This is a video about the evolution of birds in New Zealand.
From New Scientist:
Monsters of the skies: giant beasts that ruled the air
17:40 30 September 2009
Recently, researchers concluded that a huge eagle that once haunted New Zealand’s forests was a fierce predator that may have hunted humans – Anna Davison rounds up other ancient airborne behemoths
Haast’s huge eagles, Harpagornis moorei
* Wingspan: 3 metres
* Found in New Zealand until about 500 years ago
* Related to modern-day eagles
New Zealand never had many native land mammals – no tigers, wolves, or other predatory mammals – just a few diminutive bats. Before humans arrived, its forests bustled with birds, and the enormous Haast’s Eagle once ruled them all.
Its wingspan of 3 m wasn’t a big stretch, but at 18 kg (40 lbs), Haast’s Eagle was a good deal heavier than any eagle alive today, making it the largest that ever lived.
The New Scientist article continues with giant flying reptiles, called Azhdarchids; the big extinct bird Argentavis magnificens; the largest known insect, Meganeuropsis permiana, which resembled a dragonfly, had a wingspan of more than 70 cm and weighed as much as a crow; and Dasornis emuinus, wingspan: 5 metres, found in England during the Lower Eocene, about 50 million years ago, related to modern-day ducks and geese.