[shadowgovt]

Over 20 species, so causes are as varied as the species.

In several cases, it was a combination of human activity and (relatively) fragile initial population conditions. 11 of the species are native to Hawaii and Guam, and when human expansion puts pressure on your ecosystem, there's nowhere to move to. One of the fish species lived in one particularly slow-flowing section of one river.

When your whole universe is one island, there's a lot of things humans can do that would render 100% of your habitat unusable.

[daveslash]

Yeah, I agree. To add onto your sentiment that it was a combination [of things]... I'd like to add that it's a bit reductionist for people to suggest an extinction is one thing (e.g. it was pesticides, it was climate change, etc...). Sure, sometimes it might be ONE thing, but I would guess that in most cases it's a combination of stresses coming together.