Human arrival in an area is typically followed by extinction in the native avifauna, so lowering local (and often global) bird diversity. The exact causes of these extinctions have been vigorously debated, but likely drivers include hunting by humans, habitat destruction, and hunting by introduced predators. I will show how data from New Zealand help us to understand the causes of extinction in island avifaunas. I will then expand the frame of reference, presenting data from other islands to assess the extent to which some of the conclusions from New Zealand might apply to oceanic islands more generally.