eagle, the Steller's sea eagle.

And the bird's talons were as big as a tiger's claws.

"It was certainly capable of swooping down and taking a child," said Paul Scofield, the curator of vertebrate zoology at the Canterbury Museum.

"They had the ability to not only strike with their talons but to close the talons and put them through quite solid objects such as a pelvis. It was designed as a killing machine."

Its main prey would have been moa, flightless birds which grew to as much as 250kg and 2.5 metres tall.

"In some fossil sites, moa bones have been found with signs of eagle predation," Dr Scofield said.

New Zealand has no native land mammals because it became isolated from other continents in the Cretaceous, more than 65 million years ago.

As a result, birds filled niches usually populated by large mammals such as deer and cattle.

"Haast's eagle wasn't just the equivalent of a giant predatory bird," said Dr Scofield. "It was the equivalent of a lion."

[Via]