One of the reasons the kakapo is so endangered is it's defenselessness. For thousands of years, it has lived in a mammal-less environment. It's main predators were great eagles and other birds that relied on sight to hunt. Over time, it flied less and less, and ate more and more, and stayed on the ground more, and eventually ended up as a fat, flightless parrot. It's only defense mechanism is to freeze and use camoflauge to blend into its environment. Although this strategy worked well with its bird predators, it didn't work with mammals, who hunted by scent. The mammals were introduced to the areas where the kakapos lived by Europeans. Another reason is that the kakapo is supposedly very good for eating. The Maori people, as well as Europeans, ate and hunted the kakapo into near extinction.