New Zealand's isolation for millenia has led to many animals that are found nowhere else on Earth. There were no ground dwelling mammals and so the natural world was domminated by insects and birds. A third of native birds are also flightless.
Since the arrival of humans about 1000 years ago, New Zealand fauna has had to adapt to preditory mammals that have been introduced. This has resulted in the extinction of many bird species while a good deal more are endangered.
Today, there are a number of reserves on pest-free islands that have breeding programs designed to bring the population of many of these birds back to healthy levels. But a number of New Zealand species have thrived without intervention and have even adapted well to urbanisation.