Alas the giant eagles that spirited Gandalf from Sauroman's tower have been exterminated:
"With a truncated wingspan of around three metres, for flying under the forest canopy, the eagles struck their prey from the side, tearing into the pelvic flesh and gripping the bone with claws the size of a tiger's paw.
Truthfully, the blame lies squarely with the Maoris who raped the forests before the Pakeha arrived. Pakeha (White men) proceeded to rape everything else - and many species of birdlife then went extinct too. Mostly this was due to the European Rat - rather than habitat destruction.
The Maoris made a point of hunting the Moa to extinction: the world's largest bird ever was too tasty, and too stupid to avoid that fate. Sad, because a barbequed Moa leg would have been something else!
There's an eagle skull in the local museum, it's about 11 inches long from memory, and the model next to it has a wing span of nearly 5 metres - truly an impressive looking beast.
We know for a fact that the eagle preyed on fully grown Moa, because skeleton's of Moa previously found sometimes show eagle talon damage in the backbone and pelvic area.
Well according to the page, this bird was extinct 200 years before the Maori arrived. Anyway, what did they know about ecology and conservation back then? Us Europeans seem to know an awful lot about boogering up the environment anyway...
Not a lot of it, and most animals don't have habits of spending long stretches of time in the mountains.
As for bringing them back, it's theoretically possible, I suppose, if you have enough intact DNA to work from. Unfortunately long-extinct creatures such as the moa probably don't.
In future it may be possible to piece together a complete genome from fragments, but it'll be a little while before it's practical to process such huge volumes of data.