Strigops habroptila - The Kakapo
Kakapos have the smallest relative wing size of any parrot, and are also the heaviest parrots out there. Unlike other ground-dwelling birds, they actually have the ability to store fat for future use, and this has given them a quite rotund shape overall. Even in lean times, the kakapo is a huge bird, and did quite well for itself before humans arrived. Even before European colonists landed on the South Island of New Zealand, the native Maori used kakapo feathers (which are incredibly soft, as they don’t need to sustain flight) and kakapo meat at a rate that was unsustainable for a continuing population. However, the rate of decline during that period was relatively slow - though the kakapo would have eventually been hunted out, it was not in any immediate threat.
Unfortunately for the great owl parrot, their musky smell and lack of defenses made them easy targets for newly introduced predators and hunters, and the population crashed so quickly that the Kakapo was one of the first animals to have a conservation plan put into place to try and stop the decimation of the masses. Though the conservation plans helped keep the birds safe from humans, the introduced dogs, cats, ferrets, and rats, all continued to wreak havoc.
Today, there are only 127 living kakapos, and their continued survival is far from assured. Their evolutionary history and unique physiology and behavior (not to mention their very important cultural position in Ngai Tahu society) make their possible extinction that much more important to try and prevent.
A History of the Birds of New Zealand. W.L. Buller, 1888.