I believe that the problem goes back to the desire to erradicate a type of
snake that was either native or accidentally introduced (I can't remember
which). The mongoose was brought in to get rid of the snakes (which it did
quite well). I believe that the snakes had the most damaging effect on the
native bird population, then the mongoose did a significant amount of
damage. Escaped or released birds probably can take some of the blame too!
Cats were one of the lesser impacts!
Scott